Stock Discrimination Research Articles

Stock discrimination by trace-element analysis of otoliths of orange roughy (Hoplostethus atlanticus), a deep-water marine teleost.

Concentrations of trace elements in sagittal otoliths of orange roughy (Hoplostethus atlanticus) from three areas (off Adelaide, and off the eastern and western coasts of Tasmania) were measured by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Canonical-variate (discriminant) analyses of the concentrations of 10 elements (Ba, Cd, Cu, K, Mg, Na, Pb, S, Sr, Zn) showed that the patterns of element concentrations were specific to the areas where fish were captured. These results suggest that there is little movement of fish between the three areas. The elements that were most important in discriminating between the areas were Mg, Na and S.

鱗相スペクトル解析によるシロザケの母川判定の試み

鱗相スペクトル解析によるシロザケの母川判定の試み

Marine parasites: An Australian perspective

A review is given of major studies in marine parasitology in Australia. Aspects discussed include: geographical distribution of parasites in Australian coastal waters and their affinities to parasites of other zoogeographical regions; species diversity in Australian coastal surface and deep waters; use of marine parasites for stock discrimination; use of marine parasites as ecological models; ultrastructural and phylogenetic studies of marine parasites; and effects of marine parasites on their hosts.

An integrated phenotypic and genotypic approach to the stock discrimination of Atlantic salmon

An integrated phenotypic and genotypic approach to the stock discrimination of Atlantic salmon

Population bottlenecks: influence on mitochondrial DNA diversity and its effect in coregonine stock discrimination

This study was designed to test the hypothesis that anadromous populations of North American whitefish, Coregonus clupeaformis (Mitchill), believed to have suffered more intense population bottlenecks during past glaciation events, should reveal less mitochondrial DNA (mtDNA) variability and population‐genetic structuring than anadromous populations of European whitefish, C. lavaretus (L.). C. clupeaformis exhibited extremely low levels of diversity and population structuring, in terms of number and frequency of clonal lines as well as sequence divergence estimates, as compared with populations of C. lavaretus. These results support the hypothesis that the severity of population bottlenecks related to Pleistocene glaciation events may be largely responsible for the level of mtDNA variability observed. This in turn influences the sampling strategy required to maximize the usefulness of mtDNA analysis in stock discrimination.

Alaska Pollack population,Theragra chalcogramma, of Japan and its adjacent waters, I: Japanese fisheries and population studies∗

The present review starts with a brief history of Japanese Alaska pollack fishery and emphasizes its importance to that country. Alaska pollack fishery, including its history, fishing methods, fishing gears, fishing seasons, catch levels, migration of fish etc., in various parts of Japan and its adjacent waters is discussed. This is followed by a brief look at the present status of population studies, covering biological stocks in the Sea of Japan, the coast of Hokkaido, the west coast of Sakhalin and other important fishing grounds. Then successively, peculiarities of local fishery, problems of stock discrimination and interrelationships between other stocks, including Okhotsk Sea stock, Pacific ocean stock and Kamchatka stock, are taken up.

Distinction between American Eels (Anguilla rostrata) of Different Geographic Origins on the Basis of Their Organochlorine Contaminant Levels

This study presents evidence that organochlorine contaminant levels of fish tissues represent a valuable tool for stock discrimination. Variability of concentrations of 15 organochlorine contaminants allowed a discrimination among American eels (Anguilla rostrata) of unknown (captured during the migration down the St. Lawrence River) or known geographic origins. The study also exemplifies that information regarding environmental distribution of contaminants can be gained by comparing organic contaminant levels among groups of fish. Indeed we can infer from this study that mirex contaminated sediments have extensively (at least 400 km) drifted downstream from Lake Ontario in less than 19 yr.

