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In the present paper authors demonstrate detailed biomorphometry of one specimen of the sabrefish (Cyprinidae, Cypriniformes) from the lake Dąbie near Szczecin, one specimen of saithe (Gadidae, Gadiformes) caught in the Pomeranian Bay near town Kołobrzeg, and one specimen of sea bass (Moronidae, Perciformes) collected in the Pomeranian Bay, too, near village Trzęsacz.
Analysis involving 31 metric and 8 meristic characters was performed on 76 individuals of Atlantic argentine. Moreover, the material investigated was characterised in view of length (l.t.) and weight distribution. Results were presented with regard to both sexes.
Background. European hake, Merluccius merluccius, is a major predator in demersal ecosystem, and of great importance for the fishery. Knowledge of the feeding ecology of fish species is essential for implementing a multispecies approach to fishery management. Therefore this work was intended to analyse stomach contents and dietary changes according to fish size, season, sex, and depth to better understanding the ecological role of this species in Adriatic demersal marine communities. Materials and methods. A total of 1646 specimens of hake were collected in the Adriatic Sea by oceanographic bottom trawl surveys carried out from 2005 to 2006 during summer- and winter seasons. Principal feeding indices, species diversity Bray–Curtis similarity index, feeding strategy plot, barplot on numeric, and weight abundance data were obtained in order to increase knowledge on the diet of hake. Results. The hake diet mainly consisted of crustaceans (particularly Decapoda) and teleosts (particularly European anchovy, Engraulis encrasicolus, and red bandfish, Cepola macrophthalma). Cluster analysis of %N (numeric prey abundance percent) showed different feeding habits of three mainly groups: small hakes (<150 mm), medium sized hakes (from 150 to 300 mm) and large hake (> 300 mm) from crustaceans (small specimens) to teleost fishes (medium and large specimens). Conclusion. Feeding habits were size-dependant with fish diet being higher in stomachs of larger specimens. Feeding activity seemed to increase during growth, being smaller in immature individuals compared to adults, while no differences were found between females and males diet. Seasonal variation in diet showed an increase of teleost fishes in winter and crustaceans in summer.
The first occurrence of striped red mullet Mullus surmuletus in the Pomeranian Bay (in 2007) and the occurrence of three very rarely noted species (tub gurnard Chelidonichthys lucerna, Atlantic horse mackerel Trachurus trachurus, thicklip grey mullet Chelon labrosus) collected in 2007–2008 in the Pomeranian Bay, Szczecin Lagoon and Lake Dąbie are reported. Their expansion is probably due to increased sea temperatures resulting from climate change, as well as the inflow of saline water. The ‘visitors’ hosted eight pathogens from four taxonomic groups: Protozoa, Nematoda, Acanthocephala and Mollusca. Nematodes, the most numerous ones, were found in three host species. All the parasite species were new for the hosts examined; only the larvae of the acanthocephalan Corynosoma strumosum had already been recorded in one of the hosts (Chelidonichthys lucerna). The stomachs of almost all the fish examined were empty, but the species composition of the parasite fauna found showed that the fish must have ingested some food in the Pomeranian Bay.
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