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Juvenile Gulf Sturgeon Population Dynamics and Habitat Growth

Hand holding a small juvenile sturgeon over a container of water.

One of the oldest families of bony fish in existence, sturgeons are native to the lakes and coastlines of Eurasia and North America. In Florida, Gulf sturgeon are present in the Suwannee River as well as most other rivers in Northwest Florida, including the Apalachicola, Choctawhatchee, Yellow, Blackwater, Escambia, Pearl, and Pascagoula. To better understand population dynamics of sturgeon in Florida, which has been studied little, this project was proposed and initiated. 

Map of Gulf of Mexico and Louisiana, Mississippi, Alabama, Georgia, and Florida. Shading shows the historic range of Gulf Sturgeon throughout rivers and coastal areas of all states. The seven  systems of study are highlighted in blue.

Effective Gulf sturgeon restoration requires a better understanding of baseline status and conditions, an ability to identify and prioritize habitats most in need of restoration, and a framework for monitoring the results of restoration in an adaptive management context. To address these needs, FWC researchers proposed to study juvenile Gulf Sturgeon habitat use and preference in estuaries in the Northern Gulf of Mexico (NGOM).

Estuaries serve as important foraging habitat for juvenile Gulf sturgeon in winter, yet little is known about the patterns of habitat use within the estuary, or the preference for mesohabitats such as oyster reefs, seagrass beds, or mud flats. This information is critical for guiding projects through the Federal regulatory process, and for determining effective strategies for estuarine restoration to benefit Gulf sturgeon. Recruitment, growth, and survival patterns of juvenile Gulf sturgeon are poorly understood, yet this information is necessary to identify population and system priorities for restoration, and to quantify the success of Gulf-wide restoration efforts.

Sampling for this project occurs in spring, summer, and fall. Monitoring and maintenance of the telemetry array, however, is year round. The array is also monitoring Alligator Gar movement and habitat use simultaneously. All research for this project is conducted out of the Garcon Point Aquatic Research Center in Santa Rosa county.

An FWC employee is leaning over the side of a boat holding onto the tail of a sturgeon that is in shallow water.

The objectives of this project are (1) to protect and conserve marine, coastal, estuarine, and riparian habitats by identifying essential estuarine habitat for juvenile sturgeon, (2) to provide data to prioritize system and habitat-specific restoration projects, and (3) to establish baseline metrics to evaluate restoration success for juvenile (age-1) sturgeon. This project involves a 3-year assessment of the estuarine habitat use patterns by juvenile GS, and trends in juvenile sturgeon recruitment, growth, survival, genetics and kinship across the following systems: (1) Pearl, (2) Pascagoula, (3) Escambia, (4) Yellow, (5) Choctawhatchee, (6) Apalachicola, and (7) Suwannee. Alternative study designs (e.g., fewer systems targeted) could be implemented to accommodate lower levels of funding, if necessary.

Juvenile sturgeon are captured using anchored gill nets fished in riverine holding areas. Standard, 150-foot long, monofilament gill nets with 3 panels (3, 3.5, and 4-inch mesh) are used. All fish captured are fitted with a passive integrated transponder (or PIT) tag that uniquely identifies each individual. All fish captured are weighed and measured. In addition, fin ray samples will be obtained from all sturgeon.

Findings will be published upon the completion of the project. Preliminary analysis indicate that juvenile sturgeon use discrete habitats in the winter compared to adults. In the summer while residing in the river, younger (age 1 and 2 fish) use unique habitats, while older juvenile use holding areas similar to adults. Results will be published in a peer-reviewed publication and will also be used to inform future conservation and restoration efforts.

This project is crucial to developing a science-driven, adaptive management framework for Gulf sturgeon restoration. Successful completion of this project will fill data gaps that currently impede or preclude our ability to plan strategic habitat restoration for the species as a whole. By conducting this investigation across all 7 populations and systems simultaneously, and in standardized fashion, we will definitively establish the patterns of habitat use by juvenile sturgeon in estuarine and marine environments, and establish the baseline for juvenile recruitment, growth and survival, overall population size, and effective spawning cohort size. These results will enable an unprecedented, comparative analysis that will provide insights to restoration that are system, habitat, and population specific. The effects of future restoration actions will be directly assessed relative to the baseline conditions established during this project to determine outcomes and efficacy. Ultimately, this should be the goal of any adaptive management approach to ecosystem restoration conducted to benefit the Gulf sturgeon. Further, the knowledge of habitat use will help Federal regulatory agencies immeasurably when evaluating the myriad of projects proposed within the estuarine/marine footprint of Gulf Sturgeon Critical Habitat.

This project is funded by the DWH Natural Resource Damage Assessment (NRDA) Open Ocean Trustee Implementation Group (OO TIG). The OO TIG is one of seven TIG's authorized to plan and carry out restoration efforts under the DWH NRDA programmatic restoration plan finalized in 2016 (DWH NRDA PDARP/ EIS 2016) (PDARP). Open Ocean TIG restoration efforts address injured species throughout their life stages and throughout their geographic range, including areas outside the Gulf of Mexico (GOM). The PDARP states that to address impacts to sturgeon, restoration goals will focus on improving access to spawning areas and increasing reproductive success of Gulf Sturgeon. NRDA transferred funds the USFWS that were subsequently awarded to partners for the project (one of which was FWC/FWRI).