Communal larval rearing of European lobster (Homarus gammarus): Family identification by microsatellite DNA profiling and offspring fitness comparisons

wwwelseviercomlocateaqua-online

Aquaculture 247 (

Communal larval rearing of European lobster (Homarus

gammarus) Family identification by microsatellite

DNA profiling and offspring fitness comparisons

Knut E JoslashrstadaT Paulo A Prodfhlb Tore S Kristiansena Maria Hughesb

Eva Farestveita John B Taggartbc Ann-L Agnalta Andy Fergusonb

aDepartment of Aquaculture Institute of Marine Research PO Box 1870 Nordnes 5024 Bergen NorwaybSchool of Biology and Biochemistry Queens University Belfast N Ireland

cInstitute of Aquaculture University of Stirling Scotland

Received 15 November 2003 received in revised form 1 February 2005 accepted 1 February 2005

Abstract

Stock enhancement experiments of European lobster (Homarus gammarus) have been carried out around the Kvitsoslashy

Islands in south-western Norway since 1990 In addition to releases of coded wire tagged lobster juveniles (cultured) and

subsequent monitoring of commercial fishery a lobster hatchery was established in 1997 Several experiments were made on

the communal-rearing approach where the performance of mixed larval groups (families) was evaluated under identical

conditions Berried females of wild and cultured origin and their respective fertilised eggs were screened by using microsatellite

DNA profiling involving a multiplex set of six lobster specific primers thereby allowing determination of both parental

genotypes Each female were kept separately during hatching and the offspring were later mixed and raised in a communal

rearing system The early-larval survival was estimated at stage IV (bottom stage) and the survivors were identified to family

and group by microsatellite profiling Five different communal experiments were conducted representing offspring from 65

berried females Of the surviving larvae 63 could not be assigned to family due to degraded DNA and no PCR amplification

Significant differences in early survival between offspring of wild and cultured origin were found in the experiments No

differences between the groups were found in stage IV larval size Based on the pooled data on survival (as a measure of early

larvae fitness) offspring of cultured females displayed a relative fitness of 60 in comparison to offspring from wild females

Large variation in survival was also observed among families within the bwildQ and bculturedQ groups suggesting a genetic

component for these traits and a potential for selective breeding

D 2005 Elsevier BV All rights reserved

Keywords European lobster Homarus gammarus Microsatellite DNA profiling Communal rearing Offspring survival Stock enhancement

0044-8486$ - s

doi101016jaq

T CorrespondiE-mail addr

2005) 275ndash285

ee front matter D 2005 Elsevier BV All rights reserved

uaculture200502025

ng author Tel +47 55 236347 fax +47 55 236379ess knutjoerstadimrno (KE Joslashrstad)

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285276

1 Introduction

The European lobster (Homarus gammarus) is an

important and prized seafood species commanding a

premium retail price With wild lobster catches in

decline in many areas commercial interest is now

considering the establishment of lobster hatcheries for

stock enhancement schemes and the potential devel-

opment of a lobster farming industry (Bannister and

Addison 1998 Gendron 1998 Nicosia and Lavalli

1999) Hatchery production particularly of highly

fecund species can relatively quickly have deleterious

genetic consequences unless carefully managed The

problems with both deliberate and inadvertent domes-

tication selection have been discussed in detail else-

where (eg Allendorf and Ryman 1987 Busack and

Currens 1995 Campton 1995 Waples 1999) and

several recommendations have been proposed (eg

Kapuscinski and Jacobson 1987 Pepper and Crim

1996) Indeed an awareness of potential genetic

consequences are considered part of the bresponsibleapproach to marine enhancementQ proposed by

Blankenship and Leber (1995)

One particular concern to date mainly addressed

through research on salmonid fishes is that inter-

breeding between wild and domesticated individuals

(either escapes or deliberately stocked) could result in

genetic changes in wild populations which could

reduce the overall fitness and productivity of local

stocks (Utter et al 1993 Utter 2000) In the worst

case such introgression of non-adaptive genes into a

local population may lead to extinction Though direct

experimental evidence is as yet very limited work

on Atlantic salmon (Salmo salar L) has demonstrated

reduced survival and life-time success for farmed and

hybrid offspring compared to wild salmon progeny

(Fleming and Einum 1997 McGinnity et al 1997

Fleming et al 2000 McGinnity et al 2003)

