© 2004 International Council for the Exploration of the Sea
Fidelity of mature Icelandic plaice (Pleuronectes platessa) to spawning and feeding grounds
Marine Research Institute Skulagata 4, PO Box 1390, 121 Reykjavik, Iceland
*Correspondence to J. Solmundsson: tel: +354 552 0240; fax: +354 562 3790. e-mail: jonsol{at}hafro.is.
About 2200 plaice (Pleuronectes platessa) were tagged on spawning and feeding grounds off Iceland. The aim was to reveal the migration pattern of mature plaice and to estimate fidelity rates to spawning and feeding grounds. From a total of 183 plaice tagged on the spawning ground and recaptured in successive spawning seasons, 91% of males and 88% of females were recaptured within 30 km of the tagging site. From 55 plaice tagged in the feeding area and recaptured in subsequent feeding seasons, all males and 91% of females were recaptured within 30 km of the tagging location, supposedly after migration to distant spawning grounds as indicated by recaptures in the spawning season. When weighing the number of recaptures with a standardized fishing effort, a minimum level of fidelity to the spawning ground was estimated at 94% for the spawning season one year after tagging and at 72% for the second and third spawning seasons. Fidelity to the feeding area was estimated at 90% after one year and at 100% after two and three years from tagging. The study provides insights into the population structure of Icelandic plaice, relevant to the management and conservation of the population.
Keywords: fishing effort, geographic fidelity, homing, migration, plaice (Pleuronectes platessa), population structure
Received 3 September 2004; accepted 26 November 2004.
 |
Introduction |
|---|
 Top Introduction Material and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
While approaches in current fishery management are most commonly based on single stock assumptions, the importance of preserving stock units or population structure has recently received increased attention (Stephenson, 1999; Frank and Brickman, 2000; Smedbol and Wroblewski, 2002). Many marine fish populations consist of amalgamations of geographic subpopulations or spawning components with a variable degree of segregation (McQuinn, 1997; Smedbol and Stephenson, 2001; Thorrold et al., 2001; Hilborn et al., 2002). Failure in fishery management to account for stock complexity may lead to depletion of stock components with unknown ecological consequences (Stephenson, 1999; Frank and Brickman, 2000) and can critically affect the long-term stability and sustainability of the entire stock (Hilborn et al., 2002).
Tagging studies have enhanced the understanding of spatial and temporal distribution of fish stock components and the rate of mixing between them. Homing, geographic fidelity, and straying are well documented for anadromous salmonoid species (Quinn, 1993; Dittman and Quinn, 1996; Candy and Beacham, 2000) and have also been studied in fully marine species such as herring (Clupea spp.; Wheeler and Winters, 1984; Hay et al., 2001), cod (Gadus morhua; Jonsson, 1996; Green and Wroblewski, 2000; Robichaud and Rose, 2001), and halibut (Hippoglossus hippoglossus; Godø and Haug, 1988). Tagging experiments have revealed a relatively stable migratory pattern of plaice (Pleuronectes platessa) where most fish return to the same areas year after year, indicating a strong homing ability (Harden Jones, 1968; De Veen, 1978; Rijnsdorp and Pastoors, 1995; Dunn and Pawson, 2002; Hunter et al., 2003).
Plaice are found on the continental shelf around Iceland, most abundantly in the warmer waters to the south and west of the country. The main spawning takes place on several distinct spawning grounds off the southwest and west coasts, begins in late February, peaks in March and April and is mostly finished by the middle of May (Saemundsson, 1926; Sigurdsson, 1989; Hjorleifsson and Palsson, 2001; Solmundsson et al., 2003). Plaice also spawn off the north and east coasts, one to two months later than in the southwest (Saemundsson, 1926; Tåning, 1929). Mature plaice undertake annual migrations between spawning and feeding grounds, the main feeding occurring in early summer to late autumn in the south, west, and northwest (Saemundsson, 1926; Tåning, 1929; Sigurdsson, 1989).
