Marine Fisheries: Causes for Decline and Impacts by Wynn W. Cudmore, Ph.D. Northwest Center for Sustainable Resources DUE# 0757239 This project supported in part by the National Science Foundation. Opinions expressed are those of the authors and not necessarily those of the Foundation.
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Marine Fisheries: Causes for Decline and Impacts
byWynn W. Cudmore, Ph.D.
Northwest Center for Sustainable Resources DUE# 0757239
This project supported in part by the National Science Foundation.
Opinions expressed are those of the authors and
not necessarily those of the Foundation.
Causes for Marine Fishery Declines
Overfishing -
The rate of fish mortality (harvest plus
bycatch) exceeds the natural rate
of replacement.
NOAA Photo Library – Teobaldo Dioses
Causes for Marine Fishery Declines
Overfishing Highly efficient technology -
Fishing vessels and gear
Radar and sonar
Electronic navigation
Aircraft with infrared sensors
Electronic image intensifiers
NOAA Photo Library – C. Ortiz Rojas
Bottom trawl
Marine Biology Conservation Institute
Historical fishing methods
NOAA National Marine Fisheries Service
Causes for Marine Fishery Declines
Overfishing Highly efficient technology Bycatch -
The capture of non-target
fish or other marine animals
in fishing gear
NOAA Photo Library
Categories of Bycatch
Economic discards - species with low or no economic value
Regulatory discards – commercially valuable species discarded due to some regulation
Collateral mortality - species killed by contact with active or discarded fishing gear
Overfishing is the primary cause of marine fishery declines New technologies, bycatch and overcapacity contribute to
fishery declines Global climate change poses an emerging threat Fisheries declines have community- and ecosystem-level
effects Societal factors such as subsidies, increasing demand,
shifting baselines and the lack of fisheries data have allowed fishery declines to occur
OAR/National Undersea Research Program (NURP); Alaska Dept. of Fish and Game
Photo Credits Census of Marine Life - Glenn Jones Daniel Pauly Fisheries and Oceans Canada Grant Gilmore – Dynamac Corporation Lance Horn – National Undersea Research Center Marine Biology Conservation Institute (MBCI) Marine Photobank – OAR/National Undersea Research Program (NURP); Alaska Dept. of Fish and
Game, NOAA Ocean Explorer, Brooke et. al., G.Marola, Pete Naylor, John Rafferty Photography, Robert Stone
Center, Pacific Fisheries Environmental Laboratory, S. Brooke, Joe Brown C.B. Miller/K. Tande, NOAA Photo Library – Teobaldo Dioses, C. Ortiz Rojas Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) Pew Center on Global Climate Change Ray Troll Science multiple figures, reprinted with permission from AAAS Trends in Ecology and Evolution, one figure reprinted with permission from Elsevier