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K.h Nedreaas - One of the best experts on this subject based on the ideXlab platform.
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Modelling the advection and diffusion of eggs and larvae of Greenland halibut (Reinhardtius hippoglossoides) in the north-east Arctic
Fisheries Oceanography, 2004Co-Authors: Bjørn Ådlandsvik, A Stene, A.c Gundersen, K.h Nedreaas, Agnes C. Gundersen, Anne Stene, Ole Thomas AlbertAbstract:Since the late 1980s there has been considerable uncertainty in recruitment levels of the north-east Arctic stock of Greenland halibut (Reinhardtius hippoglossoides). The abundance of several year classes, originally considered very low at 0–3 yr age, appeared higher than expected at the age of 6+. This may be due to poor targeting of recruitment surveys of the younger year classes. The present work considers the transport and dispersion of eggs and larvae of Greenland halibut by numerical modelling in order to predict the locations of the initial recruitment grounds. Current fields from a 3D baroclinic hydrodynamic model are fed into a Lagrangian particle-tracking model developed for the Barents Sea area. The particles are released into the current at the spawning field along the shelf slope from Lofoten to Bear Island (69– 75� N). Vertically, the particles can follow a predefined depth-by-age curve or be kept at a fixed depth. This model system is used for different years to examine changes in the drift pattern. The results indicate that spawning location, transport depth and inflowing activity to the Barents Sea are important factors influencing the distribution of juveniles.
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Maturity classes and spawning behaviour of Greenland halibut (Reinhardtius hippoglossoides)
2001Co-Authors: Ole Thomas Albert, E.m Nilssen, A Stene, A.c Gundersen, K.h NedreaasAbstract:Abstract The maturation and spawning of Greenland halibut ( Reinhardtius hippoglossoides Walbaum) is described from six trawl surveys in the spawning area along the continental slope between North-Norway and Svalbard from October 1997 to May 1998. Different maturity classes were identified with frequency analyses of logarithmic classes of the Gonadosomatic Index. The main spawning period started in November, peaked in December and ended in late January. Mature females appeared at the spawning area in the early autumn and left during the first months of the year. Males were recorded after this with residual milt, indicating that some spawning may occur several months after the main spawning season. Observations from the fishery indicated spawning concentrations near the coast half a year after the main spawning period. Sex differences in spawning behaviour were discussed and related to the problem of representative sampling.
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Maturity classes and spawning behaviour of Greenland halibut (Reinhardtius hippoglossoides)
Fisheries Research, 2001Co-Authors: Ole Thomas Albert, E.m Nilssen, A Stene, A.c Gundersen, K.h NedreaasAbstract:Based on annual bottom trawl surveys in the Barents Sea and Svalbard area in 1983-96, the paper describes variations in abundance and composition of 1-group Greenland halibut (Reinhardtius hippoglossoides). The main pattern of variation in abundance during the period was a change from high abundance in the first half of the period, to low abundance in the second half. The reduced abundance was associated with a northerly shift in distribution. In the last two years the recruits reappeared, first in northern parts of the study area and then also further south. These periodical changes in juvenile distribution, may be driven by physical oceanographical processes. Distribution changes probably extend beyond the area covered by the annual surveys. Thus, the results add uncertainty to the resent assessment of the state of the stock
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Distribution and abundance of juvenile Northeast Arctic Greenland halibut (Reinhardtius hippoglossoides) in relation to survey coverage and the physical environment