The total recommended annual catch of Icelandic plaice has decreased from 10 000 t in 1992–1997 to 4000 t in 2000–2004 due to reduced population size (Anon., 2004). For assessment and management purposes the Icelandic plaice has been treated as a single stock (Anon., 2004). Little, however, is known of the population structure or the possibility of gene flow between distinct plaice grounds. Recent genetic research has revealed a relatively low genetic diversity in Icelandic plaice, which has been suggested to be caused by low population size, geographic position at the edge of the distributional range of plaice and possibly inbreeding (Hoarau et al., 2004). Therefore, knowledge of the spatial dynamics and population structure of Icelandic plaice is of fundamental importance.
We used conventional tag recaptures calibrated with fishing effort to study seasonal and annual changes in the distribution of plaice tagged on a spawning ground west of Iceland in spring and in a feeding area off the northwest coast in autumn. Our aim was to study the migration of mature plaice and estimate homing and fidelity rates to spawning and feeding areas. A further aim was to gather information on the population structure in Icelandic plaice, which could have implications for the management of the plaice fishery.
|
Material and methods |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
Taggings
In Breidafjordur plaice are known to spawn at a slope in the centre of the bay mainly at depths of 50–150 m (Solmundsson et al., 2003). Plaice were tagged on this spawning ground on two occasions, a total of 700 plaice on 5 April 1997 in the western part of the area and 613 plaice on 29 March 1998 in the eastern part (Figure 1a). The time of tagging was chosen to be close to the peak of spawning, and at the start of an annual 2–3 week fishing ban on the spawning grounds.
|
A total of 857 plaice was tagged at two locations on feeding grounds off Vestfirdir on 13 September 1997 (Figure 1a). This timing was selected in order to have the plaice tagged shortly before the onset of a potential migration to over-wintering and spawning areas (Saemundsson, 1926; Sigurdsson, 1989). A significant catch of plaice is taken from the feeding areas off Vestfirdir in summer and autumn. This is thought to be an assemblage of mature plaice from different spawning grounds together with local immature plaice (Sigurdsson, 1989).
Plaice were captured with Danish seine with 135-mm mesh size in the codend. The fish were kept in 660 l plastic deck tanks with a through-flow of seawater until tagging, 10 min to 2 h later. Only plaice in good physical condition with no external wounds were tagged. The tags used were conventional T-Bar anchor tags with a 20 mm monofilament attachment stalk and a 35 mm orange plastic tube with coding numbers (FLOY TAG Inc., Seattle, USA). The total length of tagged plaice was measured to the nearest centimetre. The sex and maturity of plaice tagged on the spawning ground was noted when eggs or sperm were expelled or when ovaries were greatly swollen and extending to the posterior part of the fish. Samples were taken concurrently to the taggings, where total length, body mass, age, sex, and maturity were recorded for a total of 100 plaice from the spawning ground in each year and 157 plaice from the feeding area. The stage of maturation was recorded according to a four-stage classification (see Table 2 in Solmundsson et al., 2003). A visual inspection of stomach contents indicated that plaice caught in the feeding area were mainly eating sandeel (Ammodytes marinus), bivalves, and polychaetes, whereas on the spawning ground feeding was negligible.
Recaptures
Since all recaptures of tagged plaice were expected to come from the commercial fishery, fishers were asked to return tags and otoliths from the fish to the Marine Research Institute (MRI) along with information on recapture location, date of capture, sex, and maturity of the fish. A reward of 1000 ISK (equivalent to about 11 EUR) was offered for each tag returned. Fishers were encouraged to return the entire plaice along with the recapture information, allowing a precise examination of the fish.
In the analysis, 504 plaice out of 683 recaptures from the spawning ground and 292 out of 466 recaptures from the feeding area were used. We only made use of recaptured plaice where recapture site, date, and sex of the fish was known. All fish identified as mature at tagging were included in the analysis, but all fish immature at recapture were omitted. When sexual maturity of plaice at tagging was not known, we used the samples taken concurrently to the taggings to estimate whether the fish were sexually mature or not. In samples taken from the spawning ground 98% of males >34 cm (n = 135) and 97% of females >39 cm (n = 36) were mature. In samples taken from the feeding area 93% of males >36 cm (n = 44) and 94% of females >41 cm (n = 49) were mature. When information on sexual maturity of plaice was lacking but the sex was known, we only made use of fish above these size limits since smaller fish were probably immature at tagging.
