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Trophic Interactions of Endangered Bryde’s Whales in the Gulf of Mexico

Gulf of Mexico Bryde’s whales form an extremely small, isolated population with an estimated abundance of 33 individuals, a restricted habitat range, and very low levels of genetic diversity.  Its population size is comparable to that of the North Pacific right whale (Eubalaena japonica), one of the most critically endangered large whale species in the world.  As such, the Gulf of Mexico Bryde’s whale population is currently being evaluated for potential listing as Endangered under the Endangered Species Act.  There is a critical lack of information on Bryde’s whale trophic ecology and habitat requirements limits the ability to plan restoration activities and adequately plan for the long-term protection and recovery of this population. 

The Project

In collaboration with NOAA and Scripps Institution of Oceanography, we develop a comprehensive ecological understanding of protected Gulf of Mexico Bryde’s whales, including the physical, oceanographic, and biological features defining critical habitats and their ecological role in Gulf of Mexico marine food webs. We conduct ship-based surveys to assess the habitat, spatial distribution, and foraging ecology of Gulf of Mexico Bryde’s whales using a multi-faceted approach that integrates visual and acoustic monitoring, environmental sampling, trawling, biopsy sampling for genetic, stable isotope and pollutant (trace elements and persistent organic pollutants) analyses, and deployment of animal-borne tags sampling at fine and coarse scales.  Models will be developed from the resulting data that will identify key trophic interactions, improve characterization of Bryde’s whale habitat and exposure to anthropogenic mortality, and provide information to managers that will inform restoration and population recovery activities.

The Impact

The project results will include numerous data products that will directly contribute to the management of this species including:  large-scale movement patterns to better describe habitat, home range; behavioral data to evaluate potential exposure to risks such as vessel strikes and fishing; improved understanding of foraging ecology using multiple approaches including stable isotope analyses and studies of prey distribution to improve understanding of trophic interactions, and improved understanding of abundance, habitat requirements, and seasonal occurrence through visual and passive acoustic survey data.  The project includes direct interactions with managers and stakeholders through planned workshops with an End Users Working Group that will ensure that project plans address clearly identified information gaps that will improve management and facilitate the transfer and dissemination of project results.

For more information on this project contact Dr. Jeremy Kiszka.