ICES Journal of Marine Science, 2001Co-Authors: Ole Thomas Albert, E.m Nilssen, K.h Nedreaas, A.c GundersenAbstract:Albert, O. T., Nilssen, E. M., Nedreaas, K. H., and Gundersen, A. C. 2001. Distribution and abundance of juvenile Northeast Arctic Greenland halibut (Reinhardtius hippoglossoides) in relation to survey coverage and the physical environment. – ICES Journal of Marine Science, 58: 1053–1062. Based on annual bottom-trawl surveys in the Barents Sea and Svalbard area in 1983–2000, variations in distribution and abundance of age 1 Greenland halibut (Reinhardtius hippoglossoides Walbaum) are described. The surveys showed high contrasts in abundance during the period, with extremely low abundance in 1990–1995 associated with a northerly displacement of the distribution within the survey area. A reduced abundance was not reflected in VPA-based estimates of total abundance of 1-group halibut. We conclude that the survey covered a varying proportion of the total distribution area. Survey abundance, the range of distribution within the survey area, and the proportion covered by the surveys were all negatively correlated with temperature in the Atlantic Water of the Spitsbergen Current. Possible mechanisms linking survey results to the physical environment are discussed. 2001 International Council for the Exploration of the Sea
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a comparison of greenland halibut Reinhardtius hippoglossoides walbaum fisheries and distribution in the northwest and northeast atlantic
Sarsia, 2000Co-Authors: Raymond W Bowering, K.h NedreaasAbstract:Abstract Greenland halibut (Reinhardtius hippoglossoides (Walbaum)) are widely distributed over extensive geographic areas of both the Northwest and Northeast Atlantic Ocean with no break in the continuity of the respective distributions. Although the entire Greenland halibut resource in the North Atlantic is genetically homogeneous they mainly comprise a single interbreeding stock in each of the two regional areas investigated. Both stocks show similar distribution patterns over depth. Generally, larger fish become more abundant and smaller fish less abundant in progressively deeper water with peak abundance occurring over a depth range of 400-1000 m. Greenland halibut in the Northwest Atlantic were observed to be most abundant in bottom temperatures mainly between 2 °C and 6 °C compared to 0 °C to 4 °C in the Northeast Atlantic. The fishery for Greenland halibut in the Northeast Atlantic was unregulated until 1992 although since 1995 catches substantially exceed those advised. The spawning stock size re...
Rosario Martín - One of the best experts on this subject based on the ideXlab platform.
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Genetic differentiation between sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides) by PCR–RFLP analysis of a 12S rRNA gene fragment
Journal of the Science of Food and Agriculture, 2000Co-Authors: Ana Céspedes, Teresa García, Esther Carrera, Isabel González, Alicia Fernández, Luis Asensio, Pablo E. Hernández, Rosario MartínAbstract:PCR-RFLP analysis was applied to the identification of two closely related flatfish species: sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides). Amplification of DNA isolated from fish muscle samples was carried out using a set of primers flanking a region of 321 base pairs (bp) from the mitochondrial 12S rRNA gene. Restriction endonuclease analysis based on sequence data of this DNA fragment revealed the presence of polymorphic sites for AciI and MwoI endonucleases. The restriction profiles obtained by agarose gel electrophoresis when amplicons were cut with AciI and MwoI enzymes allowed the unequivocal identification of sole and Greenland halibut species.
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genetic differentiation between sole solea solea and greenland halibut Reinhardtius hippoglossoides by pcr rflp analysis of a 12s rrna gene fragment
Journal of the Science of Food and Agriculture, 2000Co-Authors: Ana Céspedes, Teresa García, Esther Carrera, Isabel González, Alicia Fernández, Luis Asensio, Pablo E. Hernández, Rosario MartínAbstract:PCR-RFLP analysis was applied to the identification of two closely related flatfish species: sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides). Amplification of DNA isolated from fish muscle samples was carried out using a set of primers flanking a region of 321 base pairs (bp) from the mitochondrial 12S rRNA gene. Restriction endonuclease analysis based on sequence data of this DNA fragment revealed the presence of polymorphic sites for AciI and MwoI endonucleases. The restriction profiles obtained by agarose gel electrophoresis when amplicons were cut with AciI and MwoI enzymes allowed the unequivocal identification of sole and Greenland halibut species.
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Indirect enzyme-linked immunosorbent assay for the identification of sole (Solea solea), European plaice (Pleuronectes platessa), flounder (Platichthys flesus), and Greenland halibut (Reinhardtius hippoglossoides).
Journal of Food Protection, 1999Co-Authors: Ana Céspedes, Teresa García, Esther Carrera, Isabel González, Alicia Fernández, Luis Asensio, Pablo E. Hernández, Rosario MartínAbstract:Polyclonal antibodies produced against soluble muscle protein extracts from sole (Solea solea), European plaice (Pleuronectes platessa), flounder (Platichthys flesus), and Greenland halibut (Reinhardtius hippoglossoides) were used in an indirect enzyme-linked immunosorbent assay for the specific identification of fillets from these flatfish species. The assay was performed in two different formats: microtiter plates and immunostick tubes. Immunorecognition of antibodies adsorbed to their specific fish samples was made with goat antirabbit immunoglobulins conjugated to the enzyme horseradish peroxidase. Subsequent enzymatic conversion of the substrate allowed unequivocal identification of all flatfish species studied.
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Identification of sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides) by PCR amplification of the 5S rDNA gene.
Journal of agricultural and food chemistry, 1999Co-Authors: Ana Céspedes, Teresa García, Esther Carrera, Isabel González, Alicia Fernández, Pablo E. Hernández, Rosario MartínAbstract:Polymerase chain reaction (PCR) amplification of the nuclear 5S rDNA gene, has been used for the identification of sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides). Two species-specific primers were designed to amplify specific fragments of the 5S rDNA gene in each species. The remarkably different size of the amplicons obtained gives, by simple agarose gel electrophoresis, two distinguishable band patterns for both flatfish species. This genetic marker can be very useful for the accurate identification of S. solea and Greenland halibut, to enforce labeling regulations.
A.c Gundersen - One of the best experts on this subject based on the ideXlab platform.
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Estimates of reproductive potential of Greenland halibut (Reinhardtius hippoglossoides) in East Greenland based on an update of maturity status
Fisheries Research, 2014Co-Authors: James Kennedy, A.c Gundersen, Agnes C. Gundersen, Rasmus B Hedeholm, Jesper BojeAbstract:Abstract When estimating reproductive potential (RP), correct interpretation of the maturity status is essential. It has now become apparent the presence of vitellogenic oocytes within the ovary of Greenland halibut ( Reinhardtius hippoglossoides ) does not necessarily indicate they will spawn within the next twelve months. This has led to a revision of the interpretation of the maturity scale where fish which contain only a developing cohort (DC) of oocytes are considered immature. Comparisons were made of estimates of L 50 of female Greenland halibut in East Greenland using the previous interpretation of maturity status where the leading cohort (LC) and DC oocytes are not differentiated with the new interpretation where they are. Differentiation led to an increase from 63.8 to 80.2 cm and from 61.2 to 74.1 cm for the northern (between 63°40′ N and 67°00′ N) and southern area (between 61°45′ N and 62°40′ N), respectively. Combining the maturity data with abundance data of Greenland halibut in East Greenland, spawning stock biomass (SSB) and total egg production (TEP) was estimated in four quadrants between 1998 and 2012 using both the previous and current interpretation of the maturity scale. Using the new interpretation of the scale led to a decrease in SSB estimates of 28–92% in specific areas and years, with an average of 56%. Estimates of TEP were directly proportional to SSB so this approach did not offer any advantages over SSB as a measure of reproductive potential. Length composition of Greenland halibut caught by Norwegian fishing vessels fishing in East Greenland indicate that 85 and 57% of the females caught by the trawl and longline fleet respectively in the northern area and 46% caught by the longline fleet in the southern area were immature.