Areas and seasons
Icelandic coastal and shelf waters were divided into eight areas, based on the distribution of plaice, location of known spawning grounds, tagging locations, and the spatial distribution of the plaice fishery (Figure 1). Spawning grounds were identified according to published information (Sigurdsson, 1989; Solmundsson et al., 2003), but also by mapping the distribution of actively spawning (running) female plaice registered in the fish database of MRI, for the period 1987–2004 (Figure 1b). Mandatory fishing logbooks, filled out by captains of commercial vessels fishing with Danish seine or bottom trawl, were used to determine the distribution of the fishery (Figure 1c).
Adult plaice are mainly found at depths of 10–120 m (Saemundsson, 1926; Tåning, 1929), although in this study several plaice were recaptured at greater depths. Most plaice (99%) were recaptured at depths of 150 m or less, despite more than two-thirds of the fishing effort of the Icelandic bottom trawl fleet being confined to deeper waters (Ragnarsson and Steingrímsson, 2003). This is consistent with data from the annual Icelandic groundfish survey (see Pálsson et al., 1989) indicating low densities of plaice at depths of more than 150 m (Table 1). Therefore, depth boundaries of all areas were set at 10 and 150 m. In other respects, the division into areas was as follows:
- Area A Northern Vestfirdir, north of 66°10'N and west of 22°00'W, the northernmost part of the main fishing grounds (Figure 1).
- Area B Southern Vestfirdir, between 65°30'N and 66°10'N. This area was defined as the main feeding area ("feeding home range") of plaice tagged off Vestfirdir in the feeding season, based on the distribution of recaptures during the period 14 September to 15 October in the year of tagging.
- Area C Breidafjordur, between 64°50'N and 65°30'N, includes a previously identified spawning ground (Solmundsson et al., 2003). This area was defined as the main spawning area ("spawning home range") of plaice tagged in Breidafjordur during the spawning season, according to the distribution of recaptures during the period 1 April to 15 May in the year of tagging.
- Area D Northern Faxafloi, between 64°25'N and 64°50'N, an area with relatively low fishing effort and limited spawning activity.
- Area E Southern Faxafloi and Reykjanes, south of 64°25'N and west of 22°00'W, includes a previously identified spawning ground (Sigurdsson, 1989).
- Area F Off the southwest coast, between 20°00'W and 22°00'W, includes a previously identified spawning ground (Sigurdsson, 1989).
- Area G Off the southeast coast, east of 22°00'W and south of 64°25'N, an area including a few spawning sites.
- Area H Relatively cold waters off the north and east coasts, north of 64°25'N and east of 22°00'W, spawning activity confined to the northeastern part, discontinuous fishery from other areas (Figure 1).
- Area B Southern Vestfirdir, between 65°30'N and 66°10'N. This area was defined as the main feeding area ("feeding home range") of plaice tagged off Vestfirdir in the feeding season, based on the distribution of recaptures during the period 14 September to 15 October in the year of tagging.
|
The main spawning season of plaice southwest and west of Iceland is defined here as the period 1 March–15 May (Saemundsson, 1926; Hjorleifsson and Palsson, 2001; Solmundsson et al., 2003) and the main feeding season as the period 16 June–15 October (Saemundsson, 1926).
Size of plaice grounds
For each area we estimated the size of grounds occupied by plaice during the years of study. The best available information on the gross distribution of plaice around Iceland probably come from the mandatory fishing logbooks (including information on date, location, depth, effort, and estimated catch for each species). The area (square kilometres) occupied by plaice was calculated from the continuous distribution of hauls and tows taken in 1997–2001 where plaice was a part of the catch (Figure 1c), using Surfer 6.04.
