|Scientific Name:||Hydrolagus trolli|
|Species Authority:||Didier & Séret, 2002|
|Taxonomic Notes:||Synonyms = Hydrolagus sp. C Paulin et al., 1989; Hydrolagus sp. cf lemurs Séret in Grandperrin et al., 1997; Hydrolagus sp. Séret in Grandperrin et al., 1999.
A recently described, highly distinctive species, Hydrolagus trolli is often caught with a species of giant black chimaera (cf. Hydrolagus affinis), and the range of these two species may overlap in some areas, but H. trolli is readily separated by its distinctive blue colouration and more acute snout.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Compagno, L.J.V. & Dagit, D.D.|
|Reviewer(s):||Kyne, P.M. & Fowler, S.L. (Shark Red List Authority)|
This deepwater species, only described in 2002, appears to have a widespread distribution throughout the Southern Ocean and may be moderately common in New Zealand waters, but rare in other regions. Recorded on deep continental and insular slopes at depths of 650 to 1,719 m, mostly below 1,000 m. This species is possibly under threat as bycatch from intensive and widespread deepwater trawl and longline fishing (for Patagonian toothfish, orange roughy and other valuable teleost species) within its known range. Of concern because of its restricted habitat on the deep slope as well as possible low reproductive rate and slow growth. More specimens and data, particularly bycatch and life history data, are needed and this assessment should be reviewed when more data are available.
|Range Description:||Originally described from deep waters off New Zealand and New Caledonia. More recently, there have been infrequent captures of this species from deepwater seamounts in the Southern Ocean. This species is apparently wide ranging throughout the Southern Ocean and probably has a circumglobal distribution.|
Native:New Caledonia; New Zealand; South Africa (Western Cape)
|FAO Marine Fishing Areas:||
Present - origin uncertain:
Atlantic – Antarctic; Atlantic – southeast; Indian Ocean – Antarctic; Pacific – Antarctic; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Nothing is known of population size or structure. Appears to be more common around New Zealand and rarer in other parts of its range, but this may only be a reflection of fishing effort. Future research may provide evidence that separate populations exist across the range of this species.|
|Habitat and Ecology:||
A large chimaera of the deep continental and insular slopes, in depths of 750 to 1,719 m off South Africa and 650 to 1,707 m off New Zealand and New Caledonia, but mostly collected below 1,000 m depth.
Oviparous. No eggs, embryos or small juveniles are known to have been collected. Nothing is known of reproductive biology. Diet likely consists of a variety of benthic invertebrates, with dominant prey species varying based on habitat.
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (body length): Female: ~55 cm BDL; Male: ~60 to 65 cm BDL.
Longevity (years): Unknown.
Maximum size (total/body length): Recorded at 111 cm TL (91 cm BDL); maximum probably ~120 cm TL.
Size at birth (cm): Unknown.
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: Unknown.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Common from deepwater fishing grounds off New Zealand where it is threatened by deepwater benthic trawls. Off South Africa H. trolli is threatened by capture as bycatch in deep-slope longline and trawl fisheries for valuable bony fishes including toothfish, roughies and dories. Illegal fishing activities, particularly for Patagonian toothfish, are likely taking this species, and given the scope of these practices may be impacting upon its population.
A re-evaluation of the species' conservation status is recommended after additional bycatch information is obtained, which is a priority.
More information is required of bycatch levels from the teleost fisheries impacting this species. More specimens, particularly juveniles are needed, as is life history data.
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and management of all chondrichthyan species in the region.
|Citation:||Compagno, L.J.V. & Dagit, D.D. 2006. Hydrolagus trolli. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 29 August 2015.|
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