b'Loxahatchee River Bull SharksA Project SummaryBy David B. Snyder, Senior Scientist, CSA Ocean Sciences, Inc.A s part of a broader investigationceiver array is embedded within a network of elasmobranch ecology inof receivers known as the Florida the Indian River LagoonAtlantic Coast Telemetry (FACT) (IRL), myself along with, Lind- array.The FACT array, operated by say French from the Loggerheada group of cooperative researchers, Marinelife Center, and Georgeencompasses much of the coastal Burgess, Director Emeritus fromand inshore waters off east central the University of Floridas Program forFlorida.Being part of the larger array Shark Research, have initiated a study ofof receivers allows us to expand our sampling immature bull sharks inhabiting the Loxahatchee Riveruniverse well beyond the Loxahatchee River.This has which marks the southern terminus of the IRL.Wateralready paid dividends as two tagged sharks exited the quality in the IRL has degradedLoxahatchee and swam 15 miles in recent decades and this deg- north and entered the St. Lucie radation has been highlightedRiver estuary.If we depended bymassivefreshwaterdis- only on our Loxahatchee receiv-charges from Lake Okeechobeeers, we would have simply lost following tropical storms andtrack of these individuals.In hurricanes.The IRL is one ofaddition to the broad receiver the most biodiverse estuariesarray, the Loxahatchee River in the US and serves as habi- has in place a series of moored tat for a plethora of fishes andsensing instruments that col-invertebrates.Many of theselect continuous water quality species rely on the IRL and itsdata (salinity, temperature, and tributaries during their earlydissolved oxygen).We intend to life histories.One such speciescorrelate movements of tagged is the bull shark.Unlike otherindividuals with changes in requiem sharks, bull sharks utilize estuaries and coastalenvironmental conditions, particularly salinity drops as-rivers for their first 2 to 4 years of life.Thus we are ex- sociated with freshwater discharges.amining how young bull sharks respond to the riverineThis study will not only contribute to overall knowledge gradient of natural environmental conditions and habitatsof bull shark ecology and life history but will also provide to understand how water management strategies mayvaluable information to local water and environmental influence this response. managers charged with maintaining the health and in-Over the past five years we have implanted acoustictegrity of the Loxahatchee and the larger system in which transmitters in 17 immature bull sharks caught (andit is embedded.released) in the Loxahatchee River.We have an arrayProject Objectivesof acoustic receivers in the river from the mouth (Jupiter Inlet) to freshwater reaches 6 miles upstream.Our re- Passively monitor movements of immature individuals Many thanks for the PBCFFs interest along the Loxahatchees riverine gradient over time.in our research project.We are excitedAssess broad-scale habitat use and residence times for individuals of different sizes/ages.to be able to complete our juvenileAssess movement of immature bull sharks to episodic bull shark study with the additionalreleases of freshwater into the river following massive acoustic tags.Because these mini-sharksrainfall events.are so tough, post-surgical mortalityUse DNA markers to establish connections with potential parental populations on the adjacent continental shelf.is extremely low.Unlike bony fishes,Use data collected in the Loxahatchee River for compari-acoustic tags surgically placed in theson with similar studies conducted in the northern IRL gut cavity of bull sharks result in almostand the Caloosahatchee River on Floridas west coast.100% return tag retention and thereforeEditors Note:As part of its long standing support of great data gathering bang for the buck. local game fish research efforts, the West Palm Beach Fishing Clubs charitable foundation, The Palm Beach - George H. Burgess,Director Emeritus,County Fishing Foundation (PBCFF), donated 10 acoustic Florida Program for Shark Research, transmitter tags valued at $3,500 towards this project. University of Florida The PBCFF is a FACT member.'