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.

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.

scholarly journals Effects of monofilament nylon versus braided multifilament nylon gangions on catch rates of Greenland shark (Somniosus microcephalus) in bottom set longlines

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10407
Author(s):  
Scott M. Grant ◽  
Jenna G. Munden ◽  
Kevin J. Hedges
Keyword(s):  
Breaking Strength ◽  
The Body ◽  
Biological Information ◽  
Fishing Gear ◽  
Greenland Shark ◽  
Greenland Halibut ◽  
Somniosus Microcephalus ◽  
Catch Rates ◽  
Time Required ◽  
Longline Fisheries

The Greenland shark (Somniosus microcephalus) is the main bycatch species in established and exploratory inshore longline fisheries for Greenland halibut (Reinhardtius hippoglossoides) on the east coast of Baffin Island, Canada. Bycatch and entanglement in longline gear has at times been substantial and post-release survival is questionable when Greenland sharks are released with trailing fishing gear. This study investigated the effect of the type of fishing line used in the gangion and gangion breaking strength on catch rates of Greenland shark and Greenland halibut in bottom set longlines. Circle (size 14/0, 0° offset) hooks were used throughout the study. Behavior of captured sharks, mode of capture (i.e., jaw hook and/or entanglement), level of entanglement in longline gear, time required to disentangle sharks and biological information (sex, body length and health status) were recorded. Catch rates of Greenland shark were independent of monofilament nylon gangion breaking strength and monofilament gangions captured significantly fewer Greenland sharks than the traditional braided multifilament nylon gangion. Catch rates and body size of Greenland halibut did not differ significantly between gangion treatments. Although most (84%) of the Greenland sharks were hooked by the jaw, a high percentage (76%) were entangled in the mainline. The mean length of mainline entangled around the body and/or caudal peduncle and caudal fin was 28.7 m. Greenland sharks exhibited cannibalistic behavior with 15% of captured sharks cannibalized. All remaining sharks were alive and survived the disentanglement process which can be attributed to their lethargic behavior and lack of resistance when hauled to the surface. Thus, as a conservation measure fishers should be encouraged to remove trailing fishing gear prior to release. Our results are used to demonstrate benefits to the fishing industry with regard to an overall reduction in the period of time to disentangle sharks and damage to fishing gear by switching from braided multifilament to monofilament gangions in Greenland halibut longline fisheries.

scholarly journals Reproductive strategy, egg characteristics and embryonic development of Greenland halibut (Reinhardtius hippoglossoides)

2012 ◽  
Vol 70 (2) ◽  
pp. 342-351 ◽  
Author(s):  
Rosario Domínguez-Petit ◽  
Patrick Ouellet ◽  
Yvan Lambert
Keyword(s):  
Embryonic Development ◽  
Reproductive Strategy ◽  
Biochemical Composition ◽  
Incubation Temperature ◽  
Life Stage ◽  
Early Life Stage ◽  
Greenland Halibut ◽  
Hatching Time ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Reinhardtius Hippoglossoides

Abstract Domínguez-Petit, R., Ouellet, P., and Lambert, Y. 2013. Reproductive strategy, egg characteristics and embryonic development of Greenland halibut (Reinhardtius hippoglossoides). – ICES Journal of Marine Science, 70: 342–351. Despite the commercial importance of Greenland halibut (GH), important gaps exist in our knowledge of the reproductive and early life stage biology for this species. The present study examined through laboratory experiments the spawning strategy, realized fecundity, egg characteristics, biochemical composition, and embryonic development of GH. The results confirmed the hypothesis that GH is a single-batch spawner producing large eggs, resulting in low realized fecundity. Embryonic development and hatching time are highly dependent on incubation temperature; 50% hatching occurred after 46, 30, and 24 days at 2, 4, and 6°C, respectively. Few changes in the biochemical composition of the eggs are observed during embryonic development. Newly hatched larvae are not well developed, having a large yolk sac, no pigmentation and incomplete development of the jaws. Egg specific density confirmed the mesopelagic distribution of the eggs at sea. However, important buoyancy changes occurring in the last 3–4 days before hatching indicate that larvae hatch higher in the water column. These results are important for understanding advection and dispersion processes of GH eggs and larvae and the connectivity between spawning grounds and nursery areas.

