Size Grading May Alter Sex Ratios of Fingerling Channel Catfish

Publisher Website
Google Scholar
Abstract
The influence of size grading on sex ratios and growth was evaluated for small (0.2–4.0 g) channel catfish (Ictalurus punctatus). Channel catfish from 15 families were ungraded or were graded into two or three size-groups by mean of bar graders with 0.40–0.99-cm slot widths. The 57 groups obtained were reared separately for 3–4 months in 150-L fiberglass tanks. Weight, length, and sex were then determined on up to 100 fish per group. The frequency of males from all families was 51.5%; although progeny from individual families varied from 45.1 to 56.0% males, the frequencies were not different from the expected 1:1 male: female ratio. Males usually were preferentially selected (mean ± SD, 65.1 ± 3.5%) by a grader with a slot width of 0.91 cm, which retained the largest fish in a population; graders with smaller slot widths did not consistently affect the sex distribution. Harvest size of fingerlings was variable and was influenced by initial weights and densities; family-by-grader interactions wer...

This publication has 0 references indexed in Scilit: