~ CHAPTER 1 ~
~ FISHERY DEGRADATION OVERVIEW ~
Edition 9 of October 2009

~ TABLE OF CONTENTS ~ [A]~Degradation Mechanisms, [B]~Productivity, [C]~Productivity Growth, [D]~Indirect Fish Consumption, [E]~Fishing Fleets and Technology, [F]~Aquatic Primary Productivity, [G]~Over-fishing and Sustained Yield, [H]~By-catch, [I]~Tragedies of the Commons and Discounting, [J]~Fishery Politics, [K]~Key Habitats, [L]~Fishery Economics, [M]~Subsidies for Fishing Industries, [N]~Aquaculture, [O]~Aquaculture Growth, [P]~Aquaculture Impacts - [P1]~Land, [P2]~Fish food, [P3]~Environment, [Q]~Carrying Capacity,

(NOTES: Sections (11-A), -B) and -C) define terminology and units used below. Documentation supporting statements in this overview is cited in the remainder of this document.

The world's fisheries are being degraded by two main causes, over-fishing and degradation of the marine environment. Environmental degradation is depressing landings by 3-5% compared to losses due to over-fishing of 10-15%. However the potential exists for environmental losses to become greater than over-fishing losses. Some causes of environmental degradation include:

• Oil Discharges ~ 21 million barrels/ year (1985) enter the oceans from street runoff, ships flushing tanks, and effluent from industrial facilities. 600,000 barrels/ year enter the oceans from accidental spills. As little as 0.1 ppm oil in sea water has serious effects on the reproduction and growth of fish, crustaceans and plankton. Phytoplankton and zooplankton, the base of the oceanic food chain, congregate in the top 0.01 inch of the ocean, as do some fish and shellfish in the early stages of their lives.
• Red Tides / Algae Blooms ~ "Blooms" of phytoplankton caused (probably) by excess nutrients from rivers (excess fertilizer, sewage, soil sediments, etc.) kill fish and other aquatic life. Toxic blooms ("Red Tides") have been found to correlate well in location and time with nutrient levels. When algae blooms die, they deplete the oxygen over large areas of water, creating "dead zones" where nothing can live.
• Bacteria ~ e.g. hepatitis-A due to sewage discharges, cholera epidemics from fish and shellfish that contacted bacteria-laden bilge water.
• Tumors ~ apparently linked to fertilizer- or other farm-waste runoff. The trend toward concentrated animal feedlots is adding to the problem.
• Acid Precipitation ~ results in fish deaths in poorly buffered waters.
• Toxic Discharges ~ e.g. mercury, PCBs, chlordane, dioxins and DDT.
• Exotic (introduced) Species ~ Increases in ocean shipping and aquaculture are transporting aquatic animals and plants all over the world ~ to places where they have no natural enemies. This often devastates native species and biodiversity.
• Physical Habitat Degradation ~ Most of the world's trawlable shelves are impacted by trawler fishing, leaving few sanctuaries where biomasses and biodiversity remain high. Trawler nets scrape over the ocean bottom (often several times/year at any given spot in popular fisheries), leaving ocean floors as smooth surfaces devoid of features fish need for protection from predators. Over-fishing of fish species that protect coral reefs destroys such reefs ~ the habitat for numerous other fish.
• Breeding ground degradation/elimination ~ (See "Key Habitats" later in this overview.)

The world supply of fish, crustaceans and mollusks was 112.9 million tons (102.6 million tonnes (t.)) in 1995; 75% was from marine-capture fisheries. Subsistence fishermen net 24 million tonnes/ year. This is not counted in the global commercial fish catch - as is the by-catch (at least 27 million tonnes/ year). Freshwater capture-fisheries provided 6.5% of this supply (6.4 million tonnes in 1991; 7.2 million tonnes in 1995). These have little potential for growth. River production globally is declining due to pollution, dams and other habitat degradation. Aquaculture (fish-farming) provided the remaining 18.5% (6.1 million tonnes in 1984; 19.0 million tonnes in 1995, excluding aquatic plants). The global fishing industry had total sales of $125 billion in 1995 (including $42 billion from fish-farming).

