Long-term satellite tracking reveals variable seasonal migration strategies of basking sharks in the north-east Atlantic

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

doi:10.1038/srep42837

Cited by 47 publications

(52 citation statements)

References 56 publications

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“…Baduini (1995) and Darling and Keogh (1994) reported that individual basking sharks spent up to 30 or 42 days in Monterey Bay, CA, or Clayoquot Sound, Vancouver Island, Canada, respectively. Similar short-term residence times have been reported for basking sharks in coastal regions in the Atlantic Ocean (Sims et al, 2003;Gore et al, 2008;Sims, 2008;Skomal et al, 2009;Curtis et al, 2014;Doherty et al, 2017;Braun et al, 2018).…”

Section: Geographic Movements and Essential Habitatsupporting

confidence: 62%

“…In the fall and winter they were offshore but were 3,260 km apart in late January. North-South seasonal movements are also reported for sharks in both the East and West Atlantic (Sims et al, 2003;Cotton et al, 2005;Skomal et al, 2009;Doherty et al, 2017;Braun et al, 2018). Movements in the West Atlantic Ocean, however, are more extensive than in the East and sharks crossed the equator, moving as far south as Brazil.…”

Section: Geographic Movements and Essential Habitatmentioning

confidence: 88%

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Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

et al. 2018

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To fill data gaps on movements, behaviors and habitat use, both near-and offshore, two programs were initiated to deploy satellite tags on basking sharks off the coast of California. Basking sharks are large filter-feeding sharks that are second in size only to whale sharks. Similar to many megafauna populations, available data suggest that populations are below historic levels. In the eastern North Pacific (ENP) Ocean, the limited information on basking sharks comes from nearshore habitats where they forage. From 2010 to 2011, four sharks were tagged with pop-off satellite archival tags with deployments ranging from 9 to 240 days. The tags provided both transmitted and archived data on habitat use and geographic movement patterns. Nearshore, sharks tended to move north in the summer and prefer shelf and slope habitat around San Diego, Point Conception and Monterey Bay. The two sharks with 180 and 240 days deployments left the coast in the summer and fall. Offshore their paths diverged and by January one shark had moved to near the tip of the Baja Peninsula, Mexico and the other to the waters near Hawaii, USA. Vertical habitat use was variable both within and among individuals and changed as sharks moved offshore. Nearshore, most time was spent in the mixed layer but sharks did spend hours in cold waters below the mixed layer. Offshore vertical movements depended on location. The shark that went to Hawaii had a distinct diel pattern, with days spent at ∼450-470 m and nights at ∼250-300 m and almost no time in surface waters, corresponding with the diel migration of a specific portion of the deep scattering layer. The shark that moved south along the Baja Peninsula spent progressively more time in deep water but came to the surface daily. Movement patterns and shifts in vertical habitat and use are likely linked to shifts in prey availability and oceanography. Data collected indicate the potential for large-scale movements and the need for international dialogue in any recovery efforts.

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Section: Geographic Movements and Essential Habitatsupporting

confidence: 62%

Section: Geographic Movements and Essential Habitatmentioning

confidence: 88%

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

et al. 2018

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“…Protecting long-lived, highly migratory marine species is challenging since they encounter multiple threats across broad areas and in different life stages Maxwell et al, 2013;Lascelles et al, 2014), often requiring multi-faceted and multi-national conservation efforts (Blumenthal et al, 2006;Gore et al, 2008;Maxwell et al, 2011;Croxall et al, 2012;Pikesley et al, 2013b;Doherty et al, 2017). Several studies have used satellite telemetry to describe the horizontal movement data of large marine vertebrates Block et al, 2011;Hawkes et al, 2011;Hazen et al, 2012;Yurkowski et al, 2016;Citta et al, 2017;Vaudo et al, 2017) and to determine overlap with anthropogenic threats such as fisheries (seabirds: Suryan et al, 2007;Bugoni et al, 2009;Žydelis et al, 2011;sea turtles: da Silva et al, 2011;Witt et al, 2011;Revuelta et al, 2015; marine mammals: Geschke and Chilvers, 2010;Rosenbaum et al, 2014;sharks: Holmes et al, 2014), shipping (marine mammals: Mate et al, 1997;Schorr et al, 2009), and in-water habitat degradation (seabirds: Montevecchi et al, 2012;marine mammals: Johnson and Tyack, 2003;Rosenbaum et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Informing Marine Protected Area Designation and Management for Nesting Olive Ridley Sea Turtles Using Satellite Tracking

Dawson

Formia²,

Agamboué³

et al. 2017

Front. Mar. Sci.

