The Dose Makes The Poison Mercury Arsenic DDT. 3Adoi%2F10.1371%2Fjournal.pbio.1000131

The Dose Makes The Poison

Mercury

Arsenic

DDT

http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000131

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Licences to Fish in Foreign EEZs

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Chapter 9:Peruvian Anchoveta Fishery

Peruvian Anchoveta Fishery

I. The Physical Setting

II. The Upwelling Ecosystem

III. Anchoveta Ecology

IV.History of the Anchoveta Fishery

V. Managing the Anchoveta Fishery

Surface current system off the coast of Peru. Dashed line marks the approximate boundary between the Peru coastal current and the Peru oceanic current (Humboldt Current). The shaded area is the approximate area of the coastal current system occupied by the Peruvian anchovy stocks.

The Upwelling Ecosystem

I. Nutrient-rich waters from beneath the nutricline fertilize the euphotic zone with nitrate and phosphate

II. High nitrate and phosphate enables high primary productivityby phytoplankton

II. Anchoveta graze this nutritional resource

III. Anchoveta are then eaten by mackerel (from below) and guano birds (from above)

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UREP

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PERU

Up to 20 cm in length

Anchoveta Ecology

I. Population is confined to the Peru Coastal Current system

II. Feed low on the food chain

III. 4-year lifespan

IV. Spawning year-round, with peaks in Sept-Oct and Feb-Mar

V. Recruited to the fishery at 5 months of age

Anchoveta Ecology

V. Recruited to the fishery at 5 months of age

VI. Sexual maturity at 12 months of age

VII. Very high fecundity: 15,000 eggs/spawn, 24 spawns/year

VIII. Very high mortality prior to recruitment: > 99%

IX. After recruitment, mortality is ~ 16%

X. A modest drop in population size enhances recruitment

phytoplankton

flagellates

ciliatescrustacean

zooplankton

Anchovetanatural mortality,

predationMortality

Recruitment

Sexual Maturity

History of the Anchoveta Fishery

BACKGROUND

• Artisanal fishing prevails from pre-colonial times to ~1900

• Guano mining becomes Peru’s major export industryduring the 1800s into the 1900s

• Compania Administradora de Guano stifles attempts toexpand and industrialize fishing in 1910s and 1920s

• First fish processing plant built in the 1930s

• As guano supplies are depleted, CAdG shows a slightinterest in fishmeal

History of the Anchoveta Fishery

Development

• 1940s - WWII cuts off flow of European fisheriesproducts to the USA

• By 1945, there are 23 fish processing plants in Peru, and fisheries products account for 1% of exports

• In 1948, the Peruvian government decides to developthe export potential of its fisheries

• World-wide application of power and technology tofisheries in the years following WWII

POST-WAR TECHNOLOGICAL IMPROVEMENTS

I. Bigger Ships

I. Echo Locators

I. Nylon Nets

I. Power Blocks

I. Vacuum Pumps

History of the Anchoveta Fishery

Development

• 1950 - The collapse of the California sardine fishery

• Increasing demand for fish meal as feed components for the growing US livestock industry

• Transfer of reduction fisheries infrastructure fromCalifornia to Peru

• Both the government and commercial banks supportthe development of the Anchoveta reduction fishery

History of the Anchoveta Fishery

Development

• 1950s - Number of fishmeal plants grows to 49

- Fishmeal production grows from <1,000 metric tons to 117,000 metric tons

- Fishmeal value grows from $100,000

to $11,300,000

History of the Anchoveta Fishery

Development

• 1950s - Number of fishmeal plants grows to 49

- Fishmeal production grows from <1,000 metric tons to 117,000 metric tons

- Fishmeal value grows from $100,000

to $11,300,000

• 1960s - Number of fishmeal plants grows to 154

- Fishmeal production grows to 1,622,000 metric tons

- Fishmeal value grows to $183,200,000

History of the Anchoveta Fishery

Trouble

• 1960s - Biology

- Weather - Overcapitalization

- Science vs. Politics

Some facts about the Peruvian anchovy fishery

Since 1960, the catch of Peruvian anchovies (anchoveta) has accounted for about 10% of the total capture fisheries production.

During the same time, the anchoveta catch has exceeded the U.S. catch of all species by about 60%. However, the economic value of the U.S. catch is much greater.

