The Snail Resource of the Eastern Berin9 Sea and Its Fishery Flipbook PDF

The Snail Resource of the Eastern Berin9 Sea and Its Fishery RICHARD A. MaciNTOSH Buccinum sp.. photographed in Alaska&#

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The Snail Resource of the Eastern Beri n9 Sea and Its Fishery

RICHARD A. MaciNTOSH

Buccinum sp .. photographed in Alaska's Auke Bay by Lou Barr, then with the NMFS Auke Bay Fisheries Laboratory, Northwest and Alaska Fisheries Center, Auke Bay, AK 99821.

The Alaskan continental shelf is an area of vast fishery resources. Fish and crab resources are well known and have long been exploited by many fishing nations; potential resources, like eastern Bering Sea snails, are virtually unknown. Several species of large snails occur in relatively high abundance in Alaskan waters and offer considerable fisheries potential. Japan has harvested snails in the eastern Bering Sea since the early 1970's and there is potential for the development of a U.S. domestic fishery

ABSTRACT-A trawl survey in the eastern Bering Sea outlined the distribution and relative abundance ofseveral large snails of commercial importance. Snails made up 6.6 percent of the invertebrate biomass with members of the genus Neptunea being most abundant. These snails lack a larval stage and are facultative predators and scavengers. Japan has harvested snails in the area since at least 1971. Reported catch rates in pots rangedfrom 0.9 to 4.0 kg/pot and total Japanese catch has varied from 404 to 3,574 t of edible meat per year. The United States has the vessel capacity to enter the fishery but probably will not do so until there is a large increase in the value ofsnail products. May 1980

as well. This report presents information about the Japanese fishery in the eastern Bering Sea, life history characteristics for the principal snail species, and discusses the potentiality for U.S. participation in the harvest of this unique shellfish resource.

The Snail Resource and Its Composition During the summer and fall of 1975, the Northwest and Alaska Fisheries Center of the National Marine Fisheries Service (NMFS) conducted a comprehensive trawl survey over 566,000 km 2 (218,600 miles 2 ) of the eastern Bering Sea shelf and upper slope (Fig. I). This survey was designed to identify principal demersal fish and shellfish communities of the eastern Bering Sea which could be affected by development of continental shelf energy sources. Data on fish and epibenthic invertebrates were gathered from several hundred locations with a modified 400-mesh eastern otter trawl. The resulting data offered significant insight into the population and biological

Richard A. Macintosh is with the Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd., East, Seattle, WA 98112.

characteristics of numerous species of snails. Gastropods made up 1.7 percent of the total biomass and 6.6 percent of the invertebrate biomass in the survey area (Pereyra et al. I). Distribution of snails throughout the area is patchy, with the areas of highest concentration also supporting a high biomass of fish and epibenthic invertebrates. Snail biomass in some areas exceeded 3,000 kg/km 2 (17,000 pounds/ nmi 2 ); however, if the trawl is not effective at catching species of snails that sometimes burrow into the substrate, then the biomass may actually be much higher. About 15 species of large (>5 cm) snails are common in the eastern Bering Sea (Table 1). Members of the genus Neptunea are by far the most abundant in terms of both numbers and biomass. The Pribilof neptune, N. pribilojfensis, (Fig. 2), is probably the most abundant Neptunea; N. lyrata, N. ventricosa, and N. heros (Fig. 2) are also very

'Pereyra, W. T., J. E. Reeves, and R. G. Bakkala. 1976. Demersal fish and shellfish resources of the eastern Bering Sea in the baseline year 1975. Northwest and Alaska Fisheries Center, NMFS, NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. Processed rep., 6 t9 p.

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Table 1.-Sclentific names of large snails laken in the eastern Bering Sea during the 1975 trawl survey of the NMFS Northwest and Alaska Fisheries Center.

Beringius beringii (Middendorf, 1849) Buccinum angulossum Gray, 1839 B. p/eetrum Stimpson, 1865 B. po/are Gray, 1839 B. sea/ari/orme Moller, 1842 Clinopegma magna (Oall, 1875) Fusitriton oregonensis (Redfield, 1848) Neptunea heros (Gray, 1850) N./yrata (Gmelin, 1791) N. pribi/offensis (Oall, 1919) N. ventrieosa (Gmelin, 1791) Pliei/usus kroeyeri Moller, 1842) Pyru/ofusus deformis (Reeve, 1847) Vo/utopsius fragi/is (Oall, 1891) V. middendorffii (Oall, 1891)

common. The mean shell lengths of N. pribilojfensis, N. lyrata, N. ventricosa, and N. heros were 100, 115, 102, and 121 mm, respectively (MacIntosh 2 ). The genus Buccinum is also well represented in the eastern Bering Sea. Six species of this genus were taken in the 1975 survey, of which four, B. angulossum, B. plectrum, B. polare, and B. scalariforme, were fairly abundant. Although quite numerous, these smaller snails (58-75 mm average shell length) contribute relatively little to total snail biomass in the eastern Bering Sea. Buccinum angulossum (Fig. 3) is representative of the size and general form of these snails. Most species of eastern Bering Sea snails do not occur over the entire shelf but are retricted to specific depth and temperature regions. In general, those species that have continuous distributions into the Gulf of Alaska inhabit the warmer, deeper waters near the continental shelf edge, while those species having a more northerly distribution into Arctic waters inhabit the colder (at least seasonally), shallower, inshore waters. Basically, N. pribilojfensis and N. lyrata are temperate water snails and are characteristically found in deeper, warmer waters along the edge of the continental shelf. In contrast, N. heros andN. ventricosa, which range into the Arctic Ocean, inhabit shallower, sea-

2MacIntosh, R. A. 1976. A guide to the identification of some common eastern Bering Sea snails. Northwest and Alaska Fisheries Center, NMFS, 2725 Montlake Blvd. E., Seattle, WA 98112. Processed rep., 27 p.

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