In the post-WWII period, the marine catch grew 6%/ year - 3 times the rate of population growth. (Global fish-catch growth: +4%/ year during 1950-88.) Aggregate growth in the 1970s and 1980s was 2%/ year. (Global fish-catch growth was -0.8%/ year during 1988-92). The greatest growth came from high-volume-low-priced species lower on the aquatic food chain. Then, as these stocks started reaching their limits in the late 1980s, total marine catch began to fluctuate with the highly variable output of these and other high-volume, low-value fisheries. The global supply of fish would have stagnated with the marine catch if not for aquaculture production accelerating during this period. Aquaculture increases have averaged 2 million tons/ year since 1992.

Over one billion people rely on fish as their primary source of animal protein. Globally, fish and other sea-products accounted for 16% of animal-protein consumption in 1988, and 15% in the mid-1990s (under 10% in the Americas, Western Europe and the Near East; over 21% in Africa, the Far East and Asian centrally planned economies). Fish consumption was 16 kg./ capita in 1996 - 28 kg./ capita/ year in industrial countries; 10 kg./ capita/ year in developing countries. Consumption-per-capita peaked in 1989 at 19 kg./ capita.

Global fish catch/ capita (live weight)
Year - - |1950 |1960 |1970|1980|1990 |1992
kg/capita| 8.5 |13.5 |17.8|16.4|18.3 |17.9
(Includes oceanic catch, fresh-water catch, and fish-farming)

Not only has per-capita catch peaked out, but marine catch rates have also peaked out as indicated below.

Year of Peak Catch for Major Marine Fishing Regions
Atlantic Ocean (various regions)| 1973-1990
Mediterranean and Black Seas ~ ~| 1988
Pacific Ocean (various regions) | 1981-1991
Indian Ocean (both regions)~ ~ ~| still rising

About 36% of human consumption of marine-capture fish is indirect - fishmeal and fish oil fed to livestock including aquaculture fish. 17% of this portion is fed to pond- and pen-raised fish. The fraction of human consumption of riverine-capture fish that is indirect is unknown.

Global fish catch*#* used as fish meal, fertilizer, fish oil
Year - - - - - - - |1950|1960|1970|1976|1978
million tonnes/year| 3.0| 8.6|25.5|22.1|21.0
*#* Includes oceanic catch, fresh-water catch, and fish farming, though almost no aquaculture production is used for meal etc.

The amount of fish that goes to fishmeal etc. is unlikely to increase because of the limited potential for increasing the catch of these high-volume species (1998).

The world's fishing fleet is undergoing rapid change - from small boats that discard a relatively small fraction of their catch to huge factory trawlers that discard a far larger portion (about 40%) of their haul. In 1998 1% of the world's 3.5 million fishing boats accounted for at least half of the global catch. The world's fishing fleet doubled in size during 1970-90 (to 1.2 million large boats, and to 25.5 million gross registered tons), and now (1998) has a fishing capacity twice that of the sustainable yield of the world's wild fisheries. New fishing vessels and increasingly sophisticated fishing technology have increased the fishing capacity of the world's industrial fleet by 22% since 1991. Factory trawlers roam the world's oceans for months -fishing, processing and storing fish on board, 168 hours/ week. They can easily abandon depleted waters for fertile fishing grounds elsewhere in the world-leaving local, less mobile fishers to face the consequences of wasted ecosystems. The world's governments are growing increasingly alarmed at the potential for large factory trawlers to devastate local fisheries, even while subsidizing the construction of these boats. Some even argue that factory trawlers should be banned, as incompatible with sustainable, ecologically responsible fishery management.

Breakdown of the global fishing industry according to boat size, based on FAO data (Fuel- and catch data are in million tonnes/ year)
Comparison -Scale = ~ ~ ~ ~ ~ ~ ~ ~ ~|LARGE|MEDIUM| SMALL
Employment (millions) ~ ~ ~ ~ ~ ~ ~ ~|.2-.3|.9-1.0| 14-20
Employment/ $million investment ~ ~ ~|1-5 ~| 5-15 |60-3000
Earnings/ fisher ($1000)~ ~ ~ ~ ~ ~ ~|15 ~ | 8 ~ ~|0.5-1.5
Marine fish caught for human consump.|15-20| 15-20| 20-30
Marine Fish caught for meal/oil etc. |10-20| 10-20| 0
By-Catch *~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~|5-10 | 5-10 | 0
Fuel consumption~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~|7.6 ~| 12.8 | 26.2
Tons fish/ ton fuel ~ ~ ~ ~ ~ ~ ~ ~|2.6-3.9|1.6-2.3|.8-1.1
* Note: total by-catch = 27-40 million tonnes/ year (see below).

