Environmental drivers of abundance and residency of a large migratory shark, Carcharhinus leucas, inshore of a dynamic western boundary current

Lee, K. A.; Smoothey, Amy F.; Harcourt, Robert; Roughan, Moninya; Butcher, Paul A.; Peddemors, Victor M.

doi:10.3354/meps13052

Cited by 33 publications

(44 citation statements)

References 73 publications

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“…Such wide latitudinal movements among S. mokarran support known migrations across other areas of the species distribution (especially in the Atlantic Ocean), and are similar to those recorded for regional carcharhinids such as the bull shark (Carcharhinus leucas) (Lee et al, 2019), and for the reef manta ray (M. alfredi) (Couturier et al, 2011). These movements may reflect physiologically driven preferences for sub-tropical and tropical water temperatures, which in the austral summer come with abundant inshore food sources such as schooling Australian cownose rays (Rhinoptera neglecta) (Tagliafico et al, 2020).…”

Section: Discussionsupporting

confidence: 78%

Predicting Geographic Ranges of Marine Animal Populations Using Stable Isotopes: A Case Study of Great Hammerhead Sharks in Eastern Australia

et al. 2020

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Determining the geographic range of widely dispersed or migratory marine organisms is notoriously difficult, often requiring considerable costs and typically extensive tagging or exploration programs. While these approaches are accurate and can reveal important information on the species, they are usually conducted on only a small number of individuals and can take years to produce relevant results, so alternative approaches may be preferable. The presence of latitudinal gradients in stable carbon isotope compositions of marine phytoplankton offers a means to quickly determine likely geographic population ranges of species that rely on productivity from these resources. Across sufficiently large spatial and temporal scales, the stable carbon isotopes of large coastal or pelagic marine species should reflect broad geographic patterns of resource use, and could be used to infer geographic ranges of marine populations. Using two methods, one based on a global mechanistic model and the other on targeted low-cost latitudinal sampling of fishes, we demonstrate and compare these stable isotope approaches to determine the core population geography of an apex predator, the great hammerhead (Sphyrna mokarran). Both methods indicated similar geographic ranges and suggested that S. mokarran recorded in south-eastern Australia are likely to be from more northern Australian waters. These approaches could be replicated in other areas where coastlines span predictable geographic gradients in isotope values and be used to determine the core population geography of highly mobile species to inform management decisions.

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Section: Discussionsupporting

confidence: 78%

Predicting Geographic Ranges of Marine Animal Populations Using Stable Isotopes: A Case Study of Great Hammerhead Sharks in Eastern Australia

et al. 2020

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“…Here, we found seasonal changes in water temperature to be a key predictor of shark occurrence, with the probability of bull sharks being present in the Harbour increasing when water temperature was ~22°C and generally increasing with increasing temperature. Such seasonal change in water temperature has previously been shown to influence the distribution and abundance of bull sharks, with sharks present in sub-tropical and temperate waters on the east coast of Australia when sea surface temperature was between 20 and 26°C, with peak abundance at 24°C 22 . Similar seasonal patterns of temperature-mediated movements have been found for other elasmobranchs 21,47,70–73 .…”

Section: Discussionmentioning

confidence: 98%

“…Lee et al . 22 highlighted the importance of estuaries as a key predictor for sub-adult and adult bull shark abundance along the east coast of Australia, yet interestingly found that bull sharks occurred more at mid-shelf habitats (20 to 60 m) compared to nearshore areas (<20 m water depth). Here, detections of tagged bull sharks decreased over the monitoring period, with the greatest decline occurring between 2010 and 2011.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, such tolerance enables them to frequent nearshore areas where they may interact more with water-users than other shark species. Studies done on the presence and movement of bull sharks have shown that their behaviours are complex and the propensity of individuals to move or stay, varies across different spatial and temporal scales and changes according to size and sex of the individual 21,22 . It is well documented that bull sharks, use estuarine and riverine environments, however, most of that work has been done on juveniles in tropical regions 23–27 .…”

Section: Introductionmentioning

confidence: 99%

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Long-term patterns of abundance, residency and movements of bull sharks (Carcharhinus leucas) in Sydney Harbour, Australia

