Neophocaena phocaenoides

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	MAMMALIA	CETARTIODACTYLA	PHOCOENIDAE

Scientific Name:

Neophocaena phocaenoides

Species Authority

(G. Cuvier, 1829)

Common Name/s:

English	–	Finless Porpoise, Black Finless Porpoise, Finless Black Porpoise
French	–	Marsouin Aptère, Marsouin Sans Nageoires
Spanish	–	Marsopa Lisa, Marsopa Negra

Assessment Information [top]

Red List Category & Criteria:

Vulnerable A2cde ver 3.1

Year Assessed:

2008

Assessor/s

Reeves, R.R., Collins, T., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K.

Evaluator/s:

Brownell Jr., R.L. & Cooke, J. (Cetacean Red List Authority)

Justification:
There is considerable taxonomic uncertainty. When clarified, this may require separate assessments for different taxa in the genus Neophocaena. Although there is no population estimate for finless porpoises throughout their range, they are widespread and regularly sighted in some areas. However, their range appears to be discontinuous in some regions. Given the size of their range and the likely total numbers of individuals throughout that range, finless porpoises do not meet criteria B, C or D for any threatened category. Also, available data are far from sufficient to support a quantitative analysis of the probability of extinction, thus ruling out criterion E. Therefore, the only criterion to consider is A, the decline criterion.

Obtaining conclusive quantitative evidence of population trend for this species throughout its range is next to impossible. The only area with clear evidence of trend is the Inland Sea of Japan, where a decline of nearly 70% was estimated over a period of 22 years, from 1976-1978 to 1999-2000. Another area with some evidence of a rapid decline in recent decades is the Yangtze River and adjoining lake systems of China. Given that the factors responsible for these declines (mainly incidental mortality in fisheries, but also habitat degradation and loss) have not been addressed and are pervasive, and likely increasing, an overall decline of at least 30% over the last three generations (about 50 years; see Taylor et al. 2007) is suspected. Thus, the species qualifies for Vulnerable A2c,d,e, considering that the causes of decline – bycatch (interpreted here as “exploitation”), decline in habitat quality, and possibly pollution – have not ceased and are not all well understood.

There should be sufficient information to assess separately at least two threatened subpopulations or subspecies – the subpopulation in the Inland Sea of Japan, which likely qualifies for Endangered (Shirakihara et al. 2007), and the Yangtze River subspecies, which was classified as Endangered in 1996 (C2b) under the 1994 Categories and Criteria and for which a new assessment is underway.

History:

1996	–	Data Deficient (Baillie and Groombridge 1996)
1994	–	Insufficiently Known (Groombridge 1994)

Geographic Range [top]

Range Description:	The type specimen was supposed to have come from the Cape of Good Hope, but there is reason to believe that report was erroneous (Rice 1998). In general, the species occurs in a narrow strip of shallow (usually <50 m deep) coastal water around the northern rim of the Indian and western Pacific oceans from the Arabian (Persian) Gulf in the west to the Indo-Malay region in the east and to Java, Indonesia (but apparently not the Philippines, apart from Palawan), northern China, Korea and northern Honshu, Japan. The distribution also includes a few estuaries and rivers (e.g., the N. p. asiaeorientalis subspecies appears to be found exclusively in the Yangtze River system) (Gao 1991, Gao and Zhou 1995). Human coastal development and other activities already may have substantially reduced and fragmented the distribution of this species (Reeves et al. 1997). N. p. phocaenoides – Coastal marine waters, as well as some river mouths and estuaries, from the Persian Gulf eastwards around the rim of the Indian Ocean to the Taiwan Strait area (Gao 1991, Gao and Zhou 1995). It is the most tropical and wide-ranging of the three subspecies. N. p. sunameri – Coastal waters from the Taiwan Strait, including the western coast of Taiwan, through the East China Sea north to the Bohai/Yellow Sea in China and the waters of Korea and Japan (Gao 1991, Gao and Zhou 1995). Korean and Japanese populations are geographically separate (Shirakihara et al. 1992, Yoshida 2002). N. p. asiaeorientalis – Middle and lower reaches of the Yangtze River (= Chang Jiang), where it ranges (or did until recently) to 1,600 km upstream, i.e. to the gorges above Yichang (200 m above sea level). The range includes Poyang and Dongting lakes and their tributaries, the Gan Jiang and the Xiang Jiang (Gao 1991, Gao and Zhou 1995). The subspecies is thought to be restricted to fresh water.
Countries:	Native: Bahrain; Bangladesh; Brunei Darussalam; Cambodia; China; Hong Kong; India; Indonesia; Iran, Islamic Republic of; Iraq; Japan; Korea, Republic of; Kuwait; Malaysia; Myanmar; Pakistan; Philippines; Saudi Arabia; Singapore; Sri Lanka; Taiwan, Province of China; Thailand; United Arab Emirates; Viet Nam Presence uncertain: Korea, Democratic People's Republic of; Oman; Qatar
FAO Marine Fishing Areas:	Native: Indian Ocean – western; Indian Ocean – eastern; Pacific – northwest; Pacific – western central
Range Map:	(click map to view full version)

Population [top]

Population:	These porpoises are small and cryptic and therefore difficult to survey. Estimates of abundance have been made for only a few areas (Jefferson and Hung 2004, IWC 2006). Estimates from the early 2000s are available for five subpopulations in Japanese waters, distinguished on the basis of skull morphology and mtDNA variability (Yoshida 2002), as follows: 3,807 (CV=16%) in Ariake Sound/Tachibana Bay