CalCOFI Reports, Vol. 11, 1967 - California Cooperative Oceanic ...

92 CALIFORKIA COOPERATIVE OCEANIC FISHERIES INVESTIGATIONS1963 corresponding to that of the effort did not takeplace. The total landings of 1963 was only about 2%over that of 1962.The low fishing results of 1963 are also evidentfrom that data of the mean catch by vessel-lengthgroupsover the whole year (Table 4). The 1963averages are down 30 to 40 percent as compared to1962, and they are the lowest figures since 1959.We may thus conclude that relatively speaking1963 was a poor year for the anchovy fishery. Onlybecause of the great increase of fishing effort did thetotal quantity landed slightly surpass that of theprevious year.ESTIMATES OF THE FLUCTUATIONS IN THEABUNDANCE OF THE ANCHOVY POPULATIONThe Catch Per Unit of E$ortIn our previous report, we showed that a convenienttime-unit of effort is the work of the vessels during 1month and that the standardization of the vesselscan most easily be accomplished by using the grossA.- NOT ADJUSTED B., ADJUSTED FOR SATURATIONregistered ton as a unit of measure. We thus use catchper month per GRT as our basic measure of abundance.Figure 1 demonstrates this uncorrected abundanceindex.The Abundance IndexBecause it is thought that improved equipment,and increases of size of gears has affected the fishingpower of the vessels since 1959, some correctionsneed to be made in this measure of catch per unit ofeffort. The corrections made are described in our previousreport, and for the period July 1963-June1964, the same correction has been applied as for thefirst part of 1963. This corrected index is shown inFigure 2. It is also believed that when the fish is veryabundant saturation of vessels will depress the c.p.u.e.A vessel cannot catch more than its capacity, evenx6050403020JO0by1706050403020ka(3awacnz0cI!aI-w2JO070605040302010080706050903020101 I!0' OY!i J I d d 631961 62J 1 d d 64I I J'FIGURE 3. Summary of abundance by fishing season.FIGURE 4.Percent trips without cotch.