RESEARCH AND DEVELOPMENT OF STEELHEAD TROUT Oncorhynchus mykiss AQUACULTURE IN SEA CAGES BY MICHAEL DAVID CHAMBERS B.S., University of Wisconsin, 1985 M.S., Texas A&M University, 1994 DISSERTATION Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Zoology December, 2013
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RESEARCH AND DEVELOPMENT OF STEELHEAD TROUT Oncorhynchus mykiss
AQUACULTURE IN SEA CAGES
BY
MICHAEL DAVID CHAMBERS
B.S., University of Wisconsin, 1985
M.S., Texas A&M University, 1994
DISSERTATION
Submitted to the University of New Hampshire
in Partial Fulfillment of
the Requirements for the Degree of
Doctor of Philosophy
in
Zoology
December, 2013
UMI Number: 3579692
All rights reserved
INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted.
In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed,
a note will indicate the deletion.
UMIDissertation PiiblishMig
UMI 3579692Published by ProQuest LLC 2014. Copyright in the Dissertation held by the Author.
Hampshire field trial were small (0.78 m3) and in close proximity for replicate purposes
and may not illustrate commercial significance. Setting of the experiment under a pier
and with a new aquaculture species (cod) may not have been the best scenario for this
study. Bacterial infection played a major part in the survival of the cod juveniles despite
their continued growth. Future studies are warranted to reveal benefits and drawbacks of
copper netting in aquaculture.
17
Table 1.1. Growth performance of cod in nylon and copper cages. Means are ± SE. Unpaired T-tests showed no significant differences (P > 0.05) in any of the measured variables between cage types.______________________________________________
Figure 1.1. Floating raft with six net pens under the UNH pier (A). Copper net pen stocked with 200, 29 g cod with auto feeder (B).
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140
100
80
Nylon net
Copper net
April'10 May '10 June’10 July'10 Aug *10
Figure 1.2. Mean weight gain (±SE) of Atlantic cod cultured in nylon and copper nets. Mean weights from replicates in each treatment were not significantly different (Kruskal- Wallis tests, P>0.05) so all replicate weights within treatment were combined. There was no significant difference in mean weight (Unpaired t-test with Welch correction, P>0.05) between fish raised in the copper alloy and Flexgard™ treated nylon cages.
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Figure 1.3. Mean total bio-foul weight (± SE) from each cage at the termination of the experiment. Bio-foul weight on the copper pens was significantly less (16.2 ± 1.70 kg) than the bio-foul weight on the nylon pens (22.8 ± 1.54 kg) (Unpaired T-test, P < 0.05).
21
M uscle Liver
Tissue
Figure 1.4. Chemical analysis conducted on cod muscle, liver and gill from the control, (nylon nets with Flexgard™ paint) and the treatment (copper Seawire pens). Unpaired t- tests, with Welch corrections, were used to compare the two, and there was no significant difference (P > 0.05) in ppm copper between fish from the 2 cage types in muscle (P = 0.68), gills (P = 0.47) or livers (P = 0.52).
22
CHAPTER n
FIELD MEASUREMENTS OF STEELHEAD TROUT Oncorhynchus mykiss
DISTRIBUTION, SWIMMING BEHAVIOR AND RESPONSE TO WATER
CURRENT EXPOSURE IN A SEA CAGE
Abstract
This study introduces a new way to measure the distribution and behavior of
steelhead trout in a sea cage in response to fluctuating tidal currents that deform the net.
Strong currents can significantly decrease the volume of net constraining fish to a
condensed area. An ultrasonic telemetry system (Hydroacoustic Technology Inc., model
291) was deployed around a 63 m3 sea cage stocked with 200 steelhead trout
(Oncorhynchus mykiss). Fish and cage movement were monitored using ultrasonic tags
implanted into the abdominal cavities of 8 sentinel trout, 12 more were attached around
the net bottom and midsection. The signals were detected by four omni-directional
hydrophones that were connected to a receiver on a nearby pier. Signals detected at 2
second intervals were used to plot 3 dimensional locations of both the fish and net. We
found that current flow inside the net was significantly reduced (32-53%) compared to
outside and that swimming behavior was influenced by tidal currents. As current speed
increased, the positions of fish became more restricted because they were swimming into
the current to maintain their position. In contrast, during slack tides, fish exhibited typical
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schooling behavior and swam in a circular pattern. This study demonstrates the use of
acoustic telemetry on a small scale cage. This technology can be applied to a commercial
scale farm to improve fish welfare and cage design.
Introduction
Since the mid-1990s, aquaculture has been primarily responsible for the growth in
global fish production as capture production has leveled off. Its contribution to total
world fish supply climbed steadily from 20.9 percent in 1995 to 40.3 percent in 2010
(FAO 2012). Most marine aquaculture takes place in near shore waters that provide
protection from storms and easy access to the farms. However, these waters are prone to
user conflicts from traditional fishermen, commercial traffic, and recreational boaters.
Resistance also comes from seashore abutters who worry about their view-scape. Finally,
runoff from land can create unfavorable conditions for raising healthy fish. Moving
aquaculture production offshore into deeper, more energetic, waters alleviates some of
the above issues. However, moving into more exposed areas increases risk and operating
expenses, decreases days at sea to tend the farm, and creates technical challenges with
infrastructure.
Understanding high energy environments is essential to the biological
requirements of a marine fish. In ocean cage culture, fish are often exposed to more
intense physical and environmental perturbations (Oppedal, et el. 2010), which can lead
to increases in metabolism and thus reduced growth and even mortality. Stress responses
in farmed fish have been shown to result from environmental disturbances, farming
operations or high stocking densities (Begout & Lagardere 1993; Cooke et al., 2000;
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Begout & Lagardere, 2004; Chandroo et al., 2005). Measuring and understanding these
stressors can help farmers improve their operations, increase production efficiency and
optimize fish welfare. When changes occur in a cage environment, natural defense
mechanisms, such as net avoidance behavior, take effect. These behaviors have evolved
to lessen the probability of death, to mitigate the higher metabolic costs incurred by
increased swimming, and / or to maintain physiological homeostasis (Olla et al. 1980,
Schreck et at. 1997).
Fish distribution within a net pen is affected by an array of parameters such as
temperature, feeding and light (Oppedal et al., 2001; Oppedal et al., 2007; Oppedal et al.,
2010). Distribution can also be effected indirectly by bio-fouling, since bio-fouling
increases net resistance to currents, which results in cage deformation and changes in
geometry (Lader et al., 2008; Braithwaithe et al, 2007; Swift et al., 2006; DeCew et al.,
2013; Ward et al., 2012). As cage culture moves further offshore into deeper waters,
larger nets can be used allowing fish to distribute into preferred areas within the cage
environment, e.g. above or below thermoclines, zones of higher oxygen, preferred light
levels and escapement from storm surge. Recent technological advances have made it
possible to investigate how individual fish, as well as groups of fish, respond to the
aforementioned parameters. For example, Rillahan et al. (2009, 2011) studied the
behavior of Atlantic cod in an offshore (12 km) submerged, bi-conical cage (Sea
Station™). They found that cod exhibited clear diurnal rhythms, with the highest
swimming activity during daytime hours. Analysis of cage utilization revealed that cod
did not use the entire cage volume, and that individual space use was limited to small
overlapping areas within the bottom half of the net. When the density of cod reached high
25
levels, as they grew, their typical diurnal pattern of independent swimming changed to
schooling behavior with no significant difference in day and night activity. Ward et al.
(2012) studied cod behavior in near shore, rectangular floating cages at stocking densities
ranging from 5-45 kg / m3). He found that at the lowest density the cod spent the majority
(~ 64%) of their time in the bottom third of the net pen. Then, as density increased, the
fish moved higher in the water column, and this behavior was most evident at night, at all
densities. At no time during the study were there any obvious occurrences of schooling
behavior, even at the highest density. Both of these studies illustrated the usefulness of
high resolution biotelemetry for continuously monitoring the behavior of cultured fish
under a variety of circumstances, and demonstrating how fish interact with each other and
the cage.
While investigations over the past 20 years have revealed a great deal about how
fish behave in net pens in calm to moderate conditions, little is known about how both the
nets, and the fish inside the nets, respond during the intermittent storm events that are
fairly typical for exposed offshore cages. During these storms the waves and currents
increase and net deformation is likely, which may, or may not, lead to alterations in the
normal behavior of the fish. One of the goals of this study was to determine if acoustic
telemetry could be used, as a tool, to monitor both the deformation of the net, and the
movements of the fish, in a net pen exposed to stronger than normal currents. We used a
63 m3 net pen moored at the mouth of a large estuary where tidal current were strong
enough to deform the net pen.
The test species was the steelhead trout (Oncorhynchus mykiss), that is
commercially grown in near shore, protected waters in Chile, Norway, Faroe Islands,
26
Canada, and to a limited extent in the USA (states of Washington and New Hampshire).
Despite its advantages as a species for aquaculture, very little is known about its behavior
in an aquaculture setting. Therefore, by using steelhead trout, we were able to gain
valuable information about this species, as well as data relevant to the response of fish to
strong currents and the resulting deformation of the net pen in which they resided.
Methods and Materials
A 63 m3 net pen was stocked with 200 steelhead trout (Oncorhynchus mykiss),
(Mean (± SD) fish weight 571.7 ± 170.8 g, length 35.6 ± 2.8 cm). Initial stocking density
was 1.8 kg / m3. A Hydroacoustic Technology Inc. acoustic telemetry system (HTI -
http://www.htisonar.com/), similar to the one used by Rillahan et al. (2009, 2011) and
Ward et al. (2012) to study cod behavior, was used to track fish behavior and net
deformation. Eight model 795Z transmitters were surgically implanted into the
abdominal cavity of individual fish to track their temporal and spatial distribution.
Twelve more transmitters were attached around the net (8-middle, 4-bottom) to monitor
the position of the net and deformation caused by tidal currents. Four hydrophones
hardwired to a receiver (Model 291), were used to monitor the positions of transmitters,
in three dimensions, using a suite of HTI programs. Transmitters in the fish and net
“pinged” every 1-3 seconds and theses acoustical signals were detected by each of the
hydrophones. These data were then used to calculate and plot the position of each
transmitter with a resolution of ~ 10 cm, every 2-5 seconds. Stored data were used to
determine the distribution and swimming activity of the fish and movements of the net.
The study was conducted at the UNH Judd Gregg Pier Facility on Fort Point, New
Castle, NH, USA at the mouth of the Piscataqua River (Fig. 1). The telemetry receiver,
computer and video monitoring system were located in a small building at the end of the
pier adjacent to the experimental cage. The test cage was moored between two mooring
blocks (4 ton ea.) approximately 30 m from the end of the pier in a water depth of 8 m.
The site experienced 2 ebb and 2 flood cycles per day, with tidal amplitude ranging from
3-3.5 m.
Case design
The sea cage was constructed of two, 15 m circumference (10 cm dia.) high-
density polyethylene (HDPE) pipe that were bent into a ring and fused. One ring was
attached to the top of a 63 m3 cylindrical net measuring 4.6 m in diameter and 4 m in
depth. The second ring (sinker tube) was drilled with 1.25 cm holes and wrapped with a
1.25 cm dia. chain before attaching to the net bottom. The nylon net was made from a 2
mm twine and had a 2.5 x 2.5 cm knotless square mesh that was coated with a cuprous
oxide antifouling paint (Flexguard™). The HDPE rings and net were suspended from a 5
x 5 m floating platform (Fig. 2).
Environmental data collection
An Acoustic Data Current Profiler (ADCP) deployed on the ocean bottom (10 m
from the cage) recorded ambient water velocities and direction at 0.5 s intervals. A
Modular Acoustic Velocity Sensor (MAVS) suspended in the center of the cage 2 m
below surface measured water velocity every 1.0 seconds. Both current meters averaged
and stored data in 5 min bins. Additional environmental data (temperature, dissolved
28
oxygen, salinity, pH, tidal amplitude and turbidity) was collected by an YSI 6600 V2-2
Water Quality Sonde located at the end of the pier adjacent to the cage site (Table 1).
Telemetry set u p
The HTI model 291 telemetry-system (Hydroacoustic Technologies Inc., Seattle,
WA) utilizes four omni-directional hydrophones hardwired to a receiver to monitor the
positions of acoustic transmitters, in three dimensions, using a suite of HTI programs.
The hydrophones were mounted on aluminum posts (5 cm dia.) bolted to the comers of
the float platform, around the net. Two opposing hydrophones were set at a depth of 0.65
m, while the other two opposing hydrophones were at set at a depth of 2.5 m (Fig. 2).
Cabling for the hydrophones was integrated into a mooring line that ran to an
instrumentation shed on the pier. Hydrophones were hard-wired directly to a receiver,
and signals from each tag were transferred to a CPU for storage and analyses. Three-
dimensional positions of sentinel fish and selected points on the net pen were calculated
with a 10 cm resolution, every 2.0 seconds. HTI software was later used to display these
data in near real time (~ 1 minute delay) and also stored as raw data for future analyses.
These stored data points were subsequently processed to eliminate spurious detections
and thus improve the resolution and accuracy of the data. Values were calculated using
the methods previously described by Rillahan et al. (2009, 2011) and Ward et al. (2012).
The data were used to reveal the mean distribution and swimming speed of sentinel fish,
and changes in net geometry. Additional processing was conducted in Matlab and Excel,
data were imported into Tecplot for 3D visualization.
Net Transmitters
29
HTI model 795Z acoustic transmitters were used to monitor the position of the
net. Twelve tags were attached around the net (8-middle, 4-bottom) to monitor the
position of the net and deformation caused by tidal currents (Fig. 2). To isolate individual
transmitters from ambient noise and other transmitters, each was programmed to ping
with a unique inter-pulse interval, ranging from 2,000-3,100 ms. During post-processing,
data from repetitive signals were dissociated from background noise and then assigned to
the individual transmitters, allowing continuous and rapid sampling of multiple
transmitters.
Fish Transmitters
Approximately 200 steelhead trout were transferred from a local hatchery to the
UNH Pier Facility (New Castle, NH) in 1 ton insulated boxes filled with freshwater. The
trout were acclimated from freshwater to seawater (28 ppt.) over a 2 hr. period, and then
netted into the sea cage. Model 795Z transmitters were surgically implanted into the
abdominal cavities of eight individual fish to track their temporal and spatial distribution.
Prior to implanting, each tag was programmed to ping at inter-pulse intervals ranging
between 1100-1800 ms. Trout were anesthetized with tricaine methanesulfonate (MS222)
and the 2.5 x 0.8 cm tags were inserted intraperitonally through a 2 cm incision (Fig. 3) in
the abdominal wall. One suture was used to close the incision, and an external streamer
tag was placed into the dorsal musculature of the fish. The trout were then allowed to
recover for 30 min. before placement in the experimental sea cage. One week later, the
experiment was initiated. During this time, the HTI system was activated and calibrated.
30
To test the possible effect of the surgery and tags on the trout, nine fish were
randomly netted from the cage and transferred to a 2 m diameter x 1 m deep tank in the
UNH Coastal Marine laboratory. Three fish were surgically implanted with a ‘dummy’
tag (same as normal tags, but did not ping), three had surgery but had no ‘dummy’ tag
implanted, and the remaining three fish had no surgery. Fish were observed for tag
retention, initial weight and length verses final, and survival for one month. No difference
was observed between fish with and without tags.
Data processing and statistics
Net transmitters
Net deformation was estimated by determining the differences in net transmitter
(12) locations during slack, intermediate and fast tidal cycles. Changes in net volume
were calculated using scalar triple product, divergence and signed volume methods.
These volumetric calculations are summarized in DeCew et al. 2013.
Fish transmitters
The location of all the pingers was represented by X, Y, Z coordinates that were
calculated with the same frame of reference. Thus, fish could be localized with respect to
each other and with respect to the net. The mean positions of all tagged fish, during each
sampling period were used to calculate mean positions of individuals and groups of fish
during fast and slow current velocities and during night and day within the net pen.
Instantaneous swimming speeds were calculated by taking the square root of the sum of
the three-dimensional (X, Y, Z) distances the fish travelled during a time interval (ti to
t2), and dividing this by the length of the time interval (t2-ti).
31
V (((X2-X,)2) + ((Yr Y.)2) + ((ZrZ,)2)) / (t2-ti)
Mean swimming speeds were calculated during fast and slow current speeds, and
during the night (0200-0300 h) and day (1400-1500 h). Calculations were based on the
positions of the fish relative to the hydrophone array in a steady current, and thus do not
take into account for different ambient current speeds. An unpaired t-test was used to
compare day and night swimming speed (BL / s) of the same seven fish on June 18, 2010.
Linear regression analysis was used to examine the relationship between current speed
within the net pen and swimming speed.
Differences in fish depth were compared across six 1 hour time periods over 24
hours. The positions of fish were averaged individually, and as a group, to obtain a mean
depth estimate per sample period. In order to calculate the amount of the total cage
volume that was occupied by the fish at any given time (cage utilization) we used the
technique developed by Rillahan et al. (2011). First, we created a three dimensional
matrix (10m x 10m x 10m) that encompassed the cage, with grid spacing every 0.2 m in
the X, Y and Z axes dividing the net pen into 0.2 m3 units. Fish positional data was then
overlaid onto the grid and presence/absence was determined for each grid unit. Cage
volume use was then calculated by summing the total grid units utilized by a fish over the
sample period.
A combination of software programs was used to visualize and plot the
movements and positions of fish within the cage. Python Visual Studio 2.0 Alpha was
used to develop wire frame diagrams of the cage during the different tidal and current
episodes. These diagrams were then imported into TecPlot (Version 10) and fish tracks
32
were overlaid in the wire frame to show their movements relative to the modeled cage
environment.
Results
Environmental
Current flow at the study site was bidirectional, with the predominate flow along
the NW-SE vector which coincided with the direction of tidal flow into, and out of, the
river. Current direction was SE (mean 114°) during much of the tidal cycle due to local
bathymetry and eddies. Flow towards the W and NW was relatively slow (0.12 m/s), and
seen only briefly (about 1 hour), about two hours after slack low tide. Currents were
fastest (average 0.24 m/s) on the ebb tides (SE direction). Current speeds outside the net
(ADCP) reached 0.50 m/s during the ebb tide on June 18, 2010. However, current
velocities inside the cage (MAV) were reduced on average by 31% with a high of
approximately 50% (DeCew, et al. 2013). This current reduction was influenced by the
net twine diameter (2 mm) and fouling organisms that accumulated on the net (Fig. 4).
These field results are higher than tank tests (10-20%) conducted by Aames et al. (1990),
Fredheim (2005), and Patursson (2008).
Net Deformation
Net deformation was estimated by determining the differences in net tag (12) locations
during slack, intermediate and fast tidal cycles. Three methods were used to calculate
changes in net volume and included the scalar triple product method, divergence method
and the signed volume method. These volumetric calculations, and complete results, are
summarized in DeCew et al. 2013.
33
Fish Swimming Behavior and Distribution
Visual diagrams of the net pen illustrate individual (Fig. 5 a, b), group (Fig. 5 c,
d) and density plots (Fig. 6) of the trout tracked horizontally and vertically. This allowed
for 1 hour visual examinations in on June 17 and 18th on low and high current flows.
There were no significant differences (unpaired t-test, P > 0.05) in fish positions relative
to the net walls and bottom during high and low currents, or during night and day
intervals (Table 2).
Fish were more clustered together during periods with fast current speeds (Fig. 6
a, b), and less clustered during periods with slow current speeds (Fig. 6 c, d). This
influence of current speed was also manifested in terms of cage utilization. The fish
utilized less of the net volume (6.71 m3) during high currents (Fig. 6 a, b) and utilized
more net space during slow currents (14.2 m3), (Fig. 6 c, d).
Mean swimming speeds ranged from ~ 0 - 0.6 BL/s, varied between individuals,
varied over time for any given individual, and were negatively correlated with current
speed. Swimming speeds were faster during low currents and slower during high
currents (Fig. 7). Swimming speed decreased with increasing current speed because the
fish displayed rheotaxis, and simply held their position against the current. Because
current speed affected swimming speed, for day/night comparison of swimming speed,
we used data sets collected during different times of the day, but which had similar
current speeds. The comparison was made using data collected from the same four fish at
night on June 17 (0200-0300h) and during the day on June 26 (1100-1200h). Current
speeds were similar in the two time intervals (0.19 and 0.16 m/s day and night,
34
respectively). There was no significant difference (unpaired t-test, P=0.53) between
mean day (0.178 BL/s) and night (0.178 BL/s) swimming speeds (Fig. 8).
Mean (±SD) swimming depth, based on the same fish sampled during the
indicated time intervals in Table 2 ranged from 2-3 m, and did not differ over time
(ANOVA, p=0.82).
Discussion
The HTI biotelemetry system is a powerful acoustical tracking instrument that
holds promise for monitoring fish and net movement in real time. The UNH pilot scale
cage served well to evaluate the usefulness of the HTI system on a sea cage with
steelhead trout. Acoustic biotelemetry systems have been used in the past to monitor fish
movement (Bjordal et al., 1986; Floen et al., 1988; Kils, 1989; Juell et al., 1993; Begout
Anras & Lagadere, 2004; Rillahan et al., 2009, 2011) however they have not been used to
measure fish distribution relative to net deformation. In this study we examined how the
fish reacted to changes in the net environment during high and low tidal cycles, with
associated high and low currents. This and our companion study (DeCew et al. 2013)
revealed that nets did deform at high current speeds, which reduced the cage volume and
forced fish to reposition themselves. As expected, the trout tended to swim into the
current when it flowed at a high speed, and thus their position in the net pen was guided
by their reactions to both the current speed and direction, and net deformation. Current
flow inside the net was significantly reduced (32-53%) compared to outside current
velocities. We suspect volume deformation, at a given current speed, was even greater
with the addition of fouling communities over time. These results were similar to those
35
reported by Lader et al. (2008), who measured net volume reduction at two farms in
Norway, and reported that at one site, a current of 0.13 m / s resulted in 20% loss in cage
volume. At the other site, a current speed of 0.35 m / s caused a 40% net volume
reduction.
In contrast to steelhead trout, numerous studies have been conducted on Atlantic
salmon swimming behavior in larger sea cages (Sutterlin et al., 1979; Juell et al., 1993;
Magurran, 1993; Juell, 1995; Johansson et al., 2009; F0re et al, 2009; Oppedal et al.,
2011). Because of their larger volumes and depths, larger cages often have temperature,
salinity, oxygen, current speed and light gradients (Juell, 1995; Juell & Fosseidengen,
2004; Johansson et al., 2006, 2007; Oppedal et al., 2007), all of which can affect the
distribution and movements of the fish. Interactions between individuals, and the net
walls, also influence the behavior of the group (Fore et al., 2009). In general, fish occupy
areas where the suite of environmental conditions are optimal, and avoid the net walls.
Such gradients, and choices, were not present in our small cage, so it seems unlikely that
variables such as temperature, salinity, or dissolved oxygen affected our results. We did
observe positive rheotaxis (Dodson & Mayfield 1979), at high current speeds, and more
circular swimming patterns at slower speeds, which is similar to the observations of
Atlantic salmon (Kils, 1989; Pitcher et al., 1993; F0re et al., 2009). It has been shown that
in natural streams, orientation, depth, and area occupied by trout can change with current
speed (Pert & Erman, 1994). When current speeds were > 0.2 m/s, the trout generally
swam into the current and occasionally some would change direction and orient tail to the
current before circling back.