Expansion of the global fishing fleet (FAO data)
Col.1: Number of decked fishing boats
Col.2: Total Gross Registered Tons (GRT) of decked boats
Col.3: Number of non-decked boats
Year | Col. 1 |~ Col. 2 ~| Col. 3
1970 | 575,800|10,733,000|1,516,400
1980 | 805,500|16,121,000|1,802,400
1992 |1166,600|21,891,000|2,345,100

The global fleet increased by 3% in tonnage during 1992-97, and by 22% in fishing capacity through new additions to the fleet and refits, with Southeast Asian nations and China being among the most aggressive.

Aquatic systems generate 41% of global primary productivity (photosynthesis) of 224 billion tonnes/ year (biomass-dry weight). The APP required to sustain the world fisheries catch (94.3 million tonnes/ year of commercial catch in 1988-91 + 27 million tonnes/ year of discarded by-catch) is 8% of global APP (2% for open-ocean systems, 24-35% in fresh water-, upwelling-, and shelf systems). (The subsistence (non-commercial) catch of about 24 million tonnes/ year is apparently neglected in this analysis.) Open oceans account for 75% of APP.

Estimates of global APP, catch and discards (1988-91 FAO data) for each of the world's aquatic ecosystem types (95P2).

90% of ocean fish catches occur within 320 km. of a shoreline as the table above suggests. The world's major fishing grounds correspond almost exactly with the regions of highest photosynthetic productivity (APP).
*# Discards (by-catch) are thrown back into the ocean, usually dead or dying.

For the past 45 years, as fish at the upper levels of the aquatic food chain are over-fished, fishers have tended to fish at lower trophic levels. Ultimately this trend must result in fishing at such low tropic levels that the fish species are so small and diluted that it is no longer economical to fish. At the current rate of descent, it will take 30-40 years to fish down to the trophic level of plankton. If today's fishing effort and efficiency were applied (limited) to zooplankton the global catch would drop by 99%.

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Of the world's 15 leading oceanic fisheries, 13 are in a state of decline. In 1950, no marine fish stocks were known to be over-fished. World-wide, 60-70% of fish stocks require urgent intervention to control or reduce fishing to avoid further declines of fully exploited- and over-fished resources and to rebuild depleted fish stocks (1998 FAO stmt.). Global sustainable yields of marine fisheries: 62-96 million tonnes/ year. According to the FAO, the most reliable source for sustainable increased production from oceans would come from improved management. Gains of 10-15 million tonnes/ year via this means seem possible - by rebuilding stocks, reducing wasteful practices, and protecting the marine environment. The trend however has been to deplete stocks, increase wasteful practices, and degrade marine environments. Fisheries don't just dwindle away - they collapse quickly (over a few years) once a critical point is reached. Fishery biologists understand the phenomenon well enough that they have been able to predict a number of fishery collapses before their actual occurrence.

Over the past decade the marine (ocean) catch has been around 85 million tonnes/year. For comparison, the freshwater catch and aquaculture "catch" have each been around 14 million tonnes/ year. The fact that such a large fraction of the world's major fishing areas are in a state of serious decline is strong evidence that the maximum sustainable marine catch is now closer to 62 million tonnes/ year than to 96. Other experts estimate that the marine fishery potential could reach 93 million tonnes/ year if resources were better managed - a gain of 10 million tonnes/ year from the present potential (1998 FAO estimate). Others estimate that over-fishing has reduced the sustainable marine catch by about 20 million tonnes/year. So the spectacular growth in aquaculture in recent decades has barely kept pace with the declining potential of ocean fisheries.