A large-scale European lobster stock enhancement

experiment was initiated in Norway in 1990 with the

establishment of a hatchery at Kyrksampteroslashra south of

Trondheim Between 1990 and 1994 128000 lobster

juveniles were reared microtagged and released as

juveniles (age 1 year 30ndash60 mm total length) around

the Kvitsoslashy Islands in western Norway (Agnalt et al

1999 Agnalt et al 2004) The hatchery production of

juvenile lobsters for release was based on wild

berried females mainly collected from the release

areas at Kvitsoslashy The artificial production of larvae

and juveniles was however very different to the

natural environment Each juvenile lobster was reared

in a separate compartment from the stage IV until

large enough to be released (Grimsen et al 1987

Balchen 1999) Over 90 of the lobster landings at

Kvitsoslashy were monitored for cultured survivors from

1992 until 2002 During this period a yearly increase

in the proportion of cultured lobsters in the landings

(up to 50ndash60 between 1997 and 2001) was

observed (Agnalt et al 1999 Agnalt et al 2004)

The availability of berried females of both wild and

cultured origin and the opening of a local commercial

lobster hatchery in Kvitsoslashy provided a unique

opportunity to explore some of the genetic conse-

quences of the enhancement program This study was

undertaken as part of the EU funded GEL (bGeneticsof European LobsterQ) project (wwwqubacukbb

prodohlGELgelhtml) In this paper we report one

aspect of this work namely the use of microsatellite

DNA profiling (developed in GEL) to compare early

larval survival (to stage IV) from berried females of

wild and cultured origin reared in mixed family tanks

2 Materials and methods

21 Broodstock collection

In western Norway most of the mature female

lobsters spawn every second year (Agnalt unpub-

lished data) from August to September They carry

the eggs attached under the tail throughout the winter

season and hatching normally occurs during the

following summer Berried lobsters were sampled

from the local landings at Kvitsoslashy from October to

December 1999 and origin (wild or cultured) was

classified by absence or presence of magnetic micro-

tags It must be emphasized that cultured females that

had lost their microtag would be erroneously classi-

fied as wild Thus several hundred females were

purchased as potential broodstock from local lobster

fishermen and transferred and kept in a large marine

holding facility during the winter Each female was

tagged externally by an individually numbered stream

tag (Hallprint)

