Seasonal changes in basking shark vertical space use in the north-east Atlantic

Doherty, Philip D.; Baxter, John M.; Godley, B. J.; Graham, Rachel T.; Hall, Jackie; Hawkes, Lucy A.; Henderson, S. M.; Johnson, Louise; Speedie, Colin; Witt, Matthew J.

doi:10.1007/s00227-019-3565-6

Cited by 12 publications

(6 citation statements)

References 70 publications

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“…However, in our results, both inshore and offshore regions were highlighted as areas of high habitat suitability. This is particularly evident in the bimodal effect of the bathymetry predictor, where basking shark habitat suitability was observed to be highest in very shallow depths (<100 m), and again at depths between 200 and 500 m. This result is consistent with previous work where basking sharks have been shown to exhibit seasonal vertical space use in the Northeast Atlantic, with tagged individuals occupying shallow depths (<100 m) in the summer months and depths greater than 1,000 m in late winter/early spring (Doherty et al, 2019).…”

Section: Drivers Of Predicted Basking Shark Distributionsupporting

confidence: 90%

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Finucci

Duffy²,

Brough

et al. 2021

Front. Mar. Sci.

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Basking sharks (Cetorhinus maximus) were widely reported throughout New Zealand waters. Once commonly observed, and sometimes in large numbers, basking sharks are now infrequently reported. Basking shark observations are known to be highly variable across years, and their distribution and occurrence have been shown to be influenced by environmental predictors such as thermal fronts, chl-a concentration, and the abundance of prey (zooplankton). Little is known of basking sharks in the South Pacific and more information on distribution, habitat use, and migratory patterns is required to better understand the species’ regional ecology. Here, we used bootstrapped Habitat Suitability Models [HSM, ensembled from Boosted Regression Tree (BRT) and Random Forest (RF) models] to determine the drivers of basking shark distribution, predict habitat suitability and estimated uncertainty in the South Pacific for the first time. High−resolution environmental (1 km2 grid resolution) and biotic data, including inferred prey species, and all available basking shark records across New Zealand’s Exclusive Economic Zone (EEZ) were included in the ensemble HSMs. The most influential driver of modeled basking shark distribution was vertical flux of particulate organic matter at the seabed, which may indicate higher levels of primary production in the surface ocean and higher prey density in the mesopelagic zone and at the seafloor. The BRT and RF models had good predictive power (AUC and TSS > 0.7) and both models performed similarly with low variability in the model fit metrics. Areas of high basking shark habitat suitability included the east and west coasts of the South Island, Puysegur Ridge, and Auckland Island slope. The outputs produced here could be incorporated into future management framework for assessing threat and conservation needs (e.g., spatially explicit risk assessment) for this regionally protected species, as well as providing guidance for future research efforts (e.g., areas of interest for sampling).

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Section: Drivers Of Predicted Basking Shark Distributionsupporting

confidence: 90%

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Finucci

Duffy²,

Brough

et al. 2021

Front. Mar. Sci.

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“…For instance, blacktip ( Carcharhinus melanopterus ), whitetip ( Triaenodon obesus ) and Caribbean ( Carcharhinus perezi ) reef sharks all show strong patterns of residency (Randall, 1997; Papastamatiou et al, 2010; Bond et al, 2012; Heupel, Lédée & Simpfendorfer, 2018). Some wide‐ranging species, such as basking sharks ( Cetorhinus maximus ; Doherty et al, 2017; Doherty et al, 2019) and spurdog ( Squalus acanthias ; Thorburn et al, 2015) also exhibit residency at certain times of year or in specific locations. Among rajids, only a handful of studies have examined residency (Hunter et al, 2005a; Morel et al, 2013; Neat et al, 2015; Sousa et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…Research on elasmobranch movements has increased in recent years, but most studies have focused on sharks (Heuter et al, 2004; Papastamatiou & Lowe, 2012; Chapman et al, 2015; Doherty et al, 2017; Doherty et al, 2019) and the movement patterns of batoids, especially skates (Rajidae), remain poorly understood (Flowers et al, 2016; Siskey, Shipley & Frisk, 2019). A number of studies have investigated skate movement using capture–recapture data (Little, 1995; Little, 1997; Walker, Howlett & Millner, 1997; King & McFarlane, 2010; Ellis et al, 2011; Peklova et al, 2014; Siskey, Shipley & Frisk, 2019; Bird et al, 2020; Simpson, Humphries & Sims, 2020).…”

