A critical evaluation of adult blacktip shark, Carcharhinus limbatus, distribution off the United States East Coast

Bowers, Mary E.; Kajiura, Stephen M.

doi:10.1007/s10641-023-01449-3

Cited by 5 publications

(2 citation statements)

References 64 publications

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“…Although not all trends were visually linear, which is unsurprising given the natural variability in climate data, the highly suitable habitat appeared to decrease throughout the time series for all SCS and most LCS. Directional trends in DEPTH, DFS, and COA indicated potential shifts north along the Atlantic (e.g., small Atlantic sharpnose, bonnethead, and blacktip sharks) or toward deeper offshore waters in both regions (e.g., small blacktip sharks in the Atlantic, small and large tiger sharks in the GOM, and small Atlantic sharpnose sharks in both regions), which mirrors patterns observed for several teleost fishes (Bowers & Kajiura, 2023;Kleisner et al, 2017;Nye et al, 2009). Directional trends were less common for LCS compared to SCS, and besides small blacktip sharks, significant trends were relatively small.…”

Section: Habitat Metricssupporting

confidence: 70%

Niche structure and habitat shifts for coastal sharks of the US Southeast Atlantic and Gulf of Mexico

O'Brien,

Cortés,

Driggers

et al. 2024

Fisheries Oceanography

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Understanding spatial ecology and predicting animal movements in response to environmental changes, such as anthropogenic climate change and multidecadal variability, is critical for effective conservation strategies. Niche structuring is key to some coastal shark species and size classes coexisting in the US Atlantic and Gulf of Mexico to limit interspecific and intraspecific interaction. Data from four fishery‐independent bottom longline surveys were used to evaluate the abiotic ecological niches of eight species of small and large coastal sharks. Gaussian mixture models separated length composition data into 14 size categories for ecological niche analysis. Generalized additive mixed effect models were fit and coupled with output from dynamic high‐resolution ocean models to predict suitable abiotic habitats, evaluate potential shifts in distribution, and explore the impacts of large‐scale climatological trends on abiotic habitats from 1994 to 2019. The abiotic niche for small coastal sharks generally tended toward warmer, high salinity, shallow bottom waters close to shore. No overarching niche was found for large coastal sharks, but appreciable ontogenetic differences were seen. Most taxa analyzed exhibited declining annual trends in higher quality habitats, particularly during fall months. The analysis provided evidence of shifts north along the Atlantic, to deeper offshore waters in the Atlantic and Gulf of Mexico, and the potential to redistribute in response to multidecadal climate variability for multiple species. The analytical framework described could aid in developing various spatiotemporal management measures, and results provide insight into the habitat characteristics of several species over broad spatiotemporal ranges and through ontogeny.

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Section: Habitat Metricssupporting

confidence: 70%

Niche structure and habitat shifts for coastal sharks of the US Southeast Atlantic and Gulf of Mexico

O'Brien,

Cortés,

Driggers

et al. 2024

Fisheries Oceanography

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“…Waters of the Mid-Atlantic Bight (MAB) extend from coastal Massachusetts to North Carolina and provide critical habitat for many species of migratory sharks, especially during productive summer months (Curtis et al, 2018;Merson & Pratt, 2007;Shipley et al, 2021), particularly those comprising the families Carcharhinidae and Lamnidae. In nearshore waters of the MAB, the migratory shark assemblage is dominated by sandbar (Carcharhinus plumbeus Nardo Valenciennes 1839) occurring more frequently (Bowers & Kajiura, 2023). In more offshore waters the migratory shark assemblage becomes more taxonomically diverse with pelagic species such as blue (Prionace glauca Linnaeus 1758), common thresher (Alopias vulpinus Bonnaterre 1788), shortfin mako (Isurus oxyrinchus Rafinesque 1810), and white (Carcharodon carcharias Linnaeus 1758) sharks.…”

Section: Introductionmentioning

confidence: 99%

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Olin,

Urakawa,

Frisk

et al. 2023

Journal of Fish Biology

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The abundances of migratory shark species observed throughout the Mid‐Atlantic Bight (MAB) during productive summer months suggest that this region provides critical habitat and prey resources to these taxa. However, the principal prey assemblages sustaining migratory shark biomass in this region are poorly defined. We applied high‐throughput DNA metabarcoding to shark feces derived from cloacal swabs across nine species of Carcharhinid and Lamnid sharks to (1) quantify the contribution of broad taxa (e.g., invertebrates, fishes) supporting shark biomass during seasonal residency in the MAB and (2) determine whether the species displayed distinct dietary preference indicative of resource partitioning. DNA metabarcoding resulted in high taxonomic (species‐level) resolution of shark diets with actinopterygian and elasmobranch fishes as the dominant prey categories across the species. DNA metabarcoding identified several key prey groups consistent across shark taxa that are likely integral for sustaining their biomass in this region, including Atlantic menhaden (Brevoortia tyrannus), Atlantic mackerel (Scomber scombrus), and benthic elasmobranchs, including skates. Our results are consistent with previously published stomach content data for the shark species of similar size range in the Northwest Atlantic Ocean, supporting the efficacy of cloacal swab DNA metabarcoding as a minimally invasive diet reconstruction technique. The high reliance of several shark species on Atlantic menhaden could imply wasp‐waist food‐web conditions during the summer months, whereby high abundances of forage fishes sustain a diverse suite of migratory sharks within a complex, seasonal food web.

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Long‐term effects of climate change on juvenile bull shark migratory patterns

Matich,

Plumlee,

Bubley

et al. 2024

Journal of Animal Ecology

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Seasonal variability in environmental conditions is a strong determinant of animal migrations, but warming temperatures associated with climate change are anticipated to alter this phenomenon with unknown consequences. We used a 40‐year fishery‐independent survey to assess how a changing climate has altered the migration timing, duration and first‐year survival of juvenile bull sharks (Carcharhinus leucas). From 1982 to 2021, estuaries in the western Gulf of Mexico (Texas) experienced a mean increase of 1.55°C in autumn water temperatures, and delays in autumn cold fronts by ca. 0.5 days per year. Bull shark migrations in more northern estuaries concomitantly changed, with departures 25–36 days later in 2021 than in 1982. Later, migrations resulted in reduced overwintering durations by up to 81 days, and the relative abundance of post‐overwintering age 0–1 sharks increased by >50% during the 40‐year study period. Yet, reductions in prey availability were the most influential factor delaying migrations. Juvenile sharks remained in natal estuaries longer when prey were less abundant. Long‐term declines in prey reportedly occurred due to reduced spawning success associated with climate change based on published reports. Consequently, warming waters likely enabled and indirectly caused the observed changes in shark migratory behaviour. As water temperatures continue to rise, bull sharks in the north‐western Gulf of Mexico could forgo their winter migrations in the next 50–100 years based on current trends and physiological limits, thereby altering their ecological roles in estuarine ecosystems and recruitment into the adult population. It is unclear if estuarine food webs will be able to support changing residency patterns as climate change affects the spawning success of forage species. We expect these trends are not unique to the western Gulf of Mexico or bull sharks, and migratory patterns of predators in subtropical latitudes are similarly changing at a global scale.

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A critical evaluation of adult blacktip shark, Carcharhinus limbatus, distribution off the United States East Coast

Cited by 5 publications

References 64 publications

Niche structure and habitat shifts for coastal sharks of the US Southeast Atlantic and Gulf of Mexico

Niche structure and habitat shifts for coastal sharks of the US Southeast Atlantic and Gulf of Mexico

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Long‐term effects of climate change on juvenile bull shark migratory patterns

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