These assessments clearly indicate that a global reduction of fishing effort is highly desirable. Such action should lead to a moderate increase in total yield and a more substantial reduction of the exploitation costs. Moreover, it will enable the stock bio-masses to come back to higher levels and consequently to gain more stability. Finally, with the increase in average length of fish which will result from a lower rate of exploitation, the unit economic value of the yield will raise.
The Group was of the opinion that the authorities responsible for the management and exploitation of cephalopod stocks should aim at bringing the overall fishing capacity to a level, at most, equivalent to that required to take the theoretical maximum sustainable yield. Such need should be fully taken into consideration when national fishery development policies are designed, including when fishing agreements with outside partners are formulated.
The figures in the last column of table 10, which give the order of magnitude of the desirable reduction, have been calculated on the basis of the last data available (1977). Since that year some modification in the state of the stocks has probably occurred. Such changes can be expected to have been moderate inasmuch as the overall level of exploitation has tended to stabilize in recent years. It should also be noted that several fishing fleets have adopted larger mesh sizes in 1977. The long term effects of such action should start to be felt in 1978 and, as most likely they will be positive, they should facilitate the improvement of the stocks and of their fisheries.
In case the management authorities decide to control the level of exploitation through catch limitations, the Group calculated ranges within which such quotas should be selected. The 4th column in table 10 contains the figures for quotas which would only prevent the level of fishing to increase further than its 1977 value. The figures in the 5th and 6th columns correspond to catch quotas which would immediately generate fishing efforts ultimately leading to the average maximum yield in the first case, or slightly lower (F0.1) 1/in the second case.
1/ The long term advantages of keeping fishing effort at a level slightly lower than that corresponding to the theoretical average maximum has been demonstrated, on biological and economic grounds, by several authors. The objective and definition of F0.1 (Gulland and Boerema, 1973) have been adopted by various fishery bodies on many occasions.The comparison of these figures clearly show that, whatever final management objective is adopted, an appreciable reduction of present catches would be required for one or two years to bring the stocks to more wealthy and productive levels than the present ones. The need for such temporary reduction results from the fact that the biomasses have to be increased and this can only be achieved by temporarily reducing the catches. Should the catch reductions, as they are suggested by the figures in table 10, appear to be too high, it would be possible to proceed step by step. If one considers the short life span of the cephalopods, a stepwise rebuilding of the stocks should not delay excessively their full recovery.
Fully appropriate management schemes also require some control of the distribution - by areas and species groups - of the fishing effort in order to prevent an excessive concentration of the available fishing capacities on the most interesting stocks and, consequently, an under-utilization of the others. Unfortunately, the lack of detailed statistics has not permitted to undertake the assessments stock by stock, i.e. by fishing ground and by species group. It is therefore difficult to recommend how the overall limitation, either of catches or of effort, should be distributed over the various grounds and species categories. In the formulation of management schemes, the management authorities could, however, take into account the present contributions of the various species groups and fishing grounds (see section 4.1), for dividing possible overall quotas, keeping in mind that the estimates given in this section are still rough.
Finally, the Group called attention to the observations made at the second session of the CECAF Working Party on Resource Evaluation (Rome, December 1973). The report of this meeting stressed that, the cephalopods being short-living species, the same catch quota can generate very different fishing mortalities if applied at different periods of the year. To prevent an excessive concentration of fishing, for instance immediately after the recruitment when the same tonnage will be made up of a considerable higher number of individuals, it would be necessary, in case the control of effort is implemented through catch quotas, to consider the adoption of quotas by shorter periods of time, e.g. quarterly.
In that context, the Group observed that a limitation of the overall fishing capacities at a level not exceeding that required to harvest the desired quantities over the whole year would considerably reduce the risk of an over-concentration of fishing at certain seasons. For the time being, the Group was unable to say how best the effort should be distributed over the whole year. Until investigations along the lines described in sections 3.1 and 3.2 have indicated how this distribution should be adjusted to take in account possible seasonal variations in recruitment, growth, catchability, etc. - which can be expected to be appreciable for short-living species such as the cephalopods -, the Group was of the opinion that it would be wise to maintain the distribution of effort over the year as evenly as possible.
