You probably can’t keep these little crabs in your saltwater aquarium. The tuna crabs (Pleuroncodes planipes) that washed ashore on Southern California beaches last week are largely gone, but remnants of the one- to three- inch crustaceans remain on many shorelines. The crabs blanketed many shores in a sea of red, and many wondered why they washed up on the shore. Scientists say that the little crustaceans have come up from their usual Baja California habitat following the warm water currents that have been flowing off the California coast for months.
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The tiny crabs have also brought another denizen of warmer waters to Southern California waters; Yellowfin tuna have been less than a mile offshore in some locations and one was even speared in the Dana Point, Calif. boat harbor last week. These pelagic game fish have followed the crabs up from Baja California and have been providing area fishermen with hard fighting fish for several weeks. The tuna crabs have largely disappeared from the shorelines but some can still be found in pockets where there is water, if you look hard enough.
The presence of the tuna crabs off the Southern California coast is usually a precursor to an El Niño event, though the last several El Niño that occurred didn’t bring the crabs to Southern California. The Summer and Fall of 2015 may very well be an interesting time for the ocean off Southern California.