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Exploitation and mortality rates of European hake (Merluccius merluccius) in the Aegean Sea (Izmir Bay, Turkey)


Author's address: Okan Akyol, Ege University Faculty of Fisheries, TR–35100 Bornova, Izmir, Turkey.



Experimental trawl surveys in Izmir Bay (Aegean Sea) were taken seasonally between 2007 and 2009. A total of 1353 specimens were sampled ranging from 5.9 cm (1.4 g) to 44.4 cm (670 g). The main size group of Merluccius merluccius was between 14 and 25 cm total length (TL). In total, the mean catch per unit effort (CPUE) for hake by number and weight was 101.4 ± 18.4 ind h−1 and 10.7 ± 1.5 kg h−1, respectively. Highest mean CPUE by number and biomass was determined as 257.1 ± 15.1 ind h−1 and 15.1 ± 4.9 kg h−1 in summer. Mortality (M, F, Z) ratios of hake were 0.58 year−1, 1.66 year−1 and 2.24 year−1, respectively. Because of the many smaller specimens caught in this study, this seems to indicate that there may be heavy fishing pressures on the hake population; the high exploitation rate (E = 0.74) appears to confirm this conclusion.