Modelling the food web in the Irish Sea in the context of a depleted commercial fish community

  • Jacob Bentley

Student thesis: Doctoral ThesisDoctor of Philosophy (awarded by UHI)


Irish Sea landings used to be dominated by finfish but now mainly consist of molluscs and crustacea due to stock declines and changing market demands. There has been limited evidence of finfish recovery despite fishing effort reductions, gear restrictions, and area closures. Frustrated and confused, researchers, stakeholders, and policy advisors came together in 2015 to establish the first International Council for the Exploration of the Sea
(ICES) Integrated Benchmark Assessment: WKIrish. Aiming to instigate an Ecosystem Approach to Fishery Management (EAFM) for the Irish Sea, WKIrish advocated the construction of multi-species models to develop an ecosystem understanding of the drivers of commercial stocks. This thesis describes the development of an Ecopath with Ecosim (EwE) food web model for the Irish Sea as part of WKIrish. The EwE model follows the best practices for model construction, like many of the more recently developed models, yet it stands apart from others due to its creation at the science-policy interface. By working
closely with stakeholders and policy advisors, the Irish Sea model, certified as an ICES ‘key run’, has been put forward as the first EwE model to inform ICES catch advice. As the project progressed towards this end goal, opportunities were taken to develop new approaches for model parameterisation, collaborations were built with parallel fields to advance EwE uncertainty analyses, and novel methods were created for research coproduction and use of fishers’ knowledge. Environmental change stands out in many chapters of this thesis as a key driver of system production, with commercial stocks being highly susceptible to bottom-up regulation. Findings suggested that historic environmental
change suppressed the overall production of commercial finfish, limiting opportunities for the fishing industry, whilst also dampening their rate of recovery despite marked reductions in fishing effort. This thesis culminates with the proposal of a new concept for the addition of ecosystem information to ICES “pretty good yield” ranges to support continued progression towards EAFM.
Date of Award26 Jun 2020
Original languageEnglish
Awarding Institution
  • University of the Highlands and Islands
SponsorsMarine Institute, Galway
SupervisorClive Fox (Supervisor)

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