Operational evaluation tools for fisheries management options

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Operational evaluation tools for fisheries
management options www.efimas.org Tom
Catchpole (Cefas, UK) Representing 30
participating national research institutes
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Objective EFIMAS was launched to facilitate the
development of better fisheries management
regimes. The objective is to develop a set of
new tools that can simulate and evaluate the
biological, social and economical consequences of
a range of fishery management options and
objectives.
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• Background
• A problem of TACs is that when managing using
  fish landings, scientists have to make accurate
  predictions about stocks. This is difficult due
  to natural variations in fish populations and the
  limitations of the methods and data used.
• Traditional stock assessment requires
  identification of a best assessment, but this
  means rejecting other alternatives, even though
  some may also be plausible.
• Under the approach adopted in EFIMAS the
  objective is no longer to come up with the
  answer but to evaluate the consequences of
  various management strategies, i.e. to determine
  the robustness.
• We ask, what is the relative impact of
• different management measures?
• assumptions about the stock?
• fleet dynamics?

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Project structure Evaluation tools developed for
a series of case studies each characterised by
specific problem North Sea Flatfish Round
fish Baltic Sea Salmon East
Atlantic Nephrops Hake Mediterranean
Swordfish Hake Baltic Sea Cod
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• An example - Nephrops Case Study
• Simulated effects of five selective trawl designs
  (NECESSITY) on North Sea round fish stocks
• Cutback headline
• Grid with SMC
• Two SMPs
• Dyneema twine SMP
• 100 mm codend
• Also examined the hypothetical scenarios of
• No discarding in all North Sea fisheries
• No discarding in just the Nephrops fishery
• No discarding only fish that are normally
  landed are caught
• (knife-edge selection).

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Data Catch comparison trials STECF ICES
Results Cod 10 years
Development of tools to make forecasts fr lt-
function(x) ((x/(xm)stock(1-exp(-(xm)))-catch)
2) 2 minimises the negative number opt.ct lt-
optim(x,fr, method "L-BFGS-B", hessian TRUE,
lower0, upper2.0) paramd lt-
as.numeric(opt.ct1)
f.at.age lt- data.frame(age18,
fas.numeric(c(param1, param2, param3,
param4, param5,
param6, param7,param8))) rf.at.age.quant lt-
new("FLQuant") rf.at.age.quant lt-
FLQuant(dimc(8,10,1,1,1), quant'age',
dimnameslist(year20052014)) rf.at.age.quant18
,,,, lt- f.at.age,2 return(rf.at.age.quant)
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Results No discarding in all fisheries stocks
increase by 41 cod 14 haddock
29 whiting within 10
years No discarding in Nephrops fishery alone
stocks increase by 2 cod
1 haddock 10 whiting within 10
years With all selective trawl designs whiting
stock increased. For cod and haddock, only with
a trawl with a combined sorting-grid and
square-mesh codend was there a notable increase
in stock (15 and 6).
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• This Nephrops study simulated the relative
  impacts of implementing different trawl designs.
• However, the tools developed within EFIMAS could
  answer other questions, for example
• How would the results change if the biological
  parameters were different (stock-recruitment
  relationships, growth)?
• What if the data used in the simulation are
  biased?
• What would be the result of only some fleets
  adopting new trawl designs or if they adopted
  different designs?
• What are the economic implications of the
  different management options to the various
  fleets?
• What would be the effect of climate change?

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• Project Output (some examples)
• The potential for new Nephrops trawl designs to
  positively effect North Sea stocks of cod,
  haddock and whiting
• FLR an open-source framework for the evaluation
  and development of management strategies
• Validating management simulation models and
  implications for communicating results to
  stakeholders
• Evaluation of North Sea cod Recovery Plans
  comparing days at sea limitations with mesh size
  increases
• Project is on going but will produce reports for
  each case study and associated software packages

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The output from EFIMAS will guide fisheries
managers and other stakeholders in making
strategic choices. www.efimas.org