Issues in Ecology Winter 2001 Marine finfish .16 Fel Marine shrimp Salmon Trout Tilapla Carp (fed) Mollusks TOTAL ratlo of wild fsh used for fshmeal to farmed fish produced Figure 3 Wild fish inputs used in feeds for the ten types of fish and shellfish most commoy farmed in1997 presente ratio of wild fish used for farmed fish produce using compound amount of v sed in compound t that her th arp speci d catla)are no ds a not included here. are filte ed compound in plant proteins and fatty acids (eicosapentaenoic acid ifpa marine fish such as flounder.halibut.sole.cod.hake.had and docosahexaenoic acid [DHA],known as n-3 fatty acids) dock,redfish,seabass,congers,tuna,bonito,and billfish not present in vegetable oils.The fish oil and protein also Many salmon and shrimp operations use roughly three kilo provide energy,which is important because fish tend to be grams of fish biomass for each one produced (Figure 4). poor at using carbohydrates for enerqy. Only three of the ten types of fish most commonl All fish,whether omnivorous,herbivorous,or farmed. catfish.milkfish.and carp-use less fish as inputs carnivorous,require about the same quantity of dietary than is ultimately harvested.(Marine mollusks and many protein per kilogram. But freshwater herbivores and filter-feeding carp are not fed compound feeds at all.) omnivores such as carp,tilapia,and catfish are better than Aquaculture is not the world's largest consumer of carnivores at using plant-based proteins and oils,and fish meal.That distinction belongs to the poultry and swine consequently,they need only minimal quantities of fish mea industries. Aquaculture,however,has the fastest growing to supply essential amino acids.Nevertheless,compound feeds demand for fish meal and fish oil. Its share of fish meal sup for tilapia er omnivorous fish often contain about 15 plies rose from o pe rcent in 1988 to 17 percent in 199 percent me mu mor than required over-formulat and 33 percenti 99 fish than in poultry and atio dietary requirements for particular fish age o on ture fee high leve of fish meal and fish y us ake s to nly a fe ed spe spe Fo of ten type m of carnivorous h can use up to of wild fish 1 o kilo of wild fish ired for kilograms farmed fish production rea culture proponents arg ethat even it farmed fish nroduced usin re 2) The s more wild fish biomass thar highest inputs of wild-caught fish more than five kilo is ultimately harvested.it is still more efficient than the mak grams for each kilogram produced are used in raising ing of big fish from little fish in the wild.n other words.ever4 Issues in Ecology Number 8 Winter 2001 Figure 3 — Wild fish inputs used in feeds for the ten types of fish and shellfish most commonly farmed in 1997 presented as the ratio of wild fish used for fishmeal to farmed fish produced using compound feeds. In calculating the amount of wild fish used in compound feeds, we assumed a 5:1 conversion rate of fish to fishmeal and that one-sixteenth of fishmeal is obtained from processing by-products. 1 Marine finfish (other than salmon, which is listed separately because of its market significance) include flounder, halibut, sole, cod, hake, haddock, redfish, seabass, congers, tuna, bonito, and billfish. 2 Fed carp refers to carp species that are sometimes fed compound feeds. Filterfeeding carp (silver carp, bighead carp, and catla) are not fed compound feeds and are not included here. 3Mollusks are filter-feeders and are not fed compound feeds. 5.16 4.69 2.81 3.16 2.46 1.41 0.94 0.84 0.75 1.90 Marine finfish1 Eel Marine shrimp Salmon Trout Tilapia Catfish Carp (fed) Carp (fed)2 Mollusks3 TOTAL Milkfish Based on Table 2 of Naylor et al. (2000). ratio of wild fish used for fishmeal to farmed fish produced in plant proteins and fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA], known as n-3 fatty acids) not present in vegetable oils. The fish oil and protein also provide energy, which is important because fish tend to be poor at using carbohydrates for energy. All fish, whether omnivorous, herbivorous, or carnivorous, require about the same quantity of dietary protein per kilogram. But freshwater herbivores and omnivores such as carp, tilapia, and catfish are better than carnivores at using plant-based proteins and oils, and consequently, they need only minimal quantities of fish meal to supply essential amino acids. Nevertheless, compound feeds for tilapia and other omnivorous fish often contain about 15 percent fish meal — much more than required. Indeed, manufacturers often over-formulate feeds, in part because information on the dietary requirements for particular fish species is inadequate. Because of these high levels of fish meal and fish oil in aquaculture feeds, it takes more fish biomass to raise some farmed species than those species produce. For the ten types of fish most commonly farmed, for instance, an average of 1.9 kilograms of wild fish are required for every kilogram of farmed fish produced using compound feeds (Figure 3). The highest inputs of wild-caught fish — more than five kilo￾grams for each kilogram produced — are used in raising marine fish such as flounder, halibut, sole, cod, hake, had￾dock, redfish, seabass, congers, tuna, bonito, and billfish. Many salmon and shrimp operations use roughly three kilo￾grams of fish biomass for each one produced (Figure 4). Only three of the ten types of fish most commonly farmed — catfish, milkfish, and carp — use less fish as inputs than is ultimately harvested. (Marine mollusks and many filter-feeding carp are not fed compound feeds at all.) Aquaculture is not the world’s largest consumer of fish meal. That distinction belongs to the poultry and swine industries. Aquaculture, however, has the fastest growing demand for fish meal and fish oil. Its share of fish meal sup￾plies rose from 10 percent in 1988 to 17 percent in 1994 and 33 percent in 1997. Also, the proportion of fish meal in aquaculture feeds is much higher than in poultry and live￾stock feeds, which contain an average of only 2 to 3 percent fish meal as a protein supplement. The production of a kilo￾gram of pork or poultry typically uses large amounts of plant proteins, but only a few hundred grams of fish, whereas pro￾duction of a kilogram of carnivorous fish can use up to five kilograms of wild fish. Some aquaculture proponents argue that even if farmed fish production requires more wild fish biomass than is ultimately harvested, it is still more efficient than the mak￾ing of big fish from little fish in the wild. In other words, even