Chapter 13 Harvesting Living Marine Resources Most of the world ocean is intensively exploited for...

Chapter 13

Harvesting Living Marine Resources

Harvesting Living Marine Resources

Most of the world ocean is intensively exploited for fishing, recreation, military purposes, commercial shipping, dumping of waste materials, and extraction of gas, oil, and other mineral resources.

Copyright © 2004 Jones and Bartlett Publishers

A Brief Survey of Marine Food A Brief Survey of Marine Food SpeciesSpecies•The raw material of the fishing The raw material of the fishing industry includes:industry includes:– bony and cartilaginous finfishbony and cartilaginous finfish– shellfishshellfish– a variety of other aquatic organisms a variety of other aquatic organisms

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A Brief Survey of Marine A Brief Survey of Marine Food SpeciesFood Species

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A Brief Survey of Marine Food A Brief Survey of Marine Food SpeciesSpecies

•Clupeoid fishes account for about one Clupeoid fishes account for about one third of the world’s total commercial catch. third of the world’s total commercial catch. Clupeoid fishes are found in shallow coastal Clupeoid fishes are found in shallow coastal waters and in upwelling regions. waters and in upwelling regions. •Cod, pollack, hake, and other gadoid Cod, pollack, hake, and other gadoid fishes, redfish, bass, sea perch, and other fishes, redfish, bass, sea perch, and other miscellaneous coastal rockfishes, and tuna miscellaneous coastal rockfishes, and tuna are also important commercial targets.are also important commercial targets.•Bottom fishes and benthic invertebrates Bottom fishes and benthic invertebrates account for 10–15% of the total global account for 10–15% of the total global catch.catch.

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Major Fishing Areas of the Major Fishing Areas of the World OceanWorld Ocean•About 90% of the marine catch is About 90% of the marine catch is taken from continental shelves.taken from continental shelves.

•Several major fishing areas are Several major fishing areas are centered in regions of upwelling, such centered in regions of upwelling, such as those along the west coasts of as those along the west coasts of Africa and North and South America.Africa and North and South America.

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A Perspective on Sources of A Perspective on Sources of SeafoodsSeafoods•Most of the seafood harvested are animals Most of the seafood harvested are animals three or four trophic levels above the three or four trophic levels above the primary producers.primary producers.•In contrast to land, more animals than In contrast to land, more animals than plants are harvested on land.plants are harvested on land.

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A Perspective on Sources of A Perspective on Sources of SeafoodsSeafoods•The fish meal fraction had increased to about The fish meal fraction had increased to about 40% of the world catch. 40% of the world catch. •We are currently overharvesting most We are currently overharvesting most commercially important fish populations.commercially important fish populations.•As a result, only 1–2% of the food consumed by As a result, only 1–2% of the food consumed by the world human population came from the sea.the world human population came from the sea.

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Fishing Down the Food Fishing Down the Food Chain Chain •By fishing one trophic level down, a 5- to By fishing one trophic level down, a 5- to 10- fold increase could be harvested 10- fold increase could be harvested because one trophic level (and its associated because one trophic level (and its associated energy loss) would be eliminated. energy loss) would be eliminated.

•However, harvesting near the base of a However, harvesting near the base of a food web often deny larger predators food web often deny larger predators adequate prey, and their populations suffer adequate prey, and their populations suffer even though they are not directly targeted even though they are not directly targeted by commercial fisheries.by commercial fisheries.

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MaricultureMariculture

•Mariculture is the practice of using Mariculture is the practice of using agricultural techniques to raise marine agricultural techniques to raise marine animals and plantsanimals and plants

•Mariculture presently contributes less Mariculture presently contributes less than 20% of our total marine food than 20% of our total marine food production.production.

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MaricultureMariculture

•Estuaries, salt marshes, and other Estuaries, salt marshes, and other productive coastal habitats are preferred productive coastal habitats are preferred for cultivating marine species, yet for for cultivating marine species, yet for each fish pond installed, a portion of the each fish pond installed, a portion of the native populations are displaced or native populations are displaced or denied access to these productive denied access to these productive coastal waters, which often serve as coastal waters, which often serve as essential nursery areas. essential nursery areas.

