Small Fry, Big Questions: What 35 Years of Larval Data can tell us about Cabezon
Abstract
Recent revisions to the Pacific Groundfish Fishery Management Plan removed 26 species, including cabezon (Scorpaenichthys marmoratus) from federal management, raising the question of what data sources can inform future monitoring and management of these species. Using spatiotemporal models fit to 35 years of CalCOFI ichthyoplankton and oceanographic survey data, we develop a standardized, relative larval abundance index for Southern California cabezon and evaluate its relationship to stock assessment-derived quantities and surface oceanography. The CalCOFI record carries a coherent ecological signal for this species, but the derived larval index does not correlate significantly with spawning stock biomass, age-0 recruits, or recruitment deviations at any biological interpretable lag, a result we ascribe to the life history of cabezon, post-spawning and post-larval survival filters, and the fundamental differences in construction between time series. Sea surface temperature and dissolved oxygen were significant predictors of larval presence, with detection probability higher in cooler, more oxygenated waters. We conclude that CalCOFI larval data for cabezon are most informative as an environmentally-structured indicator of early life history conditions, and discuss how this framing positions these results as a tool for ecosystem-based management of a species no longer subject to formal stock assessment procedures.
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