Fishing effort
Data from fishing logbooks were used to estimate the spatial distribution and intensity of fishing effort at the time of spawning (1 March–15 May) and feeding (16 June–15 October). For these estimates the fishing effort of the years 1997–2001 was used, since 99% of recaptured plaice in the present study were caught during these years. An index of the total fishing effort by vessels using Danish seine, bottom trawl, and plaice bottom gillnets was calculated in three steps:
- Nominal effort (e): The number of hauls taken with Danish seine (unit effort ed = 1 haul), the number of towing hours with bottom trawl (unit effort eb = 1 towing hour), and the number of plaice bottom gillnets (unit effort en = 10 nets) were calculated for each area, year, and season. We only used hauls and tows where plaice was registered as a part of the catch, to filter out fishery targeting other species.
- Standardized effort (s): In order to standardize effort across gear types in each area and season, the catching efficiency of bottom trawl (sb) and plaice bottom gillnets (sn) was estimated relative to the catching efficiency of Danish seine (sd) as follows:
(1)
where c is the total catch of plaice in each area and season.
(2)
- Total fishing effort (E): For each area, year, and season the total standardized fishing effort was calculated as follows:
(3)
Distribution of tagged plaice
The number of recaptures in each area and season was calibrated with total fishing effort and size of fishing grounds. We used an equation modified from Bayliff (1979) where the number of recaptures (R) is weighted with the total fishing effort (E) and the size of plaice grounds (A). It provides an estimate on the proportion of tagged fish (Pi) present in each area i:
|
| (4) |
|
Results |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
Taggings on the spawning ground
During spawning in the year of tagging, all recaptured plaice were caught in the "spawning home range" in Breidafjordur (Figure 2a), within 35 km of tagging sites (Figure 3a). In the spawning season one year after tagging most plaice were recaptured in Breidafjordur, with two exceptions off Vestfirdir and one west of Reykjanes (Figure 2c). This pattern was repeated in later spawning seasons, most plaice homing to the spawning ground in Breidafjordur but some straying to areas off the northwest and southwest coasts (Figures 2e and 3b). In the spawning seasons (excluding the year of tagging), about half of males and a quarter of the females were recaptured within 10 km of their tagging site, and the majority of both males and females within 30 km of their tagging site (Table 2).
|
|
|
Recaptures during the feeding season in the year of tagging mainly show a 60–160 km northerly migration to areas off Vestfirdir, but they also indicate a year round fidelity of some plaice to the "spawning home range" (Figures 2b and 3a). The distribution of recaptures in later feeding seasons indicates an interannual stability in feeding migrations (Figures 2d, f and 3b). Of the plaice tagged in Breidafjordur, there were no recaptures to the south of Breidafjordur in the feeding season.
Taggings in the feeding area
Late in the feeding season in the year of tagging, plaice were recaptured in the "feeding home range" within 40 km of tagging sites (Figures 3c and 4a). In successive feeding seasons, recaptures were within the "home range" with only two exceptions (Figures 3d and 4c, e). In the feeding seasons (excluding the year of tagging), about a fifth of the males and about a quarter of the females were taken within 1 km of their tagging site, and all males and the majority of females within 30 km (Table 2).
|
The distribution of recaptures in the first spawning season indicates a migration to spawning grounds in Breidafjordur, off Reykjanes, and off the southwest coast (about 80, 220, and 350 km of the tagging site, respectively), while few plaice remained in Area B (Figures 3d and 4b). Recaptures in later spawning seasons indicate a repetition of this migratory pattern (Figure 4d, f).
Spatial and temporal distribution of fishing effort
During the spawning season, standardized fishing effort per unit area was highest in Breidafjordur (Area C), off Reykjanes (Area E), and off the southwest coast (Area F), often 10–30 times higher than off northern Vestfirdir (Area A) and in northern Faxafloi (Area D) (Appendix A). During the feeding season fishing effort was highest off southern Vestfirdir (Area B), but considerable fishing also took place in Breidafjordur and off Reykjanes. At the same time, fishing effort was much lower off the south coast (Areas F and G) and in northern Faxafloi (Appendix B).
