Extreme plasticity in life‐history strategy allows a migratory predator (jumbo squid) to cope with a changing climate

Abstract

Dosidicus gigas (jumbo or Humboldt squid) is a semelparous, major predator of the eastern Pacific that is ecologically and commercially important. In the Gulf of California, these animals mature at large size (>55 cm mantle length) in 1–1.5 years and have supported a major commercial fishery in the Guaymas Basin during the last 20 years. An El Niño event in 2009–2010, was accompanied by a collapse of this fishery, and squid in the region showed major changes in the distribution and life‐history strategy. Large squid abandoned seasonal coastal‐shelf habitats in 2010 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 to 2012, small squid were abundant and matured at an unusually small mantle‐length (<30 cm) and young age (approximately 6 months). Juvenile squid thus appeared to respond to El Niño with an alternative life‐history trajectory in which gigantism and high fecundity in normally productive coastal‐shelf habitats were traded for accelerated reproduction at small size in an offshore environment. Both small and large mature squid, were present in the Salsipuedes Basin during 2011, indicating that both life‐ history strategies can coexist. Hydro‐acoustic data, reveal that squid biomass in this study area nearly doubled between 2010 and 2011, primarily due to a large increase in small squid that were not susceptible to the fishery. Such a climate‐driven switch in size‐at‐maturity may allow D. gigas to rapidly adapt to and cope with El Niño. This ability is likely to be an important factor in conjunction with longerterm climate‐change and the potential ecological impacts of this invasive predator on marine ecosystems.

Ammonoid Intraspecific Variability

“…Populations of extant cephalopod species can show large intra-annual (seasonal) and inter-annual variations in growth rate and adult size (e.g., Boyle and Ngoile 1993;Arkhipkin and Laptikhovsky 1994;Nigmatullin et al 2001;Jackson and Moltschaniwskyi 2002;Arkhipkin 2004;Keyl et al 2011;Hoving et al 2013). This typically results in a high intraspecific variation in size-at-age data (e.g., Boyle and Boletzky 1996), which has been corroborated both by laboratory rearing experiments and population studies in the field (Pecl et al 2004 and references therein).…”

Metabolic suppression during protracted exposure to hypoxia in the jumbo squid,Dosidicus gigas, living in an oxygen minimum zone

“…The prey may be compressed between low oxygen and high temperature into a zone that provides high-density foraging opportunities for these squid (Koslow et al, 2011;Stewart et al, 2014). While D. gigas are extremely flexible predators and may benefit from climate change (Hoving et al, 2013), they may be intolerant of the synergistic effects of either low oxygen or ocean acidification with high temperatures (Rosa and Seibel, 2008;Alegre et al, 2014). All three variables reduce the efficacy of oxygen transport while temperature elevates oxygen demand.…”

Growth model selection for the jumbo squid Dosidicus gigas from the Gulf of California, Mexico

“…Changes in the ions, pH, and organic or inorganic components are related to individual metabolism, diel activity patterns and environmental conditions (Pauly 1998, Bettencourt & Guerra 2000. For D. gigas in the Gulf of California, the vertical and horizontal movements (Gilly et al 2006, Bazzino et al 2010, Hoving et al 2013, Rosa et al 2013) and largescale migrations in and out of the Gulf are caused by environmental changes such as El Niño and La Niña events (Morales-Bojórquez et al 2001a, Rosa et al 2013. These could affect the deposition process of statoliths and the daily formation of the growth rings.…”

“…The reason for this variation in growth pattern may be associated with the different age intervals used in each study and plasticity in life-history strategies of D. gigas in the Eastern Pacific (Hoving et al 2013) (Table 4). In growth studies for harvested species, the use of length-at-age data for early stages is not common.…”

“…In contrast, larger squid were reported by Díaz-Uribe et al (2006), who found mature males from 370 mm, and Quiñonez-Velázquez et al (2013) reported mature males from 320 to 420 mm ML. D. gigas may mature from ML of 20 cm or larger (Hoving et al 2013). This length may vary in the Gulf of California or western coast of the Baja California Peninsula.…”