Review of Stock Discrimination Techniques for Striped Bass

Abstract Attempts to discriminate stocks of striped bass Morone saxatilis have spanned five decades. We review and evaluate the approaches used, outline research trends, and suggest research needs and potential future applications of stock discrimination techniques. There have been moderate gains over the years in the ability to discriminate among stocks, primarily due to the use of biochemical techniques. An important mixed-stock fishery for striped bass off the northeastern USA has focused the majority of stock discrimination efforts on identification of Atlantic coast populations. Many techniques have been applied alone or in combination. Phenotypic studies have involved the presence of specific parasites, meristic and morphometric characters, trace element composition of scales, scale morphology, and densitometric analysis of isoelectrically focused eye lens proteins. Genotypic techniques have included cytogenetics, protein electrophoresis, isoelectric focusing, restriction endonuclease analysis of mi...

Intrapopulation Variation of the Esterase-2 Polymorphism in the Serum of Anadromous Arctic Charr, Salvelinus alpinus, from a Northern Labrador River

Intrapopulation variation of the diallelic Esterase-2 (serum esterase) polymorphism in the Arctic charr, Salvelinus alpinus, was studied in an anadromous population from the Ikarut River in northern Labrador. Differences in genotype frequencies observed between two sampling years, between sexes, and between juvenile and mature fish were not significant. However, considerable variation was found in the allele frequencies among year-classes. Furthermore, the allele frequency variation was associated with temperature; the frequency of the fast allele, F, was positively correlated with the mean summer temperatures in the year of hatching. The same type of association has been found in a Swedish population. Temperature-dependent selection in late incubation or post-hatching in the fry or fingerling stage could explain the observed association. The nonrandom distribution of the variation within populations has important implications for the use of the polymorphism in stock discrimination work and for the interpretation of interpopulation variation.

Stock discrimination of orange roughy,Hoplostethus atlanticus, by parasite analysis

The parasite fauna of the viscera of 1251 orange roughy,Hoplostethus atlanticus, collected in 1983 to 1986 from eight areas off southern Australia and three areas off New Zealand, was examined for evidence of discrete host populations. Fish from each area were divided into three length groups which averaged close to 28, 37, and 42 cm. Canonical multivariate analysis of data on larval nematodes (Anisakis spp.,Terranova sp., and a spirurid) and larval cestodes (Hepatoxylon trichiuri andCallitetrarhynchus sp.) discriminated five Australian and three New Zealand stocks. These were for Australia: (1) Great Australian Bight (2) South Australia/west Victoria/west and south Tasmania, (3) Cascade Plateau/Tasman Rise, (4) north-east Tasmania, (5) New South Wales; and for New Zealand: (1) north-east New Zealand, (2) south-east New Zealand, (3) west New Zealand. No significant differences in parasite fauna were detected between samples of fish taken within the spawning season and those taken outside the spawning season in the same area. In one southern Australian stock there was a north-south cline in the numbers ofAnisakis spp. This was apparent in both small (immature) and medium-sized (mature) fish. We conclude thatHoplostethus atlanticus is a sedentary species with little movement between fishmanagement zones.

Atlantic salmon, Salmo salar L., stock discrimination by scale-shape analysis

. Conventional methods of scale characterization commonly used lo discriminate between stocks of Atlantic salmon, Salmo salar L., though shown to be effective in continental distinction present obvious disadvantages and limitations. Therefore, a more powerful analytical technique is required, especially in the identification of regional or specific stocks. The objective of this work has been to test the potential usefulness of scale-shape analysis for stock identification purposes. Numerical analysis of scale morphology has been performed on 690 scales of adult Atlantic salmon originating from eight European and North American stocks. The shape features examined (shape factors, moment invariants and elliptic Fourier descriptors) have been found to provide useful information since they resulted in high levels of discrimination in pairs, except for the two stocks originating from Iceland. The appropriateness of those measurements for stock identification purposes and the necessity of a previous sampling and statistical treatment strategy are discussed.

An investigation into the Usefulness of Parasites as tags for Herring (Clupea harengus) Stocks in the Western North Atlantic, with Emphasis on Use of the Larval NematodeAnisakis simplex

Studies on the prevalence and intensity of selected herring parasites were conducted during 1981-83 in the western North Atlantic. Results are presented on three species of larval nematodes, Anisakis simplex, Hysterothylacium aduncum and Terranova sp., a larval cestode and the fungus, Ichthyophonus hoteri. Of the parasites examined, A. simplex showed the most potential as a natural tag for use in stock discrimination work. Results from this parasite are consistent with results from tagging studies.

