Modelling the effects of fishing on the North Sea fish community size composition

Douglas C. Speirs, Simon P.R. Greenstreet, Michael R. Heath

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Ecosystem-based management of the North Sea demersal fish community uses the Large Fish Indicator (LFI), defined as the proportion by weight of fish caught in the International Bottom Trawl Survey (IBTS) exceeding a length of 40cm. Current values of the LFI are ~0.15, but the European Union (EU) Marine Strategy Framework Directive (MSFD) requires a value of 0.3 be reached by 2020. An LFI calculated from an eight-species subset correlated closely with the full community LFI, thereby permitting an exploration of the effects of various fishing scenarios on projected values of the LFI using an extension of a previously published multi-species length-structured model that included these key species. The model replicated historical changes in biomass and size composition of individual species, and generated an LFI that was significantly correlated with observations. A community-wide reduction in fishing mortality of ~60% from 2008 values was necessary to meet the LFI target, driven mainly by changes cod and saithe. A 70% reduction in cod fishing mortality alone, or a 75% reduction in otter trawl effort, was also sufficient to achieve the target. Reductions in fishing mortality necessary to achieve maximum sustainable harvesting rates are projected to result in the LFI over-shooting its target.
LanguageEnglish
Pages35-45
Number of pages11
JournalEcological Modelling
Volume321
Early online date4 Dec 2015
DOIs
Publication statusPublished - 10 Feb 2016

Fingerprint

Fish
fishing
fish
Modeling
modeling
fishing mortality
Mortality
Target
effect
sea
Community
demersal fish
bottom trawling
indicator
Necessary
Shooting
Harvesting
Biomass
Ecosystem
European Union

Keywords

  • length structured population model
  • multi-species model
  • North Sea
  • fisheries
  • ecosystem based managment
  • large fish indicator

Cite this

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title = "Modelling the effects of fishing on the North Sea fish community size composition",
abstract = "Ecosystem-based management of the North Sea demersal fish community uses the Large Fish Indicator (LFI), defined as the proportion by weight of fish caught in the International Bottom Trawl Survey (IBTS) exceeding a length of 40cm. Current values of the LFI are ~0.15, but the European Union (EU) Marine Strategy Framework Directive (MSFD) requires a value of 0.3 be reached by 2020. An LFI calculated from an eight-species subset correlated closely with the full community LFI, thereby permitting an exploration of the effects of various fishing scenarios on projected values of the LFI using an extension of a previously published multi-species length-structured model that included these key species. The model replicated historical changes in biomass and size composition of individual species, and generated an LFI that was significantly correlated with observations. A community-wide reduction in fishing mortality of ~60{\%} from 2008 values was necessary to meet the LFI target, driven mainly by changes cod and saithe. A 70{\%} reduction in cod fishing mortality alone, or a 75{\%} reduction in otter trawl effort, was also sufficient to achieve the target. Reductions in fishing mortality necessary to achieve maximum sustainable harvesting rates are projected to result in the LFI over-shooting its target.",
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Modelling the effects of fishing on the North Sea fish community size composition. / Speirs, Douglas C.; Greenstreet, Simon P.R.; Heath, Michael R.

In: Ecological Modelling, Vol. 321, 10.02.2016, p. 35-45.

Research output: Contribution to journalArticle

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