CONSUMPTION AND ASSIMILATION OF SALMON NET PEN FOULING DEBRIS BY THE RED-SEA-CUCUMBER PARASTICHOPUS-CALIFORNICUS - IMPLICATIONS FOR POLYCULTURE

Fouling debris composed of fish feces, excess fish food, algae, and ot her particulate organic matter can create environmental problems for a quaculture facilities that rear fish in ocean net pens. Accumulations of organic debris can clog the nets and restrict water circulation whi ch in turn can stress fish. Experiments in which red sea cucumbers Par astichopus californicus were allowed to feed inside floating net pens at a salmon rearing facility in Southeast Alaska showed that sea cucum bers consumed fouling debris and cleared a significant amount of surfa ce area on the nets (P < 0.0001). Sea cucumbers assimilated amino acid s and other organic matter from fouling debris two to three times more efficiently than from their natural sediment diet. Muscle development of sea cucumbers consuming fouling debris inside the net pens was als o significantly greater than that of sea cucumbers feeding in their na tural environment (P < 0.0003). This work suggests that polyculture op erations in which commercially important detritivores, like the red se a cucumber, are grown in net pens along with salmon could possibly con vert the net from self-fouling to self-cleaning and could turn fouling debris into a marketable product (sea cucumber biomass).