Movement of the giant red sea cucumber Parastichopus californicus in Southeastern Alaska

Abstract

This thesis provides information on sea cucumber movement that could inform management of the growing fishery for the sea cucumber, Parastichopus californicus, in Southeast Alaska. Daily movement of individual P. californicus was quantified at six sites to assess spatial variation in movement, at three-month intervals over one year at one site to assess seasonal changes in movement, and densities were measured monthly at three depths over one year. Movements varied among seasons and sites ranging from 0 to 34.5 m·24 h⁻¹, and were highest in summer (mean ± SE = 4.6 ± 0.5 m) and lowest in fall (mean ± SE = 1.9 ± 0.3 m). Densities were highest in spring and summer and lowest in fall and winter. Recently tagged animals move, on average, 2 m more than animals tagged 72 h earlier, indicating that movement is best assessed 48 h after tagging. Stock assessments should be conducted in spring and summer to coincide with increased animal densities, with the fishery occurring in fall and winter to provide a possible refuge for a portion of the population. Overall, P. californicus demonstrate limited adult movement, indicating that populations are geographically limited with little possibility of animal migration or repopulation of adults in harvested areas.