The food and parasites of fish in some deep basins of northern L. P�ij�nne

Abstract

The composition of the fish stock, food and 'macroparasites' were studied in eleven basins (22-100 m) of Lake Jyvasjarvi and North Paijanne in August-September 1976 . The fishing was done by means of a series of nets (meshes 15, 21 and 35 mm) laid on the bottom overnight . No fish were found in the two northernmost basins owing to bad oxygen conditions caused by waste waters . Smelt and burbot were the most abundant fish in the catches in other basins but the vendace was rare . Relict crustaceans and some `deep water' copepods (e .g . Heterocope borealis) played an important role in the food of fish in all basins .Parasites spreading via relict crustaceans were abundant in smelt and burbot, but absent in vendace and ruffe . The most common parasite in smelt was Cystidicola farionis, in burbot Echinorhynchus borealis, in ruffe Triaenophorus nodulosus and in vendace the gill parasite Ergasilus sieboldi. Females of a relatively rare copepod Salmincola lotae were found in the oral cavity of five burbot (at depths of 50 and 100 m) .

Population structure, life cycle, and trophic niche of the glacial relict amphipod, Gammaracanthus lacustris, in a large boreal lake

“…However, the high density of G. lacustris near the lake bottom suggests that they could offer an important food source for benthic fish. Remains of G. lacustris has been found in stomachs of fish and seals (Auttila et al, 2015;Hill et al, 1990) and the species may even be the principal prey for smelt, burbot, and fourhorn sculpin (Bagge, 1992;Bagge & Hakkari, 1982;Hammar et al, 1996). We provide new information on the nutritional value of this glacial relict amphipod.…”

“…G. lacustris may thus not only be a prey item (Bagge, 1992;Bagge & Hakkari, 1982;Hammar et al, 1996), but also a potential competitor for certain fish species. These facts, together with our results for both stable isotopes and fatty acid biomarkers, point to G. lacustris being an opportunistic predator that feeds on zooplankton (especially on copepods), other macrocrustaceans, and potentially also on fish carcasses.…”

“…These facts, together with our results for both stable isotopes and fatty acid biomarkers, point to G. lacustris being an opportunistic predator that feeds on zooplankton (especially on copepods), other macrocrustaceans, and potentially also on fish carcasses. G. lacustris may thus not only be a prey item (Bagge, 1992;Bagge & Hakkari, 1982;Hammar et al, 1996), but also a potential competitor for certain fish species.…”

Larves d'Ascarides parasites de Poissons en Méditerranée occidentale

“…Les larves de l'espèce ont été décrites par de nombreux auteurs, entre autres Punt (1941), Janiszewska (1949), Berland (1961), Petter (1969), Fagerholm (1982. Les dimensions données par ces différents auteurs correspondent à celles que nous avons trouvées ; les larves décrites par Janiszewska ont cependant un oesophage nettement plus court.…”