Fishing = Harvesting = Predation

• Predator-Prey Interaction +- with Humans as Predator

• Very high-tech hunting-gathering– Fast boats

– Sonar, fish finders

– Factory on-board

– Midwater, bottom trawl

• Artisenal harvesting– Coral reefs, intertidal

Exploited Populations

• Sustainable or overexploited?– Small human populations: local depletion?

• Deforestation of Med/Iceland

• Oysters in Washington State

– Now:• Larger human populations

• Global markets and distribution

• More people (# and %) in coastal zones

Fishing MethodsCatch and Bycatch

Fishing Effort: The total fishing gear in use for a specified period of time.Fishing Power: The catch which a particular gear or vessel takes from a given density of fish during a certain time interval. Bycatch:Unintended catch of organisms notpart of the fishery being targeted.

Peruvian Anchovy

Peruvian Anchovy

• Small fish, live 3yr, spawn 1yr, caught 5mo+

• School near surface

• World’s largest fishery until 1972

• Major fishery started in 1955

• Catch doubled every year 1955-1961

• Peak 1971 @ 12.3mt, 18% total fish catch

Peruvian Anchovy Cont’d

• Maximum Sustainable Yield estimated at about 9 million tons/year

• Assumes no change in environment

• 1972 El Nino, no upwelling/nutrients

• 1972 few young, lots of adults, huge catch

• Crash of fishery, hasn’t recovered

• Huge economic consequences

Principles of Exploitation

• Below certain levels, populations resilient – increase growth or survival to compensate for fishing losses (removal of indivs)

• Above certain levels, local or global extinction of the resource ($ or actual)

• Somewhere in middle, level of “maximum sustainable yield” – hard to apply in the real world

• Social resilience and precautionary principle?

Beyond Single-Species Approaches

What about habitat, species interactions, climate change?

A framework for fishing pressure

Kinds of Bycatch

• Fish of wrong (non-target) species • Fish that are of the wrong size • Fish that are of the wrong sex• Fish that are damaged (caused by

gear or predation in the gear)• Excess fish discarded when quota

reached• High-grading (low market value,

damaged, or poor quality fish)• Prohibited species - any species

which must by law be returned to the sea (i.e. marine mammals, turtles, birds, and other fish)

• Population impacts vs economic benefit

Some Solutions to Bycatch

• Selective Fishing Gear– Turtle Excluder

Devices (TEDs)

– Deeper Longlines

• Integrating Fisheries and Conservation– MPAs and BFFF

– No take zones, goals?

• Product certification

Ecosystem Based Management

• The effect of the environment on the resource (population biology and habitat!)

• The effect of resource exploitation on the environment (food webs, energy)

• Complex ecosystems, uncertainty, tipping points, and the precautionary principle

• The human factor – fishing communities, cultures, practices, and economies

Other Issues to Consider

• Western Science vs Traditional Ecological Knowledge

• Enforcement of Regulations and Rules

• Markets and Externalities (ITQs)

• Climate Change and Uncertainties of Oceans’ ability to produce fish

• Social and ecological resilience, coupling!