Use of Parasites for Separating Stocks of Greenland Halibut (Reinhardtius hippoglossoides) in the Canadian Northwest Atlantic

1993 ◽  
Vol 50 (10) ◽  
pp. 2175-2181 ◽  
Author(s):  
J. R. Arthur ◽  
E. Albert
Keyword(s):  
Atlantic Coast ◽  
Large Fish ◽  
Adult Fish ◽  
Greenland Halibut ◽  
Pseudoterranova Decipiens ◽  
Saguenay Fjord ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Reinhardtius Hippoglossoides ◽  
Biological Tags ◽  
Discriminant Function Analyses

The usefulness of parasites as biological tags for stocks of Greenland halibut (Reinharditius hippoglossoides) occurring off the Atlantic coast of Canada and in the Gulf of St. Lawrence was investigated. Nonparametric discriminant function analyses of eight collections comprising a total of 231 large fish (>39 cm) using counts for selected parasite taxa (Corynosoma strumosum juvenile, Otodistomum sp. metacercaria, Contracaecinea spp. larva, Anisakis simplex larva, and Pseudoterranova decipiens larva) gave accurate results (almost 100% correct classification) for the separation of fish from the Gulf of St. Lawrence from those collected from adjacent areas of the Saguenay Fjord and the Atlantic Ocean off Labrador. Little, if any, mixing of subadult or adult fish apparently occurs among these areas.

scholarly journals Chromosome-level assembly reveals a putative Y-autosomal fusion in the sex determination system of the Greenland Halibut (Reinhardtius hippoglossoides)

2021 ◽  
Author(s):  
Anne-Laure Ferchaud ◽  
Claire Mérot ◽  
Eric Normandeau ◽  
Jiannis Ragoussis ◽  
Charles Babin ◽  
...  
Keyword(s):  
Sex Determination ◽  
Single Molecule ◽  
Sex Chromosome ◽  
Whole Genome Sequence ◽  
Greenland Halibut ◽  
Syntenic Relationship ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Reinhardtius Hippoglossoides ◽  
Sex Determination System ◽  
Chromosome Level

Abstract Despite the commercial importance of Greenland Halibut (Reinhardtius hippoglossoides), important gaps still persist in our knowledge of this species, including its reproductive biology and sex determination mechanism. Here, we combined single-molecule sequencing of long reads (Pacific Sciences) with chromatin conformation capture sequencing (Hi-C) data to assemble the first chromosome-level reference genome for this species. The high-quality assembly encompassed more than 598 Megabases (Mb) assigned to 1 594 scaffolds (scaffold N50 = 25 Mb) with 96% of its total length distributed among 24 chromosomes. Investigation of the syntenic relationship with other economically important flatfish species revealed a high conservation of synteny blocks among members of this phylogenetic clade. Sex determination analysis revealed that, similar to other teleost fishes, flatfishes also exhibit a high level of plasticity and turnover in sex-determination mechanisms. A low-coverage whole-genome sequence analysis of 198 individuals revealed that Greenland Halibut possesses a male heterogametic XY system and several putative candidate genes implied in the sex determination of this species. Our study also suggests for the first time in flatfishes that a putative Y-autosomal fusion could be associated with a reduction of recombination typical of the early steps of sex chromosome evolution.

Evidence supporting panmixia in Greenland halibut (Reinhardtius hippoglossoides) in the Northwest Atlantic

2014 ◽  
Vol 71 (5) ◽  
pp. 763-774 ◽  
Author(s):  
Denis Roy ◽  
David C. Hardie ◽  
Margaret A. Treble ◽  
James D. Reist ◽  
Daniel E. Ruzzante
Keyword(s):  
Population Structure ◽  
Population Genetic ◽  
Conservation Strategies ◽  
Greenland Halibut ◽  
Northwest Atlantic ◽  
Population Genetic Differentiation ◽  
Conservation Implications ◽  
Greenland Halibut Reinhardtius Hippoglossoides ◽  
Reinhardtius Hippoglossoides ◽  
Species Specific

Assessment of population structure is critical to the design and implementation of sound management and conservation strategies. However, population structure must be assessed using markers attuned to population genetic processes such as genetic drift and gene flow, which reflect actual levels of reproductive isolation among putative genetic clusters. This is critical for highly exploited, commercial species that form the backbone of regional and local economies. Here, we show extremely low levels of population genetic differentiation among Greenland halibut (Reinhardtius hippoglossoides) collected from throughout the Northwest Atlantic, which cannot be statistically differentiated from panmixia using 12 species-specific polymorphic microsatellite markers. In contrast, some previous studies have demonstrated significant differences among individuals collected from various parts of the species’ range using a variety of both genetic and nongenetic techniques. In accordance with other reports and consistent with the species’ life history, we demonstrate that the most parsimonious explanation reconciling observed patterns is a repeated high degree of local differentiation of new recruits and colonizers originating from a common gene pool. Such a scenario has important conservation implications in terms of devising more appropriate strategies balancing species persistence and replenishment with sustainable resource use.

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