James J. Gelsleichter

I joined the University of North Florida as an Assistant Professor of Biology in August 2008, and teach courses in shark biology, endocrinology, and toxicology and manage a large, well-funded research program focused on shark biology.  I was recently promoted to Associate Professor of Biology in Fall 2014.

I have conducted research on sharks and their relatives for more than 20 years and, prior to arrival at UNF, I worked as a staff scientist and research program director in Mote Marine Laboratory’s Center for Shark Research for a decade.

My research program, the UNF Shark Biology Program, conducts research on three major topics:

1) Ecology of shark populations in northeast Florida waters.

2) Reproductive biology and physiology of shark and their relatives.

3) Effects of environmental pollutants on sharks and other fish species.

These three research areas are highly interrelated. Our work on population ecology focuses on identifying trends in the species composition, abundance, habitat use patterns, and overall health and stability of shark populations in northeast Florida. Our work on reproduction focuses on determining the basic reproductive traits that contribute to shark population growth and stability, such as the age/size at which sharks become sexually mature, the regularity in which they reproduce, seasonal patterns in their breeding, and the number of offspring that they give birth to. We also study how hormones regulate various aspects of shark reproduction. Last, we study if populations of sharks and other fish exposed to environmental pollutants such as mercury, industrial chemicals, and oil are experiencing health effects that could impair their reproduction, survival, and overall population stability.

We are currently conducting a number of research projects that fall under these three research areas:

Shark Population Ecology

Jacksonville Shark Pupping and Nursery (JAXSPAN) Survey – The centerpiece of UNF's work on shark population ecology is our annual survey of shark populations in northeast Florida waters, which we have been conducting since 2009. Each year, we survey shark populations in Cumberland Sound, Nassau Sound, portions of the Intracoastal Waterway, and nearshore areas off of Jacksonville and St. Augustine using bottom longline, gillnet, and drumline fishing to determine time-associated trends in abundance and species composition, as well as the location of shark nursery habitats, where juvenile sharks reside during the early stages of their life before they become sexually mature. We also tag sharks using government-issued tags for long-term studies on their movements and migrations, and collect additional samples for use in studies on population genetics, reproduction, feeding ecology, and other topics. The work is partially funded by NOAA Fisheries Service, which uses these data for assessing the overall status of exploited shark populations.

Great White Shark Ecology – Since 2013, our program has been collaborating with researchers from the Massachusetts Division of Marine Fisheries (MA DMF) to examine the ecology of white shark populations on the U.S. Atlantic coast. These populations appear to have increased in recent years, likely due to conservation efforts as well as increases in some of their primary prey species such as seals. Our goals in this study are to examine the abundance and size/age/sex distribution of white sharks in northeast Florida waters, their habitat use patterns in our region, and their associations with other members of our marine ecosystem. We do this by deploying acoustic receivers in nearshore and offshore locations off the northeast Florida coast to detect regional occurrence of white sharks tagged with acoustic tags by MA DMF scientists. We augment this work by administering the Southeast U.S. White Shark Encounter Database, which collects information on confirmed white shark sightings on the southeast U.S. coast from both the scientific community and general public. We also conduct research on the reproductive biology of the white shark by using non-lethal approaches such as ultrasound and blood hormone analysis to determine stage of maturity and reproductive condition of individuals sampled by OCEACH, a non-profit research organization that uses a custom 75,000-lb capacity platform to lift live white sharks out of the water for a short period of time for sample acquisition. Our program has been fortunate to participate in two OCEARCH expeditions to date.

Shark Reproduction

Reproductive Biology of Sharks and Rays – Our program conducts research on the reproductive biology of numerous shark and ray species with the overall goal of acquiring critical data needed for determining the rate of population growth in these fishes. Some of these projects, such as recent studies on reproduction in the blacknose shark, bonnethead, and finetooth shark, have been supported by NOAA Fisheries Service so that life history data needed for improved management of small coastal sharks in U.S. Atlantic waters could be obtained. Much of this work is conducted via morphological and histological assessment of reproductive tract samples obtained from sharks collected in the JAXSPAN survey, comparable surveys conducted by our collaborators at the South Carolina and Georgia Departments of Natural Resources, and commercial and recreational fishers. We are also leaders in the development and use of nonlethal approaches such as ultrasound and blood hormone analysis for assessing reproductive condition in sharks and their relatives, and are currently using these techniques to study reproduction in the endangered smalltooth sawfish, Southern stingray, tiger shark, lemon shark, bull shark, Oceanic whitetip (in Cat Island, Bahamas), white shark, and – in the near future – the scalloped hammerhead and great hammerhead.

Reproductive Endocrinology of Sharks and Rays – In addition to studying basic aspects of reproduction in sharks and their relatives, we conduct numerous studies on the roles that hormones play in regulating elasmobranch development and reproduction. This includes current studies on the patterns of circulating sex steroid hormone concentrations during three important periods: sex differentiation in embryonic sharks, sexual maturation in pubertal sharks, and the reproductive cycle in adult males and females. We also study the distribution of hormone receptors in elasmobranch reproductive organs so that the cell-specific roles of these hormones can be identified.

Shark and Fish Ecotoxicology

Effects of the Deepwater Horizon Oil Spill on Gulf of Mexico fish – One of the most important projects that we are conducting is a multiyear investigation geared towards determining if fish populations impacted by the Deepwater Horizon Oil Spill are experiencing health effects associated with exposure to polycyclic aromatic hydrocarbons (PAHs), the most toxic components of crude oil. In fact, this “project” includes multiple “sub-projects” such as studies on oil effects in Alabama sharks and teleosts conducted in collaboration with researchers from Dauphin Island Sea Lab, research on oil effects in pelagic sharks and teleosts conducted in collaboration with researchers from Mote Marine Laboratory and Nova Southeastern University, and ongoing research on oil exposure in deepwater sharks and bony fish conducted in collaboration with Florida International University and Florida State University. We assess oil exposure and effects in animals sampled in these projects via the use of PAH “biomarkers”, such as levels of PAH metabolic enzymes and biliary PAH metabolites, which typically increase in animals in response to oil exposure. This work has been supported by several grants from the Florida Institute of Oceanography and the Gulf of Mexico Research Initiative.

Exposure and effects of mercury in sharks and rays – As demonstrated in a number of studies focused on identifying health risks to human seafood consumers, sharks tend to accumulate sizeable quantities of the non-essential toxic metal mercury in their tissues. However, few studies have investigated whether the high levels of mercury accumulation that occur in these fishes pose health risks to sharks themselves. We are currently investigating this topic by examining mercury accumulation in various critical organs of sharks and rays and determining if biological effects associated with mercury exposure are occurring in these fish.

Other studies– In addition to the studies listed above, we are currently conducting a number of other projects on shark ecotoxicology including a long-running study on the exposure of freshwater populations of bull sharks and Atlantic stingrays to wastewater-related pollutants such as the active components of human drugs, research on pollutant exposure and effects in St. Johns River fish including the Atlantic stingray, and studies on the development of new biomarkers of pollutant exposure and effects in elasmobranchs.