New Zealand Journal of Marine and Freshwater Research abstracts

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SPAWNING AND LENGTH-WEIGHT OF BARRACOUTA (TELEOSTEI: GEMPYLIDAE) FROM EASTERN COOK STRAIT

John A. P. Mehl*

Zoology Department, Victoria University of Wellington, Wellington, New Zealand

Abstract A sample of 244 barracouta, Thyrsites atun (Euphrasen), caught in eastern Cook Strait, New Zealand, between March 1966 and April 1967, was examined to determine the spawning season and length-weight relationship. Female barracouta ripened from April onwards, a month earlier than males. Females tended to attain maturity more rapidly than most males. October and November were the peak spawning months, although some barracouta (mainly females) were mature until January. The smallest spawning barracouta was 55 cm L.C.F. Disappearance of barracouta preceding the spawning months suggested a spawning migration. A mathematical analysis of the length-weight data was used to predict one value from the other, and to obtain an index of the relationship (i.e., a condition factor). There was no significant difference between the slope of the regression line n for males and females, the equations being W = 0.03867. L²-⁵²⁰⁹ and W = 0.07391 .L²-³⁶⁸⁷ respectively. The equation for the regression line for all barracouta, W = 0.05893 . L²-⁴²²², had an exponent value n lower than expected for a length-weight relationship of unmutilated fish. The condition factor of barraoouta, measured at monthly intervals, gave a good indication of the spawning cycle.

N.Z. Journal of Marine and Freshwater Research 5 (2): 300-17
(Received for publication 1 April 1969)

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