The Snail Resource of the Eastern Berin9 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 as well. This report presents informa­ characteristics of numerous species of area of vast fishery resources. Fish and tion about the Japanese fishery in the snails. crab resources are well known and have eastern Bering Sea, life history charac­ Gastropods made up 1.7 percent of long been exploited by many fishing teristics for the principal snail species, the total biomass and 6.6 percent of the nations; potential resources, like east­ and discusses the potentiality for U.S. invertebrate biomass in the survey area ern Bering Sea snails, are virtually un­ participation in the harvest of this (Pereyra et al. I). known. Several species of large snails unique shellfish resource. Distribution of snails throughout the occur in relatively high abundance in area is patchy, with the areas of highest The Snail Resource Alaskan waters and offer considerable and Its Composition concentration also supporting a high fisheries potential. biomass of fish and epibenthic inverte­ Japan has harvested snails in the During the summer and fall of 1975, brates. Snail biomass in some areas ex­ eastern Bering Sea since the early the Northwest and Alaska Fisheries ceeded 3,000 kg/km 2 (17,000 pounds/ 2 1970's and there is potential for the Center of the National Marine Fisheries nmi ); however, if the trawl is not effec­ development of a U.S. domestic fishery Service (NMFS) conducted a com­ tive at catching species of snails that prehensive trawl survey over 566,000 sometimes burrow into the substrate, 2 2 km (218,600 miles ) of the eastern Be­ then the biomass may actually be much ring Sea shelf and upper slope (Fig. I). higher. This survey was designed to identify About 15 species of large (>5 cm) principal demersal fish and shellfish snails are common in the eastern Bering communities of the eastern Bering Sea ABSTRACT-A trawl survey in the east­ Sea (Table 1). Members of the genus ern Bering Sea outlined the distribution and which could be affected by develop­ Neptunea are by far the most abundant relative abundance ofseveral large snails of ment of continental shelf energy in terms of both numbers and biomass. commercial importance. Snails made up 6.6 sources. Data on fish and epibenthic The Pribilof neptune, N. pribilojfensis, percent of the invertebrate biomass with invertebrates were gathered from sev­ (Fig. 2), is probably the most abundant members of the genus Neptunea being most eral hundred locations with a modified abundant. These snails lack a larval stage Neptunea; N. lyrata, N. ventricosa, and are facultative predators and scaven­ 400-mesh eastern otter trawl. The re­ and N. heros (Fig. 2) are also very gers. Japan has harvested snails in the area sulting data offered significant insight since at least 1971. Reported catch rates in into the population and biological pots rangedfrom 0.9 to 4.0 kg/pot and total Japanese catch has varied from 404 to 'Pereyra, W. T., J. E. Reeves, and R. G. Bak­ 3,574 t ofedible meat per year. The United kala. 1976. Demersal fish and shellfish resources States has the vessel capacity to enter the Richard A. Macintosh is with the Northwest and of the eastern Bering Sea in the baseline year fishery but probably will not do so until Alaska Fisheries Center, National Marine 1975. Northwest and Alaska Fisheries Center, there is a large increase in the value ofsnail Fisheries Service, NOAA, 2725 Montlake Blvd., NMFS, NOAA, 2725 Montlake Blvd. E., Seat­ products. East, Seattle, WA 98112. tle, WA 98112. Processed rep., 6 t9 p.

May 1980 15 Table 1.-Sclentific names of large snails laken in the eastern Bering Sea during the 1975 trawl survey ofthe NMFS Northwest and Alaska Fisheries Center.

