Telemetry

Following the nursery concept proposed by Beck et al. (2001. The identification, conservation, and management of estuarine and marine nurseries for fish and invertebrates. BioScience. 51:633-641.), the Shark Population Assessment Group is designing novel experiments to test the success of recruitment, survivorship, and growth of sharks and other protected species among various habitats.

Preliminary Active Tracking

Preliminary tracking of sharks began in July 2003. Six blacktip Carcharhinus limbatus and one blacknose shark C. acronotus from two northeast Gulf of Mexico bays (St. Joseph Bay, FL, and Crooked Island Sound, FL) were fitted with external acoustic transmitters (VEMCO Ltd. V16) and released.

The tags had a life span of 118 days and a range of 1.1 km. While contact with each animal was made immediately after release and continued for the remainder of the day of release, no animals could be relocated upon returning to the areas of release on later days throughout the life of the tags.

For a brief video of tagging procedures used above, click below:

Passive Tracking

In May 2004 and in collaboration with the Mote Marine Laboratory Center for Shark Research, a system of stationary underwater acoustic receivers (VEMCO Ltd. VR1) were placed in two habitats where juvenile blacktip C. limbatus and Atlantic sharpnose sharks Rhizoprionodon terraenovae occur during summer months (Charlotte Harbor, FL, and St. Andrew Sound, FL). Five blacktip and nine Atlantic sharpnose harks were collected using longlines and gillnets, fitted with small external acoustic transmitters (VEMCO Ltd. V8SC), and released. Data was downloaded monthly and movement patterns monitored throughout the summer and fall.

Preliminary data suggests that all of the tagged animals in Crooked Island Sound, FL, left the area and moved into the Gulf of Mexico prior to Hurricane Ivan making landfall. The change in barometric pressure is hypothesized to have caused the sharks to leave the study site (see: Heupel, M.R., C.A. Simpfendorfer, and R.E. Heuter, 2003, Running before the storm: blacktip sharks respond to falling barometric pressure associated with Tropical Storm Gabrielle. J. Fish. Biol. 63: 1357-1363). Receivers are removed for the winter in November 2004.

The receivers were placed back in the water at the same twelve stations on April 25, 2005. For the 2005 season, thirty-three age-1 Atlantic sharpnose sharks were tagged with small external acoustic transmitters (VEMCO Ltd. V8SC) and released. Additionally, HOBO data loggers (Onset Computer Corp. UA-002-64) were attached to four VR receivers throughout the bay. HOBOs monitor temperature and light intensity every 30 minutes. Data was downloaded monthly. The receivers and HOBOs were removed for the winter in October 2005.

The receivers were placed at the same twelve stations on March 27, 2006, to collect a third and final season of data. In spring 2006, eighteen age-1 Atlantic sharpnose sharks were tagged with small external acoustic transmitters (VEMCO Ltd. V8SC) and released. HOBO data loggers (Onset Computer Corp. UA-002-64) were attached to the same four VR receivers as in 2005. Data is downloaded monthly. The receivers and HOBOs will be removed in October 2006.

The use of stationary underwater receivers removes the bias of potentially "chasing" animals within the study site and has been shown to produce reliable long-term location movement patterns (see: Heupel, M.R. and R.E. Hueter, 2002, Importance of prey density in relation to the movement patterns of juvenile blacktip sharks Carcharhinus limbatus within a coastal nursery area. Mar. Fresh. Res. 53:543-550.). In addition, direct estimates of survivorship can be calculated from telemetry data. This will permit a direct comparison of the relative importance of two habitats in terms of survivorship of juvenile sharks.

PAT Tagging

Recent advances in electronic data technology make it possible to store detailed records involving both vertical and horizontal movements of marine animals.

Information on swimming depth, water temperature, and a daily record of geolocation can be stored and uploaded to ARGOS satellites from devices known as "pop-up satellite archival transmitters" or PAT tags. PAT tags can collect and relay data for periods up to 12 months depending on data recording intervals. The Shark Population Assessment Group is currently involved in two collaborative projects using satellite technology to better understand movement and activity patterns of elasmobranchs:

1. Monitoring the survival and movements of smalltooth sawfish Pristis pectinata following release from commercial fishing gear (January 2005 - Current).
2. Monitoring the summer habitat use of bull sharks Carcharhinus leucas in the Gulf of Mexico (July 2005 - Current).

Tracking Gulf Sturgeon Acipenser oxyrinchus desotoi

The Shark Population Assessment Group cooperates with biologists at the Panama City U.S. Fish and Wildlife Service to track gulf sturgeon Acipenser oxyrinchus desotoi on their winter grounds January - March. Beginning fall 2005, collaboration between the two groups will include tagging gulf sturgeon on their spawning grounds with acoustic tags and using stationary underwater receivers to track them through fall, winter, and early-spring (presumably their foraging grounds) in Escambia Bay and Choctawhatchee Bay, FL.