Foraging Competition Between Monk Seals and Other Apex Predators (Frank Parrish)
Channel: Ronald Cannarella
Date: 2012-06-07

A presentation at the Hawaii Conservation Conference 2007 by Frank Parrish1, Gregory Marshall2 (1Pacific Islands Fisheries Science Center NOAA Fisheries, Honolulu, HI, 2National Geographic Missions Program, Washington, DC) on "Foraging Competition Between Monk Seals and Other Apex Predators". CRITTERCAMs were deployed on 42 monk seals at French Frigate Shoals Atoll in the Northwestern Hawaiian Islands. Sixty-nine hours of video, comprised of 3192 recording segments collected at standardized intervals, revealed the presence of sharks, jacks, and large- bodied snappers around the seals roughly 17% of the time. Present at all but the deepest depths ( 100 m), the predators were most conspicuous during the seals’ dives to foraging grounds (60 m), particularly on the summits of neighboring banks. Predators were encountered as individuals and in large schools (46 max no.) that closely escorted the foraging seals except during their oceanic swims between the atoll and bank. The predators exploited the seals’ superior ability to flush cryptic prey from bottom cover by the probing, digging, and flipping of rocks. In many instances, the seal and predators competed for the same prey item. The jacks (Caranx ignobilis and Seriola dumerili) were the most aggressive, but carcharhinid sharks also competed with the seals and, in one instance, a shark was seen to repeatedly ram a seal in an attempt to dislodge the prey item it was handling. Competition is clearly part of the monk seals’ foraging landscape, and the abundance of predators and concerns about reduced oceanic productivity make it an important consideration in the recovery of the endangered Hawaiian monk seal.

Hawaii Conservation Alliance
Executive Producer: Ronald Cannarella