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Greenland halibut (Reinhardtius hippoglossoides) spawn annually but successive cohorts of oocytes develop over 2 years, complicating correct assessment of maturity
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: A.c Gundersen, Å S Høines, James Kennedy, Agnes C. Gundersen, Olav S. Kjesbuo.s. KjesbuAbstract:Ovary development in Greenland halibut (Reinhardtius hippoglossoides) is complex, with several cohorts of developing oocytes present during vitellogenesis; this is unusual for a determinate spawner. There are also speculations that Greenland halibut are not capable of spawning every year. To investigate this possibility, ovaries from Greenland halibut caught throughout the year were examined histologically, and successive cohorts of oocytes were tracked through development. Results showed that the initial maturation of the ovaries from immature to spawning takes more than 1 year. The ovary initially develops as far as early vitellogenesis; however, the time scale for this is unclear. During the final year of development, the cohort of vitellogenic oocytes splits to form two cohorts; the larger cohort increases in size and is spawned in the coming spawning season. The smaller cohort also continues to develop, but at a much lower rate, in preparation for development for spawning in the following year. Withi...
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Sexual maturity cycle and spawning of Greenland halibut Reinhardtius hippoglossoides in the Davis Strait.
Journal of fish biology, 2010Co-Authors: A.c Gundersen, Jesper Boje, Claus Stenberg, I. Fossen, B. Lyberth, Ole A JørgensenAbstract:Female sexual maturation cycle and the main spawning time of Greenland halibut Reinhardtius hippoglossoides in the Davis Strait were studied through regularly collected samples during 1 year starting in spring 2003. Samples were collected from the southern slope of the Davis Strait Ridge between Canada and Greenland in the depth range 1000-1500 m. Female sexual maturation was described using different approaches: gonado-somatic index, visual macroscopic maturity stage index, histological microscopic maturity index and oocyte diameter measurements. A significant increase in the gonado-somatic index was seen from September onwards until February with a maximum estimated value of 18%. The proportion of mature fish increased from December until March. At the same time, the proportion of females with a low gonado-somatic index also increased from February, indicating that spawning had occurred and females were recovering. Oocyte diameter distribution revealed a leading cohort development during autumn through to December to February. A coupling between sexual maturity and fish condition was seen for females in maturing condition indicating a steady build up of stored energy in the liver from June to November.
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When to count your eggs: is fecundity in Greenland halibut (Reinhardtius hippoglossoides W.) down-regulated?
Fisheries Research, 2009Co-Authors: James Kennedy, A.c Gundersen, Agnes C. Gundersen, Jesper BojeAbstract:Abstract Fecundity in several fish species is subjected to down-regulation by atresia so if fecundity is estimated many months before spawning, this will be an overestimation of the realised fecundity (actual number of eggs spawned). In order to get accurate measurements of fecundity it is important to have knowledge on when potential fecundity (estimated fecundity at time of sampling) closely resembles the realised fecundity. Down-regulation of fecundity for Greenland halibut ( Reinhardtius hippoglossoides W.) was assessed using fish caught off East Greenland in 1998, 1999 and 2000. The fish caught in 1998 and 1999 were in early and late stages of vitellogenesis, respectively of the same maturation cycle. The fish caught in 2000 were also in an early stage of vitellogenesis. Fecundity decreased by 43% between early and late vitellogenesis. Fecundity in 1999 appeared to be the second lowest recorded for Greenland halibut but it is believed to be due to developmental stage rather than low productivity. There was no difference in fecundity between 1997 and 1998. It is believed that differences in fecundity between years only become apparent in late maturation as size during oocyte recruitment has a very large influence on fecundity. Neither Fulton's condition nor hepatosomatic index had any significant influence on fecundity.
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Rebuilding the Stock of Northeast Arctic Greenland Halibut (Reinhardtius hippoglossoides)
Journal of Northwest Atlantic Fishery Science, 2008Co-Authors: Å S Høines, A.c GundersenAbstract:After the absence of 1989–1994 year classes of Northeast Arctic Greenland halibut (Reinhardtius hippoglossoides) in regular surveys, an annual survey programme was initiated in 1996 to map juveniles in previously unsurveyed waters north and east of Svalbard. After rather stable juvenile indices in the first years, the recruitment indices have increased tenfold from 2001 to 2006. The increase in juvenile Northeast Arctic (NEA) Greenland halibut corresponded with an increase in spawning stock biomass. The swept area abundance estimates of spawning females (i.e., females >60 cm), has nearly tripled since 1996 having achieved 29 000 t in recent years. This improvement occurred after years of strong regulations, introduced in 1992, by enforcing a moratorium on the targeted offshore fishery and strict bycatch regulations for the species. Regulations were introduced after a dramatic change in stock status for the NEA Greenland halibut during the 1980s. Females >75 cm contributed more to the stock’s total egg production (TEP) in more recent years. The contribution from these larger females increased from 10% of the TEP estimate in 1996 to 21% in 2006. The results from the present study indicate that rebuilding Greenland halibut stocks takes time, and that at least 12–15 years with restrictions are needed to recover from the low levels observed in the Barents Sea in the beginning of the 1990s.
