First Verified Record of the Smooth Hammerhead (Sphyrna zygaena) in Coastal Waters of the Northern Gulf of Mexico with a Review of their Occurrence in the Western North Atlantic Ocean

Deacy, Bethany M.; Moncrief-Cox, Heather E.; Carlson, John K.

doi:10.1656/058.019.0105

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…Smooth hammerheads have a circumglobal distribution in coastal and oceanic waters and occupy a wider latitudinal range than other sphyrnids (Compagno, 1984). Catch records from a variety of locations suggest that juveniles and sub-adults [<265 cm total length (TL)] are more common in inshore waters over coastal shelves, with larger individuals (>265 cm TL) found more frequently offshore (Diemer et al, 2011;Clarke et al, 2015;Francis, 2016;Deacy et al, 2020). This species is capable of long distance movements (e.g., 6,610 km over 150 days; Santos and Coelho, 2018), but also shows high levels of resident behavior within restricted areas (at least 80 days; Diemer et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Movements and Habitat Use of Juvenile Smooth Hammerhead Sharks in the Western North Atlantic Ocean and Significance for Management

et al. 2020

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Upper trophic level predators dramatically impacted by fisheries include the large-bodied hammerhead sharks, which have become species of conservation concern worldwide. Implementing spatial management for conservation of hammerhead populations requires knowledge of temporal distribution patterns and habitat use, identification of essential habitat for protection, and quantification of interactions with human activities. There is little such information for the smooth hammerhead shark, Sphyrna zygaena. We used fin-mounted satellite tags to examine the movements and habitat use of juvenile smooth hammerheads, a demographic segment particularly threatened by exploitation. Six sharks were tagged off the US mid-Atlantic and tracked for 49-441 days (mean 187 ± 136 days). Sharks consistently showed area-restricted movements within a summer core area in waters of the New York Bight and a winter core area off Cape Hatteras, North Carolina, with directed movements between them in autumn. There was high overlap of shark winter core area use and the Mid-Atlantic Shark Area (MASA)-a 7 month per year, bottom-longline fishery closure-indicating that this area closure offers seasonal reduction in fishing pressure for this species. Based on timing of shark movements and the MASA closure, protection for juvenile smooth hammerheads may be increased by beginning the closure period 1 month earlier than currently scheduled. Generalized additive mixed models revealed that area-restricted movements of sharks in their summer and winter core areas coincided with high primary productivity, and elevated sea surface temperature. Consistency in use of summer and winter core areas suggests that the coastal waters of the New York Bight and Cape Hatteras, North Carolina could be considered for Essential Fish Habitat designation for this species. This study reveals the first high resolution movements and habitat use for smooth hammerheads in the western North Atlantic to inform management planning for this population.

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Section: Introductionmentioning

confidence: 99%

Seasonal Movements and Habitat Use of Juvenile Smooth Hammerhead Sharks in the Western North Atlantic Ocean and Significance for Management

et al. 2020

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“…While the approach implemented here re ects the HS for the target species rather than their actual distribution -which is often limited by biogeographic barriers and the dispersal ability of the species (Ferretti et al, 2008). A similar situation is observed for S. zygaena in both the Caribbean Sea (Deacy et al, 2020) and the northern coasts of Australian (CSIRO, 2022; iBOL, 2023). On the other hand, the cases of underpredictions relative to the range recognized by the IUCN (IUCN, 2023) largely re ect the complete absence of occurrence points for the region in the GBIF database (GBIF, 2022).…”

Section: Discussionmentioning

confidence: 84%

Shifts in the habitat suitability for large hammerhead sharks under climate change

Santos,

Borges,

Guerreiro

et al. 2023

Preprint

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One of the chief consequences of climate change is the worldwide redistribution of species in the pursue of physiologically and ecologically favourable conditions. As part of one of the most threatened groups of vertebrates, assessing how climate change may affect the distribution patterns of key shark species is essential for their long-term conservation and management. The present study aims to assess how climate change projections (based on the representative concentration pathways 2.6, 4.5, 6.0, and 8.5) for the middle and end of the century may affect the global patterns of habitat suitability (HS) for large hammerhead sharks – a unique and particularly threatened group of elasmobranchs. Here, a decline in the average HS is projected for both Sphyrna lewini and Sphyrna zygaena, with the scale of HS decline generally increasing with time and RCP severity, while an increase in HS is generally projected for Sphyrna mokarran, albeit reduced over the long-term and overturned under long-term RCP8.5. Meanwhile, poleward shifts are projected for all three species, with considerable tropical declines for both S. lewini and S. zygaena. Additionally, regional shifts in suitability have the potential to affect population connectivity, the access to key habitats, and levels of exposure to other anthropogenic pressures, along with the effectiveness of conservation and management efforts. Taken together, these results showcase the importance of climate change for species’ extinction risk assessment and the urgency of its consideration for the design and implementation of conservation measures tailored to the oceans of tomorrow.

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Distribution and relative abundance of scalloped (Sphyrna lewini) and Carolina (S. gilberti) hammerheads in the western North Atlantic Ocean

et al. 2021

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First Verified Record of the Smooth Hammerhead (Sphyrna zygaena) in Coastal Waters of the Northern Gulf of Mexico with a Review of their Occurrence in the Western North Atlantic Ocean

Cited by 3 publications

References 11 publications

Seasonal Movements and Habitat Use of Juvenile Smooth Hammerhead Sharks in the Western North Atlantic Ocean and Significance for Management

Seasonal Movements and Habitat Use of Juvenile Smooth Hammerhead Sharks in the Western North Atlantic Ocean and Significance for Management

Shifts in the habitat suitability for large hammerhead sharks under climate change

Distribution and relative abundance of scalloped (Sphyrna lewini) and Carolina (S. gilberti) hammerheads in the western North Atlantic Ocean

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