Prolonged decline of jumbo squid (Dosidicus gigas) landings in the Gulf of California is associated with chronically low wind stress and decreased chlorophyll a after El Nino 2009-2010

摘要

Dosidicus gigas (jumbo or Humboldt squid) is an ecologically relevant predator in the Gulf of California, Mexico, where it supports an economically valuable fishery. The commercial jumbo squid fishery in the Gulf declined steeply after an El Nino event in 2009-2010, and subsequent landings have remained at historically low levels in the relevant squid fishing centers (Guaymas, Sonora, and Santa Rosalia, Baja California Sur). In this paper, we examined wind speed and chlorophyll a concentrations on the jumbo squid fishing grounds as factors that would be expected to be relevant to this prolonged period of low landings. Analysis from local weather stations, remote sensing, and fishery data showed that low jumbo squid landings from 2010 to 2015 occurred during a period of abnormally weak winter/spring winds and extremely low chlorophyll a concentrations off the East Guaymas Basin. Results indicate that the squid fishing area in the Guaymas region has been chronically impoverished during this period, and that this area may no longer be a productive habitat for jumbo squid. In response to this decreased productivity, size-at-maturity of jumbo squid showed a drastic decrease over the same period. Results are compared with the effect of El Nino 1997-1998 on the jumbo squid fishery and size-at-maturity of this species in the Gulf of California. The key difference between the recovery phases for El Nino 1997-1998 versus El Nino 2009-2010 was the anomalously low wind intensity as measured in the Guaymas fishing area after 2009. (C) 2015 Elsevier B.V. All rights reserved.