View
214
Download
0
Category
Preview:
Citation preview
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?
Recommended