Fisheries Management

Fisheries Management

1. "the pursuit of certain objectives through the in/direct control of effective fishing effort or some of its components" FAO of the UN, Rome, 1982

   • change minimum net size
   • regulate size of fish at capture
   • licenses to control entry
   • maximise economic returns

2. Developing Countries

   • enforcement of management impossible
   • Vital, traditional income
     • Lack of occupational and geographical mobility
       • Isolation
       • Low formal education
       • age
       • subsistence lifestyle preference
         • Dont chase fish with 'price tags' higher than cost of catching - maximise their income
           • MEY
           • Increase effort when fishing is poor - negative for fish stocks
       • lack of knowledge of wider issues
       • exposure to opportunities
       • inability to financially leave in bad seasons, no reason to leave in good
     • easy entrance to market
     • Small-Scale fishery landings omitted in trajectories and data
       • Catch Re-Construction Project (Polly and Zeller 2016) to identify these
         • Artisanal Fisheries
           • Small scale, households, local consumption
         • Subsistence Fisheries
           • consumed by kin, pure subsistence is rare as often exchanged for other goods
         • Recreational Fishing
           • Harvesting for personal use, leisure or challenge
   • Tragedy of the Commons, Hardin 1968

3. The Economics

   • Relationship between
     • Sustainable Catch
       • QFish (weight of biomass) which can theoretically be caught annually with no change in intensity of fishing
       • Net Natural Growth calculation
         • NNG = Recruitment + Growth of Pre-Existing Stock - Natural Mortality
         • what can be caught sustainably without affecting stock size
     • Fishing Effort
       • Composite index of all inputs employed for the purpose of the catch - in terms of effect on fishing stock
       • Main parameter under our control
   • The Static Constant-Price Model
     • Unit prices of fish decline as size of stocks decline as they are replaced by less valuable ones
       • Depends on tastes and norms
     • MEY occurs where there is the furthest distance between the TR and TC curves: often before the MSY is reached
       • MEY: Most appropriate goal for fisheries management
         • Maximises society's net benefit from the fishery
           • However may result in loss of fishermen from the industry
             • Opportunity cost of fishing in some communities is =0 due to lack of employment opportunities, so little sacrifice in continuing to fish
             • Widespread unemployment - social impacts
             • Multiplier effect past MEY: processing, transport, marketing, investment opportunities

4. Fishery Development

   • In addition to fishery expansion
   • post-harvesting technology
   • marketing
   • transportation
   • provision of infrastructure
   • Total biological extinction unlikely due to existence of natural reserves - un-trawlable grounds

5. Attain optimum rate of exploitation: depends on specific objectives by policy makers

   • Objective 1: Maximise Fish Production
     • defined by MSY
       • MSY
         • Too risky objective for development and management
           • Considerable annual variability in stock and species makes this inaccurate in the long term
             • Change in the abiotic environment
             • Changes in fishing intensity
             • Unprecedented knock-on effects of activities
     • maximum catch that can be obtained on a sustained basis
     • Actual Catch < MSY = Biologically Underexploited
     • Actual Catch > MSY = Biologically Overexploited
     • "Biologically" - natural growth of stock
   • Objective 2: Maximise Economic Benefit
     • defined by MEY
     • maximum sustainable surplus of revenues over fishing costs
     • Modification of MSY accounting for value of fish and costs of fishing
   • Objective 3: Improvement of Socio-Economic conditions
     • produces a bio-economic model: Maximum Social Yield (MScY)
     • requires MSY and MEY
     • level of catch and corresponding effort providing best solutions to social problems given policy objectives and all possible alternatives
       • conflicts between income and employment objectives

6. Schaefer Growth Model

   • GR of stock depends on the size of the stock
     • Determined by carrying capacity
       • Environmental Limits: Food, Space etc.
   • Stock- Effort Relationship
     • Long term response of catch changes to fishing effort:
       • Early: expansion of effort increases catch
         • As effort expands: diminishing returns: smaller growth in catches until the MSY is reached
     • Increases in catch can't be sustained in the long-run by the fishing industry
     • As fishing intensifies and develops, additional effort brings smaller and smaller increases in catch as MSY is approached
     • The Sustainable Yield Curve can be shifted by manipulating the average age at first capture - through change in fishing methods
       • Adjust this by adjusting fishing effort to the MSY at the highest SYC curve
         • Stock needs time to acclimatise

7. The Environment

   • Assumptions that environmental conditions remain unchanged
   • Non-favourable, non-random, and evolutionary changes occur that effect the strength of the stock
     • Variability arising from intensification of fishing, reductions in age classes (impact stability)
     • Natural Variability from nature, location, interactions with biotic and abiotic environment

8. Conflicts between fishermen

   • Redistribution away from spawning areas (often inland lagoons) calls for elimination of coastal, small scale fisheries
     • Costs increase when forced offshore
     • relative social costs of inputs: capital, fuel and labour
     • Alternative employment for displaced
     • Not economically or socially beneficial to fish recruitment for society

9. Multi-Species Fisheries

   • EG) Tropical Fisheries account for multispecies stocks exploited by distinct groups of fishermen
   • Multispecies composition of stocks and consequent technological and biological interactions within the fishery
     • ECONOMIC: Fish of differing value within a single hauling range
     • BIOLOGICAL: Competition between species, evolutionary change in species and distribution
     • Different diets, ages of maturity, size at maturity, lifetime, maximum size and market price
       • Vulnerability increases with age and size
         • Juveniles need to reach maturity to sustain stock - avoid fishing food
   • Maximisation of catch complex
     • Possible sequential collapse due to loss of keystone species
     • Compromise of mesh size required: some will be under/over exploited
     • Sequential Overfishing
       • Hilborn et al 2003
       • target is based on ease and profit maximisation
       • Continue to exploit where abundance is low because of the number of species available to exploit - so sustain effort
         • Worsened where a range of fishing techniques available - to maximise biomass yield
           • Collateral Damage
             • By-Catch and By-Kill
             • lack of selectivity of current techniques
               • eg. Long-Line
             • prawn and scallop dredging and trawling developed as a result of sequential overfishing
   • Approach to Management
     • Multi-species production models
       • SUM: individual yield curves = aggregate sustainable yield curve
         • 'Kinks' imply disappearance of certain species from catch

10. Reforming Management

    • Fish Less
    • Waste Less
    • Use less destructive fishing methods
    • Protect more
      • However, climate change is altering migration patterns
        • can the reserves move too?
    • Respect science and recommendations
    • Identify illegal and unregualated fishing
    • Using MEY rather than MSY to reduce habitat destruction

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