物种评估与保护

Holothuria nobilis

Source:IUCN

Taxonomy

Taxonomy in detail

Scientific name

Authority

Synonyms

Common names

Taxonomic sources

Identification Information

Taxonomic notes

Assessment Information

IUCN Red List Category and Criteria: Endangered A2bd ver 3.1
Assessment language: English
Year published: 2013
Date assessed: 2010-05-18 00:00:00 UTC

Assessment Information in detail

Previously published Red List assessments

Regional assessments

Assessor(s)

Reviewer(s)

Contributor(s)

Facilitator(s) / Compiler(s)

Partner(s) / Institution(s)

Authority / Authorities

Justification

This species is commercially exploited throughout its range for its high value as beche-de-mer to supply the Asian consumers around the world. Based on a number of quantitative and qualitative studies, many subpopulations are considered depleted and the global population is estimated to have declined between 60% and 70% in at least 80% of its range. Declines and overexploitation have occurred primarily since the 1960s, and although generation length is not known, echinoderms are not considered to go through senescence and therefore may be greater than several decades. This species is therefore listed as Endangered. However, declines of breeding individuals may be much higher as it is not known if this species is able to effectively reproduce in deeper waters.

Geographic Range

Native

Extant (resident)

Extant

Number of locations

Geographic Range in detail

FAO Fishing Areas

Estimated area of occupancy (AOO) (km²)

Continuing decline in area of occupancy (AOO)

Extreme fluctuations in area of occupancy (AOO)

Estimated extent of occurrence (EOO) (km²)

Continuing decline in extent of occurrence (EOO)

Extreme fluctuations in extent of occurrence (EOO)

Continuing decline in number of locations

Extreme fluctuations in the number of locationsN

RANGE DESCRIPTION

This species only occurs in the Indian Ocean (Uthicke et al. 2004) and does not occur in the Western Central Pacific (Kinch et al. 2008) or in Asia (Choo 2008). It is present in the Africa and Indian Ocean region (Conand 2008), and is found in Madagascar, East Africa, Seychelles, India, Sri Lanka, the Maldives, Comoros, and the Red Sea.

Population

Current population trend

Number of mature individuals

Population severely fragmented

Continuing decline of mature individuals

Population in detail

Extreme fluctuations

No. of subpopulations

Continuing decline in subpopulations

Extreme fluctuations in subpopulations

All individuals in one subpopulation

No. of individuals in largest subpopulation

Description

In the Maldives, export of Thelenota ananas, this species, and Bohadschia marmorata increased from 3 t in 1986 (start of the fishery) to 740 t in 1990 (Bruckner et al. 2003).

In the Gulf of Manner and Pal Bay, India the CPUE and size of specimens has dramatically declined (Bruckner et al. 2003).

In Mozambique, high fluctuation in exports of Holothuria scabra, this species, H. fuscogilva, H. atra, Actinopyga echinites and A. mauritiana may be due to irregular reporting or to overexploitation. Catch is reported at 500 t in 1990, 700 t in 1993, 6 t in 1995, and 54 t in 1996. In Inhambane Province, holothurian fisheries are closed until stocks rebuild (Bruckner et al. 2003). Stocks are assumed to be depleted in Mozambique.

Kalaeb et al. (2008) used transect data to calculate a population density of 1.0 individuals of this species per hectare in near shore waters of Eritrea, east Africa. Kalaeb et al. (2008) used transect data to calculate a population density of 0.66 individuals of this species per hectare in near shore waters of Egypt, east Africa. The mean densities of this species observed in their habitats vary from 0.12 to 10 individuals per hectare. (Rasolofonirina pers comm. 2010).

In Madagascar, stocks are assumed to be depleted as very few specimens have been seen the past several years especially in areas that have been heavily fished (Conand pers. comm. 2010).

In Egypt, this species has been almost completely lost due to fishery (Bruckner 2006).

In Tanzania, this species comprised a very small percentage of the total of sea cucumber species (Conand and Muthiga 2007). This species previously dominated the catch and now comprises a very small percentage of the catch.