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Understanding the horizontal and vertical habitat of olive ridley sea turtles (Lepidochelys olivacea), a threatened species, is critical for determining regions for protection and relevant gear modifications that may effectively reduce bycatch, the largest threat to this species. Satellite transmitters were used to determine the movement and dive behavior of 21 female olive ridley turtles tagged in Pongara National Park, Gabon during the 2012, 2013, and 2015 nesting seasons. A switching state-space model was used to filter the tracking data and categorize the internesting and post-nesting movements. Gridded utilization distribution (UD) home range analysis of tracking data revealed that the entire core habitat occurred in the Komo Estuary during the internesting period. Within the Komo Estuary, 58% of this core UD occurred in shipping lanes. Dive data from the 2015 tagging season revealed that during the internesting period, turtles spent the majority of their time resting on the estuary seabed. Approximately 20% of all dive time was spent on the bottom and all maximum dive depths corresponded to the depth of the seabed, indicating that bottom set gear during the internesting period may pose the greatest potential for fisheries interactions. National parks currently protect many of the nesting sites and the Gabon Bleu initiative has formally designated 10 new marine parks and a network of community and industrial fishing zones; this data was a layer used in determining the park and zone boundaries. Shared use of the estuary by fisheries, shipping, and olive ridley turtles creates a need for management measures to reduce interactions. Thus, the results from this study can further provide detailed information that can be used to support the development of evidence-based management plans.

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“…This is not generally possible for pelagic macropredatory sharks because environmental fields of their schooling fish prey for example are very difficult to obtain over sufficiently large scales to support analysis in relation to pelagic shark movements and behavior (for exceptions see Makris et al, 2006Makris et al, , 2009. Previous biotelemetry studies in the North Atlantic have revealed that basking sharks undertake extensive horizontal and vertical movements associated with oceanic and inner-shelf frontal zones, areas typically characterized by high primary production and zooplankton densities (Sims et al, 2003;Skomal et al, 2009;Curtis et al, 2014;Doherty et al, 2017), and also highlighted behavioral shifts in vertical movements linked to changes in the behavior of zooplankton (Sims et al, 2005). In contrast to filter feeding, the blue shark (Prionace glauca) is an oceanic, ram-feeding macropredator occurring in all tropical and temperate seas; in the Atlantic Ocean, blue sharks range from Newfoundland to Argentina in the west, over the entire mid-Atlantic, and from Norway to South Africa in the east (Compagno, 1984;Motta and Huber, 2012).…”

Section: Introductionmentioning

confidence: 99%

Convergent Foraging Tactics of Marine Predators with Different Feeding Strategies across Heterogeneous Ocean Environments

et al. 2017

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Advances in satellite tracking and archival technologies now allow marine animal movements and behavior to be recorded at much finer temporal scales, providing a more detailed ecological understanding that can potentially be applicable to conservation and management strategies. Pelagic sharks are commercially exploited worldwide with current concerns that populations are declining, however, how pelagic sharks use exploited environments remains enigmatic for most species. Here we analyzed high-resolution dive depth profiles of two pelagic shark species with contrasting feeding strategies to investigate movement patterns in relation to environmental heterogeneity. Seven macropredatory blue (Prionace glauca) and six plankton-feeding basking (Cetorhinus maximus) sharks were tagged with pop-off satellite-linked archival tags in the North Atlantic Ocean to examine habitat use and investigate the function of dives. We grouped dives of both species into five major categories based on the two-dimensional dive profile shape. Each dive-shape class presented similar frequency and characteristics among the two species with U-and V-shaped dives predominating. We tested the spatial occurrence of different U-and V-shape dive parameters in response to environmental field gradients and found that mean depth and mean depth range decreased with increasing levels of primary productivity (chlorophyll "a"), whereas ascent velocities displayed a positive correlation. The results suggest that a planktivore and a macropredator responded behaviourally in similar ways to environmental heterogeneity. This indicates fine-scale dive profiles of shark species with different feeding strategies can be used to identify key marine habitats, such as foraging areas where sharks aggregate and which may represent target areas for conservation.

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Long-term satellite tracking reveals variable seasonal migration strategies of basking sharks in the north-east Atlantic

Cited by 47 publications

References 56 publications

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

Informing Marine Protected Area Designation and Management for Nesting Olive Ridley Sea Turtles Using Satellite Tracking

Convergent Foraging Tactics of Marine Predators with Different Feeding Strategies across Heterogeneous Ocean Environments

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