Smoothey

Lee

Peddemors

2019

Sci Rep

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Bull sharks (Carcharhinus leucas) are known to frequent nearshore environments, particularly estuaries, resulting in interactions with humans. Knowledge of the behaviour of large individuals in temperate, estuarine environments is limited. This acoustic telemetry study reports on residency and movement patterns of 40 sub-adult and adult bull sharks in Sydney Harbour, a large temperate estuary, over seven years. Bull sharks exhibited clear seasonal patterns in their occurrence during the austral summer and autumn, with abundance peaking in January and February. This pattern was consistent between sexes and across all sizes. Bull sharks displayed weak diel differences in their spatial distribution, with individuals using areas further from the Harbour entrance more frequently during the day and at low tides. A diel pattern in depth use was apparent, with sharks utilising deeper water during daytime and moving shallower at night. Bull sharks had high individual inter-annual variability in their spatial distribution, however, when data were aggregated among all individuals and years, two locations of increased use were identified. Water temperature was the key predictor for seasonal movements and return behaviour to this estuary, suggesting that increasing water temperatures as a result of climate change may lead to higher shark abundance and possibly longer periods of residency in Sydney Harbour. Understanding the drivers for bull shark abundance and distribution will hopefully facilitate better education and shark smart behaviour by estuarine water-users, especially during summer and autumn months.

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“…These efforts would be aided by the application of acoustic and/or satellite telemetry, which would provide insights that complement traditional monitoring programs. For example, electronic tags would serve to verify habitat suitability predictions for animals outside of the range of the current study area (e.g., Lee et al, 2019). In addition, telemetry would allow investigations of long-term population dynamics, including partial migrations, which have been shown for larger, more vagile species examined in the current study (e.g., scalloped hammerhead, Hoyos-Padilla et al, 2014).…”

Section: Discussionmentioning

confidence: 98%

Defining Sex-Specific Habitat Suitability for a Northern Gulf of Mexico Shark Assemblage

et al. 2020

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Understanding the factors that influence species' distributions is crucial for implementing effective management and conservation practices, yet difficult for highly vagile species like sharks. Many shark species demonstrate either spatial and/or temporal sexual segregation, further confounding accurate quantification of habitat suitability. Given the importance of understanding spatiotemporal patterns in the distribution of coastal shark assemblages, we sought to quantify sex-specific abiotic factors that influence seasonal variation in a coastal shark assemblage using data from a long-term fisheriesindependent bottom longline program in the northern Gulf of Mexico. Catch data (individuals/100 hooks/hour) were coupled with a suite of potentially predictive variables: surface and bottom values for temperature (• C) and salinity (psu), sea surface height (m), three-dimensional surface and bottom current velocity (u, v, w, in m/s), bottom dissolved oxygen (mg/l), depth (m), substrate grain size (mm), daylength (min), and distance from shore (km). Data were analyzed using boosted regression trees (BRT) to describe the relationships between catch data and environmental factors potentially influencing sex-specific species distribution and abundance. Between May 2006 and November 2018, we conducted 1,226 bottom longline sets and caught 13,742 individuals encompassing 67 species. The majority of the animals captured (74%) were elasmobranchs, primarily sharks. Two species from each of the following three categories were selected for further analyses: small coastal sharks (Atlantic sharpnose shark Rhizoprionodon terraenovae and blacknose shark Carcharhinus acronotus), large coastal sharks (blacktip shark C. limbatus and sandbar shark C. plumbeus), and shelfassociated sharks (smoothhound sharks, Mustelus spp. and scalloped hammerhead Sphyrna lewini). Depth and distance from shore were the strongest predictors of distribution and relative abundance, followed by longitude and bottom salinity; other factors (e.g., temperature, daylength, substrate grain size) were less predictive. For the six species examined, predictive factors were often the same for males and females, although the range of preferred values varied. Surprisingly, the importance of these

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Environmental drivers of abundance and residency of a large migratory shark, Carcharhinus leucas, inshore of a dynamic western boundary current

Cited by 33 publications

References 73 publications

Predicting Geographic Ranges of Marine Animal Populations Using Stable Isotopes: A Case Study of Great Hammerhead Sharks in Eastern Australia

Predicting Geographic Ranges of Marine Animal Populations Using Stable Isotopes: A Case Study of Great Hammerhead Sharks in Eastern Australia

Long-term patterns of abundance, residency and movements of bull sharks (Carcharhinus leucas) in Sydney Harbour, Australia

Defining Sex-Specific Habitat Suitability for a Northern Gulf of Mexico Shark Assemblage

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