ON THE HOMOGENEITY OF THE MACKEREL POPULATIONS AT CALICUT DURING THE YEARS 1969 TO 1976 AS DETERMINED ON THE BASIS OF C|L, C|W AND TL|SL RATIOS

Abstract

The counts of anterior circuli on the scales (C) of the Indian mackerel,
Rastrelliger kanagurta (Cuvier), at Calicut durirng 1969-1976 were correlated with
the length (L) and weight (W) of the fish with an attempt at determining whether
the stock at the place was homogeneous. Relationship between the standard length
(SL) and the total length (TL), too, were considered for the purpose.
The weight of fish and the count of circuli showed a straight-line relationship,
the equation being Y = 10.3168 + 0.1716 X, where Y is the frequency of
circuli on scales and X is the weight of the fish. On comparing the C|W ratios of
successive years by means of the Mest, it was found that the differences from year
to year were nonsignificant.
The average TL|SL ratio for the data pooled for the entire period was
1.24, the lowest and highest monthly averages falling within 0.016% above or
below.
Basing on these C|W and TL|SL ratios, and also taking the C|L ratio
(which too is described) into consideration, it is concluded that there was no
genetic change in the stocks of mackerel at Calicut during the years.