Movement, Behavior, and Habitat Use of a Marine Apex Predator, the Scalloped Hammerhead

Wells, R. J. David; TinHan, Thomas C.; Dance, Michael A.; Drymon, J. Marcus; Falterman, Brett; Ajemian, Matthew J.; Stunz, Gregory W.; Mohan, John A.; Hoffmayer, Eric R.; Driggers, William B.; McKinney, Jennifer A.

doi:10.3389/fmars.2018.00321

Cited by 25 publications

(15 citation statements)

References 73 publications

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“…Specifically, females' predicted suitable habitat is deeper than that of males. Habitat use determined from satellite-tagged scalloped hammerheads support these findings; females more frequently use shelf-edge (>200 m isobath) areas compared to shallower depths used by males (Wells et al, 2018). Regardless of the mechanism driving sexual segregation in scalloped hammerheads, additional efforts to understand habitat use by mature females are needed to reveal habitat areas of particular concern for this species, such as potential areas for parturition (Wells et al, 2018).…”

Section: Discussionmentioning

confidence: 78%

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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Section: Discussionmentioning

confidence: 78%

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

et al. 2020

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“…For example, seasonal changes in abundance of scalloped hammerheads at offshore islands in the eastern tropical Pacific have been suggested as possibly related to movements for reproductive purposes and/or parturition, but currents and chlorophyll concentrations may also play a role in long term movements (Bessudo et al, 2011;Ketchum et al, 2014;Nalesso et al, 2019). Wells et al (2018) found scalloped hammerhead movements in the northern Gulf of Mexico to be primarily driven by static bathymetric features rather than dynamic environmental variables and did not observe any seasonal patterns in shark movements. Furthermore, great hammerhead repeated seasonal presence and residency within the Bahamas is also believed to be related to reproduction or foraging, rather than climatic processes (Guttridge et al, 2017).…”

Section: Discussionmentioning

confidence: 93%

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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“…Despite strong characterization of bony fish assemblages along the northwestern GoM shelfedge banks [62,63] and the FGBNMS [64], there have been limited studies on sharks in this region. The discovery of high overlap in tiger shark core ranges along two shelf-edge systems in the GoM highlights the potential influence of these features on the species' distribution as PLOS ONE recently demonstrated for scalloped hammerhead sharks [30]. The only study to document use of shelf-edge banks by tiger sharks in the GoM was conducted by Childs [65], who compiled visual observations from divers and boaters around the FGBNMS and adjacent area.…”

Section: Large-scale Habitat Featuresmentioning

confidence: 99%

“…The GoM is a highly productive marginal sea, home to a diverse community of coastal sharks [11,26,27], including tiger sharks [28]. To date, satellite telemetry has been used to describe the movement patterns and habitat preferences of multiple GoM shark species including scalloped hammerhead (Sphyrna lewini) [29,30], dusky sharks (Carcharhinus obscurus) [31] shortfin makos (Isurus oxyrinchus) [32], and whale sharks (Rhincodon typus) [33,34]. While all life stages of tiger shark are known to occur in the GoM [11,25,28], detailed habitat use has never been quantified.…”

Section: Introductionmentioning

confidence: 99%

Movement patterns and habitat use of tiger sharks (Galeocerdo cuvier) across ontogeny in the Gulf of Mexico

et al. 2020

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The tiger shark (Galeocerdo cuvier) is globally distributed with established coastal and open-ocean movement patterns in many portions of its range. While all life stages of tiger sharks are known to occur in the Gulf of Mexico (GoM), variability in habitat use and movement patterns over ontogeny have never been quantified in this large marine ecosystem. To address this data gap we fitted 56 tiger sharks with Smart Position and Temperature transmitting tags between 2010 and 2018 and examined seasonal and spatial distribution patterns across the GoM. Additionally, we analyzed overlap of core habitats (i.e., 50% kernel density estimates) among individuals relative to large benthic features (oil and gas platforms, natural banks, bathymetric breaks). Our analyses revealed significant ontogenetic and seasonal differences in distribution patterns as well as across-shelf (i.e., regional) and sex-linked variability in movement rates. Presumably sub-adult and adult sharks achieved significantly higher movement rates and used off-shelf deeper habitats at greater proportions than juvenile sharks, particularly during the fall and winter seasons. Further, female maximum rate of movement was higher than males when accounting for size. Additionally, we found evidence of core regions encompassing the National Oceanographic and Atmospheric Administration designated Habitat Areas of Particular Concern (i.e., shelf-edge banks) during cooler months, particularly by females, as well as 2,504 oil and gas platforms. These data provide a baseline for future assessments of environmental impacts, such as climate variability or oil spills, on tiger shark movements and distribution in the region. Future

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Movement, Behavior, and Habitat Use of a Marine Apex Predator, the Scalloped Hammerhead

Cited by 25 publications

References 73 publications

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

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

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

Movement patterns and habitat use of tiger sharks (Galeocerdo cuvier) across ontogeny in the Gulf of Mexico

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