Fisheries Management: objectives and strategies

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Fisheries Managementobjectives and strategies

• Purpose, objectives and goals
• harvest strategies
• harvest tactics
• input controls
• output controls

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Fisheries Managementpurpose

• to ensure sustainable production over time from
  fish stocks

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Fisheries Managementobjectives

• objectives depend on the type of fishery under
  consideration and the political agenda of the
  government
• and can be biological, social, economic, and
  political

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Fisheries Managementkey goals

• maximizing sustainable catches
• maximizing economic yield
• fishing to biological reference points
• maintaining minimum stock sizes
• maintaining spawning stocks
• ecologically sustainable development

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Fisheries Managementmaximizing sustainable
catches

• Provide constant yield in perpetuity
• soon realized MSY was simple-minded and often
  unachievable
• Other problems
• data collection
• brute-force capability to fine-tune
• evolutionary response leading to higher risk of
  recruitment failure
• multispecies fisheries

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Fisheries Managementmaximizing economic yield

• MSY plus monetary cost curve
• Increased effort increased costs
• When is MEY?
• Usually at a lower effort than MSY

Economic break even
MSY
MEY
Cost Revenue
fmey
fmsy
fbe
Fishing Effort (f)
11.2
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Fisheries Managementmaximizing economic yield

• But effort sometimes moves beyond MEY and well
  beyond the break-even point
• But if effort is high and costs exceed revenues,
  effort will be reduced

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Fisheries Managementmaximizing economic yield

• Fishing effort should stabilize at the
  intersection of cost and benefits
• bio-economic equilibrium
• But the stock has been reduced to a low level and
  there is no profit
• Also, the equilibrium may in fact not be stable
  at all.

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Fisheries Managementmaximizing optimum yield

• MSY plus a social costs curve
• a deliberate melding of biological, social, and
  political values designed to produce the maximum
  benefit to society from a given stock of fish.
  Roedel (1977)
• Not well defined whatever managers would like
  them to be

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Fisheries Managementother goals

• Fishing to biological reference points
• Benchmarks for making mgmt recommendations
• based on MSY or MEY to decide on TACs
• Fmsy, Fmcy, Bmsy, F 0.1, (see 7.10)
• Maintaining minimum stock sizes
• In heavily fished stocks, to improve stability of
  catch
• Maintaining spawning stocks
• Ensure a minimum stock size
• unknown for many species
• Use SR relationships to determine consequences of
  exploitation for different biological
  circumstances

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Fisheries Managementother goals

• Ecologically sustainable development
• protection for the ecosystem supporting fisheries
• reduction of a prey may decrease the abundance of
  predator species
• bycatch

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Fisheries Managementother goals

• Adaptive Management Strategies
• single management strategies have no comparisons
  with alternative strategies
• application of different strategies to different
  stocks
• like an experiment
• PROBLEM relies on government reducing fishing
  effort when required

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Fisheries Managementother goals

• Risk Assessment
• determination of acceptable level of risks of
  deleterious effects
• e.g. reduction to less than a TAC to not reduce
  the stock beyond 60 virgin biomass in any year
• using stochastic simulation models

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Fisheries Managementother goals

• Technology creep
• Basing strategies on fishing effort (input
  control)
• apparent effort remains the same but effort
  becomes more efficient, therefore decreasing the
  slope of the COST line

Revenue Costs
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Harvest strategies tactics

• A strategy
• unambiguous robust longterm plan stating catch
  goals
• all key players should participate
• biological, economic, social, and political
  decisions

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Input controls
Fishing Effort
Fishing mortality Natural mortality
Growth Recruitment
Stock
Catch/yield
Output controls
CPUE
Stock assessment
FISHERIES MONITORING
MANAGE. OBJECTIVES
MANAGEMENT STRATEGIES
REGULA- TIONS
Risk assessment
Economic sociological inputs
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Harvest strategies

• Stock-size dependent strategies
• constant-stock size (escapement)
• constant-exploitation-rate
• constant-catch (risky strategy)

Harvest rate
Stock size
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Harvest strategies

• Periodic harvest strategies
• more efficient to take large catch periodically
• larger individuals, higher value
• Strategies that include uncertainty
• Adaptive management
• Using management as an experiment
• passive, trial-and-error, active
• Sex-specific harvesting
• Females are a disproportionate contribution
• Effects of distortions in sex ratio on
  cannibalism, mating patterns, molting and growth
  of females

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Harvest strategies

• Size limit strategies
• Protect females
• Size selective gear
• Economics and harvest strategies
• fixed harvesting costs
• proportional to fleet size
• variable harvesting costs
• proportional to fishing effort
• management costs
• running the fishery

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Harvest tactics

• set of mechanisms to implement the strategy
• Input controls
• control of effective fishing effort
• Output controls
• restricting total catch

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Input controls

• limiting the number of fishing units
• license limitations (vs. open access)
• to impose predetermined level of fishing
  mortality
• Problems
• fair methods of selecting holders
• licensees fish longer
• vessel replacement restrictions

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Input controls

• limiting the efficiency and types of fishing gear
• limit size, type, and number
• restricted to a certain number of hooks per line
• restrict gill nets in length and hanging ratio
• minimum mesh sizes and escape gaps
• allow escapement of juveniles for growth to
  marketable size OR to reproductive size
• provide inefficiency and raise cost of fishing
• allow resource sharing by larger number of
  fishers (good for artisinal fishery)

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Input controls

• Closures
• temporal
• in short, well-defined recruitment periods
• reopen when fish reach an optimum size
• spatial
• protection of juveniles and/or spawning stocks
• nursery or spawning areas such as mangroves,
  estuaries, sea grass meadows, and reefs
• ecosystem approach Marine Protected Areas (MPAs)

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Output controls

• size limits (minimum legal lengths)
• oldest regulation applied to fisheries
• very applicable to recreational fisheries
• not feasible in commercial fisheries - use gear
  selectivity instead
• PROBLEM survival after handling?
• PROBLEM sequential hermaphrodites or sexually
  dimorphic species
• rejection of females or spawning females
• possible if distinguishable and handling doesnt
  harm

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Output controls

• Catch quotas
• Global
• fish to a reference point (MEY, MSY)
• DISADV competition, discontinuous short seasons
• Individual Transferable Quotas (ITQ)
• guaranteed a share of the Total Allowable Catch
  (TAC) which is allocated among all fishers
• PROBLEMS
• estimation of TAC
• using fishery-dependent data to assess the stock
• Enforcement
• dependent on accurate reporting
• Bag limits.recreational fisheries
• allow a limited resource to be shared by many

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Future trends (according to Jennings et al.)

• Fisheries Science research on
• Effects of fishing on ecosystem processes
• Limits to frequency and intensity of trawling
• Impacts measured in economic terms
• Compared to potential benefits
• Biological reference points and precautionary
  approach to dealing with uncertainty
• Indicators of vulnerability, gear design for
  bycatch reduction
• Input from conservation and behavioural
  ecologists
• Shifting burden of proof of adverse effects to
  fishers
• Effects of excessive restrictions?

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Future trends

• Fisheries Management
• Increased overexploitation
• ecosystem effects
• pressure from conservation groups
• Structural changes in fisheries
• Capacity reduction
• Subsidy removal, purchase of excess capacity,
  stock collapse
• More active involvement by fishers
• Increased use of reserves (non-target species)
• Consumers will affect actions of fishers
• Aquaculture
• Growing gap between rich and poor countries
• Sustainability, profitability and capacity for
  conservation