Sampling technique on the ovary of the striped bass (Roccus saxatilis Walbaum)

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Virginia Polytechnic Institute

In this report an investigation on the ovaries of three(3) rock fish was discussed; the sampling of eggs within these ovaries was employed to determine the distribution of large and small eggs in each. From Merriman’s report, a general description of the fish, its habits, etc., was presented, showing significant facts that make the striped bass fisheries one of the great industries of the Atlantic Coast. The rock ovaries inspected came from fish taken in May, November and March.

Sampling the ovaries was accomplished in the following manner; the ovary was sliced in six (6) cross-sections, and eight (8) samples were taken from each cross-section in order that a thorough study might be made of the egg distribution from place to place within the ovary. The randomized blocks design was used for the analysis.

The large, or mature eggs were separated from the small, or immature eggs in each sample and all were counted under an ocular micrometer. From the egg counts the percent of large eggs present was computed for each sample.

An Analysis of Variance was run on the data obtained from the samples of these three ovaries. The Analysis of Variance showed that there was no significant difference in the percent of large eggs present between any section or any position in the ovary. Thus, the large and small eggs together form a homogeneous matrix.

The most efficient method of sampling from the ovary of the rock fish, as concluded from the findings in this experiment, is to be obtain samples of eggs at random from the ovary. Each sample should contain more than one hundred fifty (150) ova; the number of samples being determined by precision desired. The number of samples are given in Tables 5a, 5b, and 5c depending upon precision .