An examination of the broodstock collection in

March 2000 revealed that 84 wild and 76 cultured

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285 277

females had eggs considered appropriate for the

experiments The status of some of the eggs suggested

too early hatching related to the start of the experi-

ments and for this reason additional berried females

were also collected during the spring fishery 2000

(AprilndashMay) Berried females (22 individuals) were

also collected for use as wild references from another

location (Rennesoslashy) in Rogaland All potential brood-

stock lobsters (about 200) were transferred to a

holding basin at Kvitsoslashy Lobster Hatchery where

they were sorted according to broodstock group

(KW=Kvitsoslashy wild KC=Kvitsoslashy cultured RO=Ro-

galand wild) and presumed hatching time of the eggs

Carapace length was recorded to closest mm below

and body weight to closest gram for each female

22 Hatching of larvae

To minimise differences broodstock from each

female group were selected based on similar size and

projected hatching time The females with eggs ready

to hatch were transferred to single hatching tanks (100

l) where the newly hatched larvae were sieved from

the overflow water in the hatching tanks every night

and collected in 15-l bottles with 1 mm screens

placed in a water bath The bottles were emptied every

morning and the larvae were counted before trans-

ferred to the mixed family larval tanks

Egg sizes at transfer to hatching tanks were

measured and sub samples of fertilised eggs from

each female were stored in 99 ethanol for micro-

Table 1

Survival of newly hatched lobster larvae to stage IIIIV in mixed family l

Experiment Group Released Observed Expected

1 KW (7) 671 24 21

KC (9) 900 17 28

RO (5) 500 23 16

2 KW (9) 900 55 52

KC (8) 800 33 46

RO (7) 700 50 40

3 KW (7) 660 53 422

KC (10) 1000 53 640

4 KW (6) 600 65 582

KC (6) 600 51 582

5 KW (4) 400 83 416

KC (6) 562 42 573

Survival index is the ratio between observed and expected survival Num

experimental group and in the experiment Experimental periods were as f

experiment 3 18ndash31 July experiment 3 28 Julyndash12 August experiment

satellite DNA profiling Following the hatching

period the females were removed from the tanks

and a tissue sample (walking legperiopod) was taken

and stored in ethanol together with the corresponding

egg sample Hatching occurred over an extended

period from June 28 to July 31 The newly hatched

larvae from each night were collected and counted

Only larvae hatching the same night were used for the

mixed tank experiments Even with the large brood-

stock available for the experiments it was not

possible to achieve synchronised hatching from as

large number of females from the three groups as

originally planned Thus five sequential communal

tank experiments were carried out (Table 1) The first

experiment was initiated in June 28 was several

weeks earlier than originally planned The dates for

the duration of the various experiments are given in

legend to Table 1 and the total experimental period

lasted 45 days

23 Experimental design

The overall design was such that 100 newly

hatched larvae from each female were mixed together

in the same larval tank In three cases a smaller

number of larvae were used due to low hatching in

some families for that particular night (see Table 1)

Ten of the newly hatched larvae from each family

group were measured to estimate average total length

in millimeter at hatching The offspring groups were

from 65 different females where 30 were of cultured

arval tanks

Survival index P (G-test) all P (G-test) KW KC

117

061 0012 0041

148

106

072 0034 0064

124

126

083 ndash 0028

112

088 ndash 017

199

074 ndash b0001

ber in parenthesis gives the actual number of families used in the

ollows experiment 1 28 Marchndash18 July experiment 2 05ndash21 July

5 30 Julyndash12 August

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285278

origin and 24 were classified as wild from the Kvitsoslashy

region Eleven females were wild lobsters (RO)

collected at Rennesoslashy Offspring from 17 different

females were used in two different experiments (see

below)

The study focused on performance in the early

larval stages expressed as survival and growth The

newly hatched lobster larva (stage I) is pelagic and

undergoes three moultings over a 2ndash3 weeks period

(depending on temperature) before reaching the first

bottom-dwelling stage (stage IV) The bmixed family

larvalQ tanks were made of 100 l circular dark green

polyethylene containers with flat bottom A water

hose with 4 mm holes drilled on the top was placed in

circle on the bottom on the tanks to make an

upwelling current About 10 l recirculated 18ndash20 8Cseawater were supplied per min and all tanks were

supplied with the same water (from the same

recirculation system) This temperature was about

the ambient temperature in the surface in Julyndash

August and the optimum temperature for lobster

development An overflow pipe was connected to a 1

mm meshed screen that was changed and washed

every day

The larvae were fed frozen Artemia supplemented

with small fresh mysids (Praunus sp) in access

every morning and evening At later stages small

frozen krill (Thysanoessa sp) were also added as

feed Cannibalism was observed especially after the

larvae reached stage IV and thus to prevent too high

mortality the experiments were terminated before all

larvae had reached the stage IV At termination the

moulting stage and total length of all larvae were

recorded to closest millimeter and the specimens were

stored in individual bottles in 99 ethanol and

transported to Queenrsquos University in Belfast for

microsatellite DNA profiling to family and experi-

mental group

24 Microsatellite DNA profiling

The sample collection consisted of the berried

females fertilised eggs from each female (to deduce

paternal DNA profile) and the survived stage IIIIV

larvae from each of the five experimental tanks Except

for the egg samples where a simple Chelex extraction

(Altschmeid et al 1997) was performed conventional

phenolchloroform DNA extraction was used for all

samples (Taggart et al 1992) All samples were

screened with a multiplex primer set comprising of six

microsatellite loci (Hgam-106 Hgam-21 Hgam-47b

Hgam-153 Hgam-105 and Hgam-197b) developed

at Queens University on a LiCork automated DNA

sequencer Control samples (ie samples of known

genotype) were employed to ensure accuracy and

consistency of typing The GeneProfiler (v346)

software (Scanalytics) was used to collect genotypic

data from the LindashCor system All data was subse-

quently compiled into an Excel (Microsoft) database

prior to subsequent analyses Male contribution in

each family was established by visual inspection (ie

subtracting observed maternal contribution from lar-

vae multilocus genotype) Family and group (KW KC

RO) assignment was carried out with the program FAP

(Family Analysis ProgramndashFAP J Taggart University

of Stirling unpublished) Of the 599 larvae collected at

termination of the mixed family experiments 561 were

unambiguously assigned to individual family The

remaining 38 individuals (63) could not be assigned

due to technical problems associated with low DNA

yieldquality (ie degraded DNA which consistently

failed to amplify for a number of loci)