Fidelity to the spawning ground
For each area, year, and season, the number of recaptures was weighted by the associated fishing effort. The weighted tag recaptures indicate that 49–55% of the plaice tagged during spawning in Breidafjordur migrated to feeding areas off Vestfirdir (Areas A and B), depending on year (Table 3). Between 44% and 51% stayed in Breidafjordur during the feeding period, using the same or nearby areas for spawning and feeding. In the spawning season one year after tagging, weighted tag recaptures indicate that 94% of the tagged plaice spawned again in the same area, while the rest were located off Vestfirdir and Reykjanes. In the spawning seasons two and three years after taggings, 72% of the plaice were located on the spawning ground in Breidafjordur, 23% off Vestfirdir, and 5% in Areas E and F (Table 3).
|
The estimated proportion of plaice homing to the spawning ground one year after tagging was reduced from 97% to 94% by weighting the tag recaptures with fishing effort (Table 3). For the spawning seasons two and three years from tagging the estimate dropped from 91% to 72%, mainly due to a single plaice recaptured in Area A despite low fishing effort there (Table 3).
Fidelity to the feeding area
Plaice tagged in the feeding area off southern Vestfirdir seem to be an assemblage of fish from several spatially distinct spawning grounds. According to the weighted recaptures, 41–47% spawned in Breidafjordur, 17–20% off Reykjanes, 11–17% off the southwest coast, 0–12% off the southeast coast, and 13–22% were resident in Area B (Table 4). Although most plaice migrated 70–360 km from southern Vestfirdir to other areas for spawning, they seem to have returned to the same feeding area the following summer. Taking fishing effort into account, the fidelity of plaice to the feeding area is estimated at 90% one year after tagging and at 100% two and three years after tagging (Table 4).
|
|
Discussion |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
When mature, the Icelandic plaice population seems to be highly structured, with some spatial interconnection between distinct spawning components in the feeding season. The spawning component in Breidafjordur consists of two subcomponents, one that dwells there throughout the year and another that migrates to the north after spawning and feeds off Vestfirdir. In the feeding area off Vestfirdir, there are at least three migratory components that spawn in Breidafjordur, off Reykjanes, and off the southwest coast, whereas a fourth component is stationary in the area.
The results show that plaice tagged in one feeding area disperse to visit several southerly spawning grounds, and plaice tagged on a single spawning ground disperse onto more northerly feeding grounds in summer. This pattern, together with a high site fidelity, indicate each feeding ground to contain a mixture of plaice (subunits) spawning in different areas. In the same way each spawning ground seems to contain a mixture of plaice using different feeding grounds. Whether plaice are found to aggregate onto discrete spawning grounds and then disperse and mix on feeding areas (De Veen, 1978), or the other way round (Hunter et al., 2004), seems to depend partly upon the selection of tagging sites and seasons. Our results indicate that both patterns occur off the coast of Iceland.
A consistency in annual migration behaviour and strong ability and tendency of plaice to return to formerly used feeding and spawning sites was observed. In agreement with our study, most tagging experiments on North Sea and Irish Sea plaice indicate a high geographic fidelity (Harden Jones, 1968; De Veen, 1978; Rijnsdorp and Pastoors, 1995; Dunn and Pawson, 2002; Hunter et al., 2003), although quantitative information is scarce. In contrast, a fidelity of only 63% (n = 462) was found in a study on adult plaice in the Irish Sea (Macer, 1972). This may, however, be an underestimate since the period defined as spawning time was considerable (January–April), and some plaice were probably recaptured during passage to or from the spawning grounds (Macer, 1972).
Plaice tagged in Breidafjordur and recaptured off the south and southwest coasts in later spawning seasons clearly indicate straying, since these areas are located in the opposite direction more than 100 km away from the feeding grounds. The taggings in Breidafjordur also suggest a pronounced northerly movement in subsequent spawning seasons, to the areas where feeding takes place. However, due to the variability in the spawning time of individual fish, late or early spawners may possibly be recaptured outside their actual spawning ground (in feeding areas or on migration routes) in the defined spawning season. Some plaice appearing to be strays could therefore have been recaptured shortly before or after spawning in Breidafjordur. In fact, only one out of five recaptured plaice appearing to have strayed to Vestfirdir was actively spawning at recapture, the others were maturing, spent, or the maturity stage unknown. The straying rates of 6–28% from the spawning ground must therefore be taken as maximum estimates. Assigning all plaice straying to the south and the only plaice spawning off Vestfirdir as strays, provides a straying rate of 1–8%.
