engleski

POPULATION STRUCTURE OF COMMON LOBSTER, HOMARUS GAMMARUS IN THE NORTHERN ADRIATIC SEA

The common lobster, Homarus gammarus is economically very important species of large crabs in the Adriatic. However, its catches are very intense and irregular. Therefore, economic importance in the last 20 years is not based on the total catch but on a very high price that this species achieved on the market. Unfortunately, there is still no sufficient biological and ecological knowledge of this species in the area of its distribution range, and especially not in the Adriatic. To elucidate some biological parameters that can indicate the status of H. gammarus in the northern Adriatic Sea and to show which consequences fishery effort may have on its population structure, sampling was carried out on the west coast of Istra using trammel nets and traps. Additionally, existence of temporal trends in landings of H. gammarus was assessed using long-term data including specimens caught in last decade. Temporal trends of H. gammarus in the northern Adriatic indicated significant increase in catch in term of both biomass (27%) and abundance (11%) over time. Also, official landings for the last five years showed an increase of almost 40%. However, this increasing trend most likely reflects the continuous change in national policies for reporting the catches. Both catch data and landings statistics showed peak in catch per unit effort during summer which coincides with catch season of H.gammarus (June). Total male to female sex ratio was 1:0.7. Length analysis revealed range from 17 cm (male) to a 48 cm long as probably the oldest specimen. Length- weight relationship revealed positive alometric growth (b = 3.092, R2 = 0.941). Length classes from 30 to 34 cm were predominant in the total catch. However, almost 32 % of immature individuals were represented in total catch. Considering the identified biological implications that confirm our assumptions of inherent vulnerabilities and negative effects arising from continued fisheries practice, existing management should be complemented by a more holistic, ecosystem approach to regulations in order to assure more effective conservation measures for this large crab.

European lobster ; population structure ; fisheries

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