One-sided G-tests (with Williams correction Sokal

and Rohlf 1995) were used to test whether the

average survival rate in the ranched groups were

smaller than the wild groups (all families within

groups pooled) in all the five experiments (Table 1)

The expected survival for each group and family was

set to be the average survival rate for the tank The

survival index for each group was calculated as the

ratio of (observed survival)(expected survival)

Si j frac14 ni jd m1i j

Ani jd Am

1i j

1

eth1THORN

where nij and mij are numbers at termination and start

of experiment respectively from family i in experi-

ment j and Anijd Amij1 is the total number at

termination divided by the total numbers released in

experiment j (average)

3 Results

The broodstock selection aimed to minimise differ-

ences in body size and time of hatching However

even with the relative large pool of berried females

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285 279

available from the Kvitsoslashy fishery this was difficult to

achieve The correlation between female carapace

length (CL) and egg size (Fig 1A) was significant

when all groups were pooled (r =039 P b0001) but

only for the RO where the broodstock had the largest

size range when the groups were analysed separately

(KC r=017 P=009 KW r =030 P=013 RO

r =092 P b0001) The correlation between CL and

size of stage I larvae was also significant for the

pooled groups (r =043 P b0001) However when

the groups were analysed separately there were no

significant correlation between CL and stage I larvae

length for any of the groups (KC r =032 P=0051

KW r=029 P=013 RO r =053 P=011) (Fig

1B) There was also a positive correlation between

16

18

20

22

24A

B

80 90 100

Mother size (cara

Mother size (carap

Egg

siz

e (m

m)

80

84

88

92

96

100

80 90 100

Tot

alt l

engt

h (

mm

)

Fig 1 (A) Mean egg size (mm) prior to hatching and (B) Mean total length

berried female used in the experiments

egg size and stage I larvae (r=039 P b0001 pooled

groups) At the termination of the experiments there

were no significant differences between groups (KW

KC RO) in relation to the size of the stage IV larvae

(Fig 2)

The survival of larvae was lower than expected

ranging from only 31 (exp 1) to 129 (exp 5)

with an overall average value of 71 for the pooled

data indicating relatively poor survival conditions in

the rearing tanks The pooled survival estimates for

each of the three groups (KW KC and RO) in the five

different experiments are given in Table 1 A survival

index larger than 10 indicates better survival com-

pared to the average value in each of the experiments

In all experiments (Table 1) the KW group had better

110 120 130

KW

KC

RO

pace length in mm)

ace length in mm)

110 120 130

of newly hatched larvae compared to body size (carapace length) of

8

10

12

14

16

18

KW KC RO KW KC RO KW KC KW KC KW KC

Exp 1 Exp 2 Exp 3 Exp 4 Exp 5

Stag

e IV

- m

ean

tota

l len

gth

(mm

)

Fig 2 Mean size of stage IV larvae at sampling for the three offspring groups in the various mixed family larval experiments

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285280

than average survival index values ranging from 103

to 199 In contrast the corresponding values for the

KC group were 061ndash088 Survival index values for

the RO group were even higher than the KW group In

four of the five tanks the KW group had significantly

higher survival (G test) than for the KC group (Table

1) The overall survivals based on pooled data from all

experiments revealed higher estimate for KW (86)

compared to KC (51) This indicates that the

offspring from berried cultured females have only

60 of the survival of the offspring from wild females

in the pelagic larval stage estimated under the given

experimental conditions

Based on the microsatellite DNA assignments the

survival indexes for each family within the three groups

were calculated Several females were used in two of

the experiments and thus providing family perform-

ance information in two tanks Eight families were

y = 17248x + 01805

R2 = 076140

1

2

3

0 1 2 3

Survival index (exp 1)

Surv

ival

inde

x (e

xp 2

)

Fig 3 Correlation between survival indexes in two different ex

tested in both exps 1 and 2 and the correlation between

the survival indexes (r=082 P=0013) is shown in

Fig 3 Clearly the high performing families were the

same regardless of tank with similar trend observed for

the low performing families This was further con-

firmed in experiment 4 and 5 In these later experi-

ments nine families were represented and an even

stronger correlation was found (r=096 P b0001)

