The analyses discussed in this report demonstrate the difficulties encountered in applying the catch and effort method for determining the state of exploitation of the sardine resources in the CECAF area. In view of the urgent need for better information on the state of the stocks, the Ad hoc Group recommends that:
(1) studies be made to compare the unit of effort of different fleets fishing in the same zone;In view of the problems of the catch/effort analyses, it is also considered important to put more emphasis on other methods of stock evaluation.(2) the countries provide data on catch/day and catch/hour fishing, and carry out studies on the best unit of effort in these pelagic fisheries, considering also the possibilities and advantages or disadvantages of including searching time in the effort estimates.
Better cohort analysis essentially depends on the improvement made in the collection of better statistics of total catches of sardine made in each of the three zones or of evenly distributed biological samples for age determination. Considering the discrepancies still observed in age reading especially of older fishes, the Group recommended that:
(3) Soviet scientists actively participate in investigations on standardization of age reading methods already initiated by the Group.In addition to Continuation of cohort analysis studies, the Group recommended that:
(4) Consideration be given to organizing periodic, standardized, acoustic surveys, combined with test fishing for species identification, in order to estimate the stock abundances in each zone and their movements, their changes from year to year, and the changes in the southern distribution of the sardine. The possibility of organizing 0 group fishing surveys should also be considered to estimate changes in yearclass strength. Also, spawning surveys would provide further insight in year to year changes in stock distribution and in stock identity.In view of the importance of variation in environmental conditions for the sardine stocks, the Group further recommended:These surveys, in particular the acoustic and the 0 group surveys, should cover the whole area from Casablanca to Cape Timiris. The echosurveys should be carried out in the warm and cold seasons. An important problem that still remains is that of stock separation. Whereas the Group realized the problems encountered in tagging experiments, it recommended that:
(5) The feasibility of organizing a successful large-scale tagging experiment for the purpose of determining sardine migration and stock separation should be carefully studied, and the conclusions should be reported to the Group. The possibility of obtaining also useful information on mortality rates from a properly designed tagging experiment should be considered in these studies.
(6) Studies on stock separation by using biochemical methods such as electrophresis should be encouraged if those studies can be carried out without detriment to the work programme of the fisheries research institutes, e.g., by interested universities, etc.
(7) That studies on the variations in the strength and the location of upwelling should be continued.Finally, the Group noted the difficulties of carrying out all the necessary tabulations and calculations during its sessions, and therefore strongly recommended that:
(8) All members of the Group make every effort to comply with the requests circulated before its meetings by the Secretariat to submit standardized, tabulated data required for stock assessment, as described in these requests, well before the meetings to designated members of the Group, who will prepare the necessary summary tables and initial analyses of these data in time for consideration during the meetings.
