Trophic ecology of Humboldt squid, Dosidicus gigas, in conjunction with body size and climatic variability in the Gulf of California, Mexico

Abstract

Over the past two decades, the Gulf of California (GOC) has experienced three strong El Niño events ), each of which was followed by a drastic reduction in mantle length of mature Humboldt squid, Dosidicus gigas (from >60 cm to <20 cm). However, it is unclear how the oceanographic changes associated with strong El Niño events affected the midwater organisms on which D. gigas feed, limiting our ability to assess the relative importance of temperature and food availability in the phenotypic response of D. gigas to environmental variability. We quantified the diet of D. gigas in the GOC before, during, and following the past three El Niño events and found that although its diet varied little across a large range of body sizes (8-85 cm), significant and predictable diet variability was observed with respect to sea surface temperature and chlorophyll-a concentration. Consumption of large numbers of relatively small, high calorie prey in both relatively cool (anchovies) and relatively warm, productive conditions (myctophids) is likely necessary to support growth to large body sizes before maturation. When warm, unproductive conditions prevailed in the GOC, only small squid were present and had diets dominated by euphausiids and pteropods, prey with relatively low caloric value. Using a time series of diet data, this work provides unique insights into the response of a midwater forage community to oceanographic variability and the effects of environmental variability on the trophic ecology of an oceanic predator.

El Niño–Southern Oscillation impacts on jumbo squid habitat: Implication for fisheries management

“…Cololabis saira (Tian, Akamine & Suda, 2003), albacore tuna Thunnus alalunga (Zainuddin, Saitoh & Saitoh, 2004), tropical crab Gecarcoidea natalis (Shaw & Kelly, 2013), and O. bartramii in the Pacific Ocean (Chen, Zhao & Chen, 2007), have strong linkages with the ENSO events. For D. gigas, previous studies have stated that the ENSOinduced sudden temperature change possibly caused biological change (individual growth, forage community and population structure) during its 1-year short life history (Keyl, Argüelles & Tafur, 2011;Arkhipkin et al, 2015;Portner et al, 2019). Furthermore, our studies demonstrated that habitat quality (suitability and range) and spatial distribution of D. gigas showed high correlations with the ENSO index.…”

Dietary Shifts and Risks of Artifact Ingestion for Argentine Shortfin Squid Illex argentinus in the Southwest Atlantic

“…On the other hand, due to the typical feeding behaviors of squid, the number of crustaceans was hard to precisely assess. Therefore, the occurrences of crustacean prey were represented based on presence or absence (Portner et al, 2019).…”

Trophic Niche and Diversity of a Pelagic Squid (Dosidicus gigas): A Comparative Study Using Stable Isotope, Fatty Acid, and Feeding Apparatuses Morphology

“…Several studies demonstrated that they can respond quickly to environmental change, such as abnormal warm surface temperatures and decreased prey availability, due to plasticity in life-history strategy. For example, environment-driven switch in distribution, size-at-maturity, and prey selectivity may allow D. gigas to rapidly cope with El Niño events, resulting in unpredictable interannual fluctuations in population size and biomass (Zeidberg and Robison, 2007;Hoving et al, 2013;Portner et al, 2019). However, given the large-scale distribution of D. gigas, knowledge of their trophic niche divergence and ecological diversification is still incomplete.…”