|Scientific Name:||Amblyraja jenseni (Bigelow & Schroeder, 1950)|
Raja jenseni Bigelow & Schroeder, 1950
|Taxonomic Notes:||In the northwest Atlantic, this species is easily confused with Arctic skate (A. hyperborea) with overlapping distribution (Bigelow and Shroeder 1953, Jensen 1848, Stehman and Burkel 1984).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Kulka, D.W., Orlov, A. & Barker, A.|
|Reviewer(s):||Dulvy, N.K., Valenti, S.V. & Fowler, S.L. (Shark Red List Authority)|
Jensen's Skate (Amblyraja jenseni) is a little-known deepwater skate, occurring from southern New England, USA, Nova Scotia and Grand Banks to Labrador, Canada, in the Northwest Atlantic, to waters off Ireland in the Northeast Atlantic, including the Mid-Atlantic ridge. The species occurs at depths of 167-2,548 m, with a shallower distribution in the northwest Atlantic, and in deeper water in the northeast Atlantic. Although part of the species’ range is fished in the northwest Atlantic, the species’ wide depth range in this area (to 2,311 m), its occurrence over the mid-Atlantic ridge and at great depths in the northeast Atlantic, offer refuges from fishing pressure. Increasing density with depth suggests that the majority of the population occurs well beyond areas surveyed and fished. In the absence of major potential threats and data to suggest declines, the species is assessed as Least Concern. If deepwater fisheries expand to greater depths within this species’ range in future, this assessment should be revisited.
|Range Description:||Recent data suggests that the species has a continuous range in the northern Atlantic, from the USA coast to waters off Ireland, including the mid-Atlantic ridge (Orlov et al. 2006).|
Northwest Atlantic: off Canada, slope waters of the Labrador Shelf (60°02’N), the Flemish Cap, the Grand Banks, Scotian,Shelf to southern New England, USA (Alpoim et al. 2002, Bigelow and Schroeder 1953,Templeman 1965, Leim and Scott 1966, Moore et al. 2003, D. Kulka pers. obs.).
Northeast Atlantic: only known from a few records north of Ireland (Gordon and Duncan 1987, 1989; Quero et al. 2000).
Note: A. jenseni may have a wider distribution in slope waters than described above, particularly in the northeast Atlantic as surveys and fisheries may not reach depths where they are distributed.
FAO Fishing Areas: 21, 27.
Native:Canada (Labrador, Nova Scotia); Ireland; United States
|FAO Marine Fishing Areas:|
Atlantic – northeast; Atlantic – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Overall, the population size is not known and no data are available to show trends in abundance.|
For the Grand Banks to the Labrador Shelf, out of 47,141 trawl survey sets to a maximum depth of the 1,455 m and dating back to the 1950s, only 85 sets contained 147 A. jenseni. Most trawls containing skates were recorded since 1995 when the maximum depths surveyed increased thus the increasing index may not reflect an increasing population (D. Kulka pers. comm.).
A scientific survey expedition during summer 2004, using bottom trawls (to depths of 3,500 m) and bottom longlines (to depths of 4,500 m) off the Mid-Atlantic Ridge, from the Azores to the Charlie-Gibbs Fracture Zone collected only 14 A. jenseni (Orlov et al. 2006).
Nothing is known of the population structure, but differences found in the external morphology of the species in different parts of its range may indicate that separate populations exist.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||A bathydemersal species, occurring at depths of 167 to 2,548 m (at an average depth of 1,213 m) (Orlov et al. 2006). In the northwest Atlantic the species occurs in shallower waters (167 to 2,311 m, with mean 846 m) and deeper waters in the northeast Atlantic (1,800 to 2,190 m, with mean 2,052 m). Average depth of capture in Canadian waters (Grand Banks to Labrador Shelf) was about 1,100 m where the benthic temperature averaged about 3.5°C.|
The species’ size also varies in different areas of its range, with the largest skates recorded on the mid-Atlantic ridge (measuring an average of 92.61 cm total length (TL)) and considerably smaller skates found on the USA and European continental slopes (49.68 cm TL and 46.85 cm TL, respectively) (Orlov et al. 2006). Size range in the northwest Atlantic is 33 to 112 cm TL (n=163, D. Kulka pers. obs.). Overall, mean TL for female skates is 72.31 cm and for males, 80.3 cm TL (Orlov et al. 2006). Maximum recorded size is 112 cm TL (A. Orlov and D. Kulka pers. obs. 2006). Like other skates, the species is presumably oviparous.
Prey includes small teleost fishes and crustaceans (Bigelow and Schroeder 1953).
The main threat to the species is fisheries and it is probably taken as bycatch by some deepwater trawl fisheries operating in the northwest, and possibly northeast Atlantic. There is no directed fishery. In the northwest Atlantic, deepest fishing sets occur at 1,500 m off Newfoundland (most deep fishing in the range of 700 to 1,200 m), and <400 m off Nova Scotia (D. Kulka pers. obs. 2006). About 10 to 20% of the northwest Atlantic slope is fished annually (D. Kulka pers. obs. 2006).
Although part of the species’ range is fished in the northwest Atlantic, the species’ wide depth range in this area (to 2,311 m), its occurrence over the mid-Atlantic ridge and at great depths in the northeast Atlantic, offer refuges from fishing pressure. Given that the species occurs mainly at depths exceeding 1,000 m, bycatch is expected to be minimal.
|Conservation Actions:||No regulations exist for this species.|
|Citation:||Kulka, D.W., Orlov, A. & Barker, A. 2009. Amblyraja jenseni. The IUCN Red List of Threatened Species 2009: e.T161491A5436001.Downloaded on 20 June 2018.|
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