Publication Date

1982

Series Number

Fisheries Report No 57

Publisher

Department of Fisheries and Wildlife, Western Australia

City

Perth

ISBN

O 7244 9090 6

ISSN

0726- 0733

Abstract

The results of catching Spanish mackerel (Scomberomorus commerson) by gillnet and troll lines during a survey extending from June 16 to October 16 1981 are presented.

The catch rate of mackerel obtained by trolling with six lines was found to be 14.35 times greater than that by gillnet, measuring 0.75 miles in length.

From the results presented, a professional fisherman should be able to assess the economic viability of fishing commercially for Spanish mackerel.

Analysis of biometrial and biological data on fish caught allowed determination of (a) length/weight relationship of (i) Spanish mackerel (ii) wahoo (Acanthocybium solandri); (b) sex ratios of (i) Spanish mackerel (ii) wahoo; (c) gonad indices for mackerel which showed that most females during this period to be in a resting stage in the reproductive cycle.

Catch rates of Spanish mackerel related to surface temperature are shown to be highest in the temperature range 22 C to 24 C, and comparison of seasonal distribution of mackerel with seasonal positions of the 22 C and 24°c isotherms is made.

Analysis for mercury content in tissue samples from black tip shark (Carcharhinus sorrah) caught by gillnet indicates that the levels of mercury in the larger individuals may cause some marketing difficulties under currently recommended health regulations.

Number of Pages

48

Keywords

Spanish Mackerel, Western Australia, Gillnet, Troll lines, Survey

Disciplines

Aquaculture and Fisheries | Marine Biology | Natural Resources and Conservation | Natural Resources Management and Policy | Sustainability

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