36
We found no significant differences between night and day swimming depths.
These results differ from those described by Cubitt et al. (2005), Johansson et al. (2006,
2007, 2009), Dempster, et al. (2008), and Korsoen et al. (2009). In those studies, Atlantic
salmon swimming depths appeared to be controlled by changes in light intensity. Salmon
descended at dawn, stayed deeper during the day, and then ascended at dusk to swim
closer to the surface. Our differing results were probably due to our small volume (63
m3), and shallow depth (4 m) sea cage, which may well have restricted normal diurnal
rhythms. Moreover, if the daily vertical migration is associated with light, the light levels
between the top and bottom of our small net pen only differed by a small amount. As
with Huse et al. (1993), Juell et al. (1995), and Femo et al. (1995) the fish avoided the net
sides and bottom as an anti-collision behavior.
Mean swimming speeds of the trout ranged from - 0 - 0.6 BL/s, which is similar
to the range seen in Atlantic salmon held in net pens (Oppedahl et al. 2011). The activity
of rainbow trout (mean weight 254 g), measured as average hourly distance traveled, was
reported by Begout Anras & Lagadere (2004). They found that fish held at their lowest
density (27 kg / m3) were more active during the day. We saw no statistical difference
between day and night swimming rates, but it is difficult to compare our results to theirs
because of differences in fish size, stocking density, containment structure, net volume
and current velocities.
Although the HTI system proved useful in this environment, it was not without its
problems. Enormous amounts of fish and cage positional data were collected during the 4
week study, but not all the data could be used. The tags used were all pinging at the same
frequency, but with different periods. Therefore, because of the number of tags in use at
37
one time, there were often overlaps among the 20 tags, which prevented us from
distinguishing individual tags at every moment. In addition, the small size of the
experimental cage, and thus the close proximity of the hydrophones, made it more
difficult to triangulate signals. Triangulation uses the time of arrival differences between
the different hydrophones to calculate the distance from the pingers to each hydrophone.
If they are close together, as in our situation, the time of arrival differences are very small
and this led to some loss of data that had a poor resolution. Another issue that may have
complicated data collection was vibration of the hydrophone posts during strong currents
and when fouled with marine seaweed and debris. While equipment set up (hydrophone
location), cabling and HTI containment would be more challenging at a remote, deep
water site, the results would likely improve on a larger scale cage with increased
distances between transmitter and hydrophones.
In summary, the HTI system was used successfully too simultaneously, and
accurately, monitor both the shape and volume of a net pen, and the fish within it. As
such, we believe it has great potential as an aquaculture research tool that can lead to
improvements in net design, mooring systems, and fish welfare.
38
Table 2.1. Environmental ranges at the experimental site during the study period (June 2010)._________________________________________________________________________________
Parameter
Oxygen:Temperature:Salinity:Tidal amplitude (relative to MLLW) Current speed outside the net (ADCP) Current speed inside the net (MAYS)
Range
7.7 - 10.3 ppm11.3 -16.9°C (3-4°C on tidal change) 26 - 33 PSU -0.3 to 3.3 m 0 - 0.50 m / s 0 - 0.37 m / s
39
Table 2.2. Mean distances of trout from net tags (one up current and one down current) during four sampling periods. There were no significant differences (unpaired t-test, P > 0.05) in distances relative to the net walls and bottom during high and low currents, or during night and day intervals. This indicates that fish were evenly distributed in the cage during slow and fast currents, and during the night and dav.__________________________________________________
CurrentSpeed(m/s)
Mean distance of fish to tae (m) Date Hour
# of fish
Net tag location
Day slow 0.083 2.32 6/26 1100 3 up currentNight slow 0.138 1.82 6/17 1400 4 up currentDay slow 0.083 2.32 6/26 1100 2 down currentNight slow 0.138 2.78 6/17 1400 4 down current
Day fast 0.52 1.45 6/18 0800 5 down currentNight fast 0.37 1.45 6/29 1900 5 up currentDay fast 0.52 2.84 6/18 0800 5 up currentNight fast 0.37 2.91 6/29 1900 5 down current
A. B.
Figure 2.1. Google Earth photos of Fort Point, New Castle, NH, USA and the Judd Gregg Marine Research Pier (A). The boxed in area (in A) magnifies the UNH Pier and experimental cage site (B).
41
Hydrophone mounts
Hydrophone^)
Weighted tower rim
Acoustic source location
Figure 2.2. Experimental cage design showing placement of the 4 HTI hydrophones and 12 net pingers (acoustic sources). Also shown is the Modular Acoustic Velocity Sensor suspended in the middle of the net. Positioning of the hydrophones at two different depths allows triangulating the position of fish in 3 dimensions.
42
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% K
*
Figure 2.3. An HTI model 795Z acoustic transmitter (left) being implanted into the abdominal cavity of a steelhead trout (right).
43
outsid«ci|« (A O C 9)> M lid ttn«6/ 4/2010
04
0 3
C 0.15 U
01
20 24
Time
Figure 2.4. An example of current velocities at the test cage site during ebb and flood tides. Currents were measured inside the cage with a Modular Acoustic Velocity Sensor and outside the cage, 10 m away, with an Acoustic Doppler Current Profiler.
44
a. Top View of Middle Net Tags and Single Fish b. Side View o f Middle Net Tags and Single Fish
d. Side View o f Middle Net Tags and Four Fishc. Top View of Middle Net Tags and Four Fish
Figure 2.5. An illustration of a single fish (a, b), and group of four fish (c, d), tracked on June 17 during at a current speed of 0.14 m / s. Red dots indicate the location of the net tags.
45
Side View Current FlowCurrent Flow
Top MewSide View
Current flow Current flow
Figure 2.6. Density plot showing the distribution of a single trout on June 18 from 0800- 0900h, when the current velocity was 0.50 m / s (ebb tide). Panel a. is a side view of the cage while panel b. is a top view. During this one hour event, the fish used 6.71 m3 (10.6%) of the available net environment. Panels c. (side view) and d. (top view) depict the density plot of three trout during a slack tide (0.083 m/s) on June 26 at 1 lOOh. During slack tide, the fish used 14.2 m3 (22.5%) of the net environment. The mean weight of the fish was approximately 600g.
Figure 2.7. Relationship between swimming speed (BL / sec) and current speed (m / sec) recorded by a Modular Acoustic Velocity Sensor (MAVS) current meter that was suspended inside the fish cage. The slope of the line (-0.35) was significantly different than zero (Regression analysis; P=0.01).
47
Mea
n (±
SD)
swim
0.250
0.200
0.150
0.100
0.050
0.000
Day Night
Figure 2.8. Mean (±SD) swimming speeds (BL / sec) of the same seven fish during day (1400-1500h) and night intervals (0200-0300h) on June 18th.
48
CHAPTER n i
SUBMERGED CULTURE OF STEELHEAD TROUT Oncorhynchus mykiss FOR
OPEN OCEAN AQUACULTURE IN THE NORTHEASTERN UNITED STATES
Abstract
To meet growing seafood demands, the US aquaculture industry will need to
consider farming the open ocean in a responsible manner. However, offshore
environments can be energetic (seas > 8 m) and difficult to maintain surface cage
systems. To minimize potential storm damage, submerged culture technologies can be
employed to safeguard the infrastructure and product. Steelhead trout (Oncorhynchus
mykiss) have potential as an offshore species, though they have open air bladders
(physostomous), and need access to air to inflate their swim bladders. To address this
concern, three experiments were developed to explore the ability of O. mykiss to cope
with extended periods of submergence.. The studies used small (~300 g) and large
(~1000 g) trout, in cages that ranged from 3.7 to 68 m3, that were submerged for periods
of one to four weeks. Data storage tags (DST), sonar and video were used to quantify
their ability to manage with submergence. Results indicated differences in growth,
condition, and mortality among the treatments. The study suggests O. mykiss can be
submerged for days to weeks with no negative effects.
49
Introduction
The New England ground fishery has nearly collapsed because of overfishing and
habitat loss (Hennessey and Healey, 2000). This shortage has stimulated new ideas to
produce seafood and to provide economic opportunities for harvesters that have, or will,
become displaced from traditional fisheries (Hennessey and Healey, 2000). Among the
most logical of the long-term solutions is the further development of marine aquaculture,
which has the capacity to produce the needed seafood, provide economic opportunities
for displaced harvesters, and contribute to economic and community development,
particularly in New England.
It is widely accepted that new marine aquaculture development in the US will
occur offshore in less populated waters. The US government has attempted to facilitate
this by developing the National Offshore Aquaculture Act of 2005. In addition, regional
centers throughout the US (NH, HI, CA and FL) were funded in to explore hatchery,
nursery and grow out technologies for cage culture (Benetti, et al., 2010; Fredriksson, et
al., 2004; Tsukrov, et al., 2000; Chambers and Ostrowski, 1999 and Tamaru, et al 1998).
New marine finfish species, both temperate and tropical were successfully spawned,
raised in hatcheries and made available for ocean growout. Submerged cages (Sea
Station™) were preferred to help protect juvenile fish after they were transferred offshore
from turbulent conditions (e.g. wind and waves) at the surface. This later proved to be a
benefit in growout to escape winter storm events and hurricanes. Other benefits of
submerged culture were less ware on the culture system, more stable temperatures, and
less bio-fouling on the nets (Chambers and Howell, 2006).
50
Rainbow trout (O. mykiss), called steelhead when they transfer from fresh to salt
water, are commercially grown in protected waters in Chile, Norway, Faroe Islands,
Canada, and to a limited extent in the USA (Washington and New Hampshire). Steelhead
trout have great potential to succeed as an aquaculture species in New England. First,
they have been domesticated for >150 years and are the basis for recreational fisheries
and fresh water aquaculture throughout the world. As a result, juveniles are readily
available from numerous commercial hatcheries. Second, unlike Atlantic salmon, O.
mykiss does not go through true smoltification (internal metabolic processes that allows
fish to migrate from fresh to seawater), so juveniles can go directly from a freshwater
hatchery to full strength seawater (32 ppt.). Third, the species has a relatively fast growth
rates in sea cages, reaching marketable size (1-3 kg) in 8 months after stocking at 250g.
Finally, they are disease resistant, are more temperature tolerant than Atlantic salmon,
and have a high market value (>13.00 / kg).
Submerged cage culture has been successfully demonstrated for several species,
including Atlantic salmon (Oppedal et al., 2011; Dempster et al., 2008, 2009; Korspen et
al., 2009), Pacific threadfin (Ryan 2004), cobia (Rapp et al. 2007), Atlantic cod and
haddock (Chambers et al., 2006, 2007; Rillahan et al., 2009, 2011), and halibut (Howell
et al., 2005). Because suitable inshore aquaculture sites are becoming scarce, and winter
icing and storms can damage surface cages, there is growing interest in culturing
salmonid species in offshore, submerged sea cages. In addition to providing more
locations and avoiding ‘visual pollution’, submerged systems could reduce the risk of fish
escapees during storms (Naylor et al., 2005), and sea-lice infestations (Hevrpy et al.,
2003). Despite these advantages, submerged systems for salmonids are only beginning to
51
be considered, and much of the essential knowledge on how submergence will affect the
fish is lacking.
The uncertainty surrounding submergence is related to the assumption that
salmonids become negatively buoyant when submerged beneath a cage roof because they
cannot access the surface to gulp air to fill their swim bladders (Smith, 1982). Near shore,
sea cage studies in Norway demonstrated that Atlantic salmon cope with submergence
quite well (Oppedal et al., 2011; Dempster el al., 2008, 2009; Korspen et al., 2009;
Osland et al., 2001). They feed actively and grow well, albeit at a slower rate than those
in surface cages. Dempster et al. (2008) found that 1.7 kg salmon increased their
swimming speeds by 1.5 times when submerged, compared to fish in control cages, and
suggested that the slower growth was due to the increased energetic expenditure for
swimming. They noted, however, that temperature and light differences between fish held
in surface cages, verses deeper submerged cages, may also have contributed to the
observed growth differences.