"By-Catch" (unwanted species caught incidentally and dumped at sea (usually dead)) now (1995) amounts to a third of world (marine) fish production. 27-40 million tonnes of (marine?) fish are discarded yearly (1995) because they are too small, the wrong species, damaged in capture, or exceed the quota. ("By-Catch" data excludes birds, turtles and other non-fish marine life.) Worldwide, shrimp fisheries have a by-catch/shrimp ratio of 5.2:1 (15:1 in some regions) with a by-catch of about 11 million tonnes/ year. In general, bigger boats have higher by-catch: retained-catch ratio.

"Tragedy-of-the-commons" effects have been a prime cause of over-fishing. The creation, by the UN's Law-of-the-Sea treaty, of 200-mile-wide "Exclusive Economic Zones" along coastlines has probably reduced, but has by no means eliminated, this effect. Under open-access resource-use, no property rights to the resource exist, and over-exploitation is highly probable. This is still a major problem in developing countries, which now account for over 50% of the global fishery harvest. Developing countries do not have the resources to enforce international agreements and laws within their own boundaries. One idea being tried to deal with the tragedy-of-the-commons problem is Individual Transferable Quotas, given or sold as a percentage of the total allowable catch. This is more efficient than limits on boat size, number, technology, or time at sea, all of which invite costly dodges.

Over-exploitation, in the physical sense of reduced productivity, may also result from a second social condition: private-property maximization of profits on a present-net-value (discounted) basis. For populations that are economically valuable, but possess low reproductive capacities, either condition may lead to extinction. Think of the concept of discounting future harvests in this way: put the extra earnings from over-fishing in a bank, and by the time the fish are extinct you may be able to substitute the bank-account interest for all the lost fishery income. In view of the likelihood of private firms adopting high discount rates, conservation of renewable resources would appear to require continual public surveillance and control of physical yields and condition of stocks to avoid fishery collapses and species extinction. (Many other natural-resource degradation processes, such as soil erosion, deforestation, over-grazing and irrigation-system salinization, are also promoted by discount economics, either implicitly or explicitly.)

"Although the problems of fishery management are now widely recognized.(fishery management globally) has generally failed to protect resources from being over-exploited, and fisheries from being economically inefficient. The main reason for the failure is the lack of political will to make changes necessary to increase fish supplies. . The persistence of direct- and indirect subsidies, lack of control of fishing fleets, and rigidity of industrial lobbies are the main issues to be addressed." (Serge Garcia, head of FAO's Fishery Resources Division, in an FAO statement of 5/19/98).

The purely economic considerations that might otherwise prevent the collapse of fisheries are being subverted by huge government subsidies to the fishing industry (See below). There are few more compelling indictments of the power of money in the political process than taxpayers being forced to finance a process that does little beyond reducing their long-term fish supply.

When confronted with uncertainty, government fishery managers have been under enormous pressure to allow continued harvest levels, and scientific advice has been discounted in favor of expediency. Over-estimation of fishery resources is a frequent result, and often no substantive action occurs until fishing boats return empty.

The most important US fisheries management law, the Magnuson-Stevens Fishery Conservation and Management Act, was amended in 1996 to prohibit over-fishing, rebuild over-fished stocks, and minimize "by-catch". Thus far the National Marine Fisheries Service (NMFS) interpretations of the 1996 Magnuson-Stevens Act have fallen far short of the Congressional intent to end over-fishing, reduce by-catch and protect fish habitat. These interpretations are riddled with loopholes that, if not changed, will fail to reverse the current decline in US fisheries.

International treaties on fisheries have yielded less-than-satisfactory results, e.g.:

• The 12/31/92 international moratorium on drift nets larger than 2.5 km. is still ignored by some nations (Taiwan in the South Pacific, Atlantic and Indian Oceans; Italy in the Mediterranean Sea);
• Developing nations cannot afford to protect their fisheries from illegal invasions by foreign ships;
• Many countries under-report their fishing harvest,
• There are 100 ongoing disputes, globally, related to depleting fisheries (1997 UN data).

Mangrove swamps, estuaries and coastal wetlands, because of their abundance of food, are nurseries for many species of fish. 2/3 of all commercially valuable fish species spend the first stage of their life in these waters. 90% (by mass) of marine animals rely on coastal areas (mangrove swamps, estuaries and coastal wetlands) for spawning grounds.