Ole Thomas Albert - One of the best experts on this subject based on the ideXlab platform.
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Genetic population structure in Greenland halibut (Reinhardtius hippoglossoides) and its relevance to fishery management.
Canadian Journal of Fisheries and Aquatic Sciences, 2017Co-Authors: Jon-ivar Westgaard, Ole Thomas Albert, Atal Saha, Matthew Peter Kent, Hanne Hellerud Hansen, Halvor Knutsen, Lorenz Hauser, Steven X. Cadrin, Torild JohansenAbstract:Exploited marine resources can be managed more effectively when accurate information on geographic population structure is available. Genetic markers offer a powerful tool for fisheries management, because they reveal biologically sound management units. Single nucleotide polymorphisms (SNPs) markers derived from restriction-site associated DNA sequencing (RAD-seq) were developed and used to investigate the stock structure of Greenland halibut (Reinhardtius hippoglossoides). A total of 96 SNPs were analyzed from 384 individuals and eight locations across the Atlantic. Our results suggest a subdivision of Greenland halibut into two populations, an eastern Atlantic population and a western Atlantic population, with a proposed border across the Denmark Strait. In general, Greenland halibut display weak but significant population structure (overall FST = 0.003; p < 0.001), which can be explained by connectivity among populations owing to the migratory behavior or egg and larval drift.
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Pelagic behavior of adult Greenland halibut (Reinhardtius hippoglossoides)
2008Co-Authors: Tone Vollen, Ole Thomas AlbertAbstract:It is evident from several field experiments with vertical longlines and archival tags, as well as concurrent studies of predator-prey relationships, that adult specimens of the deep-water flatfish Greenland halibut (Reinhardtius hippoglossoides) make regular excursions several hundred meters through the water column. The distribution of longline catches within the water column is confined to a well-defined depth layer overlapping with the distribution of blue whiting (Micromesistius poutassou), an important prey species, and depth recordings from archival tags overlap with Atlantic herring (Clupea harengus), the other major fish prey. The degree of pelagic use varies with fish size as well as seasons. Smaller individuals are found further off the bottom, and pelagic activity is greatest during early autumn. Interaction with pelagic prey species can influence results from bottom trawl surveys.
