Characterization of Kemp's Ridley Sea Turtles in the Florida Big Bend Area: Final report

The Kemp's ridley (Lepidochelys kempo is considered the most endangered of the seven extant marine turtle species (Ross et al. 1989). The US Fish and Wildlife Service (USFWS) and the National Marine Fisheries Service (NMFS) estimate the breeding population at 1,500 to 3,000 individuals. The nesting population has been reduced from approximately 40,000 on one day to no more than 700 annually (Magnuson et al. 1990, USFWS & NMFS 1992). Conservation measures for the species have focused on the protection of the nesting beach, captive rearing (head starting), and the implementation of turtle excluder devices (TEDs) on shrimp nets. Five hundred to 5,000 ridleys are still taken incidentally yearly by shrimp trawls (Magnuson et al. 1990). Lack of knowledge about early life stages of the Kemp's ridley sea turtle currently hinders recovery efforts for this federally listed species. (Document has 18 pages.

Early Life History Stages of Gulf Sturgeon in the Suwannee River, Florida

Egg sampling confirmed that Suwannee River Gulf sturgeon Acipenser ozyrinchus desotoi, a subspecies of Atlantic sturgeon A. o. oxyrinchus use the same spawning site at river kilometer (rkm) 215 from the mouth of the river each year. Forty-nine eggs were recorded in 1995, and 368 were recorded in 1996. Spawning began 4-7 d after the March new moon in both years and lasted 10-11 d; in 1996, a second 10-d spawning round began on the April new moon. Developmental synchrony among eggs recovered suggested serval discrete spawning events in both years. Total eggs deposited for three 1996 sampling days was estimated as 405,600-711,000/d, approximating the fecundity range of a large female Gulf sturgeon. Eggs were found only in the southern half of the river, an area with surface currents of 0.5-1.5 m/s and numerous eddies producing reverse bottom currents of 0.1-0.5 m/s. Egg substrate consisted of bedrock limestone thinly overlain by fine sand and densely distributed elliptical gravel 2-10 cm in diameter. Eggs were found predominantly in depths of 2-4 m at water temperatures of 17-21oC, conductivities of 20-100 uS, and dissolved oxygen levels exceeding 5.0 mg/L. The Cody Scarp, 15 rkm above the spawning ground, may mark the upstream limit of spawning areas in the river. Three 2-4-month-old riverine juveniles (82-115 mm total length, TL) collected are the smallest yet captured from any river. Data for 18 riverine age-0 juveniles (to 350 mm TL) suggest that this stage lasts 6-10 months, terminating with migration of fish to the river mouth in January-February. Less than 2% of 461 juveniles captured at the estuarine river mouth (1990-1993) were under 350 mm TL. Riverine age-0 fish were collected over long shallow stretches (typically \u3c4 m deep) of relatively barren sand (rkm 12-238)

Egress of Adult Sport Fish from an Estuarine Reserve within Merritt Island National Wildlife Refuge, Florida

A tag-recapture study was conducted within Merritt Island National Wildlife Refuge in the waters surrounding Kennedy Space Center, Florida (where public access has been restricted since 1962), to document egress of adult sport fish from an estuarine reserve. A total of 3,358 sport fish were tagged within the restricted areas. The species tagged were red drum Sciaenops ocellatus (n = 1,366), spotted seatrout Cynoscion nebulosus (n = 927), black drum Pogonias cromis (n = 760), and common snook Centropomis undecimalis (n = 305). Results showed that adult sport fish moved from the restricted areas within Merritt Island National Wildlife Refuge to surrounding areas open to fishing. The recapture rates, based on angler responses outside of the restricted areas, were 3.1%, 0.8%, 2.9%, and 16.1% for red drum, spotted seatrout, black drum, and common snook, respectively. In general, red drum, spotted seatrout, and black drum were recaptured in waters adjacent to the restricted areas. Common snook, however, migrated from the restricted areas south to inlets. Tag recaptures for red drum, spotted seatrout, and black drum, together with a previous study that found greater abundance and size of sport fish in the restricted areas than in adjacent areas open to fishing, substantiate the fish replenishment zone function of the restricted areas. The restricted areas within Merritt Island National Wildlife Refuge protect fish populations and large adult sport fish egress to surrounding waters open to fishing

Characterization of the Demersal Fish Community of a Deep-Sea Radioactive Dump Site (Results of Cruise EPA-7801, R/V ADVANCE II, 21-27 June 1978)