A survey of parasites of the American lobster, Homarus americanus (Crustacea: Decapoda), from the Canadian Maritimes

Examination of 885 lobsters (Homarus americanus) trapped in five areas of the Canadian Maritimes during 1980–1982 revealed four parasite species: Porospora gigantea (Apicomplexa: Sporozoea), Polymorphus botulus (Acanthocephala: Palaeacanthocephala), Hysterothylacium sp. (Nematoda: Secernentea), and Stichocotyle nephropis (Platyhelminthes: Trematoda). The prevalence and abundance of each parasite species did not differ significantly (p > 0.05) between lobster sexes or size groups. Lobsters in each area were characterized by a high prevalence of P. gigantea (43.6 to 84.2%) and low prevalences of P. botulus (1.3 to 9.9%) and Hysterothylacium sp. (1.1 to 5.6%). Stichocotyle nephropis was found in one lobster from German Bank. The parasite fauna were similar throughout the areas sampled, which suggests that the data were of little value for lobster stock discrimination. However, lobsters probably acquired P. botulus in the shallow coastal areas where the primary hosts of this parasite occur; therefore, the presence of P. botulus in lobsters from inshore and offshore areas south and southeast of Nova Scotia suggests some mixing between coastal lobsters and those on the continental shelf.

Reproductive Cycles of Redfishes (Sebastes) in Southern Newfoundland Waters

Rapid field identification of Sebastes mentel/a, S. fasciatus and small S. marinus is difficult. Thus, redfish species are not distinguished for commercial statistics and the beaked redfishes usually not differentiated in biological sampling, the result being a lack of biological information by species. Knowledge of the ovoviviparous reproductive cycle of Sebastes sp. is important for species differentiation and stock discrimination. Investigations of sexual maturity and spawning in redfishes of southern Newfoundland waters (NAFO Division 3P) were carried out on the basis of 11,520sex and maturity observations collected from 1957 to 1969. Stages of sexual maturity are described. Monthly changes of maturity condition and maturity factor indicated that beaked redfishes (S. fasciatus) spawned mainly in May/June and S. marinus probably spawned earlier. Materials and Method Fig. 1. Areas where redfish samples were collected off southern Newfoundland in 1957-69. During 1957-69, 11,520 redfish specimens were collected from the otter-trawl catches of research vessels during daytime in southern Newfoundland waters (Fig. 1) at bottom depths to 578 m, in which 82% of the specimens were from 200-299 m. Sampling sites were

Discrimination d'un stock de poisson, l'anguille (Anguilla rostrata), basée sur la présence d'un produit chimique de synthèse, le mirex

Mirex concentrations were measured in eels (Anguilla rostrata) from eastern Canada to determine the contribution of Lake Ontario eels to the Saint Lawrence commercial fishery. Mirex could be detected in all eels (50 specimens) collected in Lake Ontario (0.18 ± 0.11 μg∙g−1). Most sedentary eels collected from the Saint Lawrence commercial fishery and both the migratory and sedentary eels collected from the Saint Lawrence tributaries and the Maritimes had no mirex. Of the migrating eels collected in the Saint Lawrence 74% contained mirex (0.17 ± 0.19 μg∙g−1). These results show that stocks can be discriminated on the basis of the presence of synthetic chemical products such as pesticides and other contaminants that are distributed heterogeneously in the environment. Based on a presence–absence criterion, this method for stock discrimination has the distinct advantage that it is more accurate and less time consuming than similar methods based on the presence of natural chemical products.

NOTE : Vertebral Numbers in Larval and Juvenile Haddock of the Scotian Shelf and Implications for Stock Discrimination

Analysis of vertebral number in larval and juvenile haddock (Melanogramnlus aeglefinus) from different parts of the Scotian Shelf indicated that juveniles from the northeastern area (Div. 4V) had significantly fewer vertebrae than those from the central and southwestern areas (Div. 4W and 4X). This is in contrast to previous studies of vertebral number in adults. Complex segmentation in the caudal region of the vertebral column occurred in about 25% of the specimens in the length range of 15-220 mm.

