Habitat Use and Occurrence of the Bull Shark (Carcharhinus Leucas) Near the Sabine Pass Inlet of Texas and Louisiana PDF Download

Author: Jennifer Brooke Shipley
Publisher:
ISBN:
Category :
Languages : en
Pages : 138

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Author: Tobey Hayward Curtis
Publisher:
ISBN:
Category :
Languages : en
Pages :

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ABSTRACT: Distribution and habitat use of the bull shark (Carcharhinus leucas) were examined using fishery-independent sampling data, tagging, and ultrasonic telemetry to assess the potential role of the Indian River Lagoon (IRL) as a nursery area for this species. Fishery-independent sampling data were compiled and synthesized to examine patterns of seasonal occurrence, spatial distribution, and habitat associations. These data provided a comprehensive overview of bull shark ecology in the study site over a span of 30 years, based on data collected from 390 individual sharks. Tagging and acoustic telemetry methods were also employed to acquire more fine-scale information on shark movements, daily activities, and habitat utilization. A total of 50 sharks were marked with conventional tags, with four fish recaptured over the course of the study. Eleven of these sharks were tagged additionally with ultrasonic pingers, ten of which were tracked manually and one of which was monitored by moored listening stations (Vemco VR2). The manual tracking data provided fine-scale information on the patterns of movements of a small number of individuals. Integration of multiple methodologies provided a more complete picture of habitat use by this important apex predator in the IRL. Bull sharks occurred over a broad range of habitats, including depths of 0.2 - 4.0 m, temperatures of 18 - 37 °C, salinities of 1 - 42 ppt, dissolved oxygen concentrations of 3 - 8 mg/L, and water clarity levels of 70 - 170 cm. In addition, they were located over seagrass, sand, and mud substrates. Overall catch-per-unit-effort was low, relative to other systems. However, higher than average catch rates were observed at power plant outfalls and near freshwater creeks. These results may prove useful to the continued management and conservation of bull shark stocks in the northwest Atlantic.

Author:
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Category : Dissertations, Academic
Languages : en
Pages : 396

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"Education, arts and social sciences, natural and technical sciences in the United States and Canada".

Author: Jonathan Mark Werry
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 420

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Abstract : The habitat ecology of the euryhaline bull shark (Carcharhinus leucas) is poorly understood, yet vital for their conservation and management on our rapidly urbanising coastlines. This study investigated the habitat ecology of the bull shark in relation to ontogeny using a variety of approaches, including long-term catch data, acoustic telemetry, chemical indicators for trophic and habitat preferences and conventional methods for dietary analysis. Fishery-independent data from 1,060 C. leucas caught at ten locations along the east coast of Queensland (17 to 28°S) by the Queensland Shark Control Program (QSCP) from 1996 to 2006 indicated size of sharks captured ranged from 0.6 to 4 m total length (TL). Onset of female maturity was determined at 1.8 to 2 m TL. Catch per unit effort (CPUE) was higher during summer for drumlines and gill nets in tropical north QLD. Significantly larger individuals were caught on both gears in the sub-tropical southeast of Queensland compared to the tropical north. Principal components-regression analysis indicated this difference could be attributed to coastal bathymetry, i.e. distance to the 100 m contour. The number of estuaries in a region also directly influenced the C. leucas catch. General linear models (GLMs) indicated latitudinal differences in CPUE along the eastern Queensland coast with a significant decline in sub-tropical areas. QSCP data from 1996 to 2007 were analysed to investigate the effects of climate parameters on catch of this species in the nearshore habitat. Conditional generalised linear modelling (CGLM) showed that the numbers of C. leucas caught by both techniques were significantly correlated with total rainfall within eight days prior to capture. C. leucas catch on drumlines increased with prior rainfall> 300 mm and sea surface temperature, as these conditions may encourage feeding in nearshore areas. Pregnant C. leucas caught in gill nets increased with a positive Southern Oscillation Index, suggesting higher pupping during wet periods. Catch of sharks

Author: Heather Moore Niver
Publisher: Enslow Publishing
ISBN: 9780766076891
Category : Bull shark
Languages : en
Pages :

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Author: Norman Howard Jensen
Publisher:
ISBN:
Category : Bull shark
Languages : en
Pages : 164

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Author:
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Category : Seattle (Wash.)
Languages : en
Pages : 20

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Author: Jeffrey Nathaniel Childs
Publisher:
ISBN:
Category :
Languages : en
Pages : 426

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Author: Mark Grace
Publisher:
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Category : Carcharhinidae
Languages : en
Pages : 48

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Author: Charles W Bangley
Publisher:
ISBN:
Category :
Languages : en
Pages : 330

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Knowledge of shark habitat preferences and use patterns is important to effectively manage shark fisheries and account for interactions between sharks and species targeted by other fishery management or conservation efforts. To gain baseline knowledge of the availability and spatial extent of shark habitat in North Carolina waters, habitat was assessed at three spatial scales: coastal nearshore, whole estuarine, and estuarine microhabitat. The local ecological knowledge of North Carolina fishermen was also incorporated and compared with data collected using fishery-independent means. Catch data and acoustic telemetry were used to assess shark habitat at the coastal nearshore scale. Sharks captured near Cape Hatteras could be grouped into warm water and cold water assemblages. Juvenile Dusky (Carcharhinus obscurus) and Sandbar (Carcharhinus plumbeus) Sharks were tracked using acoustic telemetry, and 12 of 15 tagged Sandbar Sharks were detected over an area from New York City to Savannah, Georgia. The spatial extent of potential juvenile Sandbar Shark habitat was influenced by a combination of sea surface temperature and chlorophyll-a concentrations, with habitat restricted to an area in the northern portion of Raleigh Bay near the Hatteras Bight during winter. At the estuarine scale, boosted regression tree modeling of shark catch and environmental data from North Carolina Division of Marine Fisheries (NCDMF) gillnet and longline surveys were used to spatially delineate potential habitat for six species within Pamlico Sound. Inlet distance and temperature were among the most influential environmental factors associated with species presence, while salinity was the most influential factor on abundance. Potential habitat for most species was located on the east side of the sound near the inlets with the exception of the Bull Shark (Carcharhinus leucas), which showed hot spots of potential habitat near sources of freshwater input. At the estuarine microhabitat scale, catch and environmental data from a fishery-independent survey conducted in Back and Core Sounds and a small-scale acoustic array deployed around Middle Marsh in Back Sound were used to identify associations between species and with specific habitat types. Spatial overlap between species was generally low and species assemblages separated based on water temperature. Smooth Dogfish (Mustelus canis), and Spiny Dogfish (Squalus acanthias) occurred primarily during mid-afternoon and Blacknose Sharks (Carcharhinus acronotus) occurring most often at night. A large Bull Shark tagged in another study accounting for the majority of tag detections and occurred within the array primarily during nighttime hours, most often on receivers deployed at two oyster reef sites and one sand flat site. Local ecological knowledge (LEK) of shark distributions and habitat preferences was gathered using structured interviews with North Carolina fishermen and their observations were compared with data from fishery-independent surveys and primary literature to assess their accuracy. All hypotheses generated from LEK were classified as either supported or plausible. Overall, water temperature was identified as an important influence on shark species presence and assemblage composition, with factors such as salinity and potential interspecific interactions more important at finer habitat scales. The locations and spatial extents of shark habitats in North Carolina are influenced by dynamic environmental factors and may be affected by large-scale perturbations such as climate change.