Anadromous Sturgeons: Habitats, Threats, and Management

2007 ◽  
Keyword(s):  
River Flow ◽  
High Flow ◽  
Late Winter ◽  
Mean Flow ◽  
Strength Index ◽  
Gulf Sturgeon ◽  
Suwannee River ◽  
Class Strength ◽  
Acipenser Oxyrinchus Desotoi ◽  
Acipenser Oxyrinchus

<em>Abstract.</em>—A 19-year mark–recapture database was used to estimate yearly recruitment of Gulf sturgeon <em>Acipenser oxyrinchus desotoi</em> in the Suwannee River, Florida, using a length–age equation derived from known-age fish. Yearly recruitment information was then transformed into a relative year-class strength index, which was analyzed against monthly river flow. Recruitment was positively correlated with high monthly mean flow in September and December. It is postulated that the correlation is the result of increased survival of late-winter estuarine-feeding age-0 juveniles during high-flow years.

Anadromous Sturgeons: Habitats, Threats, and Management

2007 ◽  
Keyword(s):  
River Estuary ◽  
Upstream Migration ◽  
Movement Rates ◽  
Gulf Sturgeon ◽  
Suwannee River ◽  
Influence Of Temperature On ◽  
Acipenser Oxyrinchus Desotoi ◽  
Males And Females ◽  
Acipenser Oxyrinchus ◽  
Ultrasonic Transmitters

<em>Abstract.—</em>Eighteen Gulf of Mexico sturgeon <em>Acipenser oxyrinchus desotoi</em> netted at the mouth of the Suwannee River, Florida, in February–April 2001, were tagged with ultrasonic transmitters to examine riverine and estuarine movements. In addition, 30 fish (11 carrying ultrasonic transmitters) were fitted with archival temperature-logging tags to record temperatures encountered by Gulf sturgeon over the course of a year, including both their riverine and estuarine residency. Movement rates of Gulf sturgeon in the Suwannee River were greatest during the upstream migration in March and April 2001 (4.8 km/d) and upon their emigration from the river in September 2001 (6.4 and 16.0 km/d for males and females, respectively). Mean maximum distance that fish were relocated upstream was significantly greater for male Gulf sturgeon (165 km) than for females (126 km). This may relate to female Gulf sturgeon not spawning annually and thus not migrating to putative spawning grounds upriver. In contrast, rates of upstream movement did not differ significantly between sexes. Movements in the nearshore regions of the Suwannee River estuary did not differ between males and females (0.8 and 2.2 km/d, respectively), and was much lower than in the river. Three Gulf sturgeon bearing archival temperature tags were recovered in subsequent netting activities in 2002. Data downloaded from the tags demonstrated that on average Gulf sturgeon were exposed to a 13°C annual flux in temperature, ranging from 26°C in the river during the summer to 13°C in the estuary in the winter, although individual fish experienced as much as a 20°C range (8.1–28.5°C) over the course of a year. Given the influence of temperature on the metabolism of ectotherms such as sturgeon, this broad fluctuation in temperature may have profound implications for the bioenergetics, and hence growth and reproduction, of Gulf sturgeon.

Anadromous Sturgeons: Habitats, Threats, and Management

2007 ◽  
Keyword(s):  
Yellow River ◽  
Late Winter ◽  
Atlantic Sturgeon ◽  
Gulf Sturgeon ◽  
Marine Habitats ◽  
Acipenser Oxyrinchus Desotoi ◽  
Acoustic Tags ◽  
Florida Panhandle ◽  
Acipenser Oxyrinchus ◽  
Choctawhatchee River

Abstract.—Migrations and movements of Gulf sturgeon <em>Acipenser oxyrinchus desotoi </em>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 nonreporting 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 acoustic-tagged 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 <em>Acipenser oxyrinchus</em> and for green sturgeon <em>A. medirostris</em>.

