The Yugoslav Nephrophs fishery

Abstract

        Statistical data of the yearly Nephrops catch in the Yugoslav waters for the period 1960 /70. and the fishing effort data, the number of effective fishing days in a year, have been pointed that the average Nephrops population abun­dance in the Central Adriatic is considerably higher (53 kg/fishing day/year) — region A, then in the Northern Adriatic (22 kg/fishing day/year) — region B. Calculated values of the yield regression lines, between the catch per unit effort against the total yearly effort for the eleven years period for the both Nephrops fishing regions do not show that there is a direct relationship between them. Obtained values of the correlation coefficients (r) were: in the central open Adriatic (region A) r = -0.06, and northern channel region B, r = 0.09. It seems that behaviour of the Nephrops population inside of the clay-lomay bioceonose »Nephrops norvegicus - Thenea muricata« alonge the Yugoslav coast, more directly, determines the index of abundance of the population.

       In the selectivity Nephrops experiments with the synthetic bottom trawl, whose stretched mesh-sizes of the cod-end were: 41.6 mm, 52.8 mm, 62.6 mm, the following 50% retention lengths of Nephrops were obtained (1c) 4.3; 5.2; 9.2 cm. The selection factors of the synthetic cod-end with the knots (210/48 Den) were: 0.9, 1.5.