Dr. John Volpe Biological Sciences University of Alberta jvolpe@ualberta
Post on 22-Jan-2016
17 Views
Preview:
DESCRIPTION
Transcript
Dr. John VolpeBiological Sciences
University of Albertajvolpe@ualberta.ca
Testing assumptions associated with farm-escaped Atlantic salmon in British
Columbia
Issues
• Visual pollution (ecotourism)• Site contamination (organic & pharmacological)• Anti predator methods• Disease transfer to / from wild salmonids
• Ecological consequences of escapees
2001
1984 Import of S. salar eggs for aquaculture
1905
1934
5.5 - 13.2 M eggs + alevins released in B.C. Interspecific agonism (ST) 10 resistance factor
1987 First capture of S. salar in B.C. waters
1991 First reported escape of S. salar
1997First Atlantic salmon research on Pacific coast initiated
Phase I research complete
1995 SAR initiated
SAR released
Escapes of Atlantic salmon are rare
Escapes of Atlantic salmon are inevitable but they won't survive in the wild
Some Atlantic salmon may survive but will not ascend freshwater rivers
Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
Spawning is likely to occur but progeny will not be competitively viable
And finally, the current position, There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
⟨Escapes of Atlantic salmon are rare
⟨Escapes of Atlantic salmon are inevitable but they won't survive in the wild
⟨Some Atlantic salmon may survive but will not ascend freshwater rivers
⟨Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
⟨Spawning is likely to occur but progeny will not be competitively viable
And finally, the current position,⟨There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
Revenueloss
resulting from
escapedfish
Retention of salmonin net pens
Cost of building / maintaining net pens
0%
100%
According to DFO’s ASWP 396,552 Atlantic salmon have been reported as escaped 1991-2001
Escapes of Atlantic salmon are rare
Escapes of Atlantic salmon are inevitable but they won't survive in the wild
Some Atlantic salmon may survive but will not ascend freshwater rivers
Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
Spawning is likely to occur but progeny will not be competitively viable
And finally, the current position, There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
Atlantic salmon are commonly part of commercial salmon catches from Alaska to Washington
No data are available regarding the source of these fish(physical or DNA tags) or period since escape and performance in the interim (otolith microstructure / stableisotope analyses)
⟨Escapes of Atlantic salmon are rare
⟨Escapes of Atlantic salmon are inevitable but they won't survive in the wild
⟨Some Atlantic salmon may survive but will not ascend freshwater rivers
⟨Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
⟨Spawning is likely to occur but progeny will not be competitively viable
And finally, the current position,⟨There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
Atlantic salmon have been reported in 77 BC streams and rivers
Atlantic salmon are now part of the terrestrial food webvia predation
⟨Escapes of Atlantic salmon are rare
⟨Escapes of Atlantic salmon are inevitable but they won't survive in the wild
⟨Some Atlantic salmon may survive but will not ascend freshwater rivers
⟨Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
⟨Spawning is likely to occur but progeny will not be competitively viable
And finally, the current position,⟨There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
Tsitika River August 18 1998
•58 m channel
•Heterogeneous habitat
•30 females; 20 males transplanted without acclimatization
• 1/3 females spawned• Spawning initiated
in mid January
Spawning Chronology
Sept Oct Nov Dec Jan Feb Mar Apr May
Pink
Sockeye
Chinook
Chum
Coho
Steelhead
Little Qualicum Atlantic Salmon
Wild Atlantic salmon in native range
• Natural reproduction• Two year classes present (0+ & 1+)• ~50 juveniles identified to date• Sympatric with strong steelhead population
0+ 1+
0+ AS 0+ ST 1+ AS 1+ ST
Mean ForkLength (mm)
Mean CF(g x 100)/cm3
n
63.75 ±3.3 55.42 ±5.81 119.25±5.52 92.59±10.46
2.94±0.60 1.91±0.54 19.61±4.01 8.67±2.75
1.12 1.16 1.12 1.10
4 33 8 33
Mean Weight (g)
Port Hardy
Campbell R.