Beringius beringii (Middendorf, 1849) Buccinum angulossum Gray, 1839 B. p/eetrum Stimpson, 1865 ALASKA 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) 60'N 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 ofN. ATeH I" Iog/k. pribilojfensis, N. lyrata, N. ventricosa, ~ <~-1O and N. heros were 100, 115, 102, and 2 121 mm, respectively (MacIntosh ). 5S'N Iii >10 The genus Buccinum is also well rep­ resented in the eastern Bering Sea. Six 17S'W 170'W species of this genus were taken in the Figure I. -Location of trawl survey area of the NMFS Northwest and Alaska 1975 survey, of which four, B. an­ Fisheries Center in 1975 (inside dashed line) and areas of high snail density gulossum, B. plectrum, B. polare, and (all species combined). B. scalariforme, were fairly abundant. Although quite numerous, these smal­ ler snails (58-75 mm average shell length) contribute relatively little to total snail biomass in the eastern Bering sonally cooler waters near the coast of separate and fertilization is internal. Sea. Buccinum angulossum (Fig. 3) is western Alaska. Among the large Neptunea, sexual representative of the size and general Numerous trawl surveys have been maturity occurs at a shell length of form of these snails. conducted in the Gulf of Alaska, but 90-110 mm (MacIntosh and Paul, Most species of eastern Bering Sea very little attention has been paid to the 1977) which probably corresponds to snails do not occur over the entire shelf snail resources of the area. Although an age of about 10 years. Definitive but are retricted to specific depth and quantitative data are lacking, it is ap­ work on aging has not been completed. temperature regions. In general, those parent that N. pribilojfensis, N. lyrata, A feature of the life histories of all species that have continuous distribu­ and Fusitriton oregonensis make up the but one3 of the common large snails is tions into the Gulf of Alaska inhabit the bulk of the snail biomass. Fusitriton the production of egg capsules from warmer, deeper waters near the conti­ reaches a length of 13 cm and ranges which crawling young are hatched. nental shelf edge, while those species from the California coast to the Gulf of Thorson (1950) and Shuto(1974) have having a more northerly distribution Alaska and the eastern Bering Sea. All discussed this lack of a pelagic larval into Arctic waters inhabit the colder (at three species occur at depths from at stage (termed lecithotrophic develop­ least seasonally), shallower, inshore least 50 to 250 m with the latter also ment) among some Prosobranch gas­ waters. Basically, N. pribilojfensis and found inshore to the intertidal zone. tropods and the effect it has had on their N. lyrata are temperate water snails and Large catches of N. pribilojfensis and evolution and distribution. are characteristically found in deeper, N. lyrata have been made by trawlers In the eastern Bering Sea, egg clus­ warmer waters along the edge of the and pot fishermen of Ketchikan, ters are usually laid on the shells of continental shelf. In contrast, N. heros Petersburg, Kodiak, and Cordova. large snails. Both living and dead shells andN. ventricosa, which range into the Overall, species diversity appears to be are utilized as substrates, and there ap­ Arctic Ocean, inhabit shallower, sea- less and distribution ofsnails appears to pears to be little correlation between the be more patchy in the Gulf of Alaska than in the eastern Bering Sea. 2MacIntosh, R. A. 1976. A guide to the iden­ 3Fusifriton oregonensis , a member of the tropi­ tification of some common eastern Bering Sea Life History cally oriented family Cymaliidae, apparently has snails. Northwest and Alaska Fisheries Center, pelagic larvae although no literature on the sub­ NMFS, 2725 Montlake Blvd. E., Seattle, WA Most snails listed in Table 1 have ject exists. Pers. commun. Alan 1. Kohn, Univ. 98112. Processed rep., 27 p. similar life histories. The sexes are Washington, Seattle, WA 98195.

/6 Marine Fisheries Review o 2 3 4 5 em III Figure 3.-Buccinum angulossum, o 2 3 4 5 one of four common Buccinum in the em eastern Bering Sea.