SURGICAL REMOVAL OF CATARACTS DUE TO DIPLOSTOMUM SPECIES IN GULF STURGEON (ACIPENSER OXYRINCHUS DESOTOI)

2005 ◽  
Vol 36 (3) ◽  
pp. 504-508 ◽  
Author(s):  
Robert S. Bakal ◽  
Brian H. Hickson ◽  
Brian C. Gilger ◽  
Michael G. Levy ◽  
James R. Flowers ◽  
...  
Keyword(s):  
Surgical Removal ◽  
Gulf Sturgeon ◽  
Acipenser Oxyrinchus Desotoi ◽  
Acipenser Oxyrinchus

Biology, Management, and Protection of North American Sturgeon

2002 ◽  
Keyword(s):  
Life History ◽  
Gulf Of Mexico ◽  
River System ◽  
Ultrasonic Telemetry ◽  
Marine Habitat ◽  
Gulf Sturgeon ◽  
Sandy Substrate ◽  
Sampling Locations ◽  
Acipenser Oxyrinchus Desotoi ◽  
Acipenser Oxyrinchus

Abstract.<em>—</em>Although most species of anadromous sturgeons worldwide are threatened with extinction, information on the estuarine and marine components of their life history is generally lacking. During March 1997 to July 1999, we used ultrasonic telemetry to examine estuarine and marine habitat use of adult Gulf sturgeon <em>Acipenser oxyrinchus desotoi</em> from the Choctawhatchee Bay/River System, Florida. During winter and spring, telemetered Gulf sturgeon were distributed nonrandomly within Choctawhatchee Bay, with most relocations in nearshore areas 2–4 m deep. Within the bay, Gulf sturgeon occasionally moved long distances but usually remained in localized areas (<1 km<sup>2</sup>) for several weeks. Areas where Gulf sturgeon remained for prolonged periods were characterized by sandy substrate harboring a benthic community dominated by crustaceans and annelids. A majority of male Gulf sturgeon remained exclusively in Choctawhatchee Bay during the winter and spring. In contrast, a majority of females during this time were either relocated in the Gulf of Mexico or were absent at sampling locations, having last been detected at bay entrances. Declines in habitat quality in Choctawhatchee Bay and the Gulf of Mexico may hinder recovery of this species, since adult Gulf sturgeon rely on these areas for nourishment during periods of gonadal growth.

Effects of hydrological change and the cessation of stocking on a stream population of Salmo trutta L

1988 ◽  
Vol 39 (3) ◽  
pp. 337 ◽  
Author(s):  
PE Davies ◽  
RD Sloane ◽  
J Andrew
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
River Flow ◽  
River System ◽  
Riparian Habitat ◽  
Mean Flow ◽  
Age Composition ◽  
The North ◽  
Trout Population ◽  
Class Strength

The North Esk-St Patricks river system, northern Tasmania, was electrofished at 27 sites in 1985, 30 years after the same sites had been electrofished in a previous study on the survival of released brown trout. All sites were dominated by brown trout, Salmo trutta L. Before 1955, stocking of brown trout fry and yearlings had been heavy. Stocking ceased after 1956 and few releases were made to 1985. At all but 4 sites, the number and total biomass of brown trout were higher in 1985 than in 1955. The estimated total population of brown trout had increased by 63%, accompanied by a 55% increase in the number of fish of legal size (>22 cm). Previously described 'nursery streams' still maintained high densities of 0+ fish, despite considerable changes in the age composition at other sites. Little or no change had occurred in riparian habitat at 23 of 27 sites. Change in year-class strength was highly correlated with change in total annual river flow in the natal year. This is explained in terms of mortality in 'nursery streams' during periods of low river flow. At 19 sites out of 21, changes in age composition were related to relative changes in year-class strength due to interannual variability in river flow. Four sites where major changes in riparian habitat occurred exhibited decreased brown trout biomass but still showed changes in age structure due to variation in annual flow. Mean annual river flow had increased by three times since the 1950s and this was attributed to a doubling in the proportion of cleared land in the catchments. Effects of changes in river hydrology on the trout population are discussed. Growth of S. trutta was essentially independent of density. The number of anglers, total effort and the total harvest in 1985/86-1986/87 were significantly higher than in 1945/46-1953/54. A shift toward higher catch per season per angler was observed in 1985/86-1986/87 compared to the 1945/46- 1953/54 seasons, but catch per day had not changed. Total annual mortality remained at 70%. The effects of increased mean flow and interannual flow variability on the brown trout population of the North Esk river system are discussed.

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