The present report describes the demersal fish fauna collected by otter trawl from RV Advance II on cruise EPA-7801 in the vicinity of a radioactive waste disposal site (R.D.S.) located at a depth of about 3900 m, approximately 200 miles due east of the Virginia coast (Figs. 1, 2). Because the sampling· effort at the R.D.S. was restricted by time and funding, the limited data base accrued from there was analyzed and compared with a much larger data set collected during previous deep-sea trawling studies using the same trawl gear

Feeding habitats of the Gulf sturgeon, Acipenser oxyrinchus desotoi, in the Suwannee and Yellow rivers, Florida, as identified by multiple stable isotope analyses

Stable 13C, 15N, and 34S isotopes were analyzed to define the feeding habitats of Acipenser oxyrinchus desotoi in the Suwannee and Yellow River populations. For the majority (93.9%) of Suwannee sub adults and adults, 13C and 34S signatures indicate use of nearshore marine waters as primary winter feeding habitat, probably due to the limiting size of the Suwannee Sound estuary. In the Yellow River population, 13C isotope signatures indicate that adults remain primarily within Pensacola Bay estuary to feed in winter, rather than immigrating to the open Gulf of Mexico. A minor Suwannee River subset (6% of samples), comprised of juveniles and sub adults, displayed 13C signatures indicating continued feeding in freshwater during the spring immigration and fall emigration periods. This cannot be interpreted as incidental feeding since it resulted in a 20.5% turnover in tissue δ13C signatures over a 1–3 month period. Cessation of feeding in the general population does not coincide with high river water temperatures. The hypothesis of reduced feeding in freshwater due to localized prey depletion as a result of spatial activity restriction is not supported by the present study. Instead, Suwannee River A. o. desotoi appear to follow two trophic alternatives; 1) complete cessation of feeding immediately upon immigration in spring, continuing through emigration 8–9 months later (the predominant alternative); 2) continued intensive feeding for 1– 3 months following immigration, switching to freshwater prey, selected primarily from high trophic levels (i.e., large prey). Stable δ34S data verifies that recently immigrated, fully-anadromous A. o. desotoi adults had fed in nearshore marine waters, not offshore waters

Feeding habitats of the Gulf sturgeon, Acipenser oxyrinchus desotoi, in the Suwannee and Yellow rivers, Florida, as identified by multiple stable isotope analyses

Stable 13C, 15N, and 34S isotopes were analyzed to define the feeding habitats of Acipenser oxyrinchus desotoi in the Suwannee and Yellow River populations. For the majority (93.9%) of Suwannee sub adults and adults, 13C and 34S signatures indicate use of nearshore marine waters as primary winter feeding habitat, probably due to the limiting size of the Suwannee Sound estuary. In the Yellow River population, 13C isotope signatures indicate that adults remain primarily within Pensacola Bay estuary to feed in winter, rather than immigrating to the open Gulf of Mexico. A minor Suwannee River subset (6% of samples), comprised of juveniles and sub adults, displayed 13C signatures indicating continued feeding in freshwater during the spring immigration and fall emigration periods. This cannot be interpreted as incidental feeding since it resulted in a 20.5% turnover in tissue δ13C signatures over a 1–3 month period. Cessation of feeding in the general population does not coincide with high river water temperatures. The hypothesis of reduced feeding in freshwater due to localized prey depletion as a result of spatial activity restriction is not supported by the present study. Instead, Suwannee River A. o. desotoi appear to follow two trophic alternatives; 1) complete cessation of feeding immediately upon immigration in spring, continuing through emigration 8–9 months later (the predominant alternative); 2) continued intensive feeding for 1– 3 months following immigration, switching to freshwater prey, selected primarily from high trophic levels (i.e., large prey). Stable δ34S data verifies that recently immigrated, fully-anadromous A. o. desotoi adults had fed in nearshore marine waters, not offshore waters

