New Zealand Journal of Marine and Freshwater Research abstracts

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Spawning pattern, length at maturity, and fecundity of the southern blue whiting (Micromesistius australis) in the south-west Atlantic Ocean

M. PáJARO

Instituto Nacional de Investigación
 y Desarrollo Pesquero (INIDEP)
Paseo V. Ocampo 1
P. O. Box 175
7600 Mar del Plata, Argentina
email: mpajaro@inidep.edu.ar

G. J. MACCHI

Consejo Nacional de Investigaciones
 Científicas y Técnicas (CONICET)
Rivadavia 1917
1033 Buenos Aires, Argentina

Abstract  Southern blue whiting (Micromesistius australis Norman, 1937) inhabits the waters of the Southern Hemisphere, and in the south-west Atlantic Ocean is distributed over an area next to the Malvinas Islands. At present, this species is suffering over-exploitation and its biomass has decreased drastically. The histological analysis of ovaries and the oocyte size frequency distribution of gravid females indicate that southern blue whiting is a batch spawner with determinate annual fecundity. The spawning season of M. australis in the south-west Atlantic Ocean extends from August to October, with a main peak during September. Spawning females were recorded mainly in the waters south and south-west of the Malvinas Islands, close to the 200 m isobath. Total fecundity of seven M. australis females ranged from 148 300 to 713 900 yolked oocytes (46-55 cm total length (TL)). The mean total fecundity was 477 700 (206 783 SD) oocytes for one 51 cm TL female. Mean relative fecundity was 706 (258 SD) oocytes per g female weight, ranging from 277 to 967. The percentage of sexually mature females for each total length class indicated 50% female maturity was reached at 37.8 cm. This value was similar to those reported for this species between 1980 and 1990.

Keywords  Micromesistius australis; fecundity; spawning season; size at maturity

M99060

Received 28 October 1999; accepted 13 October 2000

New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35: 375-385

0028-8330/01/3502-0375 $7.00 (c) The Royal Society of New Zealand 2001

PDF file of entire paper: medium quality (1558K); (scanned from paper original: notes about this process)

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