New Zealand Journal of Marine and Freshwater Research abstracts

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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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