Centrophorus granulosus (Western Central Atlantic subpopulation)
|Scientific Name:||Centrophorus granulosus (Western Central Atlantic subpopulation)|
|Taxonomic Notes:||Synonyms = Centrophorus steindachneri Pietschmann, 1907; Centrophorus cf. ascus McEachran & Fechhelm, 1998 (misspelling of C. acus).
Specific identification in the Western Central Atlantic region requires review. McEachran and Fechhelm (1998) suggest that specimens from the WCA represent a distinct, undescribed species. However, until more specimens of WCA "C. acus" are examined, the designation of these records remains nominal for this species pending further research.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Horodysky, A.Z. & Burgess, G.H.|
|Reviewer(s):||Kyne, P.M., Heupel, M.R., Simpfendorfer, C.A. & Cavanagh, R.D. (Shark Red List Authority)|
Centrophorus acus is a poorly known deepwater shark with a limited known distribution in the Western Pacific. It is also nominally recorded from the Western Central Atlantic and the relationship between these forms needs taxonomic resolution when more specimens are available. The (nominal) Western Central Atlantic subpopulation is assessed as Data Deficient due to complete lack of information at this time.
|Range Description:||Nominal from the Western Central Atlantic.|
Native:French Guiana; United States
|FAO Marine Fishing Areas:|
Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Inhabits the outer continental shelves and upper slopes at depths of 150 to 950 m, mostly below 200 m . Nominal C. acus in the Western Central Atlantic have been recorded at 630 to 915 m (Compagno in prep a).
Little known of this species biology as few adults have been collected. This is a large species of Centrophorus reaching at least 161 cm TL. Yano and Tanaka (1986) described a 161 cm TL mature specimen with five enlarged (5.5 cm diameter) (ovarian) eggs and enlarged uteri. While exact litter sizes are unknown, the small number of eggs in this specimen suggests a small litter size (Compagno in prep a). This species appears to mature late with females maturing at possibly >20 years (Tanaka 1990). Estimated sizes and ages at maturity are given in the life history parameters (below).
Based on stomach fullness, C. acus appears to feed more actively at night (Compagno in prep a). A tracking study in Suruga Bay, Japan showed that tagged sharks exhibited little horizontal movements in the short term and remained mostly at 10 to 50 m above the seabed with peaks in swimming depths at 300 to 400 m and 580 to 620 m (Yano and Tanaka 1986).
Life history parameters
Age at maturity: Female: possibly >20 yrs. Females still immature at 17 to 18 yrs (Tanaka 1990); Male: ~10 yrs (Tanaka 1990)
Size at maturity (total length): Female: Females immature to 154 cm TL, mature at 161 cm TL (Yano and Tanaka 1986); Male: 50% maturity: 100 to 105 cm TL (Yano and Tanaka 1986).
Longevity: Females: >20 yrs; Male: Males: 17 yrs (dorsal spine rings), possibly up to 20 yrs (extrapolated from growth curve) (Tanaka 1990).
Maximum size (total length): At least 161 cm TL (Yano and Tanaka 1986).
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.
The vulnerability of Centrophorus species to population depletion from localized fishing has been well documented off the east coast of Australia where trawl fishing has depleted the stocks of several species (Graham et al. 2001).
Centrophorus acus may be highly susceptible to overfishing as with other deepwater dogfish with similar life-history strategies.
Threats in the Western Central Atlantic are unknown, but may include bycatch in demersal longline fisheries.
No conservation actions are currently in place.
Deepwater squaloids are highly susceptible to population depletion from localized fishing activities. This situation has been well documented with Centrophorus species off the east coast of Australia (Graham et al. 1997). There is thus an urgent need for appraisal of catches of this species where it is landed in Japan and Taiwan, and the development of appropriate management given the apparent limited life-history characteristics of the species.
|Citation:||Horodysky, A.Z. & Burgess, G.H. 2006. Centrophorus granulosus (Western Central Atlantic subpopulation). The IUCN Red List of Threatened Species 2006: e.T60216A12322802.Downloaded on 19 October 2017.|
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