1. Sustainable Seas - Marine Fisheries
- Fisheries and Fishing
- Maximum Sustainable Yield and Fishery Management
- Mariculture
Reading:
4th Ed., Ch 17 Sec 1 15-18, Ch 9 Sec 13, Ch 14 Sec 15
5th Ed., Ch 17 Sec 1, 17-20, Ch 9 Sec 13, Ch 14 Sec 11
Graphic: Chub mackerel catch, Peru, T.Dioses, photographer, courtesy of National
Marine Fisheries Service, NOAA.
2. The Cod Wars (Late 1950's to mid 1970's)
Cod was so important to Iceland and Britain that they almost went to war over
fishing rights three times in the 20th century
These conflicts led to the development of Exclusive Economic Zones (EEZs)
Graphic: Garrison, 4th Ed., Fig. 17.23, pg 460, 5th Ed., Fig. 17.25, pg 434.
3. Where are the Fish?
75% of the world's fish is caught in estuaries, nearshore regions and on the
continental shelves
Data source: National Academy of Sciences
Graphic: Ocean color, an estimate of the distribution of marine plants, image
by the SeaWiFS project, NASA/Goddard Space Flight Center and Orbimage.
4. Fishing Facts
36 million people worldwide earned their living by fishing in 1998
16 percent of animal protein consumed by people worldwide comes from fish
75% the world fish catch is used for human consumption
Data source: Food and Agriculture Organization of the United Nations.
Graphic: Fishing in the Eastern Atlantic. J.Prado, photographer, courtesy of
NOAA.
5. Some Commercially Important Fish
National Academy of Sciences: 10 major species represent 35% of world fish catch
Graphic: Garrison, 4th Ed., Fig. 17.8, pg 448, 5th Ed., see Table 17.1, pg 422.
6. Current Issues in the Marine Fishing Industry
Viability of the Industry
- return on investment
- safety
- access to stocks
Resource Management
- sustainable yields
- bycatch
- impacts on habitat and ecology
Graphic: High-tech equipment is used to locate schools of tuna. A. Urcelayeta,
photographer. Courtesy of United Nations Food and Agriculture Organization and
NOAA.
7. Fishing Methods (a sampling)
Purse seine - floating net encircles school of fish
Trawling - weighted net dragged at mid-depth or along bottom
Longline - line with 1000's of baited hooks
Graphic: Fishing gear, modified from a graphic courtesy of NOAA Photo Library.
8. Gear Selectivity
Trawls
- bycatch
- disturbance of bottom ecosystems
Purse seines
- can catch mammals, juvenile fish
Longlines and gillnets
- can catch seabirds
- abandoned equipment continues "fishing"
Graphics: (top) separating shrimp from bycatch, National Marine Fisheries
Collection, courtesy of NOAA, (bottom) "ghost" pot off Kodiak Island, Alaska,
courtesy of National Marine Fisheries Service, NOAA.
9. Maximum Sustainable Yield (MSY)
MSY: The maximum amount that can be caught without impairing future stocks
Managing at MSY must consider:
- need for breeding stock
- availability of food for animals higher in the food web
Graphic: Catch from a purse seine, National Marine Fisheries Collection,
courtesy of NOAA.
10. Possible Consequences of Exceeding MSY
1. More effort required to catch a smaller amount of fish
2. Degradation of marine environment due to more invasive
fishing techniques
3. Short-term collapse of the commercial fishery
4. Disruption of ecosystem if the fished species is replaced
with other species
5. Long-term collapse of the commercial fishery
11. World Fisheries By the Numbers
World marine fish catch peaked in 1997 at 86 million tons
About 60-70% of world fisheries are now fully or over fished
Source: (top) World fish catch 1950-1998, Food and Agriculture Organization,
United Nations, (bottom) Development of world fisheries, 1951-1994, Garrison,
4th Ed., Fig. 17.11, pg 449, 5th Ed., see Figs. 17.13-17.14, pg 424.
12. Peruvian Anchovies: "Short-Term" Collapse of a Commercial Fishery
Rapid development of the fishery was followed by a collapse in the fish's
population and slow recovery of the commercial fishery
Graphic top: Northern anchovies, cousin of the Peruvian anchovy. Courtesy of
NOAA/NURP.
13. Ecosystem Reorganization: Lessons Learned from Georges Bank
After collapse of the Georges Bank (NW Atlantic) cod, haddock and flounder
fishery in 1900-1930 the fishery never recovered
Before stocks could rebuild, the ecological niche of these valuable commercial
species was filled by "trash" fish - skates and dogfish
14. The Importance of Good Management - Orange Roughy (aka Slimehead)
Clever marketing and good eating created a strong demand in the 1980's
1998 exports from New Zealand = $80 million
Management challenges:
- slow-growing, long-lived
- 20-30 years from birth to breeding age
- small size (30-40cm)
- unknown juvenile ecology
Graphics: courtesy of New Zealand Ministry of Fisheries.
15. Mariculture – The Next Wave in the Marine Fishing Industry
Mariculture = Farming of marine organisms (in estuaries, bays, nearshore
environments or specially designed structures)
By 2030 aquaculture will dominate fish supplies, less than half of consumption
will be from "captured" fish1
1 United Nations Food and Agriculture Organization, 2000 Report
Graphic: Courtesy of U.N. Food and Agriculture Organization.
16. Mariculture and the Future – Coming Soon to a Grocery Near You
Species that can be maricultured…
- desirable as food and easy to market
- uncomplicated life cycles
- disease resistant
- high growth rate in small spaces
- easy and cheap to feed
- simple habitat
Graphic: Floating fish cage, J.P.McVey, photographer, courtesy of NOAA.
17. Mariculture in the U.S. Today
Challenges:
- high permit and investment costs
- conflicts over land use and ecological impacts
Some successfully marketed species:
- oysters, clams, mussels, salmon, shrimp
Graphics: (top) Plastic tanks used for aquaculture, Florida. E.McVey,
photographer, (bottom) First harvest of cultured cobia at the Florida research
laboratory. J.Alarcon/D.Benetti, photographer. Both courtesy of NOAA
18. Final Exam Info
40% "big picture" concepts from previous exams (see online study
guide)
60% recent material - "Open Ocean” through “Fisheries” (see the
online study questions for each lecture)
19. Preview of Next Lecture
Lake Erie - Inland Sea in Our Backyard