Caitlin Allen Akselrud1
February 21, 2017 3:30 (PST): FSH 203
A discussion-based Think Tank covering possible modeling approaches for a difficult-to-assess species, California market squid (Doryteuthis opalescens)
This will be a fun, discussion-based Think Tank covering possible modeling approaches for a difficult-to-assess species, California market squid (Doryteuthis opalescens). Please bring your model ideas, and a phone or laptop for active participation!
Market squid are short lived (6-9 months), semelparous, aggregate spawners. A recent dissertation (Cheng, 2015) suggests multiple temporally-separated sub-population, indicating multiple spawning groups throughout the year. This potentially presents a form of “portfolio effect” for this species. [You may notice some life history similarities to salmon.] Fluctuation in market squid abundance have been correlated to ENSO cycles, and squid have specific preferences for spawning ground conditions (Zeidberg et al., 2012). Currently, there is no fishery-independent survey of market squid. Fishery catch and effort data are available [reliably] from 2000-present.
Depletion methods are often used on squid populations as fishers fish down spawning aggregations. Several problems to this approach exist for the California market squid, including: a) multiple cohorts caught simultaneously (not fishing a single cohort), b) spawning aggregations immigrate into spawning grounds over several weeks (not a closed population), and c) fishing can be driven by external economic drivers, causing problems with CPUE estimates, as effort does not necessarily reflect abundance.
Bring your thinking caps and brainstorm some possible methods with me!