In 2001, a typical year, the U.S. and Peruvian capture fisheries harvests were 4.9 and 8.0 Mt, respectively. In that year, 74% of the value of Peruvian fishery exports was accounted for by fishmeal, which was worth about $430/tonne. In the same year 64% of the value of U.S. fishery exports was accounted for by fresh, chilled, or frozen fish, which was worth about $2,500/tonne. Overall U.S. and Peruvian fishery exports were worth $3.3 and $1.1 billion, respectively.

Virtually all the anchovies are converted to fishmeal, which is marketed in developed countries such the United States as a component of feed for animals like pigs and chickens, and cultured fish.

The sale of this fishmeal accounted for 25-30% of Peru’s foreign exchange in the 1970s. Only the Peruvian copper industry rivaled it as a source of foreign revenue.

The anchovy fishery employs about 12,000 people, 10,000 in full-time fishing and the remainder as factory workers. (By way of comparison, Disney World employs 30,000 people).

Why does Peru convert almost all of its anchovy catch to fishmeal rather than using the fish to feed its people? The answer is that when the anchovies are converted to fishmeal, the value of the catch increases by about 300%. From a strictly economic standpoint it makes more sense to feed the catch to chickens and pigs than to humans. There are also distribution problems. Many of Peru’s malnourished people live in mountainous regions or in slums and do not buy their food at commercial markets. Introducing anchovies into their diets would be difficult. If the entire anchovy catch were fed to humans, it would on average provide the minimum protein requirement for 37 million people.

Catch of anchoveta has been highly variable. In the decade between 1962 and 1971, annual yields averaged 9.7 Mt, but the catch dropped dramatically in 1972 and averaged only 1.3 Mt in the decade between 1976 and 1985.

One cause of the large fluctuations in anchovy catch is El Niño, an intrusion of warm, nutrient-poor water from the vicinity of the equator southward along the coast of Peru. The water is transported by the Peru Countercurrent, and in extreme cases may extend as far as 12oS latitude. The intruding water is less dense than the Peru Coastal Current, both because it is warmer (sometimes by as much as 10oC) and because it is less saline (contains a lower concentration of dissolved salts). This lighter water overrides the Coastal Current water in a nutrient-poor layer up to 30 meters deep.

During El Niño the coastal wind system sometimes slackens, and upwelling may cease. Alternatively, the coastal wind system and upwelling may continue as usual, but because the nutrient-poor upper layer is so much deeper than usual, the upwelled water comes from above the nutricline and is therefore low in nutrients. From a biological standpoint, upwelling has become ineffective. El Niño conditions have been known to persist for as long as 12 to 18 months. These events usually begin during the Christmas season; hence the name El Niño, which means “The Child” in Spanish.

El Niño

During El Niño there is a dramatic drop in photosynthetic rates in the coastal current system, in extreme cases by more than an order of magnitude. This decline in photosynthesis impacts the food supply of virtually all organisms in the coastal current ecosystem. However, not all scientists agree on the impact of El Niño events on the anchovy population. Some scientists feel that the anchovy schools do not die but simply disperse, i.e., the anchovies swim farther offshore and/or into deeper water, beyond the reach of the fishing nets. Either way, fewer fish are caught during El Niño events.

Fish-eating birds are significant and highly visible predators of the anchovy. These birds, regionally known as guano birds, sometimes number in the millions and live on islands off the coast of Peru. Their droppings, or guano, are used as fertilizer. Guano birds include cormorants, gannets or boobies, and pelicans. Anchovies account for 95% of the cormorants’ diet and 80% of the diets of gannets and pelicans.

Biological effects

Guano birds have a limited ability to fish at depth, so when El Niño occurs, the guano bird population is seriously impacted. The weaker swimmers and divers are unable to find food even if the schools of fish do nothing more than disperse into deeper water. Census data confirm that weak, immature guano birds are decimated by El Niño. In mild or moderate El Niño events, the adult guano birds are still able to find enough food for themselves but not enough to sustain their young as well. They abandon their nests, and their nestlings starve. In severe El Niño events, significant numbers of adult guano birds die as well.

Effects of El Niño on Anchoveta Catch

Effects of El Niño on Anchoveta Catch

Effects of El Niño on Anchoveta Catch

1958: Severe El Niño. No negative effects, because the catch is low.

1965: Moderate El Niño. Catch still good, but guano bird populationcrashes.

1965-72: Fishery grows and management efforts begin

1972: Strong El Niño. Fishery collapses.

1976: Moderate El Niño.