Coastal mangroves now cover 200,000 km² - about half their original area. 80-90% of the commercial seafood species that inhabit tropical oceans spend some part of their lives in coastal mangroves.

As a result of mangrove loss, the world's coastal fishers may have lost 4.7 million tons of fish/ year, including 1.5 million tons/ year of shrimp. Mangrove forests are being cut for charcoal, pulp wood, clearance for salt-making, golf courses, marinas, resort development, and shrimp- and other aquaculture ponds.

Shrimp aquaculture is especially wasteful. Farmers clear-cut mangroves and other coastal ecosystems, then bulldoze shallow pools. Drugs can control diseases in these crowded pools for about 7 years, then the pools must be abandoned and the process repeated further along the coast. The wasteland left behind is soil-deficient and too polluted to replant. (No data could be found on the fallow period for these ponds.)

Coral reefs protect tropical and sub-tropical coastlines from storm damage and beach erosion, provide shelter, breeding areas, nurseries and food for shellfish, invertebrates and fish; and form an important link in cycling nutrients from the land to the open ocean. Reefs provide food and breeding grounds for 10% of all fish caught for human consumption. Nearly a third of the world's fish (25% of all marine fish species) live in coral reefs, even though these reefs occupy only 0.11% (414,000 km²) of the Earth's ocean surface area (361 million km²). (Note: other data give a current global coral-reef inventory of 600,000 km².)

Locations of the World's Coral reefs
S.E. Asia ~|30% |Indian Ocean ~|24%
Middle East| 6% |Pacific Ocean |25%
Caribbean ~| 9% |Atlantic Ocean| 6%

The loss of 5-10% of the world's coral reefs translates to a loss of fish on the order of 250,000-500,000 tons/ year. The total catch from reefs is estimated at 4-8 million tons/ year - about 10% of the fish caught for use as human food. Coral reefs account for 20-25% of fish caught by developing countries. A third of all subsistence fishers - obtain their catch from coral reefs. 70-90% of all fish caught by coastal fishermen in tropical Asia are reef-dependent at one time or another in their life.

10% of the world's reefs have been degraded "beyond recognition" (dead or damaged beyond the capacity to recover) and 30% are in critical condition. If trends continue this 30% will be lost completely in 1-2 decades, and another 30% will be lost within 2-4 decades.

Coral reefs, globally, are increasingly threatened from over-fishing, cyanide-fishing, acid-fishing, dynamite-fishing, cement-making, destruction of mangroves (which often protect reefs from sediments), excessive inputs of sediments (industrial pollution, sewage, cropland erosion, mining, deforestation, urban developments, reef-mining, dredging), pesticides, and nutrients from human activity (fertilizer, sewage). Coral reefs are susceptible to these disturbances because they depend on sunlight. Nutrient-caused eutrophication destroys reefs by reducing sunlight and because algae that compete with coral for open spaces on the reef grow faster than coral when fertilized. Removal of herbivorous reef fish from coral reefs causes algae to overgrow corals, resulting in large-scale coral mortality. Hurricane damage, normally repaired naturally in a short time, is now often permanent due to elimination of herbivorous fish that would otherwise keep harmful algae in check.

As much as 90% of all fin- and shellfish depend on estuaries for some portion of their life cycle or for wetlands-produced food. Coastal wetlands serve as feeding and nursery grounds for 65% of commercial fish in US waters. Of the 10 fish and shellfish most valuable commercially - shrimp, salmon, tuna, oysters, menhaden, crabs, lobsters, flounder, clams and haddock - only tuna, lobster and haddock are not estuary-dependent. Two thirds of the commercially important fish and shellfish harvested along the US Atlantic coast and in the Gulf of Mexico depend on coastal estuaries and their wetlands for food sources, for spawning grounds, and for nurseries for the young (50% for the US Pacific coast). Scientific studies show a direct correlation between the amount of coastal marsh and shrimp production.

Development has destroyed 50% of the world's coastal wetlands. Shrimp ponds have consumed 27,000 km² of coastal ecosystems. The remaining coastal wetlands have been heavily damaged by pollution. Pollution has caused harvesting in about 40% of US shellfish beds to be banned or limited (vs. 21% in 1966).