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The Problems of The Problems of OverexploitationOverexploitation

•Numerous examples of overfished Numerous examples of overfished stocks can be found in most segments stocks can be found in most segments of the fishing industry:of the fishing industry:– Cod of the N. Atlantic Ocean Cod of the N. Atlantic Ocean – Anchoveta of the S. Pacific OceanAnchoveta of the S. Pacific Ocean

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The Problems of The Problems of OverexploitationOverexploitation•North Atlantic CodNorth Atlantic Cod– Among the first to be taken by factory Among the first to be taken by factory

trawlers (rather than by hand-lines for trawlers (rather than by hand-lines for individual fish). individual fish).

– When the population diminished and When the population diminished and catches declined, U.S. and Canadian catches declined, U.S. and Canadian regulatory agencies closed nearly all cod regulatory agencies closed nearly all cod fisheries in their waters in 2003. fisheries in their waters in 2003.

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•North North Atlantic Atlantic CodCod

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Fig. 13.10 The dramatic decline in Northwestern Atlantic cod harvests, 1970-2000. Data complied from UNFAO statistics.


•Peruvian AnchovetaPeruvian Anchoveta– The Peruvian anchoveta has become a The Peruvian anchoveta has become a

classic example of the consequences of classic example of the consequences of intense overfishing.intense overfishing.

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•Peruvian Peruvian AnchovetaAnchoveta

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Fig. 13.11 Changes in the anchoveta catch and the guano bird populations along the northwest coast of South America. Adapted from Muck 1989 and UNFAO statistics.

The Tragedy of the The Tragedy of the CommonsCommons

•Fishing is too often considered a right Fishing is too often considered a right without attendant responsibilities. without attendant responsibilities.

•Oceanic species exist outside the Oceanic species exist outside the jurisdictional limits of all nations and jurisdictional limits of all nations and therefore are open to access by any therefore are open to access by any nation. nation.

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The Tragedy of the The Tragedy of the CommonsCommons•Unrestricted fishing activities remove a Unrestricted fishing activities remove a valuable commodity from a common valuable commodity from a common resource pool, and all people share the resource pool, and all people share the cost of losing the fish, the great whales, cost of losing the fish, the great whales, and the other marine animals that have and the other marine animals that have nearly disappeared because of nearly disappeared because of overfishing. overfishing.

•Yet the short-term profits derived from Yet the short-term profits derived from overfishing are not similarly shared. overfishing are not similarly shared.

•This is Hardin’s concept of the “tragedy This is Hardin’s concept of the “tragedy of the commons.”of the commons.”

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International Regulation of International Regulation of FisheriesFisheries

•Concerned nations have created a Concerned nations have created a variety of multinational and variety of multinational and international regulatory commissions international regulatory commissions for the purpose of governing the for the purpose of governing the management and harvest of regional management and harvest of regional fish populations. fish populations.

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•Common strategies for management Common strategies for management include:include:– setting quotas on the amount of fish harvestedsetting quotas on the amount of fish harvested– establishing seasons and minimum size limitsestablishing seasons and minimum size limits– defining acceptable gear such as net mesh defining acceptable gear such as net mesh

sizessizes– limiting the number of boats that are allowed limiting the number of boats that are allowed

to participate in a fishery.to participate in a fishery.

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•In 1976, the United States passed the Fisheries In 1976, the United States passed the Fisheries Conservation and Management Act, which claimed Conservation and Management Act, which claimed exclusive jurisdiction over natural resources exclusive jurisdiction over natural resources (including fishing), scientific research, and (including fishing), scientific research, and environmental preservation in an EEZ extending from environmental preservation in an EEZ extending from shore 200 miles to sea.shore 200 miles to sea.•Other nations followed suit with the UN Law of the Other nations followed suit with the UN Law of the Sea Treaty.Sea Treaty.•This has dramatically changed the concept of open This has dramatically changed the concept of open access for most of the world’s continental shelves, access for most of the world’s continental shelves, coastal upwelling areas, and major fisheries.coastal upwelling areas, and major fisheries.

