Akademik Veri Yönetim Sistemi
Cahiers De Biologie Marine, cilt.61, sa.2, ss.195-205, 2020 (SCI-Expanded)
Currently, knowledge of the spatial distribution of European hake Merluccius merluccius in the Sea of
Marmara is scarce, particularly regarding the dependency of this fish on biotic or abiotic conditions. A
generalized additive model (GAM) was used to model hake abundances in relation to depth, temperature,
dissolved oxygen, pH, and spatial location variabilities in the eastern Sea of Marmara (ESM). Furthermore, the
size distribution of European hake was analyzed by depth and season. Data were collected during a 4-year
sampling period (2014-2017) in the ESM using scientific demersal trawl surveys. The GAM results indicated that
although all given variables influenced the spatial distribution patterns of hake, the variables with the greatest
contributions in the ESM were longitude and depth. Hake abundance showed a strongly nonlinear dependence
on the explanatory covariates. The results concluded that areas with the highest hake abundances were located
at approximately 90 m. The results also indicated that a bottom temperature between 15 and 15.5°C,
representing relatively warm bottom waters in the ESM, had the highest hake abundances. Low oxygen values
did not adversely affect the abundance of hake. Hake preferences for areas with specific bathymetric and ocean
environmental conditions are considered to be linked to the oceanography of the ESM ecosystem. This study
also demonstrated that the size distribution of European hake differs by depth and season, and individuals larger
than 30 cm can mostly be found in waters deeper than 80 m.