Journal
MARINE BIOLOGY
Volume 158, Issue 4, Pages 935-944Publisher
SPRINGER
DOI: 10.1007/s00227-010-1620-4
Keywords
-
Categories
Funding
- California Sea Grant [R/F-193]
- Alliance for Graduate Education
- Professoriate
- Tuna Industry Endowment Fund
- William H. and Mattie Wattis Harris Foundation
- Tinker Foundation
- Moore Family Foundation
- UC Mexus-CONACYT
- CA Ocean Protection Council
- Save Our Seas Foundation
- SIO Development Office
Ask authors/readers for more resources
The common thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DON) and supports a growing recreational fishery in California waters. This study used archival tags to examine the movement patterns and habitat preferences of common threshers of the size range captured in the CA-DON (> 120 cm fork length). Depth and temperature-logging archival tags were deployed on 57 subadult and adult common threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered, and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical distribution consisted of two distinct modes: a 'shallow mode' (wherein sharks occupied only the upper 20 m of the water column) and a 'deep mode' (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was 320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1 degrees C, and dive descent rate was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16 to 21 degrees C. The nocturnal depth distribution of common threshers has implications for management of drift gillnet deployment depths in the CA-DON.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available