Laboratory studies (Avery~) have shown that Fusitriton oregonesis. Nep­ tunea lyrata, and Buccinum plectrum respond to a variety of scents including those of freshly killed mussel, nereid worm, crab, mud shrimp, and fish. Eastern Bering Sea snails are probably facultati ve predators and scavengers. Japanese Fishery Japan has commercially harvested snails in the eastern Bering Sea since at least 1971. The fishery occurs east of long. 175°W on the continental shelf Figure 2. - The four large Neptunea from the eastern Bering Sea, clockwise from northwest of the Pribilof Islands. As­ upper left, N. heros, N. Iyrata. N. pribilojjensis, and N. ventricosa. pects of the commercial fishery have been described, including gear, species captured, and size composition of the catch (Nagai, 1974); incidental catch species of snail depositing its eggs and vidual capsules contained. The cap­ the species the cases are deposited on. sules, clusters, and young of many 4 Avery. J. 1961. Observation on certain aspects Egg clusters of the large eastern Bering species remain undescribed. of the feeding habits of four species of carnivo­ rous marine gastropods. Friday Harbor Labora­ Sea gastropods vary considerably in Very little is known about the feed­ tory Library, Friday Harbor. WA 98250. Unpubl. size, shape, cotor, and number of indi- ing habits of Bering Sea snails. manuscr.. 29 p.

May 1980 17 (Nagai, 197 Sa); and catch-per-unit­ Table 2.-Catch and effort statistics of the Japanese Fishing gear consists of pots fished at effort (N agai, 197 5b). So little informa­ snail fishery in the eastern Bering Sea. 1972·78. intervals on a groundline. The snail Fishing tion is available for this fishery that only Catch (t) effort pots are truncated cones 88 cm in height a fragmentary account of its history can edible Total (vessel (Fig. 5). The diameter of the tunnel in Year meal weight 1 days) be pieced together. Statistics available the top of the pot varies from 12 to 15 1972 '3.218 11,900 NA' since 1972 indicated an annual harvest 1973 '3.319 12.300 NA cm and webbing on the side of the pot is of about 3,000 metric tons (t) (11,000 t 1974 '3.574 13.237 NA 6-cm mesh over the lower 23 cm of the 1975 '3,447 12,767 NA live weight) of edible snail meats 1976 NA NA NA side and 12-cm mesh on the remainder. through 1975 (Table 2). Data for both 1977 '404 1,500 152 Snails, being predators and scavengers, 1978 '2,184 8,100 749 total weight and recovered meat weight 'Values are estimates derived from the weight of edible meal are strongly attracted to the fish bait in of the 1974 harvest indicated an edible and whole snails taken by the fishery in 1974. the pots. 'Data provided by the Japan Fisheries Agency through the meat recovery of27 percent. The value U.S. Embassy, Tokyo, Japan. Little is known about Japanese compares favorably with values of edi­ 3Not available. fishing techniques, but in 1973 one ves­ 'As reported to the United States under provisions of the ble meat recoveries from 26.8 percent Fishery Conservation and Management Act ot 1976. sel fished about 6,000 pots on 12 to 30.6 percent generated for four groundlines (500 pots/ground1ine) and species of eastern Bering SeaNeptunea took 3 days to pick and re-bait the entire by MacIntosh and Paul (1977). set of gear. An average catch rate of 4 The most common gastropod in ended in November. There was a con­ kg/pot per 3-day soak was reported by Japanese catches made northwest of the siderable increase over 1977 in both that same vessel (Nagai, 1975a). In the PribilofIslands in 1973 wasN. pribilof­ effort and catch, with about 2,200 t of 1977 fishery, the overall average catch fensis which composed about 70 per­ snail meats taken in about 760-vessel­ rate was reported as 0.9 kg/pot per 33­ cent of the catch by weight (Nagai, days (average 2.9 t/day). Fishing effort hour soak (unpublished data, 1979. 1974). Buccinum angulossum and B. peaked in August when nine vessels Alaska Regional Office, National scalariforme accounted for an addi­ fished northwest of the Pribilof Islands Marine Fisheries Service, NOAA, tional 23 percent of the catch. along the edge of the continental shelf. Juneau, AK 99802). Until 1977, the number of vessels Vessels Iicensed for this fishery range All processing of the snail catch now involved in the fishery was unknown. from 96 to 490 gross t and 25 to 50 m in occurs on board the catcher vessel. This In some years, the Fisheries Agency of length (Fig. 4) (unpublished data, U.S. consists of crushing the shells, briefly Japan licensed 21 vessels but it is un­ Embassy, Tokyo, Japan). Similar ves­ cooking the meats, and removing any likely that all of these vessels actually sels are used in the Japanese longline soft parts and shell fragments. The took part in the fishery. Patrols of and crab fisheries in Alaska and, in fact, meats are graded by size and quality NMFS in the eastern Bering Sea ob­ several vessels fished for crab before and quick frozen in trays. Small snails served ony 14, 5, 0, and 6 vessels switching to the snail fishery in the in the catch may be frozen whole. fishing snails in the years 1971 through 1978 season. The only available figures on the 1974, respectively, and no vessels in 5 1975 and 1976 . Records submitted for 1977 by the Japanese in compliance with the Fishery Conservation and Management Act of 1976 indicated that three vessels fished in the eastern Be­ ring Sea (east of long. 175°W) during the year. These vessels were given an allocation of 3,000 t of meat by the North Pacific Fishery Management Council. Fishing began in June and terminated on 16 October, at which time the combined catch of the vessels was 404 t of edible meat-about 15 percent ofJapan's allocation. The aver­ age catch rate in 1977 was 2.7 t ofmeats per vessel day. The 1978 season began in May and

