scholarly journals Influence of Environmental Variables on the Diel Movements of the Greenland Shark (Somniosus microcephalus) in the St. Lawrence Estuary

2016 ◽  
Vol 130 (1) ◽  
pp. 1 ◽  
Author(s):  
Jeffrey J. Gallant ◽  
Marco A. Rodriguez ◽  
Michael J.W. Stokesbury ◽  
Chris Harvey-Clark
Keyword(s):  
Shallow Water ◽  
Environmental Variables ◽  
Thermal Structure ◽  
The Arctic ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Vertical Movements ◽  
Lawrence Estuary ◽  
Somniosus Microcephalus ◽  
St Lawrence Estuary

The geographic distribution of the Greenland Shark (Somniosus microcephalus) extends from the Arctic Ocean to the North Atlantic Ocean. However, little is known about the habitat of this species, as it is generally found at great depths or in the High Arctic. In the St. Lawrence Estuary, Greenland Sharks undertake diel vertical movements into shallow water (≤ 30 m), but the reasons for these movements are unknown. To test the hypothesis that environmental variables drive the movements of this shark in the St. Lawrence Estuary, eight Greenland Sharks were tagged with acoustic telemetry transmitters during the summer of 2005. Three environmental factors, temperature, light, and tides, were associated with their movements. Movement patterns indicate a preference for deep, cold water during daylight hours and shallow, warmer water during the night. Ascending into shallow water mostly coincided with darkness and high tide. This improved understanding of the spatio-temporal distributionof the Greenland Shark will allow for assessment of the risk to these sharks from commercial fisheries, as occurs in the Greenland Halibut (Reinhardtius hippoglossoides) longline fishery. In addition, temperature-driven behavioural patterns may change as the thermal structure of the water column shifts due to global warming.

New records of the mysids Boreomysis nobilis G. O. Sars and Mysis litoralis (Banner) in the Saguenay fjord (St. Lawrence estuary)

1974 ◽  
Vol 52 (8) ◽  
pp. 1087-1090 ◽  
Author(s):  
David C. Judkins ◽  
Robert Wright
Keyword(s):  
New Records ◽  
The Arctic ◽  
Glacial Period ◽  
Isolated Populations ◽  
Lawrence Estuary ◽  
Midwater Trawl ◽  
Boreal Region ◽  
Saguenay Fjord ◽  
St Lawrence Estuary

The arctic–subarctic mysids Boreomysis nobilis and Mysis litoralis were abundant in midwater trawl collections from the Saguenay fjord but were almost absent in collections from the confluent St. Lawrence estuary and Gulf of St. Lawrence. Collections from the estuary and Gulf contained boreal mysids more typical of the latitude. The presence of apparently isolated populations of B. nobilis and M. litoralis in the fjord is further evidence that it is an arctic enclave within a boreal region. The hypothesis that populations of arctic and subarctic species in the Saguenay fjord are relicts from a previous glacial period is questioned in view of the possibility of more recent faunal exchange between the Arctic and the fjord via intermediate arctic enclaves on the eastern Canadian coast.

Non-parametric analysis of the spatio-temporal variability in the fatty-acid profiles among Greenland sharks

2016 ◽  
Vol 98 (3) ◽  
pp. 627-633
Author(s):  
Holly N. Steeves ◽  
Bailey Mcmeans ◽  
Chris Field ◽  
Connie Stewart ◽  
Michael T. Arts ◽  
...  
Keyword(s):  
Statistical Approach ◽  
Marine Ecosystems ◽  
Fatty Acid Profiles ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Sea Ice Extent ◽  
Poor Understanding ◽  
Spatio Temporal ◽  
Somniosus Microcephalus ◽  
Trophic Role

