Pêche et production animale

Abstrait

Ecosystem Reaction of Small Pelagic Fish to Different Environments

Yasunori Kompas

The impact of environmental factors on the spatial distribution of fish species has been highlighted in a number of recent scientific papers, highlighting the need for the fisheries scientific community to look into habitat choice of commercially important fish species in addition to biomass estimates. Although predominantly oligotrophic, the Mediterranean Sea is distinguished by considerable habitat variety, making it a suitable study place to examine how tiny pelagic adapt to various environmental factors. In this study, the North Aegean Sea and the Strait of Sicily, two regions of the Mediterranean Sea that significantly differ in terms of environmental regimes, are used to evaluate the habitat selection of European sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). Investigating the elements affecting anchovy and sardine habitat choices involved using a number of environmental characteristics. For this, data from acoustic surveys gathered between the summers of 2002 and 2010 were used. The full dataset in each region was subjected to the quotient analysis in order to compare or contrast the “mean” spatial behavioral patterns of each species and to determine the relationship between high density values and environmental variables. Selected environmental variables underwent principal component analysis in order to pinpoint the environmental regimes that support the two ecosystems. The results of the investigation showed that both species’ spatial distribution was influenced by the choice of bottom depth and the availability of food. Additionally, PCA analyses showed that the observed preference for shallower waters is mostly related to particular environmental processes that boost local productivity. Even though the two regions exhibit significant differences in hydrodynamics, the two species’ common trends in habitat selection appear to be driven by the oligotrophic nature of the study areas, emphasizing the importance of regions where the “ocean triad hypothesis” is met by local environmental regimes.