Do population and community metrics tell the same story about recent changes in Northern Mediterranean fish communities?

Type Proceedings paper
Date 2007
Language English
Author(s) Rochet Marie-Joelle1, Trenkel VerenaORCID1, Gil De Sola Luis2, Politou Chrissi-Yianna3, Tserpes George3, Bertrand Jacques1
Affiliation(s) 1 : Ifremer, Département Ecologie et Modèles pour l'Halieutique, Ifremer, B.P. 21105. 44311 Nantes CEDEX 03, France
2 : Instituto Español de Oceanografía, Muelle Pesquero s/n, 29640 Fuengirola, España
3 : Hellenic Centre for Marine Research, Institute of Marine Biological Resources, Agios Kosmas, 16777 Helliniko, Greece
Meeting ICES Annual Science Conference 2007
Source ICES CM 2007 / D:16
Keyword(s) Community metrics, ecosystem approach to fisheries, fish community, length-based metrics, Mediterranean, survey data
Abstract This document presents a comparative study of human impacts on the length-structure of fish communities across North-Mediterranean ecosystems. We use survey data to examine trends in length-based metrics and their consistency within and among the two levels of organisation populations and communities, and to suggest interpretations of observed trend combinations. We start from a set of population processes potentially affected by human pressures: fishing will induce mortality especially in target species, whereas the hydrological environment and eutrophication potentially affect recruitment and individual growth. How population changes will be reflected at the community level is expected to depend on community evenness. Based on this expectation, a tentative theory for predicting the joint response of a suite of population and community length-based metrics to potential changes in the environment is proposed. The trends in these metrics from survey data are then examined, focusing on the consistency with the above predictions. The potential causes suggested for the observed trends are then checked against independent evidence of environmental and human pressures on these communities. The approach is applied to the MEDITS survey data, which cover a series of neighbouring fish communities undergoing various human pressures, including fishing, coastal pollution and eutrophication, and a possible change in temperature and hydrology over the last decade.
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Rochet Marie-Joelle, Trenkel Verena, Gil De Sola Luis, Politou Chrissi-Yianna, Tserpes George, Bertrand Jacques (2007). Do population and community metrics tell the same story about recent changes in Northern Mediterranean fish communities? ICES CM 2007 / D:16.