In Kenya, mixed catch of sea cucumbers has decreased by approximately 50% since 1994, and this species is considered to be a significant portion of the catch. In 2007, this species only comprised 10% of the catch.

In Chagos marine protected area, populations have also decreased over the past 4 or 5 years, due to illegal fishing (Price et al. 2010).

In the Seychelles catches for this species from 2003-2008, catch data of individuals was relatively stable from 2003 to 2006, with a peak catch of 10371 individuals, and then fell in 2007 and 2008 to 5687 individuals (Conand pers. comm. 2010). This is one of the newer fisheries in the Seychelles.

This species has been depleted in Mozambique, India, Sri Lanka, Madagascar, Egypt, the Red Sea, Maldives and also probably in Tanzania and Kenya due to overfishing. Depletion in this sense refers to commercially unviable, and is estimated to represent between 60-70% loss, as this species can occur in deeper waters.This species is still actively fished in the Seychelles, where it is probably not depleted. Based on these inferences, it is estimated that there has been at least a 60-70% decline in over 80% of its range.

Habitat and Ecology

System

Marine

Number of mature individuals

Continuing decline in area, extent and/or quality of habitat

Generation length (years)

Congregatory

Movement patterns

Habitat and Ecology in detail

Habitat and Ecology

This species is largely restricted to coral reef habitat. It occurs on reef flats and outer slopes and it is generally solitary (Conand and Mangion 2002).

This species is common in shallow waters of reef bottom where there is no terrigenous action, at depths from 0 to 40 m. However, they are distributed mainly in shallow coral reef areas, on reef flats, slopes and shallow seagrass beds. They prefer sandy hard substrate (Rasolofonirina pers. comm. 2010).

This species is reported to mature at four years (Reichenbach 1999). It is characterized by a sexual reproduction that takes place during the cold season. The juveniles are very rarely seen, and have a different colour.

Based on closely related species (Holothuria whitmaei), this species probably lives at least for several decades (Uthicke and Benzie 2003, Uthicke and Benzie 2002).

Generation length is unknown for this species. Body size is not a good indicator of age or longevity. There is some indication, however, that many echinoderms do not go through senescence, but simply regenerate. Therefore generation length cannot be estimated, but is assumed to be greater than several decades in a natural, un-disturbed environment.

In the Africa and Indian Ocean region, this species can be found in reef flats and slopes over rubble between 0 and 40 m (Conand 2008). In Madagascar it can be found in the inner slope and the seagrass beds, with higher abundance in the former (Conand 2008). In Northern Australia, this species prefers habitats closer to the reef crest (Shiell 2004). In China, it is found between 40 and 60 m (Li 2004). In the Comores, it normally inhabits between 10 and 40 m in coarse sand (Samyn et al. 2006).

Classification scheme

Habitats	Suitability	Major importance

Threats

Use trade

This species is commercially targeted. It is targeted throughout its range, and fishing pressure has dramatically increased in the past 25 to 50 years, since the 1960s, and is expected to continue, even as stocks are depleted. When this occurs, other species are often targeted in their place.

Residential & commercial development

Agriculture & aquaculture

Energy production & mining

Transportation & service corridors

Biological resource use

Human intrusions & disturbance

Natural system modifications

Pollution

Geological events

Climate change & severe weather

Threats in detail

Threats

This is one of the most valuable commercial species and therefore is overexploited (Conand 2008).

Overfishing is a threat to this species (Uthicke and Benzie 2001, Rasolofonirina pers. comm. 2010). It is collected by hand at low tide, by skin diving or using diving gear (if not banned), making the populations very vulnerable, due to overexploitation. The processed product is of major commercial value and is very highly demanded at present, even though the stocks have declined (Palomares and Pauly 2009). Generally, this species is primarily fished to recreational diving limits of 20 m or more.

Classification scheme Threats

title	scope	timing	score	severity

Use trade

Text summary

Text summary in detail

Conservation Actions Information

The fishery for this species is currently banned in Egypt, India, and Mayotte, although the effectiveness of these bans on the species population is yet to be determined. This species is found in Chagos marine protected area, and is probably found in several other marine protected areas throughout its range.