The families were ranked according to their

survival index and Fig 4 summarizes the rank

distributions for all three groups of broodstock

Average values were used for families that were

tested in more than one experiment All groups have a

similar rank distribution and when family variation

were taken into account there were no significant

differences between groups (ANOVA F(274)=0638

P=053) However it is interesting to notice that the

KW group has six of the ten highest ranked families

0 1 2 3

y = 09608x + 00801

R2 = 093030

1

2

3

Survival index (exp 4)

Surv

ival

inde

x (e

xp 5

)

periments for families that were used in both experiments

Fig 4 Ranking of the survival index of families from three groups of broodstock raised in mixed family larval tanks Rank number was given to

each family based on the pooled data but are plotted separately for each group

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285 281

while the KC group is represented only with three

families Conversely the KC group had five families

with no survival compared to one family for the KW

group

A number of comparisons were conducted to

investigate relationships between the observed family

survival and various biological characteristics In Fig

5 the survival index is plotted against size (carapace

length) of the berried females used for the three

groups of females Although no significant correlation

was observed for the pooled groups or the individual

KW and KC groups a significant relationship was

suggested in the RO group (r =077 P=0006) For

the pooled groups a significant correlation was found

between average stage I size and survival index of the

family (r =037 P=00011)

4 Discussion

This study was carried out to compare relative

fitness of wild and cultured broodstock (measured as

y = 00588x - 46165

R2 = 00964

0

2

4

6

80 85 90 95 100 105 110 115 120 125 130

Surv

ival

inde

xSu

rviv

al in

dex

Surv

ival

inde

x

y = 00355x - 24305

R2 = 00388

0

2

4

6

80 85 90 95 100 105 110 115 120 125 130

Mother size (carapace length in mm)

y = 00396x - 31682

R2 = 05879

0

2

4

6

80 85 90 95 100 105 110 115 120 125 130

Fig 5 Survival index and size (carapace length) of berried females from three groups of broodstock used in the mixed family larval

experiments

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285282

offspring survival) in connection with the large-scale

stock enhancement program at the Kvitsoslashy Islands

(Agnalt et al 1999 2004) The experiments focused

on the pelagic stage from hatching of larvae to first

bottom living stage (stage IV) This particular period

is believed to be most critical for survival due to

exposure to predation including cannibalism The

high larval densities observed in holding tanks in

lobster hatcheries (Aiken and Waddy 1995 Grimsen

et al 1987 Nicosia and Lavalli 1999) means that

cannibalism is possibly one of the main problems

Thus differences in fitness between distinct families

and groups (ie offspring mortality) are likely to be

expressed most clearly in this period

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285 283

One of the objectives of lobster-enhancement

programmes is to rebuild local stocks in order to

ensure long-term sustainability of the fisheries Thus

the reproductive success of the released hatchery

produced lobsters and the performance of their

offspring under natural conditions are essential for

obtaining a positive long-term effect Monitoring of

local lobster such as in the Kvitsoslashy region is

expensive and time consuming The development of

lobster specific microsatellite primers which allow for

the unambiguous identification of individuals to

family offers an alternative and costeffective strategy

for the direct comparisons of offspring survival and

growth under the same environmental conditions In

the mixed-family experiments described here the

results clearly demonstrate that offspring of the

cultured group (KC) displayed only about 60 of

the survival relative to the wild group (KW)

