Overfishing: Impacts, Implications, and Resolutions

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OverfishingImpacts, Implications, and
Resolutions

• Mike Ruhl
• Marine Biology
• BIOL 475G

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What is fishing?

• Exploitation of marine organisms for sustenance,
  profit, or pleasure.
• Fish- cod, halibut, salmon, redfish, stripped
  bass
• Shellfish
• Mollusks- clams, scallops, oysters, abalone
• Crustaceans- crabs, shrimp, lobster
• Reptiles- turtles
• Mammals- whales

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Why do we fish?

• Survival- many costal communities, particularly
  in developing countries, fish as a primary food
  source.
• Recreation- fishing for fun.
• Profit- commercial exploitation as a means of
  earning a livelihood.

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Implications of Fishing

• Sociology- in some places people need to fish to
  survive, in many others they simply want to fish
  as a mode of recreation.
• Economics- individuals and regions can be
  dependent on fishing as a source of income.
• Ecology- natural systems are easily disrupted by
  intense anthropogenic pressure.

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What is overfishing?

• Removal of organisms from the marine environment
  at a rate which cannot be sustained by natural
  recruitment and therefore
• negatively affects interested human user groups.
• significantly alters natural systems.

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The Anthropocentric View

• How can we best exploit the resource?
• Maximum Sustained Yield (MSY)
• How many critters can be taken each year for an
  indefinite amount of time without disrupting the
  ability of the resource to renew itself.
• Optimum Sustained Yield (OSY)
• How many critters can be taken and have the
  resource maintain the highest level of
  profitability.

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Problems

• Estimating populations
• Estimating catch
• Predicting population
• change based on
• catch.
• environmental stochastisity.
• limited knowledge of life history.
• Tends to err on the side of over harvest
• Doesnt consider ecology

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The Ecopocentric View

• How can we utilize the resource only to an extent
  which does not significantly alter it and the
  natural system in which it occurs.
• Widely varying degrees of opinion.
• Tends to err on the side of caution.

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Problems

• Ignores the economic aspect
• Much less powerful legislative lobby
• Public perception
• Complexity of ecological
• interactions and
• environmental variation
• makes prediction of trends difficult.
• It depends.
• The solution must lie in the between the two.

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The Making of a Disaster

• Collapse of the North Atlantic Cod Fishery
• Canadian cod stock severely depleted by local and
  distant water fleets
• Canada declared Extended Fisheries Jurisdiction
  in 1979 to control and rebuild the fishery
• Expected a rise in Total Allowable Catch by 1985
• Instead the fishery continued to decline and
  effectively closed in 1992

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Why?

• Mismanagement
• Fishing mortality exceeded sustainable level
  estimates by 2.5X in 1985-87, 3.5X in 1988, 4.5X
  in 1989, 6.5X in 1990, and 7X in 1991
• Stocks never achieved 50 of predicted TAC
• Canadian fleet over harvested cod

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How?

• TAC calculated to /-30
• Upper limit was used to calculate harvest quota
  every year
• 100,000 tons example
• When upper limit became insufficient to
  economically support fishery quota was increased
• Short term economic gain won out biology because
  they are the more powerful lobby

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The Irony

• Biologists could see the catastrophe happening
  and were powerless to stop it
• What happens when resources are managed by
  politics and not biology
• Long term economic loss (closure of fishery) far
  outweighs short term benefit
• Economy loses more due to mismanagement

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Lessons Learned?

• Good Enough is dangerous
• Knowledge of the resource
• Ability to control harvesting process
• TAC should be based on lower CI, or most
  conservative estimates
• Establishment of TAC needs to be free of
  short-term economic interest
• Current status of the North Sea Cod Fishery

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Ecological Impacts of OF

• Much more complicated than reduction of one
  species
• Trophic interactions
• Top-down and bottom-up effects
• Salmon, killer whale, sea otter example
• Change in community structure
• Loss of biodiversity
• Bycatch and habitat disturbance

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The Terrestrial Connection

• What happens in the sea affects the land
• Anadromy and Catadromy
• Many anadromous fish are or were important in
  terrestrial ecosystems
• Salmon in the Pacific NW
• American shad on the East Coast
• Coastal bird communities

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Solutions

• Marine Protected Areas
• Effective if
• Large enough
• Protect source populations
• Effectively enforced
• Currently well below 1 of marine systems are
  protected by MPAs
• Valuable tool but not the silver bullet

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Legislation, Legislators, and Lobby

• Only real solution is through regulation
• Effective regulation requires 3 things
• Legislation consistent with biology
• Competent management agencies
• International Compliance
• Education
• Enforcement
• Meaningful penalties and prosecution
• Must make legislators see the benefit of proper
  management

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Responsible Recreation

• Mounting evidence suggests impacts or
  recreational angling (Science, Nov. 2004)
• Not just commercial fishing issue
• Attempts to conserve fisheries are met with
  opposition from both parties
• Blame the other guy.
• Anglers need to work for conservation not
  against it

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Conclusions

• Conservation of marine fisheries impacts peoples
  livelihoods, survival, and recreation.
• It influences the marine and terrestrial
  environments.
• It requires biologically responsible legislation
  and management.
• It is everyone's responsibility.