Award: OCE-1338432

Understanding how large predators cope with short- and long-term environmental change is critical to evaluating the interacting effects of fisheries and climate change on marine ecosystem services. A difficulty in elucidating how these predators will respond is the long lifespan of most top predators, which necessitates long-term datasets. Dosidicus gigas (Humboldt or jumbo) squid, however, is an ecologically and commercially important large predator that is distributed throughout much of the eastern Pacific. This squid has a flexible diet, high fecundity, rapid growth rate, and short life span. 2001). Moreover, individuals can tolerate a broad range of temperature and oxygen concentrations, and they can rapidly migrate long distances. These life history traits and physiological capabilities suggest that Dosidicus can respond quickly, on both an individual and population level, to climatic change. An El Niño event in 2009-2010 was accompanied by a collapse of the important commercial fishery for jumbo squid in the Guaymas Basin within the Gulf of California. As part of our NSF funded project "Physiological limits to vertical migrations of the pelagic, jumbo squid, Dosidicus gigas, in the Gulf of California", we documented major changes in distribution, diet and reproductive strategy of these squid. In early 2010, large, mature squid abandoned their normal coastal-shelf habitats in the Guaymas Basin and instead were found in the Salsipuedes Basin to the north, an area buffered from the effects of El Niño by tidal upwelling and a well-mixed water column. The commercial fishery also relocated to this region. Although large squid were not found in the Guaymas Basin from 2010-2012, much smaller squid were abundant and matured at an unusually small mantle-length (<30 cm) and young age (~6 months). This corresponds to an order of magnitude decrease in body mass at maturity and a roughly proportionate decrease in fecundity. This project continued our time-series, following the biomass and life-history traits of squid after the recovery from El Niño. We found no evidence of a return to pre-El Niño conditions during the study. We hypothesize that juvenile squid in the Gulf of California responded to El Niño with an alternative life-history trajectory in which gigantism and high fecundity in normally productive coastal-shelf habitats were traded for greatly accelerated reproduction at small size in an offshore environment that is less impacted by El Niño. During 2011, both small and large mature squid were present in the Salsipuedes Basin, indicating that both life-history strategies can coexist. Hydro-acoustic data revealed that squid biomass in the study area nearly doubled between 2010 and 2011, primarily due to a large increase in small squid that were not susceptible to the fishery because of gear limitations. Large squid have still not returned to the traditional fishing grounds in the Guaymas Basin based on a sampling we carried out in Sept 2012 and 2013 and into summer 2014. These observations suggest that a population-level benefit for Dosidicus in the Guaymas Basin may have resulted from El Niño and that the long-term persistence (through the end of the NSF funded field efforts) of the small size-at-maturity is an important element of this squidÆs life history strategy. Such a climate-driven switch in size-at-maturity allows Dosidicus to rapidly adapt to El Niño, and potentially to also optimize adaptation to longer-term climate-change involving factors, particularly global-scale warming, expanding oxygen minimum zones and changing productivity. As part of this effort, training was provided for participating graduate and undergraduate students. The established collaboration (SURMAR, Sustainable Utilization and Research in the Central Mar de Cortés, under auspices of The Ocean Foundation) was continued with a technical college in Mexico and involved Mexican ...