Journal Article

Histological analysis invalidates macroscopically determined maturity ogives of the Kattegat cod (<i>Gadus morhua</i>) and suggests new proxies for estimating maturity status of individual fish

F. Vitale, H. Svedäng and M. Cardinale

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 63, issue 3, pages 485-492
Published in print January 2006 | ISSN: 1054-3139
Published online January 2006 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2005.09.001
Histological analysis invalidates macroscopically determined maturity ogives of the Kattegat cod (Gadus morhua) and suggests new proxies for estimating maturity status of individual fish

More Like This

Show all results sharing these subjects:

  • Environmental Science
  • Marine and Estuarine Biology

GO

Show Summary Details

Preview

Assessment and management of fish populations currently rely on correct estimation of the spawning-stock biomass (SSB), which is based on accurate maturity ogives of the population. Although maturity ogives are usually calculated through macroscopic evaluation of the gonads, histology is generally considered to be more accurate. Here we show that the macroscopic analysis consistently overestimates the proportion of mature females for all age classes in Kattegat cod. The resulting bias showed minimum values for all age classes about a month before the spawning season. Consequently, estimation of the incidence of maturation in females several months before or after the spawning season can only be accurate using histological techniques. Further, the observed bias was used to reconstruct a historical data set of maturity ogives of Kattegat cod. The results showed that female spawning biomass (FSB) might have been overestimated by up to 35%. However, as histological analysis is considered a laborious procedure, proxies of maturity status were sought. It was indicated that the gonadosomatic and hepatosomatic indices may serve as robust proxies for discriminating mature females from immature, thus greatly enhancing the accuracy of the macroscopic maturity evaluation of cod gonads when histological analysis is lacking.

Keywords: GSI; HSI; Kattegat cod; maturity ogives; SSB; stock assessment; tree model

Journal Article.  4723 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.