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Ecological drivers of shark distributions along a tropical coastline.

Yates PM, Heupel MR, Tobin AJ, Simpfendorfer CA - PLoS ONE (2015)

Bottom Line: In particular, turbid environments were especially important for all species at typical oceanic salinities.Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species.Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

View Article: PubMed Central - PubMed

Affiliation: Centre for Sustainable Tropical Fisheries and Aquaculture and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland, Australia.

ABSTRACT
As coastal species experience increasing anthropogenic pressures there is a growing need to characterise the ecological drivers of their abundance and habitat use, and understand how they may respond to changes in their environment. Accordingly, fishery-independent surveys were undertaken to investigate shark abundance along approximately 400 km of the tropical east coast of Australia. Generalised linear models were used to identify ecological drivers of the abundance of immature blacktip Carcharhinus tilstoni/Carcharhinus limbatus, pigeye Carcharhinus amboinensis, and scalloped hammerhead Sphyrna lewini sharks. Results indicated general and species-specific patterns in abundance that were characterised by a range of abiotic and biotic variables. Relationships with turbidity and salinity were similar across multiple species, highlighting the importance of these variables in the functioning of communal shark nurseries. In particular, turbid environments were especially important for all species at typical oceanic salinities. Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species. Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

No MeSH data available.


Length-frequency distributions of blacktip, pigeye and scalloped hammerhead sharks.Bar shading denotes the sampling method (dark grey = longline; light grey = gill-net). Lengths at 50% maturity (reviewed in [42, 43]) are denoted by broken lines (larger dashes for the common blacktip shark; A). The lengths at 50% maturity for common blacktip, pigeye and scalloped hammerhead sharks differ between sexes and so the smallest is given (male in all cases).
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pone.0121346.g002: Length-frequency distributions of blacktip, pigeye and scalloped hammerhead sharks.Bar shading denotes the sampling method (dark grey = longline; light grey = gill-net). Lengths at 50% maturity (reviewed in [42, 43]) are denoted by broken lines (larger dashes for the common blacktip shark; A). The lengths at 50% maturity for common blacktip, pigeye and scalloped hammerhead sharks differ between sexes and so the smallest is given (male in all cases).

Mentions: A total of 1987 sharks were captured from six families. Of the 22 species encountered, carcharhiniform sharks made up 99.2% of the total catch. The catch of immature sharks was dominated by blacktip (31%), pigeye (17%) and scalloped hammerhead (14%) sharks. Length-frequency histograms indicated that these species were predominantly immature (Fig. 2).


Ecological drivers of shark distributions along a tropical coastline.

Yates PM, Heupel MR, Tobin AJ, Simpfendorfer CA - PLoS ONE (2015)

Length-frequency distributions of blacktip, pigeye and scalloped hammerhead sharks.Bar shading denotes the sampling method (dark grey = longline; light grey = gill-net). Lengths at 50% maturity (reviewed in [42, 43]) are denoted by broken lines (larger dashes for the common blacktip shark; A). The lengths at 50% maturity for common blacktip, pigeye and scalloped hammerhead sharks differ between sexes and so the smallest is given (male in all cases).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390147&req=5

pone.0121346.g002: Length-frequency distributions of blacktip, pigeye and scalloped hammerhead sharks.Bar shading denotes the sampling method (dark grey = longline; light grey = gill-net). Lengths at 50% maturity (reviewed in [42, 43]) are denoted by broken lines (larger dashes for the common blacktip shark; A). The lengths at 50% maturity for common blacktip, pigeye and scalloped hammerhead sharks differ between sexes and so the smallest is given (male in all cases).
Mentions: A total of 1987 sharks were captured from six families. Of the 22 species encountered, carcharhiniform sharks made up 99.2% of the total catch. The catch of immature sharks was dominated by blacktip (31%), pigeye (17%) and scalloped hammerhead (14%) sharks. Length-frequency histograms indicated that these species were predominantly immature (Fig. 2).

Bottom Line: In particular, turbid environments were especially important for all species at typical oceanic salinities.Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species.Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

View Article: PubMed Central - PubMed

Affiliation: Centre for Sustainable Tropical Fisheries and Aquaculture and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland, Australia.

ABSTRACT
As coastal species experience increasing anthropogenic pressures there is a growing need to characterise the ecological drivers of their abundance and habitat use, and understand how they may respond to changes in their environment. Accordingly, fishery-independent surveys were undertaken to investigate shark abundance along approximately 400 km of the tropical east coast of Australia. Generalised linear models were used to identify ecological drivers of the abundance of immature blacktip Carcharhinus tilstoni/Carcharhinus limbatus, pigeye Carcharhinus amboinensis, and scalloped hammerhead Sphyrna lewini sharks. Results indicated general and species-specific patterns in abundance that were characterised by a range of abiotic and biotic variables. Relationships with turbidity and salinity were similar across multiple species, highlighting the importance of these variables in the functioning of communal shark nurseries. In particular, turbid environments were especially important for all species at typical oceanic salinities. Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species. Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

No MeSH data available.