"The 1974 IOtaI included one faclOryship which processed snails from the five catcher vessels. This appears to be the only year in which fishing vessels did not process their own catch. Figure 4. -A Japanese snail fishing vessel in the eastern Bering Sea.

/8 Marine Fisheries Review king and snow (Tanner) crab in the eastern Bering Sea could fish for snails. Although there has been Iittle prog­ ress toward a domestic snail fishery in the Bering Sea, seafood processors have made several recent attempts to initiate fisheries in other parts of Alaska. In Prince William Sound, as in many other areas of the Gulf of Alaska, snails are regularly taken in crab pots despite the large mesh used. New Eng­ land Fish Company6, Petersburg Fisheries, Inc., and others have had samples of Alaskan snails analyzed and have explored marketing possibilities. North Pacific Processors of Cordova, in an effort to build a broader based Prince William Sound pot fishery, installed a snail crushing machine and purchased snails from fishermen during the 1977-78 snow crab season. Only 5,000 pounds of snails were delivered during the season. Small deliveries were attri­ buted to relatively good snow crab fishing, the low price (US$0.06-0.10/ Figure 5. -Snail pot used by the Japanese fishery in the eastern Bering Sea. pound) paid to fishermen, and the un­ expectedly low concentrations of snails encountered. The current attempt to develop a snail fishery in Nova Scotia, Canada, value of the snail fishery are derived tion zone. At this time, a preliminary should be of interest to Alaskan proces­ from estimates of the ex-vessel value of management plan developed by NMFS sors. The Nova Scotia Department of snail meats that are used by the United is being used by the North Pacific Fisheries has developed an escargot­ States as a base for calculating fee Fishery Management Council to man­ like product that is produced from schedules for foreign vessels fishing age the fishery. marine snails similar to those found in within the extended jurisdiction zone. Because there is currently no domes­ Alaska. It is attempting to develop a Fee schedules for the years 1977-79 tic fishery for snails in the eastern Be­ market for the marine snails Buccinum were based on the ex-vessel snail meat ring Sea, the total allowable catch has undatum and Neptunea decemcostata 7 value of $600, $600, and $1,657 per t been allocated to Japan, the only nation that are taken in the lobster pot fishery . for the years 1976-78, respectively. now involved in the fishery. So little Discussion The ex-vessel value of snail meats in data are available on the snail resource 1977 was probably higher than the re­ and fishery that Japan's 1977 and 1978 Snails are an underutilized resource ported $600. At these ex-vessel prices, quotas were set at the same level as in Alaska. Although our knowledge of the 1977 eastern Bering Sea catch was previous yearly catches, i.e., 3,000 t of their distribution and relative abun­ worth only $242,000 and the 1978 edible meats. Changes in total allow­ dance is increasing, a data base that catch was worth $1.3 million. In 1979, able catch and Japan's harvest level will provides estimates of stock size and if the total catch is similar to that made depend upon newly acquired biological condition is not yet available. Studies in 1978 (2,187 t of edible meats), its and socioeconomic data. on distribution and abundance, species ex-vessel value will probably be in ex­ associations, age and growth, trophic cess of $3.6 million. Until recently, there was no U.S. Prospects for a regulation of the eastern Bering Sea U.S. Snail Fishery snail fishery. Implementation of the United States fishermen have made 6Mention of trade names or commercial firms Fishery Conservation and Management little effort to initiate a domestic fishery does not imply endorsement by the National Act of 1976 gave the United States a for snails in the eastern Bering Sea. Marine Fisheries Service, NOAA. 'Ernest Cadegan, Nova Scotia Department of tool to monitor and manage the snail With only slight modifications, domes­ Flshenes, Box 2223, Halifax, Nova Scotia, fishery within the 200-mile conserva- tic crab vessels currently fishing for Canada. Pers. commun.

