Identifying essential spawning habitats for improving assessment and management of the market squid fishery off California

Principal Investigator: Emmanis Dorval
Co-Principal Investigators: Kevin Piner, Brian Wells, Jenny McDaniel

marketsquid.jpgThe market squid (Doryteuthis opalescens) population is distributed from Canada to Mexico, but most of its biomass and fishery are concentrated off California. Market squid are semelparous, based on current ageing methodologies they are expected to live on average 6 months, and recruit into coastal waters (20-60m depth) to spawn before dying. This species supports the most valuable commercial fishery in California, averaging 77,650 mt (~ $ 31million) per year from 1999 to 2012. The fishery is managed based on a 2-day weekend closure and an annual catch limit of 107,048 mt tons (CDFG 2005), whereas the stock is assessed using an egg escapement model (Macewicz et al. 2004, Maxwell et al. 2005, Dorval et al. 2013). Dorval et al. (2013) showed that in most years and quarters, the proportional egg escapement was, on average, higher than the recommended target in the Fisheries Management Plan, i.e. 30% (STAR 2001, CDFG 2005). However, there was disproportionate biomass among the northern, central and southern California fisheries, with maximum female spawningadult.jpgbiomass estimated at 19,528, 127,394, and 70,550 mt respectively, from 1999 to 2006. Despite these differences the annual fishing cap is enforced without taking into account region, and with no information on the provenance of the spawning biomass. Further, the quota is the maximum total catch observed in the historical fishery, and does not reflect the dynamics and the productivity of the stock in every fishing season. In 2010 and 2011 the quota was reached, forcing the fishery to be prematurely closed. Yet, the impact of such removal on the sustainability of the fishery is not well understood, and thus calls for the definition of a better allocation strategy.

eggcase.jpgA substantial fraction of the market squid habitat is within the marine preserved areas (MPAs) off California. The contribution of these MPAs to market squid recruitment is not known, precluding any quantitative assessments of these conservation measures on the sustainability of the squid fishery. However, the chemistry of biological hard parts (e.g. otoliths and statoliths) has been shown to be a powerful geochemical tool to identify natal habitat and retrace the dynamics of marine species (Campana and Thorrold 2001). Methods such as statolith chemistry (Elsdon et al. 2008, Warner 2009, Gillanders 2013) could be applied to quantify squid survivorship from both protected and exploited spawning grounds, providing new knowledge to assess the effectiveness of the MPAs. Coupled with knowledge of growth rates and environmental water conditions, this technique could allow the identification of the most productive areas, i.e. the habitats that contribute most recruits to the exploitable biomass. Likewise, the total catch that can be sustainably taken in each fishing region can be quantified, allowing a more appropriate approach to set seasonal quotas in the fishery.

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Southwest Fisheries Science Center (SWFSC)


Annual Report - Year 1

Progress Report - Year 1.5

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