To investigate the ability of steelhead trout to incur periods of submergence, three
experiments were conducted to test the null hypotheses that the behavior, growth,
incidence of fin damage, and mortality in submerged cages does not differ from trout
held in surface cages under similar environmental conditions.
Methods and Materials
Timing and Locations
The project lasted 24 months, and involved three separate, but related,
experiments. In the first, which occurred from June through August 2011, we studied
juvenile trout in small inshore cages located near the University’s Judd Gregg Marine
52
Research Pier (JGP) in New Castle, NH (Fig. 1). The second experiment took place from
October through December 2011, in the same location. This time, larger trout and cages
were used. The third and final experiment was conducted in the summer of 2012 (June -
August), at a study location ~ 0.8 km seaward from the JGP that had more exposure to
wind and waves.
Steelhead Trout
In all three experiments, juvenile steelhead trout were purchased from Sumner
Brook Trout Farm in Ossipee, NH. Sumner Brook acquires eyed eggs from Trout Lodge
in Sumner, WA. that were certified disease free and are all diploid. Fingerlings were
raised in flow through, freshwater raceways for 8 months to a size of ~ 150 g. Prior to fish
transfer to sea cages, the trout were fed a 3 mm, Skretting Bio-Transfer diet for 7 days.
This diet helps transition salmonid smolts from fresh to salt water environments. It has
elevated dietary salts that encourage the development of osmoregulatory ability, while
added betaine acts as an osmoprotectant by relieving gastrointestinal stress. Fish were
transported to the Jackson Estuarine Marine Lab in Great Bay, NH in insulated 1 m3
containers. Here, they were acclimated from freshwater to brackish bay water (20 ppt.) in
flow through, fiberglass tanks for two weeks. They were then moved to a sea cage near
the JGP for final acclimation to 30 ppt.
Fish were hand fed to satiation daily with a sinking, Bio Oregon Trout diet (45%
protein, 24% lipid), trout in submerged cages were fed through a flexible PVC hose that
extended from the surface down into the center of each cage 1 m. Underwater video
cameras were used to help determine feeding satiation in these treatments.
53
Because environmental variables can influence swimming behavior and depth of
salmonids (Johansson et al., 2006, 2007; Oppedal et al., 2001, 2007), we collected a
series of environmental measurements. HOBO® temperature loggers were installed 1 m
below the surface of each cage and an YSI 6600 V2-2 Water Quality Sonde, located at
the end of the pier adjacent to the cage site, collected additional environmental data
(temperature, dissolved oxygen, salinity, pH, tidal amplitude and turbidity). Lastly,
current speeds were measured weekly in each cage, at 1 m depth intervals. Finally,
mortalities, if any, were recorded daily.
Experiment 1
In experiment 1, six, 3.75 m3 cylindrical cages (Fig 2a.) were constructed from a
2.5 cm mesh Seawire™ netting. Seawire is a stiff, copper alloy net material that
minimizes bio-fouling that can reduce water flow and quality (Chambers et al., 2012). On
10th June 2011, each cage was stocked with 55 trout with a mean (± SEM) starting weight
of 255.6 (14.4) g and length of 27.6 (0.4) cm. The experimental design had two
treatments (A & B) and a control (C), each with two replicates, for a total of six cages.
Control cages (C1 and C2) were maintained at the surface throughout the study to allow
fish to gulp air. Treatment cages, each equipped with a nylon netting cover, were
submerged 1 m during the study to prevent fish from accessing the surface to fill their gas
bladders (Fig 2b.).
The replicate treatment cages Al and A2 were submerged for two weeks, brought
to the surface for one day, re-submerged for two weeks, brought to the surface for one
day, etc. until the experiment was complete after 8 weeks. The replicate treatment cages
B1 and B2 were submerged for 4 weeks, brought to the surface for one day, re
54
submerged for the next 4 weeks, and then brought to the surface at the end of the
experiment.
Data from replicate pairs were compared, and because there was no difference in
any of the measured variables (Mann-Whitney U tests, P > 0.1), data from the replicate
pairs were combined.
Experiment 2
In the second phase of the submergence project, two 68 m3 floating cages were
deployed at the aforementioned inshore site. Each of the 4.6 x 4.6 x 3.2 m cages were
constructed of 2.5 cm knotless nylon twine, and were supported at the surface by high-
density polyethylene floating frames with wooden walkways (Fig. 3). The control cage
was maintained at the surface so the trout could freely gulp air to fill their swim bladders
(Fig. 3. A.) while the treatment cage (submerged) had a nylon mesh net roof to retain the
fish from surfacing (Fig. 3. B.). These were then submerged 1 m below surface for
sequentially greater periods of time using a series of ropes and weights attached to the to
the float platform.
The second experiment began in October 2011, using fish retained from
experiment 1. Each cage was stocked with 84 trout with a mean (± SEM) weight of
1070.4 (53.7) g and a mean length of 41.3 (0.7) cm. The experimental design had a
single treatment (submerged) and a single surface control. Prior to the start of the
experiment, a random sample of 10 fish from the control and treatment cages were
captured, anesthetized, and fitted with electronic data storage tags (Star-Oddi™ tilt tags).
These tags, as shown in Figure 4, were attached externally, just anterio-laterally of the
dorsal fin. They recorded temperature (° C), depth (m), pitch angle (degrees head up or
55
head down) and roll angle (degrees side-to-side) at either 45 (pitch and roll) or 90
(temperature and depth) second intervals. To test tag retention and survival, six trout
were placed into a 2 m round fiberglass tank with flow through water at the UNH Coastal
Marine Laboratory (CML). Three of the trout were surgically implanted with dummy
Star-Oddi tags while the remaining three fish were not tagged. After 1 month, all six fish
had adapted to the tank, were feeding well and the three tags were still attached firmly to
the trout.
Delays with the cage manufacturer extended the trial into the fall. With
decreasing winter temperatures causing a cessation in feeding (< 5°C) and problems with
the DST tags becoming fouled in the net, the submergence schedules had to be modified.
Instead of the 2, 3 and 4 week schedule, the treatment cage was submerged for 17 days,
brought to the surface for 4 days while we reattached the data storage tags, and then re
submerged for 31 days (Nov. 4 through Dec. 5 ).
Experiment 3 (Exposed site)
In the second year of the research, the two inshore cages used in experiment 2
were towed seaward to an exposed location approximately 0.8 km from the original site.
Steelhead trout ~100 g were purchased in early May 2012 and held at the UNH Jackson
Estuarine Lab for 2 weeks to help transition them to brackish bay water (20ppt). In early
June, they were transferred to the UNH JGP (full strength salinity - 30ppt). They were
held in a net pen at the pier until they had increased to a mean weight of 308.1 g (+/-
81.1) and mean length 28.1 cm (+/- 1.8). Fish were transferred to the experimental pens
(200 / cage) on June 19th, and on June 20th, the treatment cage was submerged 2 m below
surface. Again, one cage served as a control and was maintained at the surface. The
56
experimental pen was raised to the surface on June 27th, one week later and the first set
of data was collected from fish (n = 25) in both the submerged and surface cages.
Following this 24 hour surface time, the cage was submerged for sequentially longer
periods of time (2, 3 and 4 weeks), each separated by 24 hours at the surface.
To quantify the fish swimming angles, a weighted vertical white line was placed
in the center of each cage to a depth of 1 m off the net bottom. A Go-Pro™ video
camera, mounted on a 2.3 m PVC pole, was lowered into each cage and attached to the
side net for 30 minutes on each sampling date. Video was captured as the fish passed by
the vertical white line, and later analyzed with Ethovision XT fish tracking software to
determine mean tilt angle as the fish moved past the vertical line.
Growth. Condition and Fin Damage
Fish were sampled bi-monthly throughout each experiment. A random sample of
25 fish from each cage was anesthetized with MS222, weighed and measured. Standard
indices of growth and condition were calculated for each sampling date. Specific growth
rate (SGR, % day'1) was calculated as ((In (W2 ) - In (W))) / (t2 -ti)) x 100, where W2 and
Wi are the mean live body weights at times t2 and ti, respectively. Fulton’s condition
factor (K) was calculated with the formula K = ((W/L3) x 100), where W is the wet
weight (g), and L is the total length (cm). During scheduled resurfacing of the treatment
cages, fish in both control and treatment cages were visually examined for fin damage
and/or snout abrasions that can be caused when the fish encounters the cage ‘roofs’ as
they try to surface to obtain air and refill their swim bladders. The degree of snout
damage was assigned using a subjective index from 1 (undamaged) to 5 (extreme
damage) based upon Hoyle et al. (2007).
57
Surface Rolling and Jumping Behavior
Jumping and rolling behavior of both the control (surface) and treatment
(submerged) cages were observed each time the treatment cages were brought to the
surface. When the treatment cages were raised, the total number of jumps and rolls in all
cages, during the first 30-min period, were counted. All counts were standardized to rolls
or jumps fish'1 h r_1 (e.g. Furevik et al., 1993; Juell & Fosseidengen, 1995).
Statistical Analyses
In Experiment 1, statistical analyses varied with experimental design. On those
dates when only one of the submerged treatments was brought to the surface,
comparisons to the control (surface) fish were made with Mann-Whitney U tests. On
those dates when both submerged treatments were resurfaced, either one-way ANOVA,
followed by Tukey-Kramer multiple comparison test, or a Kruskal-Wallis test, followed
by Dunn’s Multiple Comparison test (if the data were not normally distributed) were
used. Response variables compared included fish length and weight, survival percentage
(square root arcsine transformed), incidence of fin, snout and body injuries, and
condition. In Experiments 2 and 3, where there were not statistical replicates, differences
in the same response variables between treatments were compared using Mann-Whitney
U tests.
Results
Experiment 1
After 18 days of submergence, the fish in the surface cages (C) were significantly
heavier than those in the submerged cages (A) and also were in better condition (heavier
58
per unit length; Table 1). There were no differences in mean length or abrasions on the
snout between surface and submerged fish. On the second sampling date both treatments
(2 and 4 weeks submergence, A and B respectively) were sampled, along with the control
(surface) cages (C). There were no significant differences in mean lengths or snout
condition (ANOVA, P > 0.05) between treatments, or between treatments and the
controls. Fish in the surface (control) cages were significantly heavier than those
submerged for 2 weeks (P < 0.05), but no different than those that had been submerged
for 4 weeks (ANOVA, P > 0.05). There was no difference in the condition of the fish
submerged for 2 and 4 weeks (ANOVA, P > 0.05), but the condition of the control
(surface) fish was significantly higher that both treatments (ANOVA, P < 0.05). On the
third sampling date fish in the control (surface) cage were significantly (Mann-Whitney
U-test, P < 0.05) heavier, longer, and in better condition than those in the 2 weeks
submergence treatment (A). There were no differences, however, in snout abrasions
(Mann-Whitney U-test, P > 0.05) between the treatment and control fish. At the end of
the experiment, on August 11th, fish in the surface (control) cages were significantly
heavier and longer than those in both of the treatment cages (ANOVA, P < 0.01). Fish in
the control cages (C) were also in significantly better condition (ANOVA, P < 0.001)
than those in the 2 weeks submergence treatment (A), but not better than those in the 4
weeks submergence (B) treatment (ANOVA, P > 0.05). There was no difference in
condition between fish in the two treatments, or between nose abrasions in the fish in two
treatments and the control (ANOVA, P > 0.05). Overall, trout in the control cages had
significantly better weight, length, condition and less nose abrasions than fish that were
submerged for 2 weeks and 4 weeks.
59
At the end of the 2 and 4 week intervals, trout in the submerged cages were
brought to the surface. In all cases, fish that had been submerged, jumped more
frequently than control (surface maintained) fish, presumably to fill their depleted swim
bladders with air (Fig. 6).
