Can Humans and Sturgeons Coexist: Linking Gulf Sturgeon Habitat Utilization and Human Development in Choctawhatchee Bay, Florida?

Choctawhatchee Bay, Florida has been designated critical habitat for the federally protected Gulf sturgeon (Acipenser oxyrinchus desotoi); it is an important area for foraging and migration.  Like many Gulf coast estuaries, the Choctawhatchee Bay watershed has been significantly impacted by dramatic rises in human population in recent years.  Associated habitat transitions from rural/forested to urban/suburban have led to management concerns regarding modifications in water quality and degradation of benthic communities.  Adult and juvenile Gulf sturgeon were captured in the Choctawhatchee River and outfitted with acoustic transmitters (2009: n = 40; 2010: n = 55).  Following emigration to the bay, monitoring was accomplished through active and passive telemetry to examine size-specific patterns of residency and habitat use.  A significantly greater amount of adult Gulf sturgeon (74%) entered into Gulf of Mexico (GOM) waters than juveniles (47%).  Movement into marine waters was much less directed than previously reported and occurred between early-December through mid-January for juveniles, and early-November through late-December for adults. Both juvenile and adult Gulf sturgeon were documented returning to Choctawhatchee Bay over a wide-ranging time period (late-January to early-April and mid-December to mid-May, respectively). Of the Gulf sturgeon that entered marine waters, 38% of adults and 33% of juveniles transitioned between estuarine and marine habitats for varying periods of time.  The vast majority (89%) of Gulf sturgeon detected in the Choctawhatchee Bay subsequently moved upstream into the Choctawhatchee River between early-March and mid-May. The other individuals were mainly (4/6) detected in neighboring river systems.  When the Deepwater Horizon oil spill began in the GOM, most telemetered Gulf sturgeon (72%) were present in freshwater rivers; 17% were in Choctawhatchee Bay.  There were no reports of oil impacting Choctawhatchee Bay until after all known Gulf sturgeon had moved upstream into coastal rivers.  Across both years of the study, Gulf sturgeon were distributed non-randomly within Choctawhatchee Bay, with significantly more relocations occurring in nearshore sandy shelf habitat of northeastern/central embayments and a large southeastern bayou.  Contemporary habitat use by Gulf sturgeon does not appear to differ in comparison to previously documented patterns although greater utilization of marine habitats is apparent.  This research provides an increased understanding of the role that human-induced habitat alterations play in the recovery of Gulf sturgeon populations.