Aquaculture 2022

February 28 - March 4, 2022

San Diego, California

SOFTSHELL CLAM Mya arenaria CULTURE AT THE ALUTIIQ PRIDE MARINE INSTITUTE, ALASKA

Annette Jarosz*, Jennifer Wells, Michael Mahmood, Jeff Hetrick, and Maile Branson

Email: annette@alutiiqprideak.org

 



 Softshell clams (Mya arenaria ) are a clam species endemic to the East coast of North America but have been introduced to a large portion of the Northern Hemisphere, including coastal Alaska. These Clams inhabit upper to mid tidal zones in marine and estuary environments across a range of substrates.  Anecdotal evidence from local harvesters indicates s oftshell clam populations have been increasing in Southcentral Alaska, while other populations of native clams have experienced significant decline.  APMI has developed techniques for producing softshell clams for enhancement and study of life history. APMI is exploring the optimal substrate to determine the optimal outplanting substrate. The work presented here describes substrate preference and digging efficacy for juvenile clams.  In this study, we examined the habitat, culture, settlement rate, and theorized outplant success of s oftshell c lams in Resurrection Bay, Alaska as a model for  suitable substrate for  shellfish enhancement. In the spring of 2021, a habitat suitability study was conducted across several transects within known s oftshell c lam harvest areas. Habitats during these collections were evaluated for sediment composition and total s oftshell c lams observed within each sediment type and depth. A total of 220 s oftshell c lams were collected as broodstock during this effort. These clams were held at the Alutiiq Pride Marine Institute (APMI) in a downwell tank system at 12°C, and were successfully spawned in early July 2021 using heated water to 17° C and the addition of Chatocerous  spp. and Isochrysis spp. as feed. An estimated 5 million eggs at  70 µm were counted, yielding  approximately (2.7 million larva for setting by day 17 (235 microns) .  Estimated setting success was 50 % and the water was maintained at 19°C to a ccelerate growth. Clams at  10 mm and 14 months of age were placed in varying substrates and settlement and survival rates were both evaluated as a  method to determine preferred habitat  for outplanting . APMI hopes to utilize the methodologies developed in this study to further softshell clam enhancement  for  shellfish harvesters .  We believe that Softshell clam enhancement can be used as an adaptation strategy for mitigating tradition shellfish harvest loss and increase food security across Southcentral Alaska.