New Zealand Journal of Marine and Freshwater Research abstracts

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Growth of juvenile snapper, Pagrus auratus

MALCOLM P. FRANCIS

Leigh Marine Laboratory
University of Auckland
Private Bag 92 019
Auckland, New Zealand

and

Fisheries Research Centre
MAF Fisheries
P. O. Box 297
Wellington, New Zealand
(address for correspondence)

Abstract  Growth rates were estimated for juvenile (0+, 1+, and 2+ age classes) New Zealand snapper using length-frequency data, and length-at-age data based on otolith daily increment counts. Growth rates were also estimated for early juvenile snapper reared in Australia. Published estimates of snapper growth rates were reviewed, and the growth history of snapper up to 3 years old discussed. Growth rates were highest during spring-autumn, and lowest during winter. This seasonal cycle was correlated with changes in water temperature. Wild and reared juvenile snapper grew linearly after metamorphosis at rates ranging from 0.35 to 1.53 mm day-1 (typically 0.5-0.9 mm day-1). Growth of wild juveniles slowed dramatically during the first winter, and virtually ceased in subsequent winters. Growth rates during the second and third spring-summer growth periods were typically 0.2-0.4 mm day-1. Within a year class, large snapper were large because they were older, rather than because they were faster growers, than small snapper. Bimodal length-frequency distributions were common, and probably resulted from variability in spawning and recruitment success. Growth rates did not differ among snapper samples collected over an 8-12 km spatial scale.

Keywords  snapper; Pagrus auratus; growth; otolith daily increments; juveniles; seasonal cycle; temperature

PDF file of entire paper: medium quality (1331K); (scanned from paper original: notes about this process)

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