The Conservation of the Greenland Shark (<i>Somniosus microcephalus</i>): Setting Scientific, Law, and Policy Coordinates for Avoiding a Species at Risk

Davis, Brendal; VanderZwaag, David; Cosandey-Godin, Aurélie; Hussey, Nigel E.; Kessel, Steven T.; Worm, Boris

doi:10.1080/13880292.2013.805073

Cited by 22 publications

(33 citation statements)

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“…3d, e and see Fig. 1d in Davis et al 2013), indicate correct species identification. Surprisingly, a greater amount of mtDNA genetic diversity than expected was detected among Greenland sharks sampled from Scott Inlet/Sam Ford Trough.…”

Section: Discussionmentioning

confidence: 85%

“…When considering this and taking into account that the largest catch (by mass-kg) of Greenland sharks in Baffin Bay is associated with Greenland halibut trawling activities rather than gillnet (Davis et al 2013), it is certainly possible that juvenile Greenland sharks may occur at other Arctic locations outside of our study sites, including both coastal and offshore sites. Furthermore, our TL estimates from bycatch data were derived from estimated individual total weight as opposed to in situ measurements.…”

Section: Discussionmentioning

confidence: 97%

“…With decreasing ice cover extent and the expansion of fisheries in the Arctic (Christiansen et al 2014), there is concern that this species could become overexploited as bycatch in commercial and artisanal fisheries. A proactive approach to Greenland shark management is therefore being advocated (Davis et al 2013), but data on residency, movement patterns and essential habitats of this species are required particularly for juvenile and reproductively mature size classes.…”

Section: Introductionmentioning

confidence: 99%

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Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

et al. 2014

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Life-stage-based management of marine fishes requires information on juvenile habitat preferences to ensure sustainable population demographics. This is especially important in the Arctic region given very little is known about the life histories of many native species, yet exploitation by developing commercial and artisanal fisheries is increasing as the ice extent decreases. Through scientific surveys and bycatch data from gillnet fisheries, we document captures of rarely reported juvenile Greenland sharks (Somniosus microcephalus; B200 cm total length [TL]) during the ice-free period in the Canadian Arctic. A total of 22 juvenile animals (42 % of total catch; n = 54), including the smallest reliably measured individual of 117 cm TL, were caught on scientific longlines and bottom trawls in Scott Inlet and Sam Ford Trough over three consecutive years. Molecular genetic nuclear markers confirmed species identity for 44 of these sharks sampled; however, two sharks including a juvenile of 150 cm TL were identified as carrying a Pacific sleeper shark (Somniosus pacificus) mitochondrial cytochrome b (cyt b) haplotype. This represents the first record of a Pacific sleeper shark genetic signature in Greenland sharks in Eastern Arctic waters. Juvenile sharks caught as bycatch in gillnet fisheries were only observed offshore in Baffin Bay surrounding a fishery closure area, while larger subadult and mature Greenland sharks ([200 cm TL) were caught in all fishing locations, including areas where juveniles were observed. The repeatable occurrence of juvenile Greenland sharks in a fjord and their presence at two offshore sites indicates that these smaller animals either reside in nurseries or have defined home ranges in both coastal and offshore regions or undertake large-scale inshoreoffshore movements.

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Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

et al. 2014

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“…Historically, it has been hunted by the Inuit people to provide their sled dogs and community members with meat (Davis et al 2013). Ongoing climate change could impact the prey species of the Greenland shark and increase by-catch.…”

Section: The Greenland Sharkmentioning

confidence: 99%

Meet the Greenland shark, a seemingly sleepy Arctic predator

Russo

2016

Biodiversity

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“…In addition, such information may be useful to the tagging community at large, as researchers increase acoustic-tagging studies of deepwater demersal and mesopelagic species such as lingcod (Ophiodon elongatus [22,29]), rockfishes (Sebastes spp. [30]), and Greenland sharks (Somniosus microcephalus [31,32]). …”

Section: Introductionmentioning

confidence: 99%

A test of the detection range of acoustic transmitters and receivers deployed in deep waters of Southeast Alaska, USA

2017

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Background: Movement data represent important inputs to both numerical and conceptual models that contribute to the assessment and management of sablefish (Anoplopoma fimbria) and Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific. While conventional mark-recovery data have greatly increased our understanding of these populations, tagging methods that produce only endpoint data (i.e., locations at tagging and recapture) cannot address dynamics such as the timing, frequency, and recurrence of movements. As a preliminary step in evaluating the feasibility of using acoustic biotelemetry for addressing management-relevant questions for relatively deepwater (≤ 600 m depth) species, we conducted tests of the detection range between VEMCO V16-5H transmitters and VR2W receivers. Six range-test stations were established that varied from a relatively shallow (154 m), narrow (3.8 km) ocean pass; through the mouth of a wide (20 km), deep (600 + m) fjord; and over the continental shelf. Each station consisted of one receiver mooring and five transmitter moorings deployed at regular distances from 200 to 1200 m from the base of the receiver mooring. Bottom depth varied from 195 to 588 m. Transmitters were suspended 0.5 and 5 m off bottom, and receivers at 145-400 m below the sea surface depend on bottom depth. Receivers were deployed for 162-595 days; however, maximum transmission time was 365 days. Results:The rate at which acoustic transmissions were detected by the receivers decreased with distance from the transmitters, mostly monotonically; at first gradually, from transmitters at distances of 400-800 m from the receivers, and then more steeply at distances beyond 800 m. Considerable variability in detection rates was observed, including low detection rates from individual locations and distances. Temporal changes in detection rates were observed that included convergence/divergence between detection of transmitters at a given distance from receivers but that were suspended at different elevations above bottom; stepwise seasonal shifts in mean detection; diurnal periodicity that was likely due to diurnal winds; and tidally mediated detection cycles. We determined that a linear "gate" of receivers spaced 1000 m apart would have a very high probability (≥ 0.99) under most conditions of detecting an acoustically tagged Pacific halibut transiting the gate, and that tagged-halibut identification rates using 2400-m receiver spacing could approach or exceed 90%. However, during episodic periods of relatively poor tag detection, these rates are likely to decline to ~ 60-80%; and to below 10% under extreme conditions. Conclusions:Acoustic telemetry is a feasible technique for monitoring the movement of deepwater epibenthic fishes. However, temporal and spatial variability in detection rates, especially in seasonally stratified waters, has a strong potential to impart biases on study results and generate spurious patterns unrelated to tagged-fish behavior.The nature of such biases should be carefully co...

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The Conservation of the Greenland Shark (Somniosus microcephalus): Setting Scientific, Law, and Policy Coordinates for Avoiding a Species at Risk

Cited by 22 publications

References 0 publications

Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

Meet the Greenland shark, a seemingly sleepy Arctic predator

A test of the detection range of acoustic transmitters and receivers deployed in deep waters of Southeast Alaska, USA

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