Feeding Habits of the Broadbill Swordfish (Xiphias gladius) Sampled from the California-Based Drift Gillnet Fishery, 2007-2010

Broadbill swordfish (Xiphias gladius) are typically found in productive frontal and coastal zones including the California Current (CC).  Current studies reveal high variability in the diet depending upon the area, highlighting the need for regional studies.  There is currently little information on swordfish diets in the CC. 

To determine diet, 115 stomachs were examined from 2007-2010.  Food was present in 97% of stomachs with 35 prey taxa documented.  All of the five top prey were cephalopods.  The most important prey was jumbo squid (Dosidicus gigas, 79% of stomachs) followed by the boreopacific gonate squid (Gonatopsis borealis, 72% of stomachs).  The most important teleosts were Paralepididae (Barracudinas) and Scopelarchidae (Pearleyes).  The majority of prey species found are associated with the deep scattering layer, although epipelagic fish were also observed.

Swordfish diets were compared to other large predators in the CC.  For swordfish, mako and blue sharks, cephalopods are the most important prey.  Similar to bigeye thresher sharks, swordfish targets the deep scattering layer and small epipelagic fish.  Common thresher sharks feed primarily on small schooling fish.  The large variety of prey in the swordfish diet suggests these fish are generalists and capable of exploiting diverse prey throughout the water column.