Mean (+/- SE) survival rates for treatments A and B, and the control (C), in
Experiment 1 were 66.4% (+/-6.3), 40.9% (+/-10.0), and 90.9% (+/- 5.4), respectively
(Fig. 7). After square root arcsine transformation of these data, an analysis of variance
(ANOVA) found that the means were not significantly different (P > 0.05). The
relatively low survival in Treatments A and B were caused by either bacterial or viral
infection, characterized by skin lesions, and perhaps exacerbated by the periodic
submergence of these two treatments.
Trout survival was the lowest during the two week submergence period. This may
be due to the additive handling and submergence over the eight week trial.
Specific growth rates (SGR) were calculated for fish in each treatment (A, B) and
the control (C) in both Experiments 1 and 2 (Table 2). In Experiment 1, growth rates
were highest in the surface control fish (C), intermediate in the 4 weeks submergence
treatment (B), and lowest in the 2 weeks submergence treatment (A). The lower growth
rate of fish in the 2 weeks submergence treatment compared to fish in the 4 weeks
submergence treatment may have been due to the stress associated with more frequent
handling during sampling.
Experiment 2
In experiment two, 17 days after submergence, there were no differences in mean
weight, mean length, mean condition or mean nose abrasions between surface and
60
submerged fish (Mann-Whitney U-tests, P > 0.05; Table 3). However, on the final
sampling date, after the treatment fish had been submerged continuously for 31 days, fish
held at the surface (control) were significantly heavier than fish that had been submerged
(Mann-Whitney U-test, P < 0.05). In fact, surface fish gained weight more than twice as
fast as submerged fish. There were no significant differences in mean length, mean
condition or mean nose abrasions between surface and submerged fish (Mann-Whitney
U-tests, P > 0.05).
On both sampling dates, fish that had been submerged jumped more frequently
than control (surface maintained) fish, presumably to fill their depleted swim bladders
with air (Fig. 6).
Survival was good in both the surface (88%) and submerged cage (92%). No
statistical comparison was possible due to single replicates, and the cause of death from
the few fish that died is unknown.
As indicated above, the pitch and roll tags were attached externally (Fig. 4.)
because internal (surgical) placement would have made it difficult, if not impossible, to
get the pitch and roll axes of the tag aligned with the same axes of the fish. Because the
tags were external, some became snagged in the cage netting, effectively changing their
orientation relative to the axes of the fish. For this reason, pitch and roll data from
several of the tags was suspect, and therefore not used.
While acute pitch angles (20-30°) were common as the individual fish moved up
and down in the cage, mean weekly pitch angle did not change over the course of
experiment 2, in either the surface (control) or submerged cages (Fig. 7). Mean weekly
pitch angle in fish held in both the surface and submerged cages varied from -3° to +3 °.
61
If submerged fish were compensating for lost buoyancy by swimming upward, we would
have expected a ‘heads up’ (+) orientation to develop over time, but this was not
apparent.
Experiment 3
Results were similar in the 1, 2, and 3 week submergence periods and can be
found in Table 4. Mean lengths did vary between the surface and submerged treatment
during week one and week two periods. During the first week submergence, the surface
cage was significantly longer that the submerged cage. This reversed during the second
week submergence with the submerged fish becoming significantly longer than the
surface. After this point, length, weight, specific growth rates (Table 2) and body
abrasions were all similar.
Most notable in Experiment 3 was survival and jumping events (upon resurfacing)
during the third and fourth week submergence trials. At samplings 1 and 2 weeks after
submergence, survival was similar at 99% (surface) and 98% (submerged). After 3 weeks
submergence, the survival was again similar at 83% and 84% respectfully. A divergence
occurred after 4 weeks submergence with a survival of 74 % in the surface and 43% in
the subsurface cage (Fig. 6). Also interesting was jumping events decreased when the
trout were resurfaced at the third and fourth intervals perhaps indicating that fish in both
cages were under stress (Fig. 8). During this time period, high temperatures (> 16°C) and
heavy bio-fouling of the hydroid Tubularia recruited onto the net and cage frames.
Ethovison XT fish tracking software was used to analyze the underwater video of
trout swimming angle past a vertical line suspended within the center of the cages.
Results indicated no differences in swimming angle + 3° in both the control and treatment
62
cages.
Discussion
The three experiments conducted to test differences between steelhead trout held
in surface verses subsurface cages showed varied results. At the end of Experiments 1
and 2, fish maintained at the surface were significantly heavier than those in submerged
cages, but in Experiment 3 there were no differences. Location and cage size may have
been responsible for these observed differences. Experiment 1, done with relatively
small fish (-300 g), was conducted in small diameter (1.25 m), cylindrical copper-alloy
cages at an inshore site exposed to fast tidal currents (0.5 m / s). Snout damage was
severe in all treatments and more so in the submerged cages, probably because of the
small cage size and copper-alloy cage material. Submerged fish may have incurred more
nose abrasions in trying to reach the surface to access air. Survival was poor in the
submerged cages, suggesting that the stresses of snout damage and submergence were
additive.
In Experiment 2, fish (-1000 g), and cages (68 m3) were larger and made of soft
nylon mesh, snout damage was virtually non-existent, and survival was good in both the
surface and submerged cage. At the conclusion, surface fish were significantly heavier,
indicating that submergence alone can have negative effects on growth performance. It
should be noted, however, that fish were submerged for 31 days, which is probably a
longer time than would be necessary in an aquaculture application that would avoid a
storm, phytoplankton and jellyfish bloom and or warm surface temperatures during the
summer (> 16°C). The mechanisms for compromised growth, however, remain elusive.
63
We saw no change in the swimming angle and vertical depth, which would have
suggested severe swim bladder depletion as reported by Dempster et al. (2008,2009) and
Korsoen et al. (2009).
In the third experiment, with smaller trout again, 1 and 2 week submergence
period indicated now significant differences between the surface and subsurface cages.
However, during the 3 and 4 submergence periods, survival and jumping changed
significantly in both treatments that may have been brought on by changes in the cage
environment. The cause of this was probably due to warm water temperatures (> 16°C)
and heavy bio-fouling of Tubularia on the nets. Tublaria has a flowery head with
stinging nematocysts that can irritate the outer mucous membrane of fish (Fig. 9).
Anecdotal evidence has shown this to be more of a problem during July and August when
surface water temperatures can reach up to 20°C. The trout were not vaccinated in any of
the above experiments that may have safe guarded them during this exposure. Secondary
bacterial infections caused by stress (temperature and bio-fouling) may have altered
survival rates and jumping behavior. An indication of this stress can be seen in the
jumping data in Figure 6. Here, jumping in both cages decreased by the end of the
experiment.
While we do not have conclusive data, we believe that steelhead trout can be
submerged for days to weeks with no negative effects, and this is an important finding for
those interested in culturing this species. We were logistically unable to conduct the
experiments in deep (> 10m) water, and hence our submerged cages, while below the
surface, were still relatively shallow. Because pressure (depth) may have an effect on the
behavior and physiology of forcibly submerged fish, these experiments should be
64
repeated in cages submerged to greater depths (> 10 m) in open ocean conditions.
Duration of successful submergence will depend on the species, size, temporal season,
and depth (Dempster et al., 2008, 2009).
Ultimately, cage submergence can be used as an effective management tool to
temporarily escape adverse situations at sea. The additional cost associated with
submergence must be taken into consideration by farmers and balanced out with the
potential risk of maintaining live stock at the surface. As fish farming expands offshore,
it will be important to develop management tools that can measure fish welfare, biology
and oceanographic data in real time. With this, farm managers can react appropriately to
safeguard their product in varying ocean conditions.
65
T able 3.1. M ean w eights, lengths, cond itions and nose abrasion ind ices o f the fish in the 2 w eek subm ergence treatm ent (A ), the 4 w eek subm ergence treatm ent (B ) and the surface contro l (C ) on the sam pling dates in E xperim en t 1. C om parisons betw een fish in the treatm ents and con tro l, fo r each o f the lis ted response variab les, w ere m ade w ith e ith er M ann-W hitney U -tests (June 29 and Ju ly .29) o r A nalysis o f V ariance (Ju ly 14 and A ugust 1U.____________________ ;_________________________________________________________________________________
C om parison A = B (P > 0 .05) A = B (P > 0 .05) A = B ( P > 0 .0 5 ) A = B = C ( P > 0 . 0 5 )C > A ( P < 0 . 0 0 I ) C > A ( P < 0 . 0 0 1 ) B = C (P > 0.05)C > B f P < 0 . 0 1 ) C > B / P < 0 . 0 1 ) _____________ C > A ( P < 0 . 0 0 1 ) __________________________
Table 3.2. Specific growth rates (SGR (%/d)) of each of the indicated treatments at the end of Experiments 1.2 and 3._______________________________________________
Experiment Treatment Duration SGR f%/d)
1 A 8 weeks 0.8561 B 8 weeks 0.9761 C (control) 8 weeks 1.309
2 Submerged 7 weeks 0.3262 Surface 7 weeks 0.695
3 Submerged 10 weeks 1.163 Surface 10 weeks 1.33
67
Table 3.3. Mean weights, lengths, conditions and nose abrasion indices of the fish in the submerged and control cage on each of the sampling dates in Experiment 2. Comparisons between fish in the treatment and control, for each of the listed response. variables, were made with Mann-Whitnev U-tests._______________________________________________________
Sampling Mean Mean Mean MeanDate Treatment weight (s) length condition snout
Figure 3.1. Aerial photo of the Judd Gregg Marine Research Pier in New Castle, NH and proximity of the experimental sites.
70
Figure 3.2. Cage design used in Experiment 1. Six, 3.75 m3 copper-alloy cages were suspended in a 4 x 5 m floating platform made of High Density Polyurethane (A). Diagram B. illustrates cage dimensions, the Control cage C (surface) and the submerged treatments cages A and B, one m below the surface to keep fish from refilling their swim bladders.
Figure 3.3. (A) Control cage left where trout were allowed access to the surface to gulp air. (B) Treatment cage with net nylon roof submerged 1 m below surface. Note feeding tube in upper left of image.
Figure 3.4. Steelhead trout (~ 1000 g) attached with a fitted Star-Oddi™ pitch and roll data storage tag.
Snout Damage Index
4 S
Figure 3.5. Visual representations of subjective snout index, ranging from no damage (1) to severe damage (5). Nose damage can occur when fish in the submerged treatments try to resurface to gulp air and fill their swim bladders.
74
1. 0.08
0.0?
0.06c1 0-051£ 0.04a
0.03i,
0 J02
0J01
0
IS urface S ubm erged
4 w eek s
2 . 0.100 0.090
| 0.080 | 0.070 |- 0.060 ,s 0.050 j s 0.040 fc 0.030
0.0200.0100.000
S urface S ubm erged
2 w eek s
I J 0 □Sab Sarf Sab Sab Sarf Sab Sarf Sab Sab Sarr
2 week 4 week 6 week 8 week
3 0.08
007
Figure 3.6. Number of jumps fish'1 minute"1 upon surfacing of submerged cages on the indicated sampling dates during the Experiments 1, 2 and 3.
75
Tagged fish #1017, Control cage
» • XU* « '
Fig. 3.7. An example of pitch recordings, taken from a fish in the submerged cage (Tag 1037-top) and a fish in the surface cage (Tag 1017- bottom), taken during the 5th week of Experiment 2.
76
10090
80
70
60
50
40
30
2010
0 I2 weeks 4 weeks
TreatmentSurface
2 .
>
taVi
1009080706050403020100
2 Week 4 WeekTreatment
• Surface i Submerged
3. 100
90
80
70
60
50Vip 40
30
20
10
■ Surface■ Submerged
1 week 2 week 3 week 4 week
Treatment
Figure 3.8. Survival of trout in Experiments 1, 2 and 3 at different submergence periods.
