Movements of subadult prickly sharks Echinorhinus cookei in the Monterey Canyon

Abstract

The prickly shark Echinorhinus cookei is a poorly known predatory shark that occurs in the Monterey Canyon, USA. Between March 2005 and September 2006, 15 subadult prickly sharks (170 to 270 cm total length) were tagged with acoustic transmitters and tracked to determine their site fidelity, home range, habitat use, rates of movement, and diel activity. An array of moored receivers extending 3.5 km offshore from the apex of the Monterey Canyon recorded the occurrence of 8 sharks tagged with coded transmitters for 400 to 561 d. Four sharks were tagged with continuous transmitters and monitored by a moored receiver that recorded date, time, and depth for 123 to 212 d. Three sharks were tagged with archival transmitters that were monitored by a 2-way communicating moored receiver. One female and 2 males tagged with continuous transmitters were also tracked manually from a surface vessel for 61.0, 51.8 and 62.8 h, respectively, over a period of 64 to 71 d. Home ranges for these sharks were 0.20, 2.20, and 1.46 km2. All tagged sharks showed a high degree of site fidelity to the study area and demonstrated pronounced diel movements, moving along the axis of the canyon offshore to discrete areas during the day and inshore at night. Sharks were sedentary during the day and actively swam in the water column at night and were most active during crepuscular and nighttime periods.