1982: Strong El Niño. Fishery essentially closed.

1987: Strong El Niño. Catch declines by 50%.

1991: Strong El Niño. Catch declines.

1993: Moderate El Niño. No severe effects.

1994: Moderate El Niño. No severe effects.

1998: Strongest El Niño of the century. Catch plummets, fishing

restricted. Catch subsequently recovers.

2002: Moderate El Niño.

Remember -

Prior to the postwar development of the Anchoveta fishery, the elite of Peruvian society [the equivalent of the Big Five (Missionaries) in Hawaii, the Forty Thieves (Pirates and Slave and Salt Traders) in Bermuda], made their money from guano (bird shit).

Effects of El Niño on Guano Birds, Anchoveta Predators

Remember -

Prior to the postwar development of the Anchoveta fishery, the elite of Peruvian society [the equivalent of the Big Five (Missionaries) in Hawaii, the Forty Thieves (Pirates and Slave and Salt Traders) in Bermuda], made their money from guano.

Effects of El Niño on Guano Birds, Anchoveta Predators

Talk About a Reduction Fishery!

Effects of El Niño on Anchoveta Catch

After the severe El Niño of 1957 the guano bird population, then estimated to be about 27 million, dropped to 6 million. Millions of dead birds washed up on the Peruvian coast. The population gradually recovered in subsequent years and had reached 17 million just prior to the El Niño of 1965 (Figure 6). The population dropped to fewer than 5 million in 1966 and to a few hundred thousand after the 1972-73 El Niño. The population slowly increased to a peak of 6.8 million in 1996, but the birds were decimated by the very strong El Niño of 1997-98. As of 2002 the population stood at 1.8 million individuals.

Effects of El Niño on GuanoBirds, Anchoveta Predators

Record of recruitment to the anchoveta stock from 1953 through April of 1982.

Effects of El Niño on Anchoveta Recruitment

Anchoveta biomass (millions of tonnes) from 1953 through 1985. Continuous line is based on model calculations. Dots are estimates from field surveys.

Effects of El Niño on Anchoveta Biomass

In the 70s, managers thought that taking 7 million tonnes from this stock was a reasonable sustainable yield. What do we think now?

Effects of El Niño on Anchoveta Biomass

Impact of El Niño on Peruvian anchovies

Possible impacts:

anchovies starve

poor recruitment

changes in predation

Response of anchovies

concentrate in cold water nearer the coastline

move into deeper water and disperse

History of management

1964 – precursor of the Instituto del Mar del Peru (IMARPE) established

1965 – first closed season

1965 – IMARPE estimates msy to be 7.5 Mt

History of management

1970 – IMARPE MSY estimate upped to 9.5 MT

1970 – Government overrules; sets harvest at 12.4 MT

1971 – 10.5 MT harvested

1972 – Collapse!

Fishing at 15% of MSY

Fishing at 75% of MSY Fishing at 100% of MSY

1970 – 1,450 purse seiners in the fleet, enough to harvest 13 Mt of anchovies in 175 days.

1970 – Even greater excess capacity in fish meal plants. 7.5 Mt could have been converted to fishmeal in less than 40 days if the fishmeal plants were operated 24 hours a day.

1973 – Peruvian government nationalizes the fishing industry following the 1972 El Niño. The number of fishing boats was reduced from about 1,500 to 800; the number of fishmeal plants was cut from 100 to 50; the number of persons employed in the industry was reduced from 25,000 to 12,000.

1976 – fishery is de-nationalized

1982 – very strong El Niño

1987 – very strong El Niño

1991-92 – very strong El Niño

1997-98 – strongest El Niño of the century

2000 – catches of anchoveta during the 1990s averages 7.6 Mt

Ecological Summary

Advantages:

• An Extraordinary Combination of Nutritional Resourcesand an r-Selected Fish

• Short Food Chain

• “Simple” Sources of Mortality

Problems:

• Complex Biological-Meteorological Interactions

• Variable Recruitment

Management Summary

Advantages:

• An Extraordinary Combination of Nutritional Resourcesand an r-Selected Fish

• Fishery within the Peruvian EEZ

• National and International Fisheries Scientists Involved

Problems:

• Complex Biological-Meteorological Interactions

• Harvesting Prior to Sexual Maturity

• Overcapitalization and Socio-Political Pressures

• MSY as a target

Regime Shift

Modeling

• Hindcasting

• Forecasting

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