New Insights into Marine Migration and Winter Habitat of Gulf Sturgeon

Migrations and movements of Gulf sturgeon Acipenser oxyrinchus desotoi were determined using satellite pop-up archival transmitting (PAT) tags and acoustic telemetry. Adult Gulf sturgeon from four rivers in northwestern Florida were caught with gill nets and were tagged with PAT and acoustic tags in the fall of 2001 and 2002. PAT tags were programmed to release in early February 2002 and 2003 to provide information about location of late-winter marine habitats. However, only 5 of 25 provided meaningful location information. Three of the PAT-tagged fish were relocated acoustically near the PAT tag pop-up locations, one of which was in Choctawhatchee Bay. Acoustic searches near Gulf of Mexico pop-up locations led to acoustic relocation of one nonrepeating PAT-tagged fish and five fish tagged with acoustic transmitters only. Many of these fish were relocated on several dates in late winter, and many (including fish from the Yellow, Choctawhatchee, and Apalachicola rivers) were concentrated in a 25-km stretch of the Florida Panhandle coast, within 2 km from shore, and in depths less than 6 m. A fish that had been tagged with a PAT tag in the Yellow River was acoustically relocated in the concentration area and then in the Choctawhatchee River the following summer. It returned to the concentration area again the next winter and returned to the Choctawhatchee for the second summer. An acoustictagged fish was relocated very near a PAT tag pop-up location about 30 km south of the Suwannee River, within 12 km from shore, and in depths of 3–4 m. Pop-up locations and acoustic relocations showed that the Gulf sturgeon had migrated distances of at least 30– 180 km. These findings indicate a pattern in which Gulf sturgeon migrate considerable distances along the coastline, sometimes to specific areas of concentration, sometimes mixing with other populations, and primarily utilizing shallow (2–6 m), nearshore areas as late-winter habitats. This pattern is similar to that reported by others in this volume for Atlantic sturgeon Acipenser oxyrinchus and for green sturgeon A. medirostris

Patterns of fish use and piscivore abundance within a reconnected saltmarsh impoundment in the northern Indian River Lagoon, Florida

Nearly all saltmarshes in east-central, Florida were impounded for mosquito control during the 1960s. The majority of these marshes have since been reconnected to the estuary by culverts, providing an opportunity to effectively measure exchange of aquatic organisms. A multi-gear approach was used monthly to simultaneously estimate fish standing stock (cast net), fish exchange with the estuary (culvert traps), and piscivore abundance (gill nets and bird counts) to document patterns of fish use in a reconnected saltmarsh impoundment. Changes in saltmarsh fish abundance, and exchange of fish with the estuary reflected the seasonal pattern of marsh flooding in the northern Indian River Lagoon system. During a 6-month period of marsh flooding, resident fish had continuous access to the marsh surface. Large piscivorous fish regularly entered the impoundment via creeks and ditches to prey upon small resident fish, and piscivorous birds aggregated following major fish movements to the marsh surface or to deep habitats. As water levels receded in winter, saltmarsh fish concentrated into deep habitats and emigration to the estuary ensued (200% greater biomass left the impoundment than entered). Fish abundance and community structure along the estuary shoreline (although fringed with marsh vegetation) were not analogous to marsh creeks and ditches. Perimeter ditches provided deep-water habitat for large estuarine predators, and shallow creeks served as an alternative habitat for resident fish when the marsh surface was dry. Use of the impoundment as nursery by transients was limited to Mugil cephalus Linnaeus, but large juvenile and adult piscivorous fish used the impoundment for feeding. In conclusion, the saltmarsh impoundment was a feeding site for piscivorous fish and birds, and functioned as a net exporter of forage fish to adjacent estuarine waters

Frequency of sublethal injury in a deepwater ophiuroid, Ophiacantha bidentata, an important component of western Atlantic Lophelia reef communities

The occurrence and relative abundance of tissue (arm) regeneration in the ophiuroid, Ophiacantha bidentata (Retzius), was examined in individuals collected primarily among colonies of the deep-water coral Lophelia pertusa off the southeastern United States. Seven deep-water coral sites (384–756 m), located between Cape Lookout, NC, and Cape Canaveral, FL, were sampled in June 2004 using a manned submersible. The presence of regenerative tissue was evaluated by visual inspection of each individual ophiuroid, and the proportion of regenerating arms per individual was examined relative to size of individual, geographic location, and depth of collection. Ophiacantha bidentata, the dominant brittle star collected, commonly displayed signs of sublethal injury with over 60% of individuals displaying some evidence of regeneration. These levels of regeneration rival those reported for shallow-water ophiuroids. Larger individuals (\u3e6.5 mm disc size) had a higher incidence of regeneration than smaller individuals. Size of individual and percent of regeneration were negatively correlated with depth. Although O. bidentata was significantly less abundant in southern versus northern sites, ophiuroid abundance did not appear to be influenced by amount or density of coral substratum. Presence of dense aggregations of O. bidentata indicates that they are an important component of the invertebrate assemblage associated with deep-water coral habitat especially in the northern part of the study area. Assuming that observed frequencies of injury and subsequent regeneration represent predation events then dense ophiuroid aggregations in deepwater coral habitats represent an important renewable trophic resource within these communities

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

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 (\u3c6 m) marine-estuarine habitats until at least mid or late Dec. The relatively small area (~115km2) 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 likely in response to powerful cold front-generated weather conditions (under which, boat-based acoustic tracking is infeasible). A large (1,760 km2) 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, late-winter feeding areas of the Gulf of Mexico before returning to the river in spring