. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. JACK MACKEREL YIELD 201 130,000 tons; 1958-59 through 1960-61, 170,000 tons; and 1961-62 through 1963-64, 32,500 tons (Figure 4). The 1961-62 through 1963-64 period produced less than i the poundage of sardines taken during the previous tliree-season period. At the same time, jack mackerel catches for the 1961-62 through 1963-64 seasons were more than double those of the 1958-59 through 1960-61 seasons. TONS X 1000 I 75-p I 25--
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. JACK MACKEREL YIELD 201 130,000 tons; 1958-59 through 1960-61, 170,000 tons; and 1961-62 through 1963-64, 32,500 tons (Figure 4). The 1961-62 through 1963-64 period produced less than i the poundage of sardines taken during the previous tliree-season period. At the same time, jack mackerel catches for the 1961-62 through 1963-64 seasons were more than double those of the 1958-59 through 1960-61 seasons. TONS X 1000 I 75-p I 25-- OO" 7 5-- 50-- 25-- JACK MACKEREL. 1 1955-56 THROUGH 1957-58 + 1958-59 THROUGH 1960-61 SARDINE + 1961-62 THROUGH 1963-64 FIGURE 4—Comparative sardine-jack mackerel catches, to tfie nearest thousand tons, for three three-season groups, 1955—56 through 1963-64. During the 1961-62 through 1963-64 seasons, fishing effort was more specifically pointed at jack mackerel, and the catch areas for this pe- riod tend to reflect the actual distribution of jack mackerel. As men- tioned previously, there has been an offsliore shift in jack mackerel catches during the nine seasons covered in this article, with the heaviest offshore catches being made in the 1961-62 through 1963-64 seasons. Clothier and Greenhood reported a parallel case for the 1952-53 through 1954-55 period, when a decline in sardine catches resulted in increased offshore jack mackerel catches. These two periods suggest that the center of abundance of jack mackerel tends to be far offshore. Other factors affecting the apparent abundance of jack mackerel on the fishing grounds include availability to the fishermen, and changes in actual abundance within these fishing areas. We are currently proc- essing 20 years of back data on jack mackerel commercial landings. These data include information on the year-class composition of the landings over this period. From an analysis of the year-class data, some inferences may
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