New Zealand Journal of Marine and Freshwater Research abstracts
Assessment of size at maturity and gonad index methods for the scallop
Pecten novaezelandiae
James R. Williams
Leigh Marine Laboratory
University of Auckland
P.O. Box 349 Warkworth,
New Zealand
email: jwilliams_nz@hotmail.com
Russell C. Babcock
CSIRO Marine Research
Private Bag No. 5 Wembley
WA 6913, Australia
Abstract Size at sexual maturity and gonad indices appropriate
for measuring reproduction were examined in the scallop Pecten novaezelandiae
at two sites in the Hauraki Gulf, New Zealand. Size at maturity was assessed
using gonad visual grading and allometric calculation methods. Size of the
smallest mature individual varied from 52 to 59 mm shell height between sites.
In general, 50% of scallops were mature at 60 mm and 100% were mature at
65 mm. Small differences in size at maturity between sites may be related
to differences in environmental conditions that affect growth rates. Our
results were broadly similar to those reported from the South Island, however
direct comparisons were compromised by the wide range of methods and definitions
used in previous studies. Here we applied a method that directly scaled gonad
mass to shell height, removing the need for a reference mass, and combined
it with an objective method to establish size at maturity that will facilitate
future comparisons.
Keywords allometry; gonad mass; maturity; reproduction;
scallop; size; age
M04119; Online publication date 17 June 2005 Received 9 June 2004; accepted
14 January 2005
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
851-864
0028-8330/05/3904-0851 © The Royal Society of New Zealand 2005
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