Site fidelity and seasonal movement patterns of adult California sheephead Semicossyphus pulcher (Labridae): an acoustic monitoring study

The California sheephead Semicossyphus pulcher Ayres (Labridae) is a temperate, rocky-reef/kelp-bed fish that is sought by recreational and commercial fishermen. Long-term acoustic monitoring was used to ascertain site fidelity and seasonal movement patterns of S, pulcher. We implanted 16 adult (24 to 36 cm standard length) fish with long-term (similar to 1 yr) acoustic transmitters and their presence and movement patterns were monitored in the Catalina Marine Science Center Marine Life Reserve using an acoustic receiver array. A method was developed that explained some of the variability in detection frequencies. A negative relationship between detection frequency and activity (rate of movement) was found for S. pulcher moving within the array. Most fish exhibited high site fidelity to the general area of the reserve, with 13 of the 16 fish detected spending an average of 99 +/- 2% of their total days at liberty in the study area, with a mean of 90 +/- 9% of total residence time spent within a 600 m core area. However, these fish showed some variability in area use between months, exhibiting periods of expansion in their range. Fish also tended to increase activity as seasonal water temperature increased. These expanded movements resulted in some fish crossing the reserve boundary for extended periods or leaving the reserve permanently.