NORTHERN ANCHOVY

NorthernAnchovy

Distribution and Habitat

Northern anchovy are distributed from the Queen Charlotte Islands, British Columbia, to Magdalena Bay, Baja California and anchovy have recently colonized the Gulf of California. The population is divided into northern, central and southern subpopulations, or stocks. The southern subpopulation is entirely within Mexican waters. The central subpopulation, which supports significant commercial fisheries in the U.S. and Mexico, ranges from approximately San Francisco, California, to Punta Baja, Baja California. The bulk of the central subpopulation is located in the Southern California Bight, a 20,000-square-nautical-mile area bounded by Point Conception, California, in the north and Point Descanso, Mexico, (about 40 miles south of the U.S.-Mexico boarder) in the south. Northern anchovy in the central subpopulation are typically found in waters that range from 12°C to 21.5°C; however, laboratory defined lethal temperatures occur at seven degrees Celsius and 29°C (Brewer 1976). There is a great deal of regional variation in age composition and size, with older and larger anchovy found farther offshore and to the north (Parrish et al. 1985). The pattern is accentuated in warm years and during the summer (Methot 1989).

There is a great deal of regional variation in age composition and size with older and larger individuals further offshore and to the north (Parrish et al. 1985). These patterns are accentuated during warm years such as El Nino and when abundance is high (Methot 1989). The geographic distribution of northern anchovy has been more consistent over time and is more nearshore than the geographic distribution of Pacific sardine. In the Oregon to Vancouver Island region northern anchovy must overwinter in upper mixed layer temperatures as low as eight degrees Celsius to nine degrees Celsius; short term laboratory lethal temperatures for northern anchovy are seven degrees Celsius (Brewer 1976). Eggs and larvae are found near the surface, generally at depths of less than 50 meters and in the same areas as spawning adults. Anchovy eggs are most abundant at about 14°C. All life stages are found in the surface waters of the EEZ. Methot found that near shore habitat areas (<90 meters) between Pt. Conception, California and Pt. Banda, Baja California represented 23% of the available habitat for central stock juvenile northern anchovy . Densities of juvenile anchovy in near shore areas were about ten times higher than in other habitat areas. He concluded that near shore habitats supported at least 70% of the juvenile anchovy population (Methot 1981, Smith 1985).

Life History

Northern anchovy are small, short-lived fish typically found in schools near the surface. Northern anchovy rarely exceed four years of age and 18 cm total length, although individuals as old as seven years and 23 cm have been recorded. Natural mortality is thought to be M = 0.6 to 0.8 year', which means that 45% to 55% of the total stock would die each year of natural causes if no fishing occurred. Northern anchovy eat phytoplankton and zooplankton by either filter feeding or biting, depending on the size of the food. Anchovy spawn during every month of the year, but spawning increases in late winter and early spring and peaks from February to April. Preferred spawning temperature is 14°C and eggs are most abundant at temperatures of 12°C to 16°C. Females spawn batches of eggs throughout the spawning season at intervals as short as seven to ten days. The eggs, found near the surface, are typically ovoid and translucent and require two to four days to hatch, depending on water temperatures. Both the eggs and larvae are found near the surface. Anchovy in the central subpopulation are all sexually mature at age two. The fraction of one-year-olds that is sexually mature in a given year depends on water temperature and has been observed to range from 47% to 100% (Method 1989). This phenomenon affects estimates of spawning population.

Fisheries

Northern anchovy in the central subpopulation are harvested by commercial fisheries in California and Mexico for reduction, human consumption, live bait, dead bait, and other nonreduction commercial uses. Anchovy landed in Mexico are used primarily for reduction, although small amounts are probably used as bait. The northern subpopulation supports a small bait fishery (one to four boats) off Oregon and Washington. The small quantities of the northern subpopulation are taken for use as bait. Anchovy landed by the reduction fisheries are converted to meal, oil, and soluble protein products sold mainly as protein supplements for poultry food and also as feed for pigs, farmed fish, fur-producing animals, laboratory animals, and household pets. Meal obtained from anchovy is about 65% protein (meal from other fishes is 50% to 55% protein). Anchovy harvested by the live bait fishery in California are not landed but are kept alive for sale to anglers as bait and chum (in contrast anchovy sold as "live" bait off Oregon and Washington may be killed at time of sale). Transactions between buyers and sellers of live bait take place either at sea or at bait wells tied up at docks. Bait dealers generally supply party boats on a contract basis and receive a percentage of the fees paid by passengers. Bait is also sold by the scoop to anglers in private vessels. Anchovy landed by the nonreduction (other than live bait) fishery are used as dead frozen bait, fresh fish for human consumption, canned fish for human consumption, animal food, and anchovy paste.

Relevant Trophic Information

Northern anchovy are subject to natural predation throughout all life stages. Eggs and larvae fall prey to an assortment of invertebrate and vertebrate planktivores. As juveniles, anchovy are vulnerable to a wide variety of predators, including many recreationally and commercially important species of fish. As adults, anchovy are fed upon by endangered salmon stocks, endangered birds (California brown pelican Pelecanus occidentalis califomicus and least tern Sfema albifrons browni) numerous fishes (some of which have recreational and commercial value) mammals, and birds. Links between brown pelican breeding success and anchovy abundance have been documented (Anderson et al. 1980, 1982; Jacobson and Thomson 1989).

NORTHERN ANCHOVY

SUMMARY TABLE