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.
A survey of the parasites of Greenland halibut (Reinhardtius hippoglossoides) caught in Canadian Atlantic waters extending from Cumberland Sound, Northwest Territories, to the Gulf of St. Lawrence and Saguenay Fjord was conducted during the period January 1990 to March 1991. From examination of 350 fish a total of 46 parasite taxa were identified (4 Myxosporea, 1 Monogenea, 19 Digenea, 6 Cestoda, 8 Nematoda, 5 Acanthocephala, 2 Crustacea, and 1 Hirudinoidea). Included among these are 15 taxa previously unreported from this fish (Genolinea laticauda Manter, 1925; Gonocerca phycidis Manter, 1925; Neophasis sp.; Podocotyle reflexa (Creplin, 1825); Prosorhynchus squamatus Odhner, 1905; Steringophorus sp.; Eubothrium parvum Nybelin, 1922; Proteocephalus sp.; Ascarophis arctica Polyansky, 1952; Ascarophis filiformis Polyansky, 1952; Spirurida gen. sp. larva; Corynosoma validum Van Cleave, 1953; Corynosoma wegeneri Heinze, 1934; Gnathia elongata (Krøyer, 1849); and Notostomum laeve Levinsen, 1882). New Canadian records include only Steringophorus sp. and N. laeve. The parasite fauna of Greenland halibut is characterized by a large number of ubiquitous species, including many larval forms that show little host specificity, and a smaller number of species typical of pleuronectiform fishes, two of which (Myxoproteus reinhardti (Wierzbicka, 1986) and Hatschekia reinhardtii Wierzbicka, 1989) are known only from this fish. A complete listing of all parasites reported from Greenland halibut is included as an appendix.
A survey of the parasites of capelin (Mallotus villosus) caught on the spawning grounds at five localities in the estuary of the St. Lawrence River and the Gulf of St. Lawrence, Canada, was conducted in 1994. From examination of 125 fish, a total of 21 parasite taxa was identified (2 Protista, 3 Monogenea, 4 Digenea, 4 Cestoda, 7 Nematoda, and 1 Acanthocephala). Seven new host records are reported for this fish (Trichodina sp., Brachyphallus crenatus, Bothrimonus sturionis, Ascarophis sp., Pseudoterranova decipiens larva, Spirurida gen.sp. larva, and Echinorhynchus laurentianus). The parasite fauna of capelin is comparatively depauperate. It is characterized by the relative abundance of a few species showing a high level of host specificity (Microsporidium sp., Trichodina sp., Gyrodactyloides andriaschewi, G. petruschewskii, Laminiscus gussevi, and Eubothrium parvum) that mature on or in capelin, several ubiquitous adult digeneans (e.g., B. crenatus, Derogenes various, Hemiurus levinseni, and Lecithaster gibbosus), and a number of species that use capelin as intermediate or transport hosts (e.g., Scolex pleuronectis plerocercoid, Anisakis simplex larva, Contracaecinea gen.sp. larva, and Hysterothylacium aduncum larva).