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population genetic structure in the north atlantic greenland halibut Reinhardtius hippoglossoides influenced by oceanic current systems
Canadian Journal of Fisheries and Aquatic Sciences, 2007Co-Authors: Halvor Knutsen, Ole Thomas Albert, Per Erik Jorde, Rus A Hoelzel, Nils Chr StensethAbstract:We report statistically significant genetic structure among samples of Greenland halibut (Reinhardtius hippoglossoides), rejecting the null hypothesis of panmixia in the North Atlantic. The species appears instead to be subdivided into partially isolated populations, with some evidence for isolation by distance. However, there is a dichot- omy between transatlantic sample comparisons and those within a regional current system, even when geographic dis- tance is similar. Calculating geographic distance along the flow of ocean currents gave a more linear correlation with genetic differentiation than straight-line geographic distances, suggesting that gene flow follows ocean currents. We hy- pothesize that gene flow is mediated by drift of eggs and larvae with ocean currents, a hypothesis that is consistent with the extended pelagic phase of Greenland halibut larvae. This implies an important role for ocean currents in shap- ing the genetic structure of this and potentially other deep-sea species. Resume : Nous signalons l'existence d'une structure genetique significative dans des echantillons du fletan du Groenland (Reinhardtius hippoglossoides) et nous rejetons donc l'hypothese nulle de panmixie dans l'Atlantique Nord. L'espece semble plutot subdivisee en populations partiellement isolees, avec des indications d'un isolement par dis- tance. Il y a cependant une dichotomie entre les comparaisons faites entre les echantillons recoltes en travers de l'Atlantique et entre ceux qui appartiennent a un systeme de courants regionaux, meme lorsque les distances geographi- ques sont semblables. Le calcul des distances geographiques le long du parcours des courants oceaniques donne une correlation plus lineaire avec la differenciation genetique que les distances geographiques en ligne droite, ce qui in- dique que le flux genetique suit les courants oceaniques. Nous emettons l'hypothese selon laquelle le flux genetique est gere par la derive des oeufs et des larves dans les courants oceaniques, une hypothese qui est compatible avec la phase pelagique prolongee des larves du fletan du Groenland. Notre etude reconnait un role important aux courants oceani- ques dans l'elaboration de la structure genetique chez cette espece et potentiellement chez d'autres especes marines des eaux profondes. (Traduit par la Redaction) Knutsen et al. 866
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Diet composition and feeding behaviour of juvenile Greenland halibut (Reinhardtius hippoglossoides) in the Svalbard area
Journal of Sea Research, 2004Co-Authors: Tone Vollen, Ole Thomas Albert, E.m Nilssen, Einar M. NilssenAbstract:The diet of trawl-captured juvenile Greenland halibut (Reinhardtius hippoglossoides Walbaum) from three locations on the western and northern coasts of Svalbard, Norway, in December 1995 and January 1996 is described. Stomach fullness was recorded for 1216 fish of 7 to 65 cm length, and stomach contents were analysed for 353 non-empty stomachs. The diet differed only slightly between the sampling areas and no differences were found between males and females. The overall percentage of empty stomachs (PES) was comparable to other nursery areas and lower than recordings from feeding and spawning areas. PES decreased and prey size increased as predator length increased. Fish and crustaceans dominated the diet, the most important prey species being Atlantic cod (Gadus morhua), polar cod (Boreogadus saida) and northern shrimp (Pandalus borealis). The relative importance of fish and crustaceans, respectively, was independent of predator length. However, a size-dependent variation in preferred prey was found, as smaller fish preyed upon small crustaceans and polar cod while larger individuals displayed a preference for northern shrimp, juvenile Atlantic cod, and other larger fish. Finally, there was a close resemblance between the length distribution of prey species from the trawl and from the stomachs.
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Modelling the advection and diffusion of eggs and larvae of Greenland halibut (Reinhardtius hippoglossoides) in the north-east Arctic
Fisheries Oceanography, 2004Co-Authors: Bjørn Ådlandsvik, A Stene, A.c Gundersen, K.h Nedreaas, Agnes C. Gundersen, Anne Stene, Ole Thomas AlbertAbstract:Since the late 1980s there has been considerable uncertainty in recruitment levels of the north-east Arctic stock of Greenland halibut (Reinhardtius hippoglossoides). The abundance of several year classes, originally considered very low at 0–3 yr age, appeared higher than expected at the age of 6+. This may be due to poor targeting of recruitment surveys of the younger year classes. The present work considers the transport and dispersion of eggs and larvae of Greenland halibut by numerical modelling in order to predict the locations of the initial recruitment grounds. Current fields from a 3D baroclinic hydrodynamic model are fed into a Lagrangian particle-tracking model developed for the Barents Sea area. The particles are released into the current at the spawning field along the shelf slope from Lofoten to Bear Island (69– 75� N). Vertically, the particles can follow a predefined depth-by-age curve or be kept at a fixed depth. This model system is used for different years to examine changes in the drift pattern. The results indicate that spawning location, transport depth and inflowing activity to the Barents Sea are important factors influencing the distribution of juveniles.
