Biometrical distribution of sharks in a low Elasmobranches-diversified shelf, the eastern Mediterranean Sea
22 March 2022
Biometrical distribution of sharks in a low Elasmobranches-diversified shelf, the eastern Mediterranean Sea
Erhan MUTLU, Mehmet Cengiz DEVAL, Claudia MIGLIETTA, İsmet SAYGU, Ilaria de MEO
ABSTRACT:
Spatiotemporal distribution of sharks collected by the Otter trawl in 2009-2001 and 2014-2015 was studied for their biometrical characteristics, and fish assemblage and ecology in shelf-slope of Antalya Gulf. Four species was found only on the shelf, two species from middle shelf to shelf break and three species from shelf edge to shelf break. Scyliorhinus canicula was the most dominant and the most frequently occurred species during 2009-2010 and then occurrence of Scyliorhinus canicula decreased. The rarest species were Etmopterus spinax and Oxynotus centrina. Annual average abundance was above 800 ind/km2 in 2010-2011 and below 50 ind/km2 in 2014-2015. Species richness decreased from winter to spring. Abundance ranged from 5 ind/km2 in June to 964 ind/km2 in August. Sallower zone inhabited lower number of species than the deeper zone. Abundance increased from shallower to the deeper waters. The species had a positive allometric or isometric growth. Unimodal species peaked at 75-100 m and at 300 m. Ubiquitous species had a bimodal distribution. The species were discriminated from the deeper water to the shallower water. The species-environment relation was correlated positively by the bottom depths, followed negatively by Secchi disk depth, and water salinity and positively by near-bottom chl-a and finest bioseston.
ACTA BIOLOGICA TURCICA 35(2), A2:1-22, 2022