The monetary value for preserved marshlands and estuaries of the US South Atlantic and Gulf Coasts in terms of fishery nurseries; aquaculture potential and wastewater treatment is estimated at $20 million/ km² ($82,000/ acre).

Nearly 50% of fish caught today are traded between nations (vs. 32% in 1980). The US, Canada, Europe and Japan import 84% of world fishery imports by value. (The US imported twice as much sea food as it exported in 1996 - at least the 26th consecutive year that the US has run up a seafood trade deficit.) This reflects increasingly global, trade-oriented fishery policies that have left low-income consumers in a lop-sided bidding war with high-income consumers at home and abroad.

Between the 1970s and 1990s the global average export price of fish tripled, while the price of beef, pork and chicken rose 50-80%, making the price of fish comparable to that of red meat, and more expensive than chicken. In 1991 the price of fish was $278/ ton, compared to $284 for beef, $272 for pork, and $163 for chicken. Fish prices have remained relatively stable in the 1990s.

US fish prices (for any given specie) have more than doubled (in constant $ terms) since the mid-1960s. During this time, beef and pork prices have held constant, while chicken prices have declined. During the past decade the world price of seafood for any given specie (in constant $) has risen nearly 4%/year. Total US catch value (inflation-adjusted) has remained stagnant since 1982, though US fish-catch tonnage increased 60%. Between 1982-95 the average of all US seafood prices dropped 15% in real terms. The average price earned at the dock of individual fish fell from $0.41 (1986) to $0.25 (1995) - almost exclusively because cheaper, low-value fish accounted for a much larger share of the total catch.

Governments worldwide subsidized the fishing fleet by amounts that the FAO estimates to be greater than the value of the annual catch. The FAO estimates that the operating cost of the global marine fishing fleet in 1989 was $22 billion in excess of total revenues. For every dollar earned from fishing (globally) in the late 1980s, governments, taxpayers and fishers spent $1.77. 25-33% of global fishing revenues come from subsidies. The FAO estimates that, globally, $124 billion/ year is spent catching $70 billion/ year worth of fish. Government subsidies apparently make up the $54 billion/ year difference (low-interest loans, access fees for foreign fishing grounds, direct subsidies for boats and operations). This neglects government subsidies for coastal development that lead to destruction of coastal wetlands and their fishery breeding grounds. Only 5% of government subsidies are targeted at solving the problem of industry over-capacity.

US licensing fees for commercial fishing fail to cover the cost of fishery management, even for foreign vessels. The US Government offered tax credits and loan guarantees to expand the US commercial fishing fleet during the 1970s and 1980s and in the 1990s has subsidized the construction of factory trawlers, even while legislation is being considered to limit these ships.

Without subsidies, the costs of going after that last fish would become prohibitive and this would limit the amount of over-fishing. Nearly all forms of natural-resource consumption are subsidized, attesting to the power of money in the political process worldwide. But fishing subsidies are probably among the most environmentally destructive of these subsidies.

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For every 5 kg. of beef produced world-wide, there are now 2 kg. of farm-raised fish (probably dressed-weights, not raw-weights).

Aquaculture production: (UNFAO data)
Year - - - - - |1975|1983|1984|1991|1994|1995|1996|2010
Million tons* ~| - -| 7.1| 6.7|12.7| - -|20.9|23.0|39.0**
Million tons~ ~| 6.0| 9.3|10.0|16.0|25.5|28.7| - -| - -
$billion(gross)| - -| - -| 9.5|- - |40.0|42.0| - -| - -
* Excluding aquatic plants // ** estimate

These numbers can be compared to the world supply of fish, crustaceans and mollusks of 112.9 million tons, and total sales of $125 billion, in 1995. Note that aquaculture concentrates on higher-value species.

About 70% of aquaculture production is fin-fish; 24% is mollusks, and 6% is shrimp and other crustaceans when aquatic plants are not included. About 63% of aquaculture production is from freshwater; 7% is from brackish water (mainly shrimp and prawn), and 30% is from marine aquaculture when aquatic plants are not included (1995 data). However freshwater aquaculture output is worth only 50% of the total value of aquaculture production.

