Assessment of pelagic fish abundance along the eastern Adriatic coast with special regard to sardine (Sardina pilchardus Walb.) population

Abstract

       Taking into account statistical catch and corresponding fishing effort data for sardine (Sardina pilchardus Walb.) population along the eastern Adriatic coast studies of pre­sent status of sardine stock size, maximum sustainable yield and optimum fishing effort have been carried out by apply­ing and combining S c h a e f e r (1954) and F o x (1970) surplus yield models.

       The applied method is based on Yugoslav annual catch statistics for the 1963 - 1978 period. In calculating the catch per unit effort, fishery statistics of one fishing organization was used. The purse-seiners fleet of this organization ope­rates along the eastern Adriatic coast. Fishing effort unit used is one fishing day/boat with only one net shot.

       Biological characteristics of exploited sardine population meet the requirements for better and more accurate appli­cation of surplus model results (Fox, 1977).

      General conclusions for a management policy are mostly based on 1967 - 1978 series data owing to the 1963 - 1966 period might be considered as a period of lower sardine population availability to the fishing gears, mostly due to the lower skippers skilfulness for pelagic fish school dete­ction of means of new devices (echo-sounders) which were more and more used by the commercial fishing fleet.

        Recently reported sardine catch and fishing effort vary about optimum values of production model for this Adriatic area, but the exploitation rate (E = 0,28) of sardine popu­lation along the eastern Adriatic coast is constantly low. Catchability coefficient was found to be reduced and inver­sely related to stock size up to 1979. It may be assumed that only a part of population inhabiting this area was under constant exploitation.