Maintenance of genetically differentiated spawning stocks south and west of Iceland as a consequence of a lack of straying and gene flow between spawning grounds seems improbable. During the feeding season the spawning components seem to be partly broken down, possibly by social transmission of migratory behaviour (Dodson, 1988; Corten, 2002). For example, the spawning components from Reykjanes and the southwest coast found to be present in the feeding area off Vestfirdir seem to draw 1–5% of the Breidafjordur spawning component with them annually, when heading back to spawn. On the other hand, the results did not reveal movement of mature plaice from the spawning and feeding grounds off the west coast to the relatively cold waters north and east of Iceland.
Some straying of adults between several segregated spawning grounds may suggest a metapopulation structure in Icelandic plaice. A metapopulation is a set of local non-autonomous subpopulations linked by a variable degree of movement and gene flow, and also by the potential of subpopulations to undergo extinction and recolonization (McQuinn, 1997; Smedbol and Wroblewski, 2002; Smedbol et al., 2002). Whether extinction and recolonization events have occurred in Icelandic plaice subpopulations is unknown. Yet, the location of the population at the northern edge of the species' range (Wimpenny, 1953), at the boundaries of cold- and warm-water masses (Valdimarsson and Malmberg, 1999), are factors that could promote such events (Smedbol et al., 2002). Furthermore, repeated extinctions followed by recolonization by a few individuals could lead to a decreased genetic variability (Smedbol et al., 2002), consistent with the relatively low genetic diversity reported for Icelandic plaice (Hoarau et al., 2004).
In conclusion, the results unveiled geographically distinct spawning locations maintained by site fidelity and connected by straying, indicating a complex structure in Icelandic plaice. As a precautionary approach, we suggest that the management of the plaice fishery should aim to preserve all known subcomponents. Current knowledge on the substructure of the total stock is, however, not sufficient for fine - scale management, but could be extended by a combination of extensive tagging and genetic research. This might be critical for retaining biocomplexity and sustainability of the population.
|
Appendix A |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
The estimated size of plaice grounds, nominal fishing effort, and total fishing effort by area (Figure 1) in the spawning season (1 March–15 May) in 1997–2001. Effort units are: Danish seine = 1 haul, bottom trawl = 1 towing hour, and plaice bottom gillnets = 10 set nets. The average catching efficiency of bottom trawl and plaice bottom gillnets in 1997–2001 relative to the catching efficiency of Danish seine, is shown. See Material and methods for the calculation of catching efficiency and total fishing effort.
|
|
Appendix B |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
The estimated size of plaice grounds, nominal fishing effort, and total fishing effort by area (Figure 1) in the feeding season (16 June–15 October) in 1997–2001. Effort units are: Danish seine = 1 haul, bottom trawl = 1 towing hour, and plaice bottom gillnets = 10 set nets. The average catching efficiency of bottom trawl and plaice bottom gillnets in 1997–2001 relative to the catching efficiency of Danish seine, is shown. See Material and methods for the calculation of catching efficiency and total fishing effort.
|
|
Acknowledgements |
|---|
We are grateful to many colleagues at MRI for various advice and assistance. We thank Kristjan Lilliendahl, MRI, Olafur P. Olafsson, University of Iceland, and anonymous reviewers for constructive comments on earlier versions of this paper. The project was financially supported by Lydveldissjodur (Icelandic Republic Fund 1994–1999).
|
References |
|---|
|
TopIntroductionMaterial and methodsResultsDiscussionAppendix AAppendix BReferences |
|---|
-
Anon. (2004) State of marine stocks in Icelandic waters 2003/2004. Prospects for the quota year 2004/2005. Hafrannsoknastofnunin, fjolrit nr. 102. 181 pp.
Bayliff W.H. (1979) Migrations of yellowfin tuna in the eastern Pacific Ocean as determined from tagging experiments initiated during 1968–1974. Inter-American Tropical Tuna Commission Bulletin 17:447–506.
