The meaning of fish size spectra, the effects of fishing on them and the usefulness of their slope as indicator of fishing impacts

Type Proceedings paper
Date 2003
Language English
Other localization https://www.ices.dk/sites/pub/CM%20Doccuments/2003/N/N0503.PDF
Author(s) Benoit Eric1, Rochet Marie-Joelle2
Affiliation(s) 1 : Laboratoire de mathématiques, Université de la Rochelle, avenue Michel Crépeau, 17042 LA ROCHELLE, FRANCE
2 : Laboratoire MAERHA, IFREMER, Rue de l'Ile d'Yeu, B.P. 21105, 44311 NANTES Cedex 03, FRANCE
Meeting ACS 2003 - ICES Annual Science Conference 2003. 24-27 September 2003. Tallinn, Estonia
Source ACS 2003 - ICES Annual Science Conference 2003. 24-27 September 2003. Tallinn, Estonia. ICES CM 2003/N:05. 10p.
Keyword(s) biomass size spectra, size-dependent processes, fishing effects, indicators
Abstract

A new time-dependent continuous model of biomass size spectra is developed. In this model, predation is the single process governing the energy flow in the ecosystem, as it causes both growth and mortality. Predation is size-dependent. The ratio of predator to prey is assumed to be distributed: predators may feed on a range of prey sizes. Under these assumptions, it is proven that linear size spectra are stationary solutions of the model. The slope of this size spectrum is insensitive to the magnitude of processes in the food web, such as the width of prey size distribution, the volume of water searched while foraging or the assimilation efficiency. Exploited fish communities are simulated by adding a size-dependent fishing mortality to the model: it is found that realistic fishing pressures should not affect the slope of size spectra, but their shape and stationarity.

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Benoit Eric, Rochet Marie-Joelle (2003). The meaning of fish size spectra, the effects of fishing on them and the usefulness of their slope as indicator of fishing impacts. ACS 2003 - ICES Annual Science Conference 2003. 24-27 September 2003. Tallinn, Estonia. ICES CM 2003/N:05. 10p. https://archimer.ifremer.fr/doc/00694/80608/