Furthermore the differences in offspring survival

observed between the KC and KW groups can not

be explained by variation in berried female size

fertilized egg or larval size Within each of the three

experimental groups however a large family varia-

tion in offspring survival was observed Although no

significant differences where observed among the

groups (ie degree of family variation among groups

is quite similar) it is worth noticing that the KC

groups had the larger number of families with no

survivors while the KW groups dominated the

number of surviving families

One of the main concerns about interaction between

wild and farmed populations is that interbreeding is

likely to cause reduction in population fitness under

natural conditions This has been linked to population

decrease and in worst-case scenarios to population

extinction Although studies providing empirical sup-

port for this are still rare the long term investigation on

Atlantic salmon (McGinnity et al 2003) which

evaluated the performance of various groups com-

prised of wild farmed and hybrid fish (first and second

generation back-crosses) has clearly demonstrated

significant reductions in overall life-history fitness

for the later two groups In the lobster experiment

described here a reduction in fitness of the cultured

individuals (ie poorer offspring survival) is evident

Part of the reason for the high mortality rate

observed in the mixed family tanks is possibly related

to cannibalism among the larvae caused by the high

density in these artificial environments Thus this

represents a very extreme situation compared to wild

conditions The natural produced offspring from

cultured females are now also hatching under wild

conditions at Kvitsoslashy Island and these are not

exposed to high larvae densities and cannibalism as

in the hatchery environment described above How-

ever they are exposed to all other kinds of environ-

mental pressures (eg predators) Thus a reduction in

early survival of pelagic larvae of cultured origin

under natural conditions will possibly limit the long-

term rebuilding of lobster stock by hatchery oper-

ations With reference to the salmon studies (McGinn-

ity et al 1997 McGinnity et al 2003) the offspring

of wild and farmed broodstock have intermediate

fitness between the pure wild offspring and the pure

farmed offspring In the lobster case the eggs of the

various females used in the experiments were actually

fertilised under natural conditions and we have no

information about the males involved At least

theoretically both experimental groups KW and

KC could consist of some offspring groups that are

actually bhybridsQ between wild and cultured lobsters

This implies that the experiments described here

should be extended incorporating new approaches

where origin of both male and female broodstock is

known and various crossing schemes between wild

and cultured lobsters are followed

The large variation in survival between families

and groups is also of importance for future lobster

farming The high correlation in survival of the same

families in different experiments clearly indicates

consistent differences in performance Commercial

farming of American lobster has been discussed for

over 20 years (see review of Van Olst et al 1980

Aiken and Waddy 1995 Nicosia and Lavalli 1999)

and growth performance has been tested in a variety

of hatchery approaches demonstrating the high

growth potential of lobsters to reach market size of

about 400 g in 2 years (Hedgecock and Nelson 1978

Hedgecock et al 1976) For the European lobster

high survival and growth were observed for juveniles

(after stage IV) in tanks with natural substrate and

shelters (Joslashrstad et al 2001) The application of

molecular markers as described here also opens for

the opportunity for detailed comparisons of family

performance in communal rearing of lobster juveniles

at least in the early bottom stages Thus reliable

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285284

estimates of heritabilities for important traits such as

survival growth disease resistance and aggression

could be readily obtained in new up scaled experi-

ments following the design described here Such

experiments are now developed together with com-

mercial interests and will provide new and important

information for development of a future lobster

farming industry

Acknowledgements

The experiments were part of GEL (bGenetics of

European LobsterQ) with financial support from EC

FAIR CT98 4266 We are indebted to Einar Noslashstvold

at Kvitsoslashy Lobster Hatchery Kvitsoslashy Norway for

using the hatchery facilities and close cooperation

during this study Directorate of Fisheries Bergen

supported the collection of berried females in the

Kvitsoslashy lobster fishery

References

Agnalt A-L van der Meeren GI Joslashrstad KE Nampss H

Farestveit E Noslashstvold E Sv3sand T Korsoslashen E

Ydsteboslash L 1999 Stock enhancement of European lobster

(Homarus gammarus) a large scale experiment off south-

western Norway (Kvitsoslashy) In Howell B Moksness E

Sv3sand T (Eds) Stock Enhancement and Sea Ranching

Fishing New Books Blackwell Science Oxford United

Kingdom pp 401ndash419

Agnalt A-L Joslashrstad KE van der Meeren GI Noslashstvold E

Farestveit E Nampss H Kristiansen T Paulsen OI 2004Enhancing the European lobster (Homarus gammarus) stock at

Kvitsoslashy Islands perspectives on rebuilding Norwegian stocks

In Leber K Kitada S Blankenship HL Sv3sand T (Eds)Stock Enhancement and Sea RanchingndashDevelopments Pitfalls