Shifting prey distributions due to global warming are expected to generate dramatic ecosystem-wide changes in trophic structure within Arctic marine ecosystems. Yet a relatively poor understanding of contemporary Arctic food webs makes it difficult to predict the consequences of such changes for Arctic predators. Doing so requires quantitative approaches that can track contemporary changes in predator diets through time, using accurate, well-defined methods. Here we use fatty acids (FA) to quantify differences in consumer diet using permutational multivariate analysis of variance tests that characterize spatial and temporal changes in consumer FA signatures. Specifically we explore differences in Greenland shark (Somniosus microcephalus) FA to differentiate their potential trophic role between Svalbard, Norway and Cumberland Sound, Canada. Greenland shark FA signatures revealed significant inter-annual differences, probably driven by varying seal and Greenland halibut responses to environmental conditions such as the NAO, bottom temperature, and annual sea-ice extent. Uncommon FA were also found to play an important role in driving spatial and temporal differences in Greenland shark FA profiles. Our statistical approach should facilitate quantification of changing consumer diets across a range of marine ecosystems.

scholarly journals Greenland shark (Somniosus microcephalus) feeding behavior on static fishing gear, effect of SMART (Selective Magnetic and Repellent-Treated) hook deterrent technology, and factors influencing entanglement in bottom longlines

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4751 ◽  
Author(s):  
Scott M. Grant ◽  
Rennie Sullivan ◽  
Kevin J. Hedges
Keyword(s):  
Feeding Behavior ◽  
Fishing Gear ◽  
Magnetic Alloy ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Winter Storms ◽  
Ice Conditions ◽  
In Situ Observations ◽  
Somniosus Microcephalus

The Greenland Shark (Somniosus microcephalus) is the most common bycatch in the Greenland halibut (Reinhardtius hippoglossoides) bottom longline fishery in Cumberland Sound, Canada. Historically, this inshore fishery has been prosecuted through the ice during winter but winter storms and unpredictable landfast ice conditions since the mid-1990s have led to interest in developing a summer fishery during the ice-free season. However, bycatch of Greenland shark was found to increase substantially with 570 sharks captured during an experimental Greenland halibut summer fishery (i.e., mean of 6.3 sharks per 1,000 hooks set) and mortality was reported to be about 50% due in part to fishers killing sharks that were severely entangled in longline gear. This study investigated whether the SMART (Selective Magnetic and Repellent-Treated) hook technology is a practical deterrent to Greenland shark predation and subsequent bycatch on bottom longlines. Greenland shark feeding behavior, feeding kinematics, and variables affecting entanglement/disentanglement and release are also described. The SMART hook failed to deter Greenland shark predation, i.e., all sharks were captured on SMART hooks, some with more than one SMART hook in their jaw. Moreover, recently captured Greenland sharks did not exhibit a behavioral response to SMART hooks. In situ observations of Greenland shark feeding show that this species uses a powerful inertial suction mode of feeding and was able to draw bait into the mouth from a distance of 25–35 cm. This method of feeding is suggested to negate the potential deterrent effects of electropositive metal and magnetic alloy substitutions to the SMART hook technology. The number of hooks entangled by a Greenland shark and time to disentangle and live-release a shark was found to increase with body length.

scholarly journals A feasibility study to determine the use of baited pots in Greenland halibut (Reinhardtius hippoglossoides) fisheries, supported by the use of underwater video observations

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10536
Author(s):  
Margaret H. Folkins ◽  
Scott M. Grant ◽  
Philip Walsh
Keyword(s):  
Underwater Video ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Future Studies ◽  
Video Observations ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Reinhardtius Hippoglossoides ◽  
Somniosus Microcephalus ◽  
Catch Rates ◽  
Upper Chamber

