scholarly journals Helminth parasites as biological tags in population studies of Greenland halibut (Reinhardtius hippoglossoides(Walbaum)), in the north-west Atlantic

1997 ◽  
Vol 54 (5) ◽  
pp. 886-895 ◽  
Author(s):  
J Boje
1993 ◽  
Vol 50 (10) ◽  
pp. 2175-2181 ◽  
Author(s):  
J. R. Arthur ◽  
E. Albert

The usefulness of parasites as biological tags for stocks of Greenland halibut (Reinharditius hippoglossoides) occurring off the Atlantic coast of Canada and in the Gulf of St. Lawrence was investigated. Nonparametric discriminant function analyses of eight collections comprising a total of 231 large fish (>39 cm) using counts for selected parasite taxa (Corynosoma strumosum juvenile, Otodistomum sp. metacercaria, Contracaecinea spp. larva, Anisakis simplex larva, and Pseudoterranova decipiens larva) gave accurate results (almost 100% correct classification) for the separation of fish from the Gulf of St. Lawrence from those collected from adjacent areas of the Saguenay Fjord and the Atlantic Ocean off Labrador. Little, if any, mixing of subadult or adult fish apparently occurs among these areas.


1997 ◽  
Vol 54 (8) ◽  
pp. 1813-1821 ◽  
Author(s):  
M L Vis ◽  
S M Carr ◽  
W R Bowering ◽  
W S Davidson

Greenland halibut (Reinhardtius hippoglossoides) have become of great importance to the Canadian fishery since the moratorium on northern cod (Gadus morhua), and an understanding of stock relationships among populations at the northern and southern extremes of their commercial range is crucial for proper management. We compared mitochondrial DNA sequence variation among fish taken from thoughout the Northwest Atlantic (Flemish Pass, the Grand Banks, Davis Strait, and Northwest Greenland) with samples from the Gulf of St. Lawrence, Iceland, and Norway. Within a 401 base pair portion of the cytochrome b gene, 22 genotypes were identified. Three of these occur at frequencies >10% and in the same relative abundances in all samples (except the Gulf of St.Lawrence). Genotype proportions do not differ significantly among samples, and genetic subdivision among samples (measured by the coancestry coefficient theta ) is nil. Genetic distances among samples are not related to geographic distribution: pairwise differences between the Gulf sample and other western Atlantic samples exceed those for trans-Atlantic comparisons. These data suggest that there is sufficient mixing of Greenland halibut, not only within the NAFO regulatory area, but among sites in the North Atlantic generally, to prevent the development or maintenance of genetically independent stocks.


1989 ◽  
Vol 67 (6) ◽  
pp. 1476-1481 ◽  
Author(s):  
James S. Scott ◽  
Shelley A. Bray

Examination of the alimentary tracts of 272 Atlantic halibut (Hippoglossus hippoglossus (L.)) and 71 Greenland halibut (Reinhardtius hippoglossoides (Walbaum)) from the Scotian Shelf yielded a total of 25 helminth parasite species, 23 from H. hippoglossus (16 Digenea, 3 Cestoda, 2 Acanthocephala, 2 Nematoda) and 16 from R. hippoglossoides (11 Digenea, 3 Cestoda, 1 Acanthocephala, 1 Nematoda). Parasite prevalence and intensity were low (< 50% and < 10%, respectively) in both hosts, except for Derogenes varicus and Steganoderma formosum in H. hippoglossus and anisakid nematodes in R. hippoglossoides. Consideration of change in parasite prevalence and mean intensity in relation to fish length and diet suggests fish prey as transport hosts for D. varicus in larger halibuts, and crustaceans as the intermediate hosts for S. formosum before transmission to its principal host, H. hippoglossus. Geographical change in parasite prevalence and intensity was in the form of southwest to northeast clines along the Shelf, probably related to environmental factors. There was no evidence for stock differentiation in either of the hosts based on parasite fauna.


2007 ◽  
Vol 64 (6) ◽  
pp. 857-866 ◽  
Author(s):  
Halvor Knutsen ◽  
Per Erik Jorde ◽  
Ole Thomas Albert ◽  
A Rus Hoelzel ◽  
Nils Chr. Stenseth

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 dichotomy between transatlantic sample comparisons and those within a regional current system, even when geographic distance 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 hypothesize 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 shaping the genetic structure of this and potentially other deep-sea species.


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