Abstract
Ultrasonic telemetry was used to investigate the home ranges and homing routes of 11 copper, Sebastes caurinus, and quillback, Sebastes maliger, rockfishes. Home ranges of four copper and quillback rockfishes were monitored to determine if movement occurred during the day, night, or strong current (7.4 km/h). As expected from previous conventional tagging work, home ranges were small (most 2) on high relief reefs and considerably larger (within 4000 m2) on low relief reefs. No off-reef movement by copper and quillback rockfishes was detected on either reef type. To determine homing routes, the daily positions of seven copper and quillback rockfishes were monitored as they proceeded back to their home sites after experimental 500-m displacements from a high relief rocky reef to a low relief rocky reef. Six of the seven displaced copper and quillback rockfishes took from 8 to 25 days to return home; one quillback rockfish was followed for 16 days and lost, it was last located approximately halfway back to the original home site. Once displaced rockfish returned to their original capture site, no subsequent movement was detected, suggesting home site recognition. Homing seemed to consist of three phases: (i) initial movements along a bimodal northwest-southeast axis that are possibly associated with directional preferences in exploratory migrations, (ii) movement (westerly) towards the home reef, and (iii) the final location of the home site. Homing and exploratory migrations may be characteristic behaviors in the speciose rockfish group; the evolutionary advantage ensures rockfishes locate and utilize high quality habitats.