• Shrimp farming is a $6.3 billion industry that spans 50 countries. Global shrimp and prawn production from aquaculture: 2% of total production around 1980; 25% around 1990; 33% in 1997.
• Carp is nearly 50% of all aquaculture production (1995).
• About 82% of aquaculture production (by weight) comes from the Asia/Pacific region.
• Farm-raised salmon account for 50% of global salmon sales (1996) (vs. 7% in 1986).
• 40% of the global mollusk harvest (including oysters, clams and mussels) has lived mostly in farm environments.
• 65% of the global freshwater fish harvest has lived mostly in farm environments.

Aquaculture has become one of the fastest growing food-production activities in the world (UNFAO data) (1998). Since 1992 aquaculture growth has been 2 million tons/ year. The FAO projects that growth will slow to 0.8-1.4 million tons/ year, reaching 27-39 million tons/ year in 2010. The largest aquaculture industry (in China) plans to double its area under fish-cultivation to 70,000 km² by 2010 (compare to its grain area of 857,000 km²) (1998).

Some data on intensities of aquaculture:
Practice- - - - - - - - - - - - - - - - -(tonnes/ km²/ year)
Carp and catfish in fertilized ponds ~ ~ ~ ~ |~ ~ ~48
Carp and catfish fed grain ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ ~ 150
Carp and catfish fed grain+high-qual. protein|~ ~ 320
~ ~ Supplement feeds (fish/soybean meal) ~ ~ |- - - -
Tilapia in Africa~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ 10000
Mussels in Spain ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ 30000
Carp in Japan (running water)~ ~ ~ ~ ~ ~ ~ ~ | 100000
Carp in Japan (more typical) ~ ~ ~ ~ ~ ~ ~ ~ |~ ~ 300
Carp in Germany~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ ~ ~50
Crawfish in flooded La. rice fields~ ~ ~ ~ ~ |~ ~ ~56
Fish in a pond ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ ~1000
Catfish in a pond~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |~ ~ 700
Shrimp in Taiwan ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ |140-360

Globally, shrimp farms cover 9842 km² of coastal land (1996). During 1985-95, 1500 km² of shrimp farms fell into disuse worldwide. The average fishpond is good for about 10 years, but for high-density shrimp ponds, typical pond lifetimes are about 5 years. Thus land requirements for aquaculture are at least several times that indicated above, even neglecting the land needed to grain for fish food (See below).

About 2/3 of aquaculture production comes from inland fish culture in rivers, lakes, ponds and buildings. The rest is coastal - pens in bays or open ocean.

Quantity of farmed oceanic fish and shrimp raised in 1996 by using ground-up wild ocean fish as feed: 1 million tonnes. Compare this to the quantity of wild ocean fish that had to be ground up to provide the feed: 5 million tonnes. (Note: other data give 3.5-4.3 tonnes of wild fish to produce 1 tonne of farm-fish.)

Worldwide, about 36% (32 million tonnes/ year) of the global fish harvest goes to non-food uses, primarily animal feed, fishmeal and oils. Of this, 17% goes to feed farm-fish, while the balance is used to feed cattle and poultry. By 2010, carnivorous fish on farms could be taking all the world's fish meal, using protein that could otherwise be used for direct human consumption-a redistribution of marine biological wealth from the poor to the rich.

Note: Meat (dressed) weight of fish is about 65% of live (wet) weight.

Global grain productivity is about 240 tonnes/ km²/ year, so grain-fed fish require about 1 km² of grain land for every 120 tonnes of fish/ year.

Shrimp- and salmon farming constitute two of the most resource-intensive food-production systems in the world. Fish-farmer efforts to control production costs result in fish being grown in extremely confined quarters, and this results in problems with disease, parasites, etc. These tend to spread to wild fish species in nearby rivers, estuaries and oceans. Some examples:

• Shrimp farming in Asia and Central America is now seen as inherently unsustainable and destructive, an example of industrial aquaculture gone awry. When wastes from cultivated shrimp are released into a bay, wild shrimp are destroyed.
• Shrimp farmers in Taiwan intensified production from 1.4 to 3.6 tonnes/ha/year during 1965-85. By the late 1980s the industry had collapsed due to a series of disease outbreaks and financial disasters.
• Irish stocks of wild sea trout dropped over 90% in 1989 due to sea lice attributed to salmon farming that begin around 1985.
• The Swedish Environmental Protection Agency declared salmon farming an "environmentally dangerous industry". Norway and Scotland have stopped building salmon cages in coastal waters.

