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#Topic Sentences

##Intro

Background

  • Sustainable management of any renewable resource requires understanding of system dynamics in response to exploitation.
  • Sustainable and scientifically defensible fishery management is built on the foundation of fisheries stock assessment
  • In Canada, stock assessments are lacking in most fisheries (@hutchings2012canada), especially for non-target species.
  • A lack of assessments for some species within a multi-species fishery threatens sustainable management of the whole fishery in two ways.

Technical Interactions

  • Stock assessments are traditionally performed for a single species at a time, even though this approach may lead to sub-optimal outcomes for multi-species fisheries (@sugihara1984ecosystems; @gulland1984observed).
  • Within the single-species paradigm, major stocks typically comprise several distinct but interacting sub-stocks (@walters2004fisheries; @benson2015evaluating), such as Pacfic salmon (Onchorynchys spp.) (@simon1972stock).
  • Managing Pacific salmon in runs has both advantages and disadvantages.
  • The aggregation management approach used for Pacific salmon could be extended to other multi-species fisheries rich with technical interactions, such as groundfish fisheries.
  • Managing groundfish would require a similar but distinct approach due to several key differences to Pacific salmon.
  • Technical interactions between fishes have led several groundfish fisheries in the north Pacific (??) to integrate harvest output controls by making shares of the Total Allowable Catch (TAC) for every species available to harvesters.
  • Para about FAO/fisheries lit: removals scaled to stock status? Requires assessment to estimate abundance and productivity.
  • Although integration acknowledges technical interactions in multi-species groundfish fisheries through TAC distribution, challenges remain in managing integrated fisheries optimally.

Assess or Avoid - Layer questions in here?

  • The profitability constraints on directed fisheries caused by pinch-point species may be alleviated by either assessing data-limited stocks, or avoiding pinch-point species.
  • One option for overcoming data limitations is to extend stock assessments to explicitly acknowledge interactions between species (@punt2011among; @zhou2010modified; @mueter2006using).
  • Figure 2 shows three possible models of fishery operation and management.
  • I study a version of model (b) in Figure (1) that is called the Robin Hood (RH) approach to stock assessment.
  • The RH approach to stock assessment could help shape how scientific surveys are designed.

Study System

  • The British Columbia Integrated Groundfish Fishery (BCIGF) (@PRIFMP2015) is an integrated multi-species groundfish fishery operating year-round in Pacific waters on the west coast of Canada.
  • A lack of up to date assessments threatens both access to markets by and the sustainable management of the BCIGF.
  • Some species in the BCIGF appear on the Species at Risk Act (SARA) or COSEWIC (footnotes, refs) lists.
  • Both unassessed and SARA/COSEWIC species in the BCIGF can act as pinch-point species: lower productivity stocks that constrain the exploitation of directed, high-value stocks.
  • Two solutions to the problem of pinch-point species are evident, based on the present knowledge of stock status.

Questions