Candy J.R. and Beacham T.D. (2000) Patterns of homing and straying in southern British Columbia coded-wire tagged chinook salmon (Oncorhynchus tshawytscha) populations. Fisheries Research 47:41–56.[CrossRef][Web of Science]
Corten A. (2002) The role of "conservatism" in herring migrations. Reviews in Fish Biology and Fisheries 11:339–361.[Web of Science]
De Veen J.F. (1978) On selective tidal transport in the migration of North Sea plaice (Pleuronectes platessa) and other flatfish species. Netherlands Journal of Sea Research 12:115–147.
Dittman A.H. and Quinn T.P. (1996) Homing in Pacific salmon: mechanisms and ecological basis. The Journal of Experimental Biology 199:83–91.[Abstract]
Dodson J.J. (1988) The nature and role of learning in the orientation and migratory behavior of fishes. Environmental Biology of Fishes 23:161–182.[CrossRef][Web of Science]
Dunn M.R. and Pawson M.G. (2002) The stock structure and migrations of plaice populations on the west coast of England and Wales. Journal of Fish Biology 61:360–393.[CrossRef][Web of Science]
Frank K.T. and Brickman D. (2000) Allee effects and compensatory population dynamics within a stock complex. Canadian Journal of Fisheries and Aquatic Sciences 57:513–517.
Godø O.R. and Haug T. (1988) Tagging and recapture of Atlantic halibut (Hippoglossus hippoglossus) in Norwegian waters. Journal du Conseil International pour l'Exploration de la Mer 44:169–179.
Green J.M. and Wroblewski J.S. (2000) Movement patterns of Atlantic cod in Gilbert Bay, Labrador: evidence for bay residency and spawning site fidelity. Journal of the Marine Biological Association of the United Kingdom 80:1077–1085.[CrossRef][Web of Science]
Harden Jones F.R. (1968) Fish Migration(Arnold, London) 325 pp.
Hay D.E., McCarter P.B., Daniel K.S. (2001) Tagging of Pacific herring Clupea pallasi from 1936–1992: a review with comments on homing, geographic fidelity, and straying. Canadian Journal of Fisheries and Aquatic Sciences 58:1356–1370.
Hilborn R., Quinn T.P., Schindler D.E., Rogers D.E. (2002) Biocomplexity and fisheries sustainability. Proceedings of the National Academy of Sciences of the United States of America 100:6564–6568.[CrossRef][Web of Science]
Hjorleifsson E. and Palsson J. (2001) Settlement, growth and mortality of 0-group plaice (Pleuronectes platessa) in Icelandic waters. Journal of Sea Research 45:321–324.[CrossRef]
Hoarau G., Piquet A.M-T., Van der Veer H.W., Rijnsdorp A.D., Stam W.T., Olsen J.L. (2004) Population structure of plaice (Pleuronectes platessa L.) in northern Europe: a comparison of resolving power between microsatellites and mitochondrial DNA data. Journal of Sea Research 51:183–190.[CrossRef]
Hunter E., Metcalfe J.D., Arnold G.P., Reynolds J.D. (2004) Impacts of migratory behaviour on population structure in North Sea plaice. Journal of Animal Ecology 73:377–385.[CrossRef][Web of Science]
Hunter E., Metcalfe J.D., Reynolds J.D. (2003) Migration route and spawning area fidelity by North Sea plaice. Proceedings of the Royal Society Series B – Biological Sciences 270:2097–2103.
Jonsson J. (1996) Tagging of cod (Gadus morhua) in Icelandic waters 1948–1986. Rit Fiskideildar 14:7–82.
Macer C.T. (1972) The movements of tagged adult plaice in the Irish Sea. Fishery Investigations of Ministry of Agriculture, Fisheries and Food, London, Series II 27:1–41.
