Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why
Unprovoked shark bites have increased over the last three decades, yet they are still relatively rare. Bull sharks are globally distributed throughout rivers, estuaries, nearshore areas and continental shelf waters, and are capable of making long distance movements between tropical and temperate reg...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-08-01
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| Series: | Biology |
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| Online Access: | https://www.mdpi.com/2079-7737/12/9/1189 |
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| author | Amy F. Smoothey Yuri Niella Craig Brand Victor M. Peddemors Paul A. Butcher |
| author_facet | Amy F. Smoothey Yuri Niella Craig Brand Victor M. Peddemors Paul A. Butcher |
| author_sort | Amy F. Smoothey |
| collection | DOAJ |
| description | Unprovoked shark bites have increased over the last three decades, yet they are still relatively rare. Bull sharks are globally distributed throughout rivers, estuaries, nearshore areas and continental shelf waters, and are capable of making long distance movements between tropical and temperate regions. As this species is implicated in shark bites throughout their range, knowledge of the environmental drivers of bull shark movements are important for better predicting the likelihood of their occurrence at ocean beaches and potentially assist in reducing shark bites. Using the largest dataset of acoustically tagged bull sharks in the world, we examined the spatial ecology of 233 juvenile and large (including sub-adult and adult) bull sharks acoustically tagged and monitored over a 5.5-year period (2017–2023) using an array of real-time acoustic listening stations off 21 beaches along the coast of New South Wales, Australia. Bull sharks were detected more in coastal areas of northern NSW (<32° S) but they travelled southwards during the austral summer and autumn. Juveniles were not detected on shark listening stations until they reached 157 cm and stayed north of 31.98° S (Old Bar). Intra-specific diel patterns of occurrence were observed, with juveniles exhibiting higher nearshore presence between 20:00 and 03:00, whilst the presence of large sharks was greatest from midday through to 04:00. The results of generalised additive models revealed that large sharks were more often found when water temperatures were higher than 20 °C, after >45 mm of rain and when swell heights were between 1.8 and 2.8 m. Understanding the influence that environmental variables have on the occurrence of bull sharks in the coastal areas of NSW will facilitate better education and could drive shark smart behaviour amongst coastal water users. |
| first_indexed | 2024-03-10T23:01:09Z |
| format | Article |
| id | doaj.art-25e3d74cbf06415da99d61b8055b37eb |
| institution | Directory Open Access Journal |
| issn | 2079-7737 |
| language | English |
| last_indexed | 2024-03-10T23:01:09Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Biology |
| spelling | doaj.art-25e3d74cbf06415da99d61b8055b37eb2023-11-19T09:38:17ZengMDPI AGBiology2079-77372023-08-01129118910.3390/biology12091189Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and WhyAmy F. Smoothey0Yuri Niella1Craig Brand2Victor M. Peddemors3Paul A. Butcher4NSW Department of Primary Industries, Fisheries Research, Sydney Institute of Marine Science, Mosman, NSW 2088, AustraliaDepartment of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW 2113, AustraliaNSW Department of Primary Industries, Fisheries Research, National Marine Science Centre, Coffs Harbour, NSW 2450, AustraliaNSW Department of Primary Industries, Fisheries Research, Sydney Institute of Marine Science, Mosman, NSW 2088, AustraliaNSW Department of Primary Industries, Fisheries Research, National Marine Science Centre, Coffs Harbour, NSW 2450, AustraliaUnprovoked shark bites have increased over the last three decades, yet they are still relatively rare. Bull sharks are globally distributed throughout rivers, estuaries, nearshore areas and continental shelf waters, and are capable of making long distance movements between tropical and temperate regions. As this species is implicated in shark bites throughout their range, knowledge of the environmental drivers of bull shark movements are important for better predicting the likelihood of their occurrence at ocean beaches and potentially assist in reducing shark bites. Using the largest dataset of acoustically tagged bull sharks in the world, we examined the spatial ecology of 233 juvenile and large (including sub-adult and adult) bull sharks acoustically tagged and monitored over a 5.5-year period (2017–2023) using an array of real-time acoustic listening stations off 21 beaches along the coast of New South Wales, Australia. Bull sharks were detected more in coastal areas of northern NSW (<32° S) but they travelled southwards during the austral summer and autumn. Juveniles were not detected on shark listening stations until they reached 157 cm and stayed north of 31.98° S (Old Bar). Intra-specific diel patterns of occurrence were observed, with juveniles exhibiting higher nearshore presence between 20:00 and 03:00, whilst the presence of large sharks was greatest from midday through to 04:00. The results of generalised additive models revealed that large sharks were more often found when water temperatures were higher than 20 °C, after >45 mm of rain and when swell heights were between 1.8 and 2.8 m. Understanding the influence that environmental variables have on the occurrence of bull sharks in the coastal areas of NSW will facilitate better education and could drive shark smart behaviour amongst coastal water users.https://www.mdpi.com/2079-7737/12/9/1189acoustic telemetryintra-specific variabilityanimal movementseasonalityspatialtemporal |
| spellingShingle | Amy F. Smoothey Yuri Niella Craig Brand Victor M. Peddemors Paul A. Butcher Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why Biology acoustic telemetry intra-specific variability animal movement seasonality spatial temporal |
| title | Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why |
| title_full | Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why |
| title_fullStr | Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why |
| title_full_unstemmed | Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why |
| title_short | Bull Shark (<i>Carcharhinus leucas</i>) Occurrence along Beaches of South-Eastern Australia: Understanding Where, When and Why |
| title_sort | bull shark i carcharhinus leucas i occurrence along beaches of south eastern australia understanding where when and why |
| topic | acoustic telemetry intra-specific variability animal movement seasonality spatial temporal |
| url | https://www.mdpi.com/2079-7737/12/9/1189 |
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