Fluctuations in the size of the sardine and in the yield of its fishery in the central eastern Adriatic

Abstract

      The annual fluctuations in the size of sardines from the open waters of the central Eastern Adriatic are compared with those in the yield of their fishery in the central Eastern Adriatic in the period 1959-1961 (Fig. 1). The comparison points to a predominant influence on the yield of the fluctuations in year class strength as shown by length distributions. The same assumption was made earlier for the period 1947-1958 (M u ž i n i ć, 1960).

     A look at the fluctuations in both size and catch in the whole period (Fig. 1) shows the following:

     In 1957-1962 sardines showed high and similar lengths (corrected means: 17.1-17.5 cm.) which indicates a lack of strong year classes. In 1957-1961 a mediocre and slightly variable yield of the sardine fishery was recorded.¹)

     In the earlier years a variability in the length of sardines was observed which points to differences in year class strength. That variability coincided with a variability in the catch of sardine.

      In 1947 and 1948 extremely low values of the length of the fish were recorded, these ones revealing the existence of at least one strong year class. In 1949 and 1950 the yield reached extremely high values. The data on the age composition of sardine catch in the open waters of the central Eastern Adriatic showed that a strong year class well represented in 1948 dominated in 1949 and 1950 (M u ž i n i ć, 1954).

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           1) According to data obtained afterwards, the catch in 1962 was lower than expected. The eventual causes of it are not fully analysed.