Stock Discrimination of Capelin (Mallotus villosus) in the Northwest Atlantic

Although capelin is an important commercial and forage species of the Newfoundland region, firm evidence for the designation of separate stocks does not exist. In a previous analysis of meristic characters of capelin, the authors assumed that meristic data were multivariate normal, an assumption that is not usually met. Consequently, the data were reanalyzed by using non-parametric methodology to assess differences in meristic characters, and the results of the analyses were examined to determine the relative importance of individual characters in the separation of stocks. Groups of capelin samples from five areas were tested by using 11 meristic characters in two age-groups. Capelin from western Newfoundland and Southeast Shoal of the Grand Bank continued to be clearly identified as separate stocks. The delineations of capelin from the other three areas were less clear, although independent paired comparisons with age combined differentiated the Labrador-Northeast Newfoundland and the northern Grand Bank-Avalon stocks, and separate analysis of age 3 and 4 capelin indicated that these two stocks were different from the St. Pierre Bank stock.

NOTE: Regressions of Weight on Length for Witch Flounder,Glyptocephalus cynoglossus, of the Eastern Newfoundland Area

An important routine in assessment of fish stocks is deriving the numbers of fish removed from the population through fishing by converting the nominal catches from weight to numbers at age. The relationship between length and weight of a given species is a useful parameter in performing this routine. Lengthweight regressions for witch flounder on the Scotian Shelf (NAFO Div. 4VWX) were reported by Powles (1967) and Kohler et al. (1970). Previous work on the length-weight relationship of witch flounder in the Newfoundland area was reported by Bowering (1976), but that equation was based on a combination of data collected from all areas around Newfoundland over several years and was calculated from mean weight-atlength data. This paper presents length-weight relationships for both round and gutted weights of witch flounder sampled in the autumn of 1982 from the eastern Newfoundland area (Div. 2J, 3K and 3L), which is the most important in the Northwest Atlantic in terms of catch. Recent stock discrimination studies have demonstrated that there are breeding populations in each of the divisions (Fairbairn, 1981; Bowering and Misra, 1982), and hence the present analysis considers data for each division separately.

Comparison of the properties of phosphoglucomutase from muscle of turbot ( Reinhardtius hippoglossoides, greenland halibut) and witch flounder ( Glyptocephalus cynoglossus) from the Northwest Atlantic and the Gulf of St. Lawrence

1. 1. Phosphoglucomutase from muscle of turbot and witch has been purified and the properties studied from two regions of the Northwest Atlantic and the Gulf of St. Lawrence. 2. 2. The enzyme, purified 157 fold from turbot and 164 fold from witch had specific activities of 596 and 475 U/mg/min respectively. 3. 3. The M.W. and pH optimum of the enzyme from both species were 63,500 and 7500; and 63,000 and 7800 for the Northwest Atlantic and the Gulf samples respectively. 4. 4. The amino acid contents and responses towards different inhibitory agents were different for the enzyme from the Gulf than the Northwest Atlantic samples. 5. 5. The findings compares well with the genetic analysis of the electrophoretic properties of the enzyme in relation to stock discrimination of the two species.

Which Witch is Which? A Study of the Stock Structure of Witch Flounder (Glyptocephalus cynoglossus) in the Newfoundland Region

Genetic variability at two protein loci (phosphoglucomutase and superoxide dismutase) was assessed both within and among three major management areas for witch flounder (Glyptocephalus cynoglossus) in the Newfoundland region. The genetic analysis revealed population subdivision within each of the major management areas, giving a total of six subpopulations or stocks. These genetically defined stocks also differed with respect to population structure, time of spawning, individual growth rate, and temperature and depth of capture. These results suggest that witch flounder in the Newfoundland region exist in relatively small, independent subpopulations with little inter-stock migration. This population structure is at odds with current practices of managing witch flounder as large homogeneous stock units.Key words: witch flounder, stock discrimination, biochemical genetics, phosphoglucomutase, superoxide dismutase, electrophoresis