and Opportunities Blackwell Publishing Ltd pp 415ndash426

Aiken DE Waddy SL 1995 Biology of the lobster Homarus

americanus In Factor JR (Ed) Aquaculture Academic

Press New York pp 153ndash175

Allendorf FW Ryman N 1987 Genetic management of hatchery

stocks In Ryman N Utter F (Eds) Population Genetics and

Fishery Management University of Washington Press Seattle

WA USA pp 14ndash159

Altschmeid H Hornung U Schlupp I Gadau J Kolb R

Schartl M 1997 Isolation of DNA suitable for PCR for field

and laboratory work Biotechniques 23 228ndash229

Balchen JG 1999 Thirty years of research on application of

cybernetic methods in fisheries and aquaculture technology

Modeling Identification and Control 21 (2) 3ndash64

Bannister RCA Addison JT 1998 Enhancing lobster stocks a

review of recent European methods results and future prospects

Bulletin of Marine Science 62 (2) 369ndash387

Blankenship HL Leber KM 1995 A responsible approach to

marine stock enhancement American Fisheries Society Sym-

posium 15 166ndash167

Busack CA Currens KP 1995 Genetic risks and hazards in

hatchery operations fundamental concepts and issues American

Fisheries Society Symposium 15 71ndash80

Campton D 1995 Genetic effects of hatchery fish on wild

populations of Pacific salmon and steelhead what do we really

know American Fisheries Society Symposium 15 253ndash337

Fleming IA Einum S 1997 Experimental tests of genetic

divergence of farmed from wild Atlantic salmon due to

domestication ICES Journal of Marine Science 54 1051ndash1063

Fleming IA Hindar K Mjoslashlnerud IB Jonsson B Balstad T

Lambert A 2000 Lifetime success and interactions of farmed

salmon invading a native population Proceedings of the Royal

Society of London Series B 276 1517ndash1523

Gendron L (Ed) Proceedings of a Workshop on Lobster Stock

Enhancement Held in the Magdalen Islands (Quebec) from

October 29 to 31 1997 Canadian Industry Report of Fisheries

and Aquatic Sciences vol 244 xi + 135 p

Grimsen S Jaques RN Erenst V Balchen JG 1987 Aspects

of automation in a lobster farming plant Modelling Identi-

fication and Control 8 61ndash68

Hedgecock D Nelson K 1978 Components of growth rate

variation among laboratory cultured lobsters (Homarus) Pro-

ceedings of the World Mariculture Society 9 125ndash137

Hedgecock D Nelson K Shleser RA 1976 Growth differences

among families of the lobster Homarus americanus Proceed-

ings of the World Mariculture Society 7 347ndash361

Joslashrstad KE Agnalt A-L Kristiansen TS Noslashstvold E 2001

High survival and growth of European lobster juveniles

(Homarus gammarus) reared communally with natural bottom

substrate Marine and Freshwater Research 52 1431ndash1438

Kapuscinski AL Jacobson LD 1987 Genetic guidelines for

fisheries management Sea Grant Research Report 17 Minne-

sota Sea Grant College Program University of Minnesota

Duluth

McGinnity P Stone C Taggart JB Cooke D Cotter D

Hynes R McCamley C Cross T Ferguson A 1997

Genetic impact of escaped farmed Atlantic salmon (Salmo

salar L) on native populations use of DNA profiling to assess

freshwater performance of wild farmed and hybrid progeny in

a natural river environment ICES Journal of Marine Science

54 998ndash1008

McGinnity P Prodohl P Ferguson A Hynes R OrsquoMaoleidigh

N Baker N Cotter D OrsquoHea B Cooke D Rogan G

Taggart JB Cross T 2003 Fitness reduction and potential

extinction of wild populations of Atlantic salmon Salmo salar

as result of interaction with escaped farm salmon Proceedings

of the Royal Society of London Series B 270 (October 15)

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Nicosia F Lavalli K 1999 Homarid lobster hatcheries their

history and role in research management and aquaculture

Marine Fisheries Review 61 (2) 1ndash57

KE Joslashrstad et al Aquaculture 247 (2005) 275ndash285 285

Pepper VA Crim LW 1996 Broodstock management In

Pennell W Barton BA (Eds) Principles of Salmonid

Culture Development in Aquaculture and Fisheries Science

vol 29 pp 231ndash289

Sokal RR Rohlf FJ 1995 Biometry 3rd edition WH Freeman

and Company New York 815 p

Taggart JB Hynes RA Prodohl PA Ferguson A 1992 A

simplified protocol for routine total DNA isolation from

salmonid fishes Journal of Fish Biology 40 963ndash965

Utter FM 2000 Patterns of subspecific anthropogenic introgres-

sion in two salmonid genera Reviews in Fish Biology and

Fisheries 10 265ndash279

Utter F Hindar K Ryman N 1993 Genetic effects of

aquaculture on natural salmonid populations In Heen K

Monahan RL Utter F (Eds) Salmon Aquaculture Fishing

News Book Oxford pp 144ndash165

Van Olst JC Carlberg JM Hudges JT 1980 The biology and

management of lobsters In Cobb JS Phillips BF (Eds)

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Waples R 1999 Dispelling some myths about hatcheries Fish-

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