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Fig. 13.12 Worldwide extent of the 200-mile Exclusive Economic Zones sanctioned by the United Nations LOS Treaty.

Marine OrnamentalsMarine Ornamentals

•Keeping personal marine aquaria Keeping personal marine aquaria supports a trade that may be worth as supports a trade that may be worth as much as $330 million annually.much as $330 million annually.

•Unfortunately, destructive collection Unfortunately, destructive collection techniques, overexploitation of some techniques, overexploitation of some species, and careless handling and species, and careless handling and transport all undermine potential transport all undermine potential benefits of the trade. benefits of the trade.

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Marine OrnamentalsMarine Ornamentals

•Fisheries for marine ornamentals Fisheries for marine ornamentals need to be managed to ensure need to be managed to ensure sustainable use and application of sustainable use and application of proper regulations to decrease conflict proper regulations to decrease conflict with other user groups (such as sport with other user groups (such as sport divers).divers).

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Sealing and WhalingSealing and Whaling

•Pinnipeds and whales have long been Pinnipeds and whales have long been targets of commercial harvesting for targets of commercial harvesting for their meat, oil, and skins with dense their meat, oil, and skins with dense insulating fur.insulating fur.

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•PinnipedsPinnipeds– The gregarious nature and relatively poor The gregarious nature and relatively poor

terrestrial locomotion of pinnipeds make terrestrial locomotion of pinnipeds make them easy targets for sealers.them easy targets for sealers.

– As predators near the tops of their food As predators near the tops of their food webs, the reduction of the their prey webs, the reduction of the their prey species by human fishers can have a species by human fishers can have a large negative effect on their survival.large negative effect on their survival.

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•PinnipedPinnipedss

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Fig. 13.13 Steller sea lion rookery beach photographed on the same day of the year in (a) 1969 and (b) 1987.

(a) (b)


•Baleen WhalesBaleen Whales– In the 18th and 19th centuries, whales In the 18th and 19th centuries, whales

became major items of commerce as became major items of commerce as demand for their oil grew and whaling demand for their oil grew and whaling as an industry grew into a profitable as an industry grew into a profitable commercial enterprise.commercial enterprise.

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• Baleen WhalesBaleen Whales– Aided by cannon-fired harpoons Aided by cannon-fired harpoons

equipped with explosive heads and equipped with explosive heads and pelagic factory ships fitted with stern pelagic factory ships fitted with stern ramps to haul whale carcasses ramps to haul whale carcasses aboard for processing, the kill of large aboard for processing, the kill of large rorquals rose dramatically, and rorquals rose dramatically, and several species were pushed to the several species were pushed to the edge of extinction.edge of extinction.

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Sealing and WhalingSealing and Whaling•Baleen WhalesBaleen Whales

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Fig. 13.14 Harvests of blue, fin, sei, and minke whales in the Antarctic, 1920-2000. Data complied from UNFAO statistics.


•Baleen WhalesBaleen Whales– In 1948, 20 whaling nations established In 1948, 20 whaling nations established

the IWC to oversee the utilization and the IWC to oversee the utilization and conservation of the world’s whale conservation of the world’s whale resources. Unfortunately, the IWC has resources. Unfortunately, the IWC has neither inspection nor enforcement neither inspection nor enforcement powers.powers.

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Concluding Thoughts: Concluding Thoughts: Developing a Sense of Developing a Sense of StewardshipStewardship•The world ocean provides food, The world ocean provides food, transportation, and recreation while transportation, and recreation while absorbing the effluvia of human societies.absorbing the effluvia of human societies.•Our continued wise use of the seas for Our continued wise use of the seas for these purposes depends on a better these purposes depends on a better understanding of the consequences of understanding of the consequences of our intrusion on the workings of marine our intrusion on the workings of marine ecosystems.ecosystems.

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I am only one, but I am oneI am only one, but I am oneI cannot do everything, but I I cannot do everything, but I

can do somethingcan do somethingI will not let what I cannot do I will not let what I cannot do

interfere with what I caninterfere with what I can

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