1991. Prevalence and abundance of helminth parasites in an intensively fished population of brook trout (Salvelinus Jontinalis) at a small subarctic lake. Can. J . Zool . 69: 69 1 -697. Brook trout from a 5-ha lake near Schefferville, Quebec, were intensively sampled by small-mesh gill nets during 2 successive years to study patterns of helminth parasite occurrence in relation to changes in the age and size class structure of the fish population. Nearly 1800 brook trout were removed from the lake, of which all were measured and weighed, 568 were aged by otolith readings, and 36 1 were examined for parasites. The digeneans Crepidostomumfurionis, Phyllodistomum umblae, and Diplostomum sp. and the cestode Eubothrium salvelini were present in more than 50% of the necropsied fish, and the prevalence and (or) abundance of all species except C . furionis increased from the first to the second year of the study. The fish catch in the first year was dominated by the 3+ year class and older fish, whereas by the second year I + and 2+ fish were proportionately more abundant, and the importance of older cohorts declined. This change in brook trout population structure, resulting from gill net selectivity, appears to have had the effect of improving per capita food availability for members of the residual stock. After the initial year of intensive fishing, the fish that remained fed more upon both benthic and planktonic invertebrates and their acquisition of parasites was intensified. ALBERT, E., et CURTIS, M. A. 199 1. Prevalence and abundance of helminth parasites in an intensively fished population of brook trout (Salvelinus fontinalis) at a small subarctic lake. Can. J . Zool. 69 : 691 -697. Des Ombles de fontaine (Salvelinus fontinalis) ont eti echantillonn6s pendant 2 annkes const!cutives au moyen de filets maillants, dans un lac de 5 ha situe pres de Schefferville, Quebec; cet ichantillonnage intensif a permis d'ktudier les variations des populations d'helminthes en fonction des variations de la structure de la population de poissons quant a 1'Age et a la taille. Pres de 1800 ombles ont ete captures dans le lac; tous ont ete mesures et, 568 peses ont ete soumis 2 i une lecture de ]'Age sur les otolithes et les parasites ont ete inventories chez 36 1 d'entre eux. Les digeniens Crepidostomum farionis, Phyllodistomum umblae et Diplostomum sp. et le cestode Eubothrium salvelini ont it6 trouves chez plus de 50% des poissons examines et la prevalence et (ou) l'abondance de toutes les especes sauf C . farionis a augmente entre la premikre et la deuxieme annees de I'etude. Les echantillons recueillis la premiere annee etaient dominees par les poissons de la classe d'ige 3+ et les poissons plusAges, alors que les kchantillons de I'annke suivante contenaient plus de poissons des classes 1 + et 2 + et l'importance des cohortes plus Agkes avait decline. Ce changement dans la structure de la population d'ombles, resultat de la sklectivitk de I'engin de capture, semble avoir eu I'effet d'ameliorer la disponibilite per capita de la n...
Stranding records have long been used to monitor marine mammal mortalities and to help identify threats to populations. In coastal areas, marinemammals face numerous anthropogenic threats such as marine traffic and commercial fishing. The objective of this study was to investigate marinemammal stranding records from the St. Lawrence Estuary (SLE) and the northwestern Gulf of St. Lawrence (NWGSL), Quebec, Canada from 1994to 2008 for evidence of anthropogenic trauma caused by entanglement in fishing gear, ship collisions and gunshots. Of 1,590 marine mammalstranding records, 12% (n = 192) had evidence of anthropogenic trauma, most incidents being reported during summer when activities such asmarine traffic, most commercial fishing and recreational boating, occurred and a greater number of species were present in the area. These incidentswere classified into five categories (Incidental catch, Ship collision, Severe injury, Gunshot, Other). There were 1,245 mortalities and observationson carcasses suggested that anthropogenic trauma led to the death of 11% (141/1,245) of marine mammals: 14% (87/627) of cetaceans and 9%(54/618) of seals. Mortality of seals due to anthropogenic trauma was low, involving mainly Gunshot for grey (26% or 8/31) and harbour seals(26% or 8/31). Over the study period, marine mammal incidents with evidence of anthropogenic trauma increased significantly, driven by an increasein Incidental catch for two mysticete species, the common minke whale, 42% (39/92) and humpback whale, 13% (12/92) and Other for harbourporpoise 67% (16/24). Ship collision was the most common anthropogenic trauma for fin whales (22% or 8/36) and SLE beluga5 (22% or 8/36).Severe injury was reported for 22% (2/9) of small cetaceans and 78% (7/9) of seals. Evidence from some harbour porpoise stranding records(categorised as Other) suggests illegal hunting, incidental catch, predation or scavenging by grey seals in a marine protected area. The observedincrease in Incidental catch of common minke and humpback whales may be due to: (1) a shift in distribution of these two species into the SLE andNWGSL, possibly related to changes in the ecosystem; (2) changes in fishery practices; and (3) an increase in detection of marine mammal strandings.Anthropogenic trauma affecting marine mammals was documented including some species at risk, such as the harbour porpoise, the St. LawrenceEstuary beluga population, blue and North Atlantic right whales, in the St. Lawrence ecosystem including in a marine protected area. This studydemonstrates the usefulness of stranding records in helping to monitor human-caused mortality in marine mammal populations.
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