Movement and habitat preference of sharks, sturgeon and other charismatic species

w_porBeaglejpgUnderstanding both large (i.e., migratory) and small (i.e., diel) scale movement patterns are essential components of successful fisheries management plans, especially for species that are considered highly migratory and/or are commercially harvested.

Such data can be used to, among other ways, evaluate the spatial distribution and fishery interactions of a species and identify ‘hotspots’ (i.e., areas with high fishery interactions) both spatially and temporally. From this information, practical bycatch avoidance strategies can be
developed that will help reduce fishery interactions. In addition, this information can be used to designate and understand critical habitat (areas that are essential to the survival of those fish) and explore what changes in distribution do to climate change. James and his team use a variety of methods to track the movement of both marine and estuarine fish species which include:

  • Atlantic sturgeon Acipenser oxyrinchus acoustic and satellite tag tracking
  • Shortnose Sturgeon Acipenser brevirostrum acoustic and satellite tag tracking
  • Monkfish Lophius americanus satellite tag tracking
  • Porbeagle sharks Lamna nasus satellite tag tracking
  • Spiny dogfish Squalus acanthias satellite tag tracking
  • Thorny skate  Amblyraja radiata satellite tag tracking

Post release mortality in commercial and recreational fishing gear

w_byBlueBoatWhen fish are captured, they are either retained for human consumption or released back into the their environment. The unwanted fish that are released (discarded) are termed bycatch. James’ research aims at understanding how both commercial and recreational fishing capture/handling methods affect the survival of those fish and how we can develop w_byCatchCagemethods/techniques to increase their survival upon release. This information is important because it can be used to help establish effective management measures for fish species. Past and present projects along with collaborators (CO-PI) and funding source include:

  • Quantifying and reducing post-release mortality for Dusky sharks discarded in the commercial pelagic longline fishery.
  • Determining the discard mortality rate and best capture-handling methods for Atlantic cod (Gadus morhua) captured in the Gulf of Maine commercial lobster industry.
  • Evaluating the Condition and Discard Mortality of Scallops Following Capture and Handling in the Sea Scallop Dredge Fishery
  • Evaluating the Condition and Discard Mortality of Winter Skate, Leucoraja ocellata, Following Capture and Handling in the Sink Gillnet Fishery
  • Evaluating the Condition and Discard Mortality of Skates Following Capture and Handling in the Sea Scallop Dredge Fishery:
  • Elucidating post-release mortality and “best capture and handling” methods in sublegal Atlantic cod discarded in Gulf of Maine recreational hook fisheries.
  • The Immediate and Short-Term Post-Release Mortality of Species in the Northwest Atlantic Skate Complex Captured by Gillnet and Otter-Trawl. 

Evaluating the Saco Bay estuary system as a nursery ground for commercially valuable and ecologically important fish species

w_SacoBay1Coastal river systems, such as the lower Saco River, are known to play an important role in the early life history of many marine species within the Gulf of Maine (GOM). Specific areas’ estuarine habitats (where river and oceanic waters mix) are often nursery grounds for many fish species.

Since the survival during early life stages of fish is crucial to success of the overall population, monitoring estuarine nursery grounds in New England is essential for future conservation and management of commercially important and threatened fish  w_SacoBay2stocks in our region.

Since the start of the Sulkowski Lab’s work in 2006, 68 fish species have been observed in the Saco river and its associated estuary, including endangered (e.g. shortnose sturgeon), threatened (e.g. Atlantic sturgeon), and species of concern (e.g. blueback herring). Since new species are continually being observed, this ongoing project will continue to compile data for this dynamic habitat.






Shark, Skate and Ray Life History

James holding sharkElasmobranchs (sharks, skates and rays) are slow growing, long lived, reach sexual maturity at a late age and reproduce few young. These life history characteristics make this group of fish very susceptible to human induced impacts (overfishing) and environmental impact (i.e. climate change). Age information forms the basis for the calculations of growth rate, mortality rate and productivity, making it one of the most influential variables for estimating a population’s status and assessing the risks associated with both human and environmental impacts. Collaborating with Jill Hendon of University of Southern Mississippi’s Gulf Coast Research lab, Dr. Eric Hoffmayer and Dr. Trey Driggers, James and his team are currently studying several species of sharks within the Gulf of Mexico in order to update this important life history characteristic. They are also collaborating with colleagues from Canada’s Department of Fisheries and Oceans (Gulf Fisheries Center in Moncton, NB and the Northwest Atlantic Fisheries Center in St. John’s, NL), and Firat University (Elazig, Turkey) to further investigate elasmobranchs in international waters.

Reproduction is another important life history trait that must be fully understood if successful management of elasmobranchs is to occur.  A large portion of the lab’s work is focused on developing non-lethal techniques or protocols for the study of this life history characteristic.  Researchers can take a blood or muscle sample and analyze it for reproductive hormones that are present within the shark or ray. In addition, we use a portable ultrasound to take images and video of growing shark babies within the mother. In collaboration with Dr. Neil Hammershlag of the University of Miami’s Rosenstiel School of Marine & Atmospheric Science, James and his team are using these techniques to track the reproductive cycle and length of gestation of tiger sharks in the Bahamas and several species of sharks along the coast of south Florida.