Marine Conservation Marine Conservation Marine vs, terrestrial? • Overview ), Ocean habitat spatially • Resource overexploitation • Study Guide: Monday !" April labile % Impacts on target spp • Upwelling# downwelling % Impacts on non'target spp, • Discussion: Wednesday# !$ April • Currents % Impacts on community/ecosystem % Marine Reserves !, Species geographic ranges % Marine protected areas % See web page larger Friday: • Review: Monday# "& April# !'" pm# ", Habitat destruction# • Global climate change % !"( Todd fragmentation limited • Invasive species (, Natural populations • Solutions • Final: Tues# May )# *')& am exploited for food
Marine Conservation Resource overexploitation Resource overexploitation • Risks to Marine Biodiversity • Overexploitation of marine resources • Impacts of Fishing: • Impacts of Fishing: • Global climate change • to the target resource species • to the target resource species • Pollution • to non'target species • Most are top'predators • Coastal habitat destruction or • to the community/ecosystem • !!+ of fish stocks are overexploited degradation • Collapsed fisheries: NW Atlantic cod • Invasive species
Target species overexploitation Target species overexploitation Target species overexploitation
Why? Why? Problems ), Changes in !, Single species stock assessment: • Harvest rates politically determined Maximum Sustained Yield -MSY. fishing % known short'term economic losses technology Problems: % uncertain long'term losses in stock' • Overly simplistic models ignore health community interactions • Ex, New Zealand orange roughy % Estimated MSY (0#&&& metric tons % Resource crashing % New estimate: *(+ lower -0#$&& metric tons. % After ! years# quota lowered by !&+ Non'target Non'target species: Bycatch Non'target species: Bycatch species • Longline impact • Gill net# pelagic: % Bluefin tunas# % N Pacific squid# tuna: Southern Ocean • Bycatch • )!& million hooks • Depends on •!&! million miles of net / yr in peak year )1*& •non'target catch • Wandering types of albatrosses gear % (&+of total declined by (&+ % !&& species since )12&
Community/ecosystem impacts Community/ecosystem impacts Non'target species: Bycatch • Target one/few species: top trophic levels • Direct physical damage • Trawls: • Shortens food chain: Community changes? • Benthic trawling % shrimp trawls • Trophic cascade? worldwide • Keystone species? • (,( billion pounds of shrimp • )&'(! billion pounds finfish • $&&&'$&#&&& sea turtles % Yellowtail flounder NE US: • 02+ Non target
Community/ecosystem impacts Community/ecosystem impacts
Shrimp trawler • depths to )*&& m • 2$ ft wide nets • scrapes ) sq mi per !( hour % Trawl return time: shorter than recovery time Before After % Up to 0&&+ coverage per year Gulf of Maine# "& m depth after one pass of scallop trawl Lophelia deep sea coral trawling Norway Marine conservation laws: fisheries Open ocean fisheries: Open ocean fisheries: • International Commission for the • 4Tragedy of the Commons5 Conservation of Atlantic Tuna -ICCAT. % Individuals maximize own gain % But Bluefin tuna down 1$+ since )10$ Before After • International cooperation
NW Australia# continental shelf# 0& m depth
Marine conservation laws: Marine Protected Areas Marine reserves fisheries • No take zones: &,&)+ of the seas Coastal shelf fisheries: • MPA3s • Advantages within reserves: % Marine parks# refuges • UN Law of the Sea Conference# )1*! % Reduce fishing mortality: % !&& mile EEZ -economic exclusive zone. % Marine sanctuaries • more effective than quotas • In US: Unregulated before )102 % Marine reserves % Reduce habitat destruction % Magnusson Fishery Conservation and • E,g, Trawling damage Management Act of )102# )112 % Preserve biodiversity • !&& mile EEZ • Regional management councils
Marine reserves
• Advantages outside reserves: Spillover effects % larval export % enhance fisheries