Movements of Gulf Sturgeon (Acipenser oxyrinchus desotoi) in Nearshore Habitat as Determined by Acoustic Telemetry

Abstract

Gulf sturgeon were tagged with telemetry tags and were tracked and relocated in fall and early winter of 1996 and 1998 to determine migration patterns and winter feeding habitats after they emigrated from the Suwannee River, Florida, into the Gulf of Mexico. We hypothesized that their migration would generally follow the drowned Suwannee River channel across the West Florida shelf. Fish left the river in late Oct. or early Nov., about the time river water temperatures fell below 20 C. Tracked and relocated fish moved slowly and remained offshore of Suwannee Sound in nearby shallow (<6 m) marine-estuarine habitats until at least mid or late Dec. The relatively small area (~115lrm 2) within which fish were consistently relocated in 1998 probably is a critically important feeding habitat because adult Gulf sturgeon, which do not feed while in the river, occupy it for up to half their short (4-5 mo) marine residency. The fish left the area in late Dec. or early Jan., most lil<ely in response to powerful cold front-generated weather conditions (under which, boat-based acoustic tracking is infeasible). A large (1, 760 lrm 2) adjacent area was searched for sonic-tagged sturgeon in early Jan. 1999, but only one was relocated (~50 km northwest of the Nov.-Dec. area). Although we were unable to address the hypothesis that their migration follows the Suwannee paleochannel, the results do indicate that Gulf sturgeon move to yet unknown, distant, latewinter feeding areas of the Gulf of Mexico before returning to the river in spring.

Estuarine and Coastal Habitat Use of Gulf Sturgeon (Acipenser oxyrinchus desotoi) in the North-Central Gulf of Mexico

“…Ripe fish tend to enter freshwater somewhat earlier than nonbreeding fish, usually from March to mid-April (Fox et al 2000). Gulf sturgeon natal to the Suwannee River show a similar timing for movement into salt water (Edwards et al 2003).…”

“…1) by listening for tag signals every 2-3 km along a given course heading. Detection ranges for sonic tags vary from 1.0 to 6.4 km, depending on sea conditions (Frank Parauka, USFWS Panama City, FL, personal communication; Edwards et al 2003;Heise et al 1999). Most searches were done using 5.2 or 6.4 m outboard skiffs.…”

“…Until recently, there has been much greater attention given to the freshwater phase of both the Gulf sturgeon (Carr et al 1996;Parauka et al 2001;Fox et al 2002;Edwards et al 2003) and Atlantic sturgeon (Bain 1997;Smith and Clugston 1997;Stein et al 2004). In fact, Fox et al (2002) concluded that the marine foraging locations for Gulf sturgeon were still not known.…”

“…Two studies have thus far concentrated on marine habitat use of Gulf sturgeon in the easternmost portion of its range. Edwards et al (2003) tracked Gulf sturgeon offshore of the Suwannee River estuary in the northeastern Gulf of Mexico using sonic telemetry. They located seven fish in 1996 and 18 fish in 1998-1999 in the Suwannee Sound region at generally shallow depths (0.5-4.5 m).…”

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…Because the adult and large sub-adult sturgeon have spent at least six months fasting or foraging sparingly on detritus (Mason and Clugston 1993) in the rivers, it is presumed they immediately begin foraging. Telemetry data indicate Gulf sturgeon are found in high concentrations near the mouths of their natal rivers with individual fish traveling relatively quickly between foraging areas where they spend an extended period of time Edwards et al 2003).…”