Section: Introductionmentioning

confidence: 99%

Movement patterns of a Critically Endangered elasmobranch (Dipturus intermedius) in a Marine Protected Area

Lavender

Aleynik

Dodd

et al. 2021

Aquatic Conservation

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Marine Protected Areas (MPAs) are widely used in marine management, but for mobile species understanding the spatio‐temporal scale of management measures that is required to deliver conservation benefits depends on a detailed knowledge of species’ movements that is often lacking. This is especially the case for species of skate (Rajidae) for which relatively few movement studies have been conducted. In Scotland, the Loch Sunart to the Sound of Jura MPA covering 741 km2 has been designated for the conservation of the Critically Endangered flapper skate (Dipturus intermedius), but fine‐scale movements within this area remain poorly understood. A passive acoustic telemetry study which coupled acoustic tagging of 42 individuals and a static array of 58 receivers was conducted from March 2016 to June 2017. Using acoustic detection time series, angler capture–recapture data and depth time series from archival tags, fine‐scale movements of individuals were investigated. Overall, 33 of the 42 tagged individuals were detected. Residency, site fidelity and transiency were documented. Residency around receivers, lasting from 3 to more than 12 months, was documented in 16 acoustically detected individuals (48%) and all life‐history categories, but was most noticeable among females. Acoustic detections were associated with depth, salinity and season, but there was no evidence that individuals formed close‐knit groups in the areas in which they were detected. Taken together with historical occurrence records of flapper skate, the prevalence and scale of residency documented here suggest that the MPA is sufficiently large to benefit a notable percentage (38 [24–52]%) of skate found in the study area over monthly and seasonal timescales. This result strengthens the case for the use of MPAs to support the conservation of flapper skate and other skate species that display similar movement patterns in areas of high local abundance.

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“…Over short timescales, many elasmobranchs exhibit tidal-driven movement, moving into shallower waters with incoming tides to minimise energy expenditure or predation risk or to forage (Ackerman et al 2000;Wetherbee et al 2007;Starr 2009, 2010). Over diel scales, solar light levels are often linked to vertical movement via DVM, with crepuscular or nocturnal movement into shallower or deeper water (normal and reverse DVM, respectively), and changes in vertical activity (Carey et al 1990;Andrews et al 2009;Doherty et al 2019;Arostegui et al 2020). In many cases, these movements are associated with prey availability, but links to thermoregulation and bioenergetic efficiency are also documented (Matern et al 2000;Sims et al 2006;Papastamatiou et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Environmental cycles and individual variation in the vertical movements of a benthic elasmobranch

Lavender

Aleynik

Dodd³

et al. 2021

Mar Biol

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Trends in depth and vertical activity reflect the behaviour, habitat use and habitat preferences of marine organisms. However, among elasmobranchs, research has focused heavily on pelagic sharks, while the vertical movements of benthic elasmobranchs, such as skate (Rajidae), remain understudied. In this study, the vertical movements of the Critically Endangered flapper skate (Dipturus intermedius) were investigated using archival depth data collected at 2 min intervals from 21 individuals off the west coast of Scotland (56.5°N, −5.5°W) in 2016–17. Depth records comprised nearly four million observations and included eight time series longer than 1 year, forming one of the most comprehensive datasets collected on the movement of any skate to date. Additive modelling and functional data analysis were used to investigate vertical movements in relation to environmental cycles and individual characteristics. Vertical movements were dominated by individual variation but included prolonged periods of limited activity and more extensive movements that were associated with tidal, diel, lunar and seasonal cycles. Diel patterns were strongest, with irregular but frequent movements into shallower water at night, especially in autumn and winter. This research strengthens the evidence for vertical movements in relation to environmental cycles in benthic species and demonstrates a widely applicable flexible regression framework for movement research that recognises the importance of both individual-specific and group-level variation.

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Seasonal changes in basking shark vertical space use in the north-east Atlantic

Cited by 12 publications

References 70 publications

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Movement patterns of a Critically Endangered elasmobranch (Dipturus intermedius) in a Marine Protected Area

Environmental cycles and individual variation in the vertical movements of a benthic elasmobranch

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