Aquaculture also produces 300-1000 kg. of solid wastes from each 1000 kg. of farm-fish production. These wastes can cause over-nutrification and algae blooms that precipitate bacteria growth, deplete oxygen, and kill fish.

Aquaculture also produces wastes harmful to land resources, e.g. when waste from fish-rearing ponds is dumped on the ground, coconut trees turn brown and well waters go bad. Aquaculture also eliminates land resources required by wild fish species. For example, mangrove swamps and estuaries are often converted to aquaculture, reducing catches of wild fish species that need mangrove swamps and estuaries for breeding. China now prohibits converting arable land to aquaculture ponds.

For the consumer, the growth of aquaculture has meant the replacement of lean, nutritious meat with soft, fatty meat laces with drugs and pesticides. Farm salmon is not even red - it must be dyed red.

Intensive production of common carp and tilapia requires roughly the same amount of fresh water (8 tons/ ton of meat), as the amount needed to raise grain-fed cattle (8.5 tons water/ ton of beef) or pigs (5 tons water/ ton of pork). Intensive shrimp production requires up to 10 times more water per ton of meat. (Presumably these numbers refer to consumptive uses of water.)

It is of interest to gauge the human-carrying capacity of the world's wild fisheries under the assumptions that the degradation of marine and riverine environments can be halted, and that over-fishing can be halted. Carrying capacity is gauged in two terms-proteins and Calories.
Proteins: The sustainable marine catch is believed to be 83 million tonnes/ year. This apparently assumes the by-catch (27 million tonnes/ year) and the subsistence catch (24 million tonnes/ year) that aren't counted don't change much. The sustainable riverine catch is probably no more than the current catch of 7 million tonnes/ year. About 36% of the marine catch (32 million tonnes/ year) goes for fishmeal and fish oil that is fed to animals that humans eat. This fraction is not likely to change significantly - assuming the tendency for fishers to fish lower on the food chain is balanced by the willingness of people to eat less-desirable fish. The same fraction is assumed to apply to the riverine catch. Take the efficiency of transfer of fish protein to human-consumed protein via animal intermediaries to be no more than 20%. (The presently accepted transfer efficiency between trophic levels is 10%.) 20% of the live weight of the marine (and riverine?) animal catch is human-consumed protein. This gives a sustainable protein supply attributable to wild fisheries of 12.9 billion kg./ year. An adequate protein diet is considered to be 13.1 kg./ person/ year, although Americans consume 23.7 kg./ person/ year. This gives a carrying capacity, in terms of protein, of one billion people (540 million based on a US protein-consumption rate).
Calories: 65% of the live-weight of fish caught is consumed by humans, and the efficiency of transfer of fish Calories to human-consumed Calories characterizing fish meal and fish oil fed to animals is 20% (see protein analysis above). A typical Calorie content of fish is 52 Calories/ oz. (= 1834 Calories/ kg.). Then the sustainable Calorie supply attributable to fisheries is 77 trillion Calories/ year. An adequate Calorie diet is considered to be 2500 Calories/person/day (913,000 Calories/ person/ year). This gives a carrying capacity, in terms of Calories, of 84 million people. (Less than 1% of world food-calories is obtained from aquatic environments (94K1).) For aquaculture, considering the land requirements alone would give a net negative carrying capacity, Calorie-wise.

The very concept of a "carrying capacity" depends on the existence of some sort of steady-state. In the case of the world's fisheries, this overview offers compelling evidence that nothing approaching a "steady-state" exists. Unfortunately, the world's other major life-support systems - croplands, irrigation systems, grazing lands and forests are also far from being steady-state systems. The "Carrying Capacity" concept should thus be seen for what it is-more an instrument for self-delusion than a basis for rational analyses.

Index created by Marine Fish Conservation Network, in honor of World Ocean's Day, 6/8/03. For a PDF or graphic version with citations, call 202-543-5509, or visit www.conservefish.org.
The State of the World's Oceans (03M2)

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