A recent worldwide decline of ocean fishery stocks has stimulated rapi

A recent worldwide decline of ocean fishery stocks has stimulated rapid growth in cultivated production of fish and shellfish, usually known as fish farming. Between 1987 and 1997, for example, global fish production from farming doubled. Fish farming produces a quarter of all fish and shellfish eaten by humans, and, as global population increases, fish farming will probably become even more important in supplying human protein needs. Some experts even argue that in addition to helping to compensate for the decline in ocean harvests, fish farming will restore wild populations by relieving pressure on ocean fisheries. There is, however, little if any evidence that fish farming will restore ocean fishery stocks. The complexity of production systems leads to an underlying paradox: fish farming is a possible solution, but also a potential contributing factor, to the continued decline of ocean fishery stocks worldwide.

In the first place, the more intensive forms of fish fanning, oriented toward high-volume production, threaten the sustainability of ocean fisheries through water pollution and ecological disruption. Intensive fish farming usually involves the enclosure of fish in a secure system; population densities are typically high, resulting in the generation of large amounts of waste and increased potential for the spread of pathogens. Habitat destruction through the spread of untreated waste, the escape of species not native to the farm's region, or contamination by new pathogens can all ensue, seriously damaging ocean and coastal resources and, ultimately, wild fishery stocks.

Even more important, intensive farming of many species of fish requires large inputs of fish meal and fish oil in order to supply fatty acids that vegetable matter lacks or essential amino acids that it inadequately supplies, like lysine and methionine. For the ten species of fish most commonly farmed, an average of 1.9 kilograms of wild fish is required for every kilogram of fish produced. Of the ten species, only three—catfish, milkfish, and carp—require less fish input than is eventually harvested, while the farming of carnivorous species like salmon has a very high input-to-output ratio. Although some defenders of fish fanning contend that predatory carnivores in the wild consume even more fish than they would on a farm, farming of such carnivorous species requires up to 5 kilograms of wild fish for every kilogram of fish produced.

Expanding farm production does have the potential to alleviate some of the pressure on wild fishery stocks. For example, increasing the farm production of fish like salmon can reduce prices, deterring investment in fishing fleets and, over time, reducing fishing efforts. Similarly, other farmed fish like tilapia and channel catfish provide alternatives to ocean fish like cod and haddock. Nonetheless, even these benefits may in the end be lost because niche markets have started to develop for several species of wild-caught fish, causing their catch rates to remain high even as the production of viable farmed substitutes has increased.

1. Which one of the following most accurately describes the main point of the passage?

(A) The recent decline of ocean fishery stocks was caused by damage to ocean habitats resulting from fish farming.
(B) Fish fanning has some potential both for increasing global fish supplies and for threatening those very supplies.
(C) Fish farming is destined to supply ever-larger percentages of human protein needs.
(D) The high catch rates for several types of wild-caught fish overshadow the advances made by fish farming.
(E) Because of their diet, carnivorous fish are more expensive and difficult to farm than noncarnivorous fish.

2. There is information in the passage sufficient to answer which one of the following questions?

(A) How does the escape of species not native to a farm's region result in habitat destruction?
(B) What sort of shellfish is most commonly raised on fish farms?
(C) Approximately how many kilograms of fish, on average, does a wild salmon consume during its lifetime?
(D) What proportion of the fish and shellfish eaten by humans is produced on fish farms?
(E) How long does it take for niche markets for wild-caught fish to have an appreciable effect on wild populations?

3. Which one of the following is closest to the meaning of the phrase "relieving pressure on ocean fisheries" as used in the middle of the first paragraph?

(A) making up for the scarcity of wild-caught fish
(B) supplementing the incomes of people who make a living from ocean fishing
(C) causing fewer wild fish to be caught
(D) reducing the amount of income to be earned from ocean fishing
(E) reducing overall demand for fish and fish products

4. The information in the passage most strongly supports which one of the following statements?

(A) Any further decline in ocean fishery stocks would not be caused entirely by human activities.
(B) The best way to reduce the price of wild-caught fish is to put a farmed variety of the same species on the market.
(C) If fish fanning does not continue to increase, then it is unlikely that worldwide human protein needs can be met.
(D) Most consumers do not perceive a difference in taste between wild-caught and farmed varieties of the same species of fish.
(E) The use of wild fish to meet the nutritional needs of fanned fish could result in the overfishing of worldwide fish stocks.

5. The views put forward in the passage conform most closely to which one of the following principles governing new methods of food production?

(A) They should be employed only if they do not result in major changes in consumer demand for foods produced using traditional methods.
(B) They should be employed if they are economically more efficient than existing methods and their use will not result in business failures or loss of jobs.
(C) They should not be employed if they will ultimately result in a net decrease in food of the type produced.
(D) They should be employed if they promote diversification in the types of foods available for human consumption and help to bring about environmental improvement.
(E) They should be employed only if they replace other methods that have undesirable ecological effects.

6. The statements in the passage provide the most support for the view that the author believes which one of the following?

(A) Most farmed fish are carnivorous.
(B) Farmed and wild fish consume the same foods.
(C) Pollution is currently more damaging to wild fish populations than is overfishing.
(D) Market forces can either encourage or discourage overfishing of ocean fisheries.
(E) The market for wild-caught fish is likely to remain a small one.

7. The information in the passage most strongly supports which one of the following statements?

(A) Wild fish require different nutrients than farmed fish do.
(B) It is more profitable to farm species such as catfish, milkfish, and carp than to farm species such as salmon.
(C) The farming of tilapia and channel catfish produces as much environmental damage as the farming of cod and haddock.
(D) A growing number of consumers are choosing wild-caught fish of certain species in preference to fanned fish.
(E) Noncamivorous fish in the wild typically do not consume more food than their farmed counterparts do.

8. The author of the passage would be most likely to agree with which one of the following statements regarding pollution caused by fish farming?

(A) Such pollution is problematic primarily because of the genetic mutations it would cause in wild fish that live near fish farms.
(B) Such pollution contributes to coastal degradation more than any other type of pollution.
(C) Such pollution is less likely to occur if fish fanning enterprises do not pursue intensive production methods.
(D) Such pollution cannot be prevented by fish farmers alone without the involvement of government agencies.
(E) Such pollution is, however harmful, unlikely to prevent fish farming from eventually relieving the pressure on wild fishery stocks.