Use of Microwave Telemetry X-PSAT tags to monitor behavior of cobia and dolphinfish. – Year II
Rationale:
This project will follow-up on the Sea Grant funded study conducted in 2006 and 2007 to assess the ability of pop-off satellite archival tags to provide information on the behavior of cobia and dolphinfish. The initial study showed these instruments capable of providing quality information on their underwater behavior and environment. The proposed study will take the next step in studying the behavior of these two important species by examine the tag's ability to provide information as to their daily geo-location and their long-term vertical movement behavior as well as thermal preferences. It will assess the instruments ability to document coastal and offshore depths utilized by each species. Successful tracking data will provide some of the first information defining the geographic range utilized by individual fish as opposed to the species as a whole. The study also has the potential to generate data relating to spawning behavior of cobia. Additionally, the project will serve to join recreational fishermen in a collaborative effort with the SC Sea Grant Program and the SC DNR to gain needed information about two important marine species.
Dolphin and cobia are two of the most popular recreational species found off the US's East and Gulf coasts. Both are fast growing species that appear to migrate northward along the east coast during spring. However, relatively little else is known about the movements of cobia and only recently has information on dolphin movements started to be acquired. This is the second study utilizing satellite tags on cobia off the US Atlantic seaboard and the second study ever to deploy them on dolphinfish.
Recent studies using traditional dart tags have shown that cobia found in Port Royal Sound show strong site fidelity returning year after year. Port Royal Sound is one of only three east coast locals that have been identified as a spawning area for cobia. This significantly increases the importance in acquiring life history data on cobia that utilize the sound. This information could be useful in examining the effects of environmental cues on the species' daily and seasonal movements. Also, because recoveries of traditional tags only link the release site to the recovery site by a straight line and provide no information on the actual movement track, this work could provide data on the value of satellite tags in examining coastal movements and behavioral patterns never before documented.
Objectives:
- Deploy a minimum of two of the new, miniaturized pop-off archival satellite tags (model X-PTT) in cobia captured in or adjacent to Port Royal Sound.
- Deploy a minimum of three similar tags in dolphinfish captured off South Carolina.
- Develop a six month water temperature selection profile for each species utilizing time-at-temperature as recorded by the archival tags.
- Analyze vertical water column movement behavior for region-specific behavioral patterns using time-at-depth as recorded by the archival tags.
- Attempt to identify areas utilized during summer and fall using depth and temperature records along with calculated geo-locations.
- Attempt to generate individual movement tracks defining individual geographic range during monitoring for each fish using the satellite tag geo-positioning system.