The California Giant Sea Cucumber Parasitichus californicus was once a very important commercial dive fishery throughout Alaska but harvest levels have declined in recent years due to a litany of reasons including sea otter predation, conservative management practices, environmental changes manifested by slow growth rates and sporadic recruitment.
The Alutiiq Pride Marine Institute has been refining culture techniques for P. californicus as a possible tool for wild stock enhancement, species preservation and potential aquatic farming.
A major obstacle for hatchery production at APMI has been the procurement of healthy brood stock due to logistical constraints. Commercial harvesters from Southeast Alaska must dive to collect the adults often several hours from port, match airline schedules to get the broodstock to Anchorage and then transported to Seward completing a 1,200-mile journey. The shipping stress causes an up to an 80% evisceration rate and 20% mortality. The recovery and acclimation time impact their natural reproduction schedule.
Despite these challenges APMI has managed to spawn and culture juveniles for almost twenty years anticipating the eventual need for hatchery produced juveniles. Temperature, feeding strategies and culture practices are routinely modified in attempts to increase survivals.
An impediment to releasing sea cucumber for enhancement is the inability identify hatchery produced seed to monitor their growth, survival, and behavior. APMI has been experimenting with calcein dye as a marking tool. Soaking the sea cucumbers for 1 hour in a calcein dye has resulted in mark retention for up to two years in the facility.
In 2024 APMI started a collaborative project with the Canada Department of Fisheries and Oceans Bioinformatics/Molecular Genetics lab by providing juveniles for stock assessment studies who are using the methylation of rDNA as an aging tool.
In 2024 broodstock were retained at APMI into September, several months beyond the supposed reproductive cycle. Despite their loss of weight, the adults were “stress” spawned by elevating the temperature 16°C water (ambient is 12°C). Surprisingly, they quickly spawned with competent larvae indicating that timing and appearance may not be an indicator of their reproductive potential.