Davis, C.V., Shumway, S.E.
Abstract:
The Arctic surfclam (Mactromeris polynyma, Stimpson 1860) is a cold water circumboreal species, distinguished from other surfclams by it's purple colored foot, siphon and mantle edge which turn brilliant orange-red when cooked. Increased demand for wild surfclams to supply the Japanese sushi market prompted an investigation of the aquaculture potential for rearing this species in Maine waters.
On four occasions over two years, adult clams were naturally conditioned and induced to spawn using temperature shock, sperm suspension and flowing seawater. Larvae were reared in either 40 or 400 liter conical tanks and fed daily a mixture of cultured microalgae. Prodissoconch I larvae developed in 24 or 96 hours depending on culture temperature (15.0 and 8.5 C respectively). Metamorphosis occurred in 24 to 42 days at 15.0 and 10.0 C respectively. Size of metamorphosing pediveligers varied from 320 micro m (SD=22) shell length at 15.0 C to 271 micro m (SD=26) shell length at 10.0 C. Juvenile growth was strongly influenced by the substrate they were growing in. Individuals reared on Nitex plastic screening in ambient sea water grew significantly slower than those reared in a silty/sand sediment. Growth of juveniles occurred year round, varying from 0.009 mm/day during the winter months to 0.102 mm/day in late spring. Clams grew to 12.5 mm shell length, 0.29 g live weight and 23.5 mm, 2.86 g at one and two years respectively. After 29 months of growth, clams measured 31.4 mm in shell length and 4.93 g live wt. These growth rates are approximately twice those seen in natural populations and may be further optimized through improved culture methods. Given the rapid growth rates we observed, we believe this species may be amenable to aquaculture development in Maine, the Canadian Maritimes and the Pacific Northwest.
(Darling Marine Center, University of Maine, 25 Clarks Cove Rd.
Walpole, Maine 04573, USA)
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