High incidental catches of Greenland shark (Somniosus microcephalus) in Nunavut’s Greenland halibut (Reinhardtius hippoglossoides) fishery has led to studies on the feasibility of capturing Greenland halibut with baited pots. In this study, catch rates among six experimental pots are compared. In addition to this, underwater video observations of Greenland halibut interacting with two of these experimental pot types are quantified in order to help provide recommendations on future pot designs. Catch rates of Greenland halibut differed among pots with different entrance mesh types, and none of the pots produced substantial amounts of bycatch. Strings of pots were deployed within a narrow corridor between baited gillnets targeting Greenland halibut, which may have affected catch results. Video observations revealed Greenland halibut entangled by their teeth significantly more often in entrance funnels constructed with 50 mm than with 19 mm clear monofilament netting and the entrance rate was 45% higher with the 19 mm netting. Greenland halibut that successfully entered a pot repeatedly became entangled by their teeth in 58 mm netting used in the side and end panels and in a horizontal panel used to separate the pot into a lower and upper chamber. The majority (80%) of Greenland halibut were observed to approach a pot against the current. The downstream entrance was aligned with the current in 52% of the observed Greenland halibut approaches. Seventy percent of entry attempts and 67% of successful entries occurred when fish approached against the current and when the entrance was aligned with the current. These observations lead to recommendations that future studies consider developing a four entrance pot to ensure an entrance is always aligned with bottom currents. Based on these observations of entanglements, it is recommended to use 19 mm clear monofilament netting in the entrance funnel, 100 mm polyethylene netting in the exterior panels, and 19 mm polypropylene netting in the horizontal panel when targeting Greenland halibut. Three Greenland sharks were observed interacting with the pots in the video sets, but none were captured or damaged the pots during the potting experiments, providing validity to the use of pots to mitigate the capture of Greenland shark in Nunavut territorial waters.

scholarly journals Greenland shark (Somniosus microcephalus) feeding behavior on static fishing gear, effect of SMART (Selective Magnetic and Repellent-Treated) hook deterrent technology, and factors influencing entanglement in bottom longlines

2018 ◽  
Author(s):  
Scott M Grant ◽  
Rennie Sullivan ◽  
Kevin J Hedges
Keyword(s):  
Feeding Behavior ◽  
Fishing Gear ◽  
Magnetic Alloy ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Winter Storms ◽  
Ice Conditions ◽  
In Situ Observations ◽  
Somniosus Microcephalus

The Greenland Shark (Somniosus microcephalus) is the most common bycatch in the Greenland halibut (Reinhardtius hippoglossoides) bottom longline fishery in Cumberland Sound, Canada. Historically, this inshore fishery has been prosecuted through the ice during winter but winter storms and unpredictable landfast ice conditions since the mid-1990s have led to interest in developing a summer fishery during the ice-free season. However, bycatch of Greenland shark was found to increase substantially with 570 sharks captured during an experimental Greenland halibut summer fishery (i.e., mean of 6.3 sharks per 1,000 hooks set) and mortality was reported to be about 50% due to in part to fishers killing sharks that were severely entangled in longline gear. This study investigated whether the SMART (Selective Magnetic and Repellent-Treated) hook technology is a practical deterrent to Greenland shark predation and subsequent bycatch on bottom longlines. Greenland shark feeding behavior, feeding kinematics, and variables affecting entanglement/disentanglement and release are also described. The SMART hook failed to deter Greenland shark predation i.e., all sharks were captured on SMART hooks, some with more than one SMART hook in their jaw. Moreover, recently captured Greenland sharks did not exhibit a behavioral response to SMART hooks. In situ observations of Greenland shark feeding show that this species uses a powerful inertial suction mode of feeding and was able to draw bait into the mouth from a distance of 25-35 cm. This method of feeding is suggested to negate the potential deterrent effects of electropositive metal and magnetic alloy substitutions to the SMART hook technology. The number of hooks entangled by a Greenland shark and time to disentangle and live-release a shark was found to increase with body length.