77
Figure 3.9. (A) Bio-fouling of the hydroid Tubularia on a fish net. (B) A heavily fouled net being pulled up for fish sampling.
78
C H A P T E R IV
TECHNOLOGY TRANSFER OF SMALL SCALE INTEGRATED MULITROPHIC
AQUACULTURE TO COMMERICAL FISHERMEN IN NH
Abstract
Over the last five years, the commercial fishing fleet in New England has been
subjected to increasingly restrictive management measures established to rebuild
declining stocks. By design, these measures have limited fishing opportunities and
significantly reduced the inshore small vessel fleet. To help support New Hampshire
(NH) fishermen, an extension program was developed by the University of New
Hampshire (UNH) and NH Sea Grant, to train fishers on small scale integrated multi-
trophic aquaculture (IMTA). Because federal and state regulatory agencies had concerns
about nitrogen input from fish production in the coastal waters of the state, a program
was designed to measure nitrogen uptake from shellfish and seaweed integrated with the
finfish production. The program was evaluated as the fishermen were taught the
necessary husbandry skills for culturing steelhead trout, blue mussels and sugar kelp
together. Nitrogen extraction by the mussels and kelp exceeded the nitrogen added from
trout production, and thus had a positive effect on the ecosystem. The training program
provided the fishermen with a new skill set, that they could adopt either part time or full
time, to provide additional income.
79
Introduction
Commercial fishing has been a vital component of New England’s economy for
over two centuries, and has grown to a half-a-billion dollar per year industry. Equally
important, recent economic studies based on National Marine Fisheries Service (NMFS)
data suggests that every job created in the seafood industry generates one-and-a-half jobs
in the regional economy: jobs in other sectors such as food processing, tourism,
restaurants and boatyards (Hoagland et. al 2005).
Over the last five years, however, the commercial fishing fleet in New England
has been subjected to increasingly restrictive management measures established to
rebuild declining stocks. By design, these measures have limited fishing opportunities
and significantly reduced the inshore small vessel fleet. The catch allocation groundfish
fishermen receive will result in a 40% decrease in potential landings, and may reduce the
current groundfish fishing fleet by 50% (NH Sea Grant, 2013). For many local
communities this will mean the loss of their historic fishing heritage. New Hampshire had
180 commercial fishing permits in 2009. The number declined by about 50% from 2009
to 2010, and the value of New Hampshire’s landings decreased by approximately 40%
(NH Sea Grant, 2013).
As fishers become displaced by federal management measures, they could adopt
small-scale aquaculture operations. They have vessels, water front infrastructure, and
experience working on the ocean, all of which would be useful in transitioning to
aquaculture. Although we envision that such a transition would be gradual for any given
individual, aquaculture could eventually become full time employment for some. It is
80
worth noting that the US is the third largest consumer of seafood in the world, yet we
import over $10 billion annually. Marine aquaculture has the potential to contribute to US
seafood production, reduce our reliance on imported seafood (FAO, 2010), and provide
economic opportunities to displaced fishers.
UHN established an Open Ocean Aquaculture research farm in 1999
(http://ooa.unh.edu/) to develop new technologies for growing seafood in New England.
The site was located 12 km offshore, in 50 m water depth, away from commercial
fishing, recreational boating and navigational routes. To escape surface energies (waves)
experienced offshore, submersible cage and mooring systems were employed. Culture
methods for new marine fish species were investigated (cod, haddock and halibut) to
relieve fishing pressures on wild stocks. The project developed and demonstrated new
submersible cages (Chambers et al., 2011), mooring systems (DeCew et al., 2012),
mussel longline technologies (Langan et al., 2003) and remote feeding systems (Rice et
al., 2003). It also demonstrated that is was feasible to produce cold water, marine finfish
in submerged cages (Howell et al., 2005; Chambers et al, 2006,2007; Rillahan et al.,
2009,2011), and collect environmental data in real time from the offshore site (Irish et
al., 2004,2001). Although the project succeeded in generating significant amounts of
data and new information, the high costs, exposed nature of the site, and slow growth of
the fish species cultured, created operational and economic challenges.
Based upon the experiences and lessons learned from the offshore project, an
alternative aquaculture model was designed that would emphasize small-scale production
closer to shore. These smaller systems would be more affordable and user friendly for
fishermen. However, concerns were made by the EPA regarding near shore aquaculture
winter months and early spring. Markets are still developing for fresh kelp, and prices
will dictate whether or not interest will continue for this marine seaweed.
The fishermen brought inherent knowledge to the project that was gained from
working many years on the ocean. They quickly learned and adapted the new skill sets
they were taught for aquaculture. In the end, they were able to sell the trout for $13.20 /
kg (Fig. 4.10) and have over 3000 kg of mussels in relay for sale in 2014.
Environmental Monitoring
Water quality
Environmental and water quality data were collected on three different dates
throughout the trout growout in 2012-13 (Table 4.3 and 4.4). Water temperatures
decreased from 17.5°C in July to 5.3°C by January. Current speeds during this time
ranged from slack to 0.35m / sec and the direction was NE-SW. The pH of the seawater
differed slightly from 7.6 to 8.0. Dissolved oxygen levels were the lowest in September
(87.96 % saturation) and highest in January (103.5 % saturation). Water samples
collected for nitrogen analysis indicated no differences in ammonia, nitrite or nitrate
levels between the sample locations (Table 4.4).
Benthic and video sampling
The bottom samples consisted of sand (60 %), with some silt (20 %) and
fragmented shell and rocks (20 %). Larger rocks, scattered throughout the area, were
covered with encrusting colonies of sponges and seaweeds. Numerous lobster and crabs
inhabited the areas along the entire 30 m transect at each sample period.
97
No visual differences appeared along the 30 m transect throughout the IMAT
growout. Also, no fish food or anoxic areas were seen in the study site. The captured
video files were recorded onto a DVD and mailed to the EPA and NH Fish & Game for
their review. The video files were also archived, and benthic samples were frozen for
future analysis, if warranted (Fig. 4.11).
Market survey of steelhead trout
The steelhead trout were marketed between 2010 and 2012. Results of the market
survey were positive, with particular interest in a product that was raised locally.
Reported weekly demands ranged from 15-25 kg / restaurant, at they were willing to pay
-$15 / kg. Whole gutted fish at > 1.5 kg were acceptable, but larger fillets were preferred.
Surveyors commented on their mild taste that differed from farm-raised salmon. On a
scale of 1 (excellent) - 5 (poor), freshness, smell, texture and taste all rated number 1.
Steelhead Trout Economics for NH Fishermen
Simple economic spreadsheets for steelhead trout production, at three different
production scales, are given in Tables 4.5,4.6 and 4.7. Each table estimates the expenses
and income over a 3 year period, and assumes a stocking density of 20 kg / m3 at harvest.
Since fishermen already own and operate their vessels, no labor, boat payment or boat
insurance was included. Survival from stocking to harvest was estimated at 85%, feed
conversation ratio at 1.2, and yield (gutted weight to whole weight) at 75%. Price for
each 450 g fingerling ($5.00) from Sumner Brook Trout farms was based on prices we
have paid in the past. Selling price for harvested product at 2.5 kg round weight (1.87 kg
gutted weight) is given as $14 / kg, which was been the price paid in 2013. Feed cost
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($2993 / mt) has been steady for the last two years. An additional charge of $0.50 / kg
was estimated for processing and distribution.
Profit improves as cage size increases from 100 to 1000 m3 (largest scale of
production). This is due to similar operational expenses to feed and maintain a single
large cage. Increased cage volume allows for more production per unit of effort. As cage
size increases, however, so does the amount of nitrogen added to the environment. For
this reason, larger cage(s) would likely be sited in deeper waters (>15 m) that have
moderate current flow (> to 0.20 m / sec) to help dissipate the added nutrients. Thus,
although there are greater economic rewards at a larger scale (>1000 m3), moving the
cage further offshore could increase the costs and risks of fanning. If profits increase
with scale, as we predict, and if larger scale systems have to move offshore, it is likely
that farmers will partner in a cooperative venture to share in the capital investment, and
spread the risk. They may also consider crop insurance that is now becoming available
through the FDA.
Results from these simple spreadsheets indicate that raising steelhead trout could
be profitable for commercial fishermen, particularly if done on a larger scale. There are
two primary reasons for this. First are cost savings for the fishermen. These individuals
already have vessels, vessel insurance, and other infrastructure, associated with their
primary business of fishing. All of these represent a considerable saving should they
initiate fish farming. Second, steelhead trout are relatively fast growing, have a good
food conversion ratio, and command a relatively high market price, which reduces
production costs and maximizes income.
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It is likely that state and federal regulatory agencies will insist that steelhead trout
culture, particularly in coastal areas, be accompanied by shellfish and /or seaweed culture
to mitigate the addition of nutrients to the environment. Although these secondary crops
would add additional expenses to the operation (e.g. labor), these costs would be
recovered by their sale and could improve income gains to the farm.
Discussion
Results from the IMTA of steelhead trout, blue mussels and sugar kelp proved
successful in extracting more nitrogen from the Piscataqua River than was added from
trout production (Table 4.2). This is important as Reid (2007) reported uptake efficiency
from IMTA in open water is essentially unknown. What we do know is that mussel and
kelp recycle nutrients derived from fish waste (ammonia and phosphorus). Inorganic
nutrients are extracted directly by the kelp from the environment (Chopin, 2006; Neori et
al., 2004) while organic nutrients released by the fish are consumed by the mussels
(Lander et al., 2004; Troell et al., 2003; Mazzola and Sara, 2001). We were able to
culture three species in situ and quantify N input and uptake that resulted in ecosystem
benefits from aquaculture. Not only were the extractive organisms healthy for the
environment, they produced additional economic value to the farmer.
During the IMTA demonstration, NH fishermen were able to train “hands on”
with the basic skills to culture all three species. Additional training will be necessary to
improve current aquaculture methods for the steelhead. This includes developing a
custom vaccine for bath immersion, using new antifoul paint products to reduce bio-
fouling and working with a semi-moist feed formulation that will aid trout acclimate to
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seawater. Also important will be the development of larger scale, robust, flexible
platforms that can safely maintain and grow multiple species together.
Blue mussels and sugar kelp can be grown in concert with the trout. However, the
mussels could not be sold due to the water classification of the cage site. This is due to
the proximity of a waste water treatment plant 2.8 km up river. This classification may
change in 2014 based upon water and shellfish samples collected by NH Department of
Environmental Services. Their data indicated the water quality was safe for shellfish
harvest at the cage site. If EPA re-classifies the head waters of the Piscataqua River, this
would greatly improve the logistics and economics for shellfish production.
Environmental monitoring indicated no negative effects to the bottom or to the
water column from farming on a small scale. This information has been given to the
regulatory agencies, and we are optimistic that this will help guide future permitting, and
allow the expansion of ocean farming.
Results of this EMTA project, although still preliminary, could be used in other
New England coastal areas. In particular, the fishing communities of the northeast where
fishery management initiatives have limited wild harvests. An important part of the
fishing industries strategy for maintaining their heritage and livelihood is to find
alternative ways to complement and diversify their operations. Aquaculture plays an
important role in maintaining an active water front and fishing heritage. Specific benefits
include alternative and economically viable uses for underutilized fishing vessels,
employment opportunities for displaced fishermen, business and marketing opportunities
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for suppliers, restaurants, wholesale and retail outlets, and the benefit of locally produced,
high quality seafood for local, regional and national consumers.
The market survey suggested that steelhead trout is highly regarded, and that a
fresh, locally raised product is more preferable than a foreign import. Market capacity is
still unknown.
The fishermen are eager to increase aquaculture production in NH. Initial farming
sites that were applied for in 2011 are now being revisited for IMTA culture in 2014.