Louis Bernatchez - One of the best experts on this subject based on the ideXlab platform.
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Estimating the contribution of Greenland Halibut ( Reinhardtius hippoglossoides ) stocks to nurseries by means of genotyping‐by‐sequencing: Sex and time matter
Evolutionary applications, 2020Co-Authors: Emilie Carrier, Anne-laure Ferchaud, Eric Normandeau, Pascal Sirois, Louis BernatchezAbstract:Identification of stocks and quantification of their relative contribution to recruitment are major objectives toward improving the management and conservation of marine exploited species. Next-generation sequencing allows for thousands of genomic markers to be analyzed, which provides the resolution needed to address these questions in marine species with weakly differentiated populations. Greenland Halibut (Reinhardtius hippoglossoides) is one of the most important exploited demersal species throughout the North Atlantic, in particular in the Gulf of St. Lawrence, Canada. There, two nurseries are known, the St. Lawrence Estuary and the northern Anticosti Island, but their contribution to the renewal of stocks remains unknown. The goals of this study were (a) to document the genetic structure and (b) to estimate the contribution of the different identified breeding stocks to nurseries. We sampled 100 juveniles per nursery and 50 adults from seven sites ranging from Saguenay Fjord to offshore Newfoundland, with some sites sampled over two consecutive years in order to evaluate the temporal stability of the contribution. Our results show that after removing sex-linked markers, the Estuary/Gulf of St. Lawrence represents a single stock which is genetically distinct from the Atlantic around Newfoundland (FST = 0.00146, p-value = .001). Population assignment showed that recruitment in both nurseries is predominantly associated with the St. Lawrence stock. However, we found that the relative contribution of both stocks to the nurseries is temporally variable with 1% contribution of the Newfoundland stock one year but up to 33% for the second year, which may be caused by year-to-year variation in larval transport into the Gulf of St. Lawrence. This study serves as a model for the identification of stocks for fisheries resources in a context where few barriers to dispersal occur, in addition to demonstrating the importance of considering sex-linked markers and temporal replicates in studies of population genomics.
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estimating the contribution of greenland halibut Reinhardtius hippoglossoides stocks to nurseries by means of genotyping by sequencing sex and time matter
Evolutionary Applications, 2020Co-Authors: Emilie Carrier, Anne-laure Ferchaud, Eric Normandeau, Pascal Sirois, Louis BernatchezAbstract:Identification of stocks and quantification of their relative contribution to recruitment are major objectives toward improving the management and conservation of marine exploited species. Next-generation sequencing allows for thousands of genomic markers to be analyzed, which provides the resolution needed to address these questions in marine species with weakly differentiated populations. Greenland Halibut (Reinhardtius hippoglossoides) is one of the most important exploited demersal species throughout the North Atlantic, in particular in the Gulf of St. Lawrence, Canada. There, two nurseries are known, the St. Lawrence Estuary and the northern Anticosti Island, but their contribution to the renewal of stocks remains unknown. The goals of this study were (a) to document the genetic structure and (b) to estimate the contribution of the different identified breeding stocks to nurseries. We sampled 100 juveniles per nursery and 50 adults from seven sites ranging from Saguenay Fjord to offshore Newfoundland, with some sites sampled over two consecutive years in order to evaluate the temporal stability of the contribution. Our results show that after removing sex-linked markers, the Estuary/Gulf of St. Lawrence represents a single stock which is genetically distinct from the Atlantic around Newfoundland (FST = 0.00146, p-value = .001). Population assignment showed that recruitment in both nurseries is predominantly associated with the St. Lawrence stock. However, we found that the relative contribution of both stocks to the nurseries is temporally variable with 1% contribution of the Newfoundland stock one year but up to 33% for the second year, which may be caused by year-to-year variation in larval transport into the Gulf of St. Lawrence. This study serves as a model for the identification of stocks for fisheries resources in a context where few barriers to dispersal occur, in addition to demonstrating the importance of considering sex-linked markers and temporal replicates in studies of population genomics.
