New Zealand Journal of Marine and Freshwater Research abstracts

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Age, growth, and commercial landings of yellowtail scad (Trachurus novaezelandiae) and blue mackerel (Scomber australasicus) off the coast of New South Wales, Australia

JOHN STEWART
DOUGLAS J. FERRELL

NSW Fisheries
Cronulla Fisheries Centre
P. O. Box 21, Cronulla
NSW 2230, Australia
email: stewartj@fisheries.nsw.gov.au

Abstract  Size and age compositions of yellowtail scad (Trachurus novaezelandiae Richardson 1843) and blue mackerel (Scomber australasicus Cuvier 1832) were studied in the inshore purse-seine fishery off the coast of New South Wales, Australia. Ages were assigned by counting annual marks in otoliths for both species. Sampling from two regions showed no geographical differences in the age compositions of catches for either species. The fishery for yellowtail scad was based on 2- and 3-year-old fish, but with significant numbers of fish up to 11 years. Seventy percent of the fishery for blue mackerel was based on fish aged 1 year, with the majority of the rest being in their first or third years. Maximum ages recorded in this study were 14 years for yellowtail scad and 7 years for blue mackerel. We found no major differences in the sizes of blue mackerel landed in either region sampled, but yellowtail scad were larger in the northern region than in the southern. Growth rates of blue mackerel were the same from both regions, but yellowtail scad sampled grew significantly faster in the northern region. The fishery for yellowtail scad off New South Wales is currently based on younger and smaller fish than other trachurid fisheries around the world. This, together with the observed spatial variation in growth and population structure, suggests that the fishery for yellowtail scad in New South Wales should be carefully monitored.

Keywords  growth; Trachurus; Scomber

New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35: 541-551

0028-8330/01/3503-0541 $7.00 (c) The Royal Society of New Zealand 2001

PDF file of entire paper: medium quality (713K); (scanned from paper original: notes about this process)

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