Cait Nelson & Stephanie Avery-GommOct 22 2010

IntroductionTechnological Advances of Fishing Fleets

No Refugia = Can’t Run, Can’t Hide

Resource Depletion

Catch per Unit Effort Maintained

Models are based on data that is imprecise and error prone

Fishing Down; Removal of large long lived fish

Food webs are altered, lack buffering capacity

Reverse Trends; Reduction of Fleet, Increased Regs

Solutions…Reduce Pressure on Fisheries

Maximum Sustainable Yield management of single species stocks

The largest yield (or catch) over an indefinite period

At intermediate population densities individuals are able to breed to their maximum rate

Surplus of individuals that can be harvested

Growth rate of the population is at max due to the large number reproducing individuals

Figure 1. Maximum sustainable yield occurs not at the maximum population level, but rather at a lower, optimal population level.

Maximum Sustainable Yield

Approach has been criticized as ignoring several key factors involved in fisheries management

What might some of these key factors be?

Fishing Down Marine Food Webs Mean TL of fished species declined from 1950- 1994

Gradual transition in landings from long-lived, high trophic level, piscivorous bottom fish toward short-lived, low trophic level invertebrates and planktivorous pelagic fish.

Fishing down food webs leads at first to increasing catches, then to a phase transition associated with stagnating or declining catches.

Fishing Down Marine Food Webs

Fishing Down Marine Food Webs

DiscussionWhat effects might overexploitation of top

trophic levels have on species and ecosystems?

What other effects may FDMFW have?

Other effects of FDMFWTrophic cascade examples

What are the solutions to achieve sustainable fisheries?

Solutions to achieve sustainable fisheries?

AquacultureBridge the gap

between supply and demand

Reduce pressure on wild populations

Aquaculture DiscussionWhy might aquaculture not help to reduce

fishing pressure?

Solutions to achieve sustainable fisheries?

No take zonesNTZ protect

populations by creating reserves for sedentary species

What other solutions exist?

What other solutions exist?

Marine Protected AreasHave been shown to have positive effects in rebuild

depleted stocks of sedentary species.

NTZ

What other solutions exist?

Consumer driven choicesConsumer driven choices to avoid

unsustainably fished stocks and endangered species

Eg. Eco-labeling

What other solutions exist?

Consumer driven choices

Ocean Wise simplifies eating seafood sustainably

Towards Sustainability or

Rebuilding Fisheries?