However, it is likely that inshore siting will be limited. Ultimately, if fishermen choose to
expand cage farming, they will have to consider moving offshore to deeper, more
exposed locations. Open ocean aquaculture will increase capital investment, daily
operational costs, and risk from oceanic storms. To overcome these obstacles, the
fishermen could form a cooperative to share investment, risk, and rewards. If they choose
to move offshore, UNH and NH Sea Grant will be on standby to assist them with the
expansion of marine aquaculture in New England.
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Table 4.1. Consumer survey form that accompanied the steelhead trout delivered to seafood markets and restaurants in New England.____________________________
1. Approximate Yield (weight of filets / weight of whole fish):_____________
2. Product: Scale of 1 (excellent) to 5 (poor). Please enter a number.
Freshness (appearance of gills, eyes, skin)_________
Smell (fresh to old)___________
Texture (firm to soft)____________
Taste (excellent to poor)____________
Additional comments on product:
3. What is the optimal size/form of this product? Please check one or more.
Whole gutted (1-2 lbs.)_________
Whole gutted (2-4 lbs.)_________
Whole gutted (>4 lbs.)_________
Filets_________
Steaks_________
4. Comparison of this product to salmon:
________Same
________Different
________If different, describe difference.
5. Approximate price paid for similar product(s) ($/lb.) ___________________
6. What would be your demand (lbs.) daily/weekly/monthly)_______________
7. Is ‘produced locally’ important in marketing?
_______Very important
_______Somewhat important
_______Not at all important
8. General Comments (from wholesaler and consumers):- Overall impression:
- Suggestions for improvements:
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Table 4.2.Nitrogen inputs and outputs from integrated multi-trophic aquaculture
Nitrogen input from feed
Total N Total N retained Date inout (kg) in trout (kg)Dec. 2012 37.10 14.0
Total N loss to environment 23.1 kg
Nitrogen extraction bv mussels (weight/m = 25.6 kg)
Total weight Total N Date Total line (m) (kg) Oct. 2013 120 3072
extracted (@ 2.0%) 61.44 kg
Nitrogen extraction bv sugar kelp (weigh t /m = 11.6 kg)
Total weight Date Total line (m) (kg)June 2013 55 638
Total Nextracted (@ 2.4%) 15.31 kg
Total N input from trout production Total N extraction from mussels and kelp
23.1kg 76.75 kg
Net N extracted from the river 53.65 kg
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Table 4.3. Water quality data collected on 7/26/2012, 9/29/2012 and 1/9/2013 during the demonstration project.
Date Temp Current Current DO Salinity
(°C) Direction (°) Speed f°) dH (%) (pot)
7/26 16.3 220 0.18 7.97 101.4 29
9/26 17.5 45 0.35 7.6 87.96 30.8
1/9 5.3 35 0.1 8.0 103.5 30.1
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Table 4.4. Water sampling for nitrogen content was conducted on 7/26/2012,9/29/2012 and 1/9/2013 from three locations; 1) inside the cage, 2) 15 m up current and 3) 15 m down current of the fish cages._______________________________________________
Date 7/26/2012
Water TestDown current of cage Inside case
Up current of cage
NH3 0-0.25 0-0.25 0-0.25
N02 0 0 0
NQ3 0.05-0.1 0.05-0.1 0.05-0.1
Date 9/26/2012
Water TestDown current of cage Inside cage
Up current of cage
NH3 0-0.25 0-0.25 0-0.25
N02 0 0 0
N03 0.05-0.1 0.05-0.1 0.05-0.1
Date 1/9/2013
Water TestDown current of cage Inside cage
Up current of cage
NH3 0-0.25 0-0.25 0-0.25
N02 0 0 0
NQ3 0.05-0.1 0.05-0.1 0.05-0.1
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Table 4.5 Economic spreadsheet (3 yr.) for steelhead trout production in a 100 m3 cage at 20 kg / m3
Expenses Process &Cost / Total Cost Cage/Nets/ Handling
Notes: All expense and income amounts are in US dollars.1 Number stocked is designed to achieve a harvest stocking density of (20 kg/m3).2 Feed costs are based on an estimated FCR of 1.2, and is calculated based on the weight that survive to harvest.3 Boat fuel is estmated at $3.75/gal; 4 gallons/d over 100 days.4 Number alive at harvest is based on 85% survival.5 Crop value at harvest is based on 77% gutted, heads on weight, valued at $14/kg.
Table 4.6 Economic spreadsheet (3 yr.) for steelhead trout production in a 500 m3 cage at 20 kg / m3
Notes: All expense and income amounts are in US dollars.1 Number stocked is designed to achieve a harvest stocking density of (20 kg/m3).2 Feed costs are based on an estimated FCR of 1.2, and is calculated based on the weight that survive to harvest.3 Boat fuel is estmated at $3.75/gal; 4 gallons/d over 100 days.4 Number alive at harvest is based on 85% survival.5 Crop value at harvest is based on 77% gutted, heads on weight, valued at $14/kg.
Table 4.7 Economic spreadsheet (3 yr.) for steelhead trout production in a 1000 m3 cage at 20 kg / m3______
ExpensesProcess &
Year Item Number1Cost/
fingerlingTotal Cost
of fingeriings Feed cost2Cage/Nets/ Handling
Mooring Boat fuel3 $0.50/kg Total costs1 Fingeriings2 Fingeriings3 Fingeriings
IncomeNo. alive
Year at harvest4
900090009000
Mean total wgt. at
harvest (kg)
555
Total round wgt. At
harvest (kg)
450004500045000
Crop value harvest (kg)s
68,66668,66668,666
30,000 3,000 9,563 0 3,000 9,563 0 3,000 9,563
Total:
156228.5126228.5126228.5
$ 408,686
Profit/Loss over 3 years1 7650 2.5 19125 206168oVO 2 7650 2.5 19125 206168 Costs s $ 408,6863 7650 2.5 19125 206168 Income = $ 618,503
Gain = $ 209,817Total: $ 618,503
Notes: All expense and income amounts are in US dollars.1 Number stocked is designed to achieve a harvest stocking density of (20 kg/m3)2 Feed costs are based on an estimated FCR of 1.2, and is calculated based on the weight that survive to harvest.3 Boat fuel is estmated at $3.75/gal; 4 gallons/d over 100 days4 Number alive at harvest is based on 85% survival5 Crop value at harvest is based on 77% gutted, heads on weight, valued at $14/kg.
Figure 4.1. A. Two trout cages moored at the mouth of the Piscataqua River, NH used in the integrated multi-trophic aquaculture project. B. Diagram of a fish cage and net with the New Zealand fuzzy rope suspended from the perimeter of the wooden walkway.
Figure 4.2. Natural settlement of sugar kelp on the trout cages in the Piscataqua River, NH.
I l l
Figure 4.3. Fishermen harvesting steelhead trout for local markets in Portsmouth, NH.
112
Figure 4.4. A. Juvenile mussel spat that settled on the New Zealand fuzzy rope suspended around the cage platform. B. Mussel spat that attached onto the nylon mesh fish nets.
Figure 4.5. A. Mussels being set into modified lobster pots for relaying offshore near Gunboat Shoals NH. B. The F/V Beatrice A relocating the mussel pots offshore. They will be harvested and sold in the spring of 2014.
Figure 4.6. A. Spools of juvenile sugar kelp line that was wrapped around 3.0 m polyester lines and submerged 0.5 m below surface in floating fish cage frames for growout (B).
115
u
i AFigure 4.7. Sugar kelp after 4 months growout in the Piscataqua River, NH. Kelp averaged 0.7 m length in April 2013.
116
Nitrogen Input of Feed(45% protein, 22% lipid)
Excretion 50%
Retention 40% (Hardy, 2012)
Figure 4.8. The fate of nitrogen from fish food to the environment.
117
Figure 4.9. A. NH fishermen towing empty cages to site for growout of steelhead trout, mussels and sugar kelp in the Piscataqua River. B. Fishermen gathered around a cage to discuss fish health and feeding.
118
Figure 4.10. A. Harvest of steelhead trout from the sea cages with the Portsmouth fishermen. B. Trout fillets on ice at Sanders Fish Market in Portsmouth, NH for $ 14.99/lb.
119
Figure 4.11. A. Diver with a Go ProTM underwater camera filming a 30 m bottom transect under the sea cages in the Piscataqua River, NH. B. Diver preparing to take a sediment sample with a PVC pipe sampler (5 cm x 10 cm) at the end of the transect.
DISSERTATION SYNOPSIS
This dissertation research had three goals, all of which related to fostering marine
aquaculture in New England. The first (Chapter 1) investigated an alternative cage
material potentially useful in reducing or eliminating bio-fouling, which is a major
problem in cage culture wherever it is practiced. The second was to experimentally
investigate the responses of caged steelhead trout (Onchorhynchus my kiss) to different
culture environments. In Chapter 2, we examined the fishes’ response to high currents,
and associated net deformation, that would be typical of many coastal areas of New
England. In another section (Chapter 3), we gathered preliminary data on the ability of
steelhead to survive and grow in submerged cages, which may be necessary if the
industry grows and expands offshore. In the final chapter (4), we report on the final goals
of the research, which were to provide hands-on aquaculture training to commercial
fishermen, and to evaluate the efficacy of Integrated Multi-trophic Aquaculture (IMTA)
to mitigate the addition of nutrients by the finfish growing operations.
Results of the research reported in Chapter 1 showed that fish cages built from a
copper alloy mesh (Seawire™) had less bio-fouling compared to traditional, nylon mesh
nets, which became heavily fouled with the hydroid Tubularia sp. Further, cod held in
the Seawire and nylon mesh cages for extended periods of time displayed similar feed
conversion ratio, specific growth rates, condition factor and survival. Importantly, Cu
levels were similar in the tissues of cod (gill and liver) held in the two cage types,
indicating that there was no additional Cu ion absorption from the Seawire net material.
121
In addition to reducing bio-fouling, alloy netting such as Seawire also has greater
tensile strength than nylon, and thus is better at retaining fish in the cage, and keeping
predators out. This is especially important in areas with large populations of seals like
New England. Although Seawire has some positive attributes, it is more expensive than
nylon mesh, more difficult to build into cage shapes, and much heavier to deploy and
handle in the field. This initial higher cost, and other negative attributes, may be offset by
less need for net cleaning and mending. As well, Cu alloy nets can be recycled, so the
user can recoup some of the purchase price when the nets are retired.
In Chapter 2 we determined that a biotelemetry system could be used to
simultaneously monitor the shape of a fish cage, and the fish within it. At current speeds
of > 0.2 m / s, we detected some net deformation, and at current velocities of 0.5 m / s,
the net lost > 30% of its volume. During high tidal currents (>_0.35 m / s) trout exhibited
rheotaxis, and the group used a smaller percentage of the cage volume. During slack tides
the fish exhibited typical circular, schooling behavior that utilized more space in the cage.
No differences were found in trout swimming speed, or depth occupied, between night
and day. The small cage size (63 m3) we used may have affected trout behavior, which
makes it difficult to compare our results to other similar studies, or to extend these results
to larger commercial size cages. We believe, however, that understanding fish behavior
in cages is a worthwhile goal since behavior ultimately affects fish welfare and
production. Additional research is certainly warranted, and we are confident that the
techniques we developed will be useful to those who follow.
The three trout submergence studies reported in Chapter 3 had varied results.
Cage size (3.73 - 68 m3), cage material (Seawire™ vs. nylon nets) and fish size (300 -
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1000 g) all contributed to the variation. Despite the variation, the data indicated that
steelhead trout can be submerged for days to weeks with no significant negative effects
on growth or survival. We believe, however, that surface cage systems are preferred
since fish in surface cages have access to the surface to refill their swim bladders. As a
management tool, however, submerging the cages for short periods of time (days to
weeks) to escape adverse surface situations conditions (e.g. storms, high water
temperature, ice, red tide) will be useful, and can now be done more confidently. Future
submergence research should be conducted at deeper depths (> 10 m) because increased
pressure may well have an effect on the behavior and physiology of forcibly submerged
fish.
