New Zealand Journal of Marine and Freshwater Research abstracts
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)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
