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Open Access Publications from the University of California

Fish Bulletin No. 76. Average Lunar Month Catch by California Sardine Fishermen 1932–33 Through 1948–49


Several studies have been made of the return to the fishermen per unit of effort expended in fishing along the Pacific coast for the sardine, Sardinops caerulea. The first, by Hart (1933), was based on the British Columbia fishery for the years 1925–32. Hart calculated the average season catch per boat and the average daily catch per boat. Appropriate corrections were made to eliminate the influence of differences between boats in the total number of days fished within the season. The data indicated an increase in the return to the fishermen in the last three seasons included in the study. In California until about 1930 the daily tonnage delivered by fishing boats was determined by the capacity of the processing plants and not by the availability* of sardines on the fishing grounds. Gradually increasing plant capacities and corresponding increases in size of boats and adoption of more efficient fishing methods resulted in a continuing increase in the fishermen's catches. When plant capacities were large enough to absorb the tonnages delivered on most days, limitations were no longer placed on the boat's catch or were infrequent enough to have little effect on the average catch. This condition was reached in the early thirties, and by 1932–33 it was possible to use the fisherman's catch as a rough measure of the availability of the sardine population on the fishing grounds. Clark (1939) then calculated the average lunar month catch for the Monterey and the San Pedro sardine fisheries for 1932–33 through 1937–38. Although some limitations were at times placed on the daily catch of the fishermen these were disregarded as negligible. Boat sizes were increasing throughout the time interval and to meet this problem the catch of each boat was compared to the catch of the same boat for the corresponding lunar month of the previous season. This study showed an increase in the average lunar month catch from 1932–33 through 1934–35 and then a decline through 1937–38. The above study assumed that the influence of many items which determine fishing success would average out in calculations covering several years. Such factors are the limitations placed on the fisherman's daily catch, the number of hours of darkness, and changes in weather conditions. To determine their importance, Silliman and Clark (1945) calculated the average weekly catch adjusted as far as possible to eliminate the influence of these factors. The calculations were carried through 1941–42 and applied to the fisheries out of the ports of San Francisco, Monterey and San Pedro. They indicated an increase in average weekly catch from 1932–33 through 1934–35, a decline to 1937–38 and an upward trend to 1941–42. The adjustments made to eliminate extraneous factors which might affect fishing success, however, did not change the seasonal averages sufficiently to justify continuance of such elaborate and time consuming calculations. The adjustments either failed to accomplish the end desired or the extraneous influences were unimportant in a study covering a period of years. The present report covers the results of a study using the same boat catches as in the two former investigations for the seasons of 1932–33 through 1941–42, and extending the calculations through 1948–49. The method of treatment has been simplified by use of the average lunar month instead of the average lunar week catch, by making no adjustments for the influence of hours of darkness or unfavorable weather, or for the effect of limits except in the 1948–49 season. The fisherman's success has been measured both in tons per lunar month and in number of fish per month.

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