Nanaimo
Victoria
Tofino
Port Alberni
Feral Atlantic Salmon populations in Vancouver Island Rivers
Eve R.N
100 km
Amor de Cosmos Cr.Tsitika R.
<1% potential spawning and rearing habitat has been surveyed on Vancouver Island. Coastal mainland systems remain entirely uninvestigated.......?
⟨Escapes of Atlantic salmon are rare
⟨Escapes of Atlantic salmon are inevitable but they won't survive in the wild
⟨Some A tlantic sa lmon may survive but will not ascend freshwater rivers
⟨Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
⟨Spawning is likely to o ccur but progeny will not be competitively viable
And finally, the current position,⟨There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
Wetted area:2.2m x 0.6m x 0.9 m
Coarse river cobble (19.4 5.6cm)
~ 10% replacement perhour
Flow 0.85 ms-s (4542.5 L min-1)
10 hp centrifugal pump
Water temp maintained by a 240V, 60amp chiller
Clear Lexan viewing windows
Natural prey provided by a unique “upweller”feeding system
4 AS 4 AS
4 AS
4 AS
4 ST4 ST
4 ST4 ST4 ST
4 AS
High Forage
AA SA assembly
4 AS 4 AS
4 AS
4 AS
4 ST4 ST
4 ST4 ST4 ST
4 AS
Low Forage
SS AS
Treatments• High / low forage• Density• Intra- / interspecies comp.• Assembly of “community”
Response Variables• Growth• Foraging• Agonism (action + result) • Territory size
comp. coefficient (Δ g)A = Atlantic salmonS = Native Steelhead
ST on average engage in agonism 5:1 over AS ST show agonistic bias towards other steelhead 2 : 1
AS show bias towards steelhead2.2 : 1
Therefore, steelhead are agonism targets, Atlantic salmon are not
Of all treatment combinations the only consistent and significant predictor of performance is assembly order
Residents with 3 days prior residency performed better than challengers under all conditions - regardless of all other parameters
Atlantic salmon
Perform wellrelative to steelhead
Perform poorly relative to steelhead
+ residency - residency
1905-1934: Very low likelihood of establishing prior residency in Vancouver Island rivers
Today: Vancouver Island steelhead populations are at ~ 10 - 20% of historical abundance
Potential for successful colonization is likely much
higher today than during historical intentional introductions
Are production fish capable of spawning?
Sufficient spawner densities for natural reproduction?
YES (3)
YES
Are juvenile Atlantic salmon competitively viable?
YES
YES (qualified)
Are such conditions present in coastal B.C.?
Presence of feral populations?
Feral individuals perform as predicted?YES
At present YESHistorically NO
Prognosis?
Pink salmon smolts
June 2001
Sea lice are native however the density of farms may act as bio-magnifiers of parasites and disease such that the migratory habitat becomes saturated ie. pink smolt run
⟨Escapes of Atlantic salmon are rare
⟨Escapes of Atlantic salmon are inevitable but they won't survive in the wild
⟨Some Atlantic salmon may survive but will not ascend freshwater rivers
⟨Some adult Atlantic salmon are likely to be found in freshwater rivers but can't spawn
⟨Spawning is likely to occur but progeny will not be compet itively viable
And finally, the current position,⟨There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
The Explanation Cascade
There is no scientific evidence to show that the presence of feral juvenile Atlantic salmon in some rivers pose a threat to native populations.
There is no evidence that salmon aquaculture as currently practiced in BC will not result in serious harm to native
salmon populations or their environment.
Principle 15 of the 1992 Rio Declaration on Environment and Development (towhich Canada is a signatory) explains the precautionary principle as, "Wherethere are threats of serious or irreversible damage, lack of full scientific certaintyshall not be used as a reason for postponing cost-effective measures to preventenvironmental degradation."
1) all reasonable actions must be taken to protect the environment
2) inherent to this statement is the understanding of “reverse onus” - the burden of proof lies with industry to satisfactorily demonstrate their activity is not detrimental to the environment. The burden is not on the public to demonstrate the opposite
top related