Applying Bayesian spatiotemporal models to fisheries bycatch in the Canadian Arctic

2015 ◽  
Vol 72 (2) ◽  
pp. 186-197 ◽  
Author(s):  
Aurelie Cosandey-Godin ◽  
Elias Teixeira Krainski ◽  
Boris Worm ◽  
Joanna Mills Flemming
Keyword(s):  
Computational Cost ◽  
Conservation Strategies ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
High Incidence ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Fisheries Bycatch ◽  
Somniosus Microcephalus ◽  
Spatiotemporal Models ◽  
Physical Features

Understanding and reducing the incidence of accidental bycatch, particularly for vulnerable species such as sharks, is a major challenge for contemporary fisheries management. Here we establish integrated nested Laplace approximations (INLA) and stochastic partial differential equations (SPDE) as two powerful tools for modelling patterns of bycatch through time and space. These novel, computationally fast approaches are applied to fit zero-inflated hierarchical spatiotemporal models to Greenland shark (Somniosus microcephalus) bycatch data from the Baffin Bay Greenland halibut (Reinhardtius hippoglossoides) gillnet fishery. Results indicate that Greenland shark bycatch is clustered in space and time, varies significantly from year to year, and there are both tractable factors (number of gillnet panels, total Greenland halibut catch) and physical features (bathymetry) leading to the high incidence of Greenland shark bycatch. Bycatch risk could be reduced by limiting access to spatiotemporal hotspots or by establishing a maximum number of panels per haul. Our method explicitly models the spatiotemporal correlation structure inherent in bycatch data at a very reasonable computational cost, such that the forecasting of bycatch patterns and simulating conservation strategies becomes more accessible.

Ommatokoita superba n.g. et sp., a Parasitic Copepod of Somniosus microcephalus

Parasitology ◽  
1926 ◽  
Vol 18 (2) ◽  
pp. 224-229 ◽  
Author(s):  
W. Harold Leigh-Sharpe
Keyword(s):  
Parasitic Copepod ◽  
The Arctic ◽  
Greenland Shark ◽  
Parasitic Copepoda ◽  
Somniosus Microcephalus

The animal under consideration, or one very like it, has been observed by most collectors of parasitic Copepoda since the publication by Grant appeared in 1827. All authors subsequent to Grant have placed it in the genus Lernaeopoda. Whilst there is a singular unanimity that the area of fixation is the eye, there is a considerable divergence with regard to the host: thus, while Grant originally found it upon the Greenland shark, Scott (1912) records the principal host as Lamna cornubica (which he also calls the Greenland shark), and quotes Norman as having obtained a specimen from Mustelus vulgaris at Polperro. Wilson (1915), an accurate observer, has no record of the host for most of the specimens he examined but stated that one came from a shark. It does not however follow that all these animals are of the same species. The following description is based on two specimens taken from the Arctic shark Squalus borealis = Somniosus microcephalus (Syn. Laemargus and Scymnus) off Greenland on 11. viii. 1923, by W. S. Bristowe.

Observations on the Greenland Shark, Somniosus microcephalus, in Northern Baffin Island

1969 ◽  
Vol 26 (1) ◽  
pp. 143-145 ◽  
Author(s):  
B. Beck ◽  
A. W. Mansfield
Keyword(s):  
The Arctic ◽  
Baffin Island ◽  
Greenland Shark ◽  
White Whale ◽  
Monodon Monoceros ◽  
Somniosus Microcephalus ◽  
Food Consumed

Eighteen immature Greenland sharks (Somniosus microcephalus (Bloch and Schneider) 1801) were captured during the course of a study on the biology of the narwhal, Monodon monoceros. Most had been feeding on offal resulting from the whaling operation and on fish and seal meat discarded at the campsite. Other food consumed included two egg cases of the arctic skate, Raja hyperborea, previously unrecorded from this locality. Four narwhals and one white whale were attacked in the nets, the sharks removing large chunks of skin and blubber from the carcasses.

Sea Lamprey Attached to a Greenland Shark in the St. Lawrence Estuary, Canada

2006 ◽  
Vol 13 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Jeffrey Gallant ◽  
Chris Harvey-Clark ◽  
Ransom A. Myers ◽  
Michael J. W. Stokesbury
Keyword(s):  
Sea Lamprey ◽  
Greenland Shark ◽  
Lawrence Estuary ◽  
St Lawrence Estuary
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