The pelagic red crab (Pleuroncodes planipes) related to active upwelling sites in the California Current off the west coast of Baja California

The red crab, Pleuroncodes planipes, is the most abundant species in the microneckton of the southern part of the California Current and plays an important role in the use of energy made available by primary production. During April 2002, hydroacoustics were used to study the spatial distribution of this Galatheid as related to oceanographic conditions off the west coast of Baja California, Mexico. Red crabs were found in several areas, close to the shore, above the continental platform, and near the shelf break. They were found in large swarms several kilometers long at midwater, or compacted close to the bottom. More than 90% of the total abundance was found in areas where chlorophyll-a was intensified by upwelling, supporting the hypothesis that active upwelling sites may play an important role in shaping the spatial distribution of this species. Studies on this crustacean have associated changes in distribution and abundance with the major upwelling cycles occurring along the west coast of Baja California. Results of our present work, together with analysis of results from a similar study done in October 1994, suggest that red crabs living close to the shore are able to remain in local active upwellings whatever the season.