McQuinn I.H. (1997) Metapopulations and the Atlantic herring. Reviews in Fish Biology and Fisheries 7:297–329.[CrossRef][Web of Science]
Pálsson Ó.K., Jónsson E., Schopka S.A., Stefánsson G., Steinarsson B.Æ. (1989) Icelandic groundfish survey data used to improve precision in stock assessments. Journal of Northwest Atlantic Fisheries Science 9:53–72.
Quinn T.P. (1993) A review of homing and straying of wild and hatchery-produced salmon. Fisheries Research 18:29–44.[CrossRef][Web of Science]
Ragnarsson S.Á. and Steingrímsson S.A. (2003) Spatial distribution of otter trawl effort in Icelandic waters: comparison of measures of effort and implications for benthic community effects of trawling activities. ICES Journal of Marine Science 60:1200–1215.
Robichaud D. and Rose G.A. (2001) Multiyear homing of Atlantic cod to a spawning ground. Canadian Journal of Fisheries and Aquatic Sciences 58:2325–2329.
Rijnsdorp A.D. and Pastoors M.A. (1995) Modelling the spatial dynamics and fisheries of North Sea plaice (Pleuronectes platessa L.) based on tagging data. ICES Journal of Marine Science 52:963–980.
Saemundsson B. (1926) Fiskarnir. The fishes(Bokaverslun Sigfusar Eymundssonar, Reykjavik) [In Icelandic] 583 pp.
Sigurdsson A. (1989) Skarkolamerkingar við Island arin 1953–1965. Tagging experiments of plaice in Icelandic waters 1953–1965. Hafrannsoknir 39: pp. 5–24 [In Icelandic].
Smedbol R.K., McPherson A., Hansen M.M., Kenchington E. (2002) Myths and moderation in marine "metapopulations". Fish and Fisheries 3:20–35.[CrossRef]
Smedbol R.K. and Stephenson R. (2001) The importance of managing within-species diversity in cod and herring fisheries of the north-western Atlantic. Journal of Fish Biology 59:109–128.[Web of Science]
Smedbol R.K. and Wroblewski J.S. (2002) Metapopulation theory and northern cod population structure: interdependency of subpopulations in recovery of a groundfish population. Fisheries Research 55:161–174.[CrossRef][Web of Science]
Solmundsson J., Karlsson H., Palsson J. (2003) Sexual differences in spawning behaviour and catchability of plaice (Pleuronectes platessa) west of Iceland. Fisheries Research 61:57–71.[CrossRef][Web of Science]
Stephenson R.L. (1999) Stock complexity in fisheries management: a perspective of emerging issues related to population sub-units. Fisheries Research 43:247–249.[CrossRef][Web of Science]
Tåning Å.V. (1929) Plaice investigations in Icelandic waters. Rapports Procés-Verbaux des Réunions Conseil Permanent International Pour l'Exploration de la Mer 57:1–134.
Thorrold S.R., Latkoczy C., Swart P.K., Jones C.M. (2001) Natal homing in a marine fish metapopulation. Science 291:297–299.
Valdimarsson H. and Malmberg S-A. (1999) Near-surface circulation in Icelandic waters derived from satellite tracked drifters. Rit Fiskideildar 16:23–39.
Wheeler J.P. and Winters G.H. (1984) Homing of Atlantic herring (Clupea harengus harengus) in Newfoundland waters as indicated by tagging data. Canadian Journal of Fisheries and Aquatic Sciences 41:108–117.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  C. Loots, S. Vaz, B. Planque, and P. Koubbi What controls the spatial distribution of the North Sea plaice spawning population? Confronting ecological hypotheses through a model selection framework ICES J. Mar. Sci., March 1, 2010; 67(2): 244 - 257. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Schopka, J. Solmundsson, S. A. Ragnarsson, and V. Thorsteinsson Using tagging experiments to evaluate the potential of closed areas in protecting migratory Atlantic cod (Gadus morhua) ICES J. Mar. Sci., December 24, 2009; (2009) fsp281v1. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Armannsson, S. Th. Jonsson, J. D. Neilson, and G. Marteinsdottir Distribution and migration of saithe (Pollachius virens) around Iceland inferred from mark-recapture studies ICES J. Mar. Sci., July 1, 2007; 64(5): 1006 - 1016. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||