The final chapter of the dissertation reports on our efforts to involve and train
several NH commercial fishermen on the techniques of small-scale aquaculture, and to
demonstrate and quantify integrated multi-trophic aquaculture as a means of nitrogen
mitigation. The IMTA model demonstrated that N extraction by shellfish and seaweed
exceeded the nitrogen input from trout production. The model was verified through
environmental monitoring, which indicated no measurable environmental effects from
fish production. The information gathered was reported to the EPA and NH Fish &
Game, and we are hopeful it will be useful as they consider future aquaculture permit
applications. The training program provided participating fishers with a new skill set that
they could adopt either part or full-time, to help offset economic hardships caused by
federal management measures that have decreased catch allocations. Seafood markets
were very interested in all three marine species raised during the project. The trout were
sold (gutted, heads on) for $13.20 / kg. The mussels have not yet been sold, but we
123
expect, based on the sale of other cultured mussels, to sell for > $4.00/kg. The sugar kelp
was test marketed at a local restaurant in Portsmouth, NH. Their estimated demand was
10-20 kg / week at a price of $20 / kg.
In summary, we believe we have achieved our overall goals. We have tested an
alternative cage material, and we have conducted experiments on steelhead trout that
have increased our understanding of their behavior and physiology when grown in strong
currents or in submerged cages. We have also provided hands-on aquaculture training to
commercial fishermen, and evaluated the efficacy of IMTA to mitigate the addition of
nutrients associated with finfish production. Finally, we have made an attempt to
evaluate the economics of steelhead aquaculture, at three different scales, which should
be useful as potential growers make early and fundamental decisions in their business
plans.
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Appendix
A. UNH IACUC Approval 2013
University of New Hampshire
Research Integrity Services, Service Building 51 College Road, Durham, NH 03824-3585
Fax; 603-862-356427-Sep-2013
Chambers, Michael D School of Marine Science - EWOS 24 Cokwos Road Durham, NH 03824
The Institutional Animal Care and Use Committee (IACUC) reviewed and approved the protocol submitted for this study under Category C on Page 5 of the Application for Review of Vertebrate Animal Use in Research or Instruction • the research potentially involves minor short-term pain, discomfort or distress which will be treated with appropriate anesthetics/analgesics or other assessments.
Approval Is granted for a period of three years from the approval date above Continued approval throughout the three year period is contingent upon completion of annual reports on the use of animals. At the end of the three year approval period you may submit a new application and request for extension to continue this project Requests for extension must be filed prior to the expiration of the original approval.
Please Note:1. Ail cage, pen, or other animal identification records must indude your IACUC # listed above.2. Use of animals in research and instruction is approved contingent upon participation in the
UNH Occupational Health Program for persons handling animals. Participation is mandatory for aH principal investigators and their affiliated personnel, employees of the University and students alike. Information about the program, including forms, is available at http;//unh.edu/research/occupational-health-Droqram-anlmal-handlers.
If you have any questions, please contact me at 862-4629 or Julie Simpson at 862-2003.
IACUC,
Vice Chair
cc FileHowell, William
125
B. UNH IACUC Approval 2010
University of New Hampshire
Research Integrity Services, Office of Sponsored Research Service Building, 51 College Road, Durham, NH 03824-3585
Fax:603-862-3564
08-Mar-2010
Chambers, Michael Atlantic Marine Aquaculture Center Chase Ocean Engineering Lab Durham, NH 03824
IACUC#; 100204 Category: DProject: SINTEF Bilateral Escape- Use of Biotelemetry to Quantify Fish in Net Pat Movement
Simultaneously
The Institutional Animal Care and Use Committee (IACUC) has reviewed and recommended approval of the protocol submitted for this study contingent upon your response to the following:
1. As the study was proposed as a pilot study (Section 27, C), IACUC approval is limited to one yeaijstudy completion dats should be revised accordingly).2. In Section n, B (personnel information), the IACUC anticipated personnel other than those listed handling fish (e.g., graduate students or other project staff) In the study. Anyone handling animats on the study needs to be Inducted on the application.3. The researcher needs to explain why steelhead trout are being used in the study instead of Atlantic salmon.4. In Section IV, A (experimental design), the researcher needs to address the following:
a. Describe the process for acdhnadng /fefr to saltwater from freshwater, including where the process will take place, the duration, and pertinent Information, such as tank size, water temperature, densities, and feeding schedule.b. Estimate mortality during the acdimadon process (see 4a). c Indude information on the total duration of the expenment.d. Provide details of the process for transporting fish from the source to the pen, and for stacking the pen.
5. In Section V, C (evaluation of outcomes), the IACUC did not consider vocalization as an appropriate outcome for this study so removed this attribute.6. In Section VI, A (method to determine animal numbers), the researcher needs to provide the method for determining the number of animals proposed to have pingers inserted (eight). (The justification for the total number in the pen is adequate.)7. As this pen is a new animal facility, Dr. Dean Bder must inspect the pen and approve the standard operating procedure before any animals are transported to the site.8. The researcher stated that fish will be saved for future use a t the end o f the study. If the pen is to be removed from the ocean, the researcher needs to explain what will happen to the fish (i.e., where the fish will be housed and the details of transportation and stacking). This explanation should specifically Identify what will happen to the fish with pingers inserted.
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9. In Section 7 of the Surgical Procedures Form (surgical procedures), the researcher needs to add Information about surgical site preparation (I.e., stte deaned with cNorhexkffne solution), aeration of the cooler, and the length of time for recovery after F&-222administration.
As soon as the IACUC receives an appropriate response to its concerns, above, it wffl Issue you an approval letter for this protocol. You may not commence activities in this protocol involving vertebrate animals until you frave received IACUC approval. Please respond to the IACUC within sixty days of this letter. If the IACUC does not receive a response within sixty days, your protocol will be withdrawn.
If you have any questions, please contact either Dean Elder at 862-4629 or Julie Simpson at 862- 2003.
For the IACUC,
A. Bolker, Ph.D.Chair
cc: File
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C. NH Aquaculture Permit
H EAD Q U AR TER S: 11 H a re n Ofive, C on cord , N H 0 3 3 0 1 -6 5 0 0 (6 0 3 ) 2 71-3421 FAX (6 0 3 ) 2 7 1 -1 4 3 8
New HampshireFish and Game Department
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TDD A c c e s s R e la y NH 1 -8 0 0 -7 3 5 -2 9 6 4
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Michael Chambers/Hunt Howell UNH. Jere Chase Ocean Engineering Lab 24 Colovos Road Durham, New Hampshire 03(24
MARIHE AQVACVIiTVRE LICENSE 2812-13
In compliance with Part Fis (07 Rules on Aquaculture, the New Hampshire Fish A Came Department has reviewed and approved an application submitted by Michael Chambers aad Huat Howell, for cage culture of steelhead trout (Oncorhynchus m yiia) and blue mussel (Ktytlhu tdulls).
Conditions of the license include:
1. Steelhead juveniles may be provided by Summer Brook Trout Farm in Ossipee, N.H. The fish must be diploid and all female. Prior to movement Don the Ossipee hatchery to the coastal fish cages, health certificates must be reviewed by New Hampshire Fish A Game. Up to 600 may be stocked into the cages in 2012.Blue mussel will be gathered from the wild, caught on lines m coastal New Hampshire waters aad will be suspended around the perimeter of the cage platform.
2. The cage and surrounding cage platform will be moored in a New Hampshire Port Authority approved location using a double mooring block/anchor system. The dimensions of the surface cage shall not exceed 2S' x 30' and have a surrounding walkway of IS* width. The location lies off Newcastle beach at Lat43.04.365/Long 70.42.3>0. The water depth at this site is about 25 It MW. The cage must not be closer than 10' from the bottom on any tide. The area covered by this license is a 1/10 acre pkx.
3. Trout from the Ossipee, Summer Brook Trout Farm will be stocked into the cage at about 150g end be grown to 2-3kg. Hwvest and processing of the fish will be on site or seaward of the site such that no resulting waste remains are washed ashore. Continuing deployment of the cage system will require renewal of the annually issued Marine Aquaculture License.
4. The blue mussels caught there and elsewhere at the she may not be put to maeket as the location is not approved by NHDES for shellfish harvest. Mussels may be disposed of on dry land at a site approved by New Hampshire Fish A Game or at sea m water deeper than 75', beyond the line that demarcates the outer boundary ofthe nitrogen impaired estuary. Disposal either dry land or at sea, must be supervised and attended by New Hampshire Fish A Came. Should the licensee seek to market these blue mussels, an acceptable plan for relocating them to an area approved by NHDES for harvest and culturing them in the new location for a sufficient amount of time must be developed by the stale agencies (NHF A G. NHDES, and NHDHHS). The plan, which will include provisions for state personnel observation of the relocation operations and appropriate labeling and documentation of relocated product will become a required condition of this license.
(60S) 788-31*4 FAX (* 0 0 )7 8 * 4 8 2 3
•mail: reg l •w M H e.nh.gov
829B Hem S eeet Lancaster, NH 03684-3*12
REGIO N 1
(603) 744*5470 FAX (803) 744-8302
email: i e g 2 < wS0He.nh.gov
N ew Hampton. NH 0325*
REGION 2 PO Bo* 417
Durham, NH 03824-4732(8 0 3 )8 8 8 -1 0 9 6
FAX (803) 868-3306
8EGJQH3 2 2 5 Main Street
R E G IO N *15 A sh Brook Court K eene. NH 03431
< 003)362-9880 FAX (803) 362-879*
emaS: reg30 iisatei.nh.gov em ail reg4«w *dSte.nh.|
128
NH Fish and Game Cont.
5. Environmental monitoring at tbe cage site shall consist of biannual video inspections by underwater camera ofthe tea floor at key locations at and around the cage. In addition, water quality testing on a bimonthly frequency is required.Further detail of the required environmental monitoring is in the attached Environmental Monitoring Program
6. Any observed disease problems shall be reported immediately to the Executive Director and the Chief of Marine Fisheries Division of the New Hampshire Fish & Game Department, followed by a letter outlining die circumstances and providing as much dkail as possible.
7. Any control methods for eradication or removal of project fouling organisms, predators, or diseases other than by hand and pumped water shall be discussed with the Chief of Marine Fisheries, New Hampshire Fish ft Game Department Written approval of control methods must be obtained from the Executive Director prior to implementation.
8. The permittee shall notify the Executive Director and the Chief of Marine Fisheries within 48 hours of any unusual event as defined in Fis 807.08.
9. Aquaculture operations shall not interfere with or cause damage to recreational and/or commercial activities in and around the licensed she including, but not limited to, lobster traps, moorings, navigational aids, and piers.
10. Annual reports of disposal of aquaculture products shall be made in accordance with Fis 807.10.
11. A copy of records relevant to harvesting (i.e. dates, quantity harvested, etc.) and disposition of aquaculture product shall be retained by the permittee for a period of one year (or until turned over to New Hampshire Fish ft Game Department). Such records shall be subject to inspection at any time by fee Executive Director or his agent.
12. This license is valid upon the applicants receiving all necessary federal or state permits.
13. The permittee shall prepare and submit to New Hampshire Health and Human Services a Hazard Analysis Critical Control Point Plan (HACCP) thirty (30) days prior to the marketing of shellfish.A copy of this shall be sent to fee New Hampshire Fife ft Game Department
This license shall expire on December 31,2012, unless sooner revoked or rescinded. The annual report required by Fis 807.10 must be submitted by January 31 of 2013.
GN/BWS/vjb
Enclosure
cc: Doug Grout, Chief Marine FisheriesLt. Jeffrey A. Marston Law Enforcement Sandy Falicon, Rules Coordinator
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