May 1980 19 relationships, and biochemical genetic have expressed interest in the Alaskan Literature Cited relationships of four species of eastern snail resource, but their future in­ MacIntosh, R. A., and A. J. Paul. 1977. The Bering Sea Neptunea are now being volvement is more uncertain than the relation of shell length to total weight, tissue conducted by NMFS. future involvement of Japan. The weight, edible-meat-weight, and reproductive organ weight of the gastropods Neptunea The prospects for rapid development rapidly expanding and highly profitable heros, N.lyrara, N. pribiloffensis, andN. ven­ of Alaska's snail resources are uncer­ king and snow crab fisheries are cur­ tricosa of the eastern Bering Sea. Proc. Natl. Shellfish. Assoc. 67:103-112. tain. Snail stocks in the Gulf of Alaska rently dominating domestic fishing ac­ Nagai, T. 1974. Studies on the marine snail re­ are essentially unexploited and eastern tivities in the area. While crab vessels sources in the eastern Bering Sea. I. Species Bering Sea stocks may well be under­ would be well suited to snail pot composition, sex ratio and shell length com­ position of snails in the commercial catch by exploited. Recent fluctuations in snail fishing, most crab fishermen are look­ snail-basket-gear in the adjacent waters of catch and effort in the Japanese eastern ing at Gulfof Alaska and eastern Bering Pribiloff Islands, 1973. [In Jpn., Engl. Bering Sea fishery are probably a re­ Sea bottomfish stocks as an alternate or abstr.l Bull. Far Seas Fish. Res. Lab. 10: 141-156. sponse to political and economic fac­ supplemental activity. Attempts to ini­ 1975a. An analysis of the snail fish- tors and not to the availability ofsnails. tiate a snail fishery in the Gulf of Alaska ing data in the eastern Bering Sea. I. On the variation of catch per unit effort. lin Jpn., The increased cost of distant water have not been productive to date. They Engl. abstr.] Bull. Far Seas Fish. Res. Lab. fisheries and the remarkably low have been exploratory in nature but 12:121-135. 1975b. Studies on the marine snail dockside value of snail meats (est. show promise as potential off-season resources in the eastern Bering Sea. II. List of $1,700/t in 1978) would seem to limit operations in the next few years. As in Gastropoda and Bivalvia (Mollusca) species the growth of the fi shery. The recent the eastern Bering Sea, the resource and collected with snail-basket and some informa­ tions about the incidental catch in the adjacent reduction of Japanese snail allocations harvesting capacity now exists. Innova­ waters of the Pribiloff Islands, 1973. [In Jpn., in the 200-mile fisheries zone of the tive processing and marketing Engl. abstr.] Bull. Far Seas Fish. Res. Lab. U.S.S.R. and the strength of the techniques as well as continued in­ 12: 137-143. Shuto, T. 1974. Larval ecology of prosobranch Japanese yen in world money markets, crease in the value of the traditional gastropods and its bearing on biogeography however, might have the opposite ef­ frozen meat product will be necessary and palenontogy. Lethaia 7:239-256. Thorson, G. 1950. Reproductive and larval ecol­ fect. conditions for the initiation of a domes­ ogy of marine bottom invertebrates. BioI. Rev. Domestic fishermen and processors tic snail fishery. (Camb.) 25:1-45.

20 Marine Fisheries Review