Growth and condition of juvenile sole (&lt;em&gt;Solea solea&lt;/em&gt; L.) as indicators of habitat quality in coastal and estuarine nurseries in the Bay of Biscay with a focus on sites exposed to Erika oil spill

Camille Gilliers,Yves Desaunay,Daniel Guerault,Nathalie Schreiber,Jean-Pierre Bergeron,Rachid Amara,Olivier Le Pape

doi:10.3989/scimar.2006.70s1183

Abstract

Indicators of growth and condition were used to compare the habitat quality of nurseries of juvenile sole (Solea solea L.) in the Bay of Biscay, based on one survey in 2000. The four biological indicators are poorly correlated with each other, suggesting that no single measure may give an adequate description of fish health and of its habitat's quality. Growth indicators showed significant differences between northern and southern areas. Juveniles from the two southernmost nurseries, the Gironde estuary and the Pertuis Antioche, displayed significant lower otolith increment widths and mean sizes. These differences were inversely related to water temperature and unrelated to genetic or age differences, and are unlikely to be due to limiting trophic conditions in the nurseries. Hence, they may be considered in terms of differences in habitat quality and potential anthropogenic impacts. Condition indices do not show this north-south pattern but highlight low condition values in the Pertuis Antioche. Shortterm and fluctuating biochemical indicators such as RNA/DNA ratios appeared to be unreliable over a long-term study, while morphometric indices seemed to be relevant, complementary indicators as they integrate the whole juvenile life-history of sole in the nurseries. The growth and condition indices of juveniles in September 2000 from nursery grounds exposed to the Erika oil spill in December 1999 were relatively high. These results lead us to suggest that there was no obvious impact of this event on the health of juvenile sole and on the quality of the exposed nursery grounds a few months after the event.

Highlights

Despite evidence of important ecological linkages between environmental conditions and fishery production (Engel et al, 1999), the management of commercial fishery resources has historically concentrated on assessing stock size and controlling fishing mortality
SUMMARY: Indicators of growth and condition were used to compare the habitat quality of nurseries of juvenile sole (Solea solea L.) in the Bay of Biscay, based on one survey in 2000
Juveniles from the two southernmost nurseries, the Gironde estuary and the Pertuis Antioche, displayed significant lower otolith increment widths and mean sizes. These differences were inversely related to water temperature and unrelated to genetic or age differences, and are unlikely to be due to limiting trophic conditions in the nurseries

Summary

Introduction

Despite evidence of important ecological linkages between environmental conditions and fishery production (Engel et al, 1999), the management of commercial fishery resources has historically concentrated on assessing stock size and controlling fishing mortality. The habitat quality of the nurseries has potential effects on the growth and survival of the juvenile fish and on their recruitment. The assessment and the conservation of habitat quality, for species of economic importance, are becoming ongoing concerns (Able, 1999). Highquality nursery habitats are assumed to be those where growth and survival of juvenile fish are enhanced and where reproductive potential is optimised (Gibson, 1994). Estimations of growth and condition of young fish are often used as a mean to assess the effects of environmental conditions on individuals in order to appreciate their habitat quality Estimations of growth and condition of young fish are often used as a mean to assess the effects of environmental conditions on individuals in order to appreciate their habitat quality (Sogard and Able, 1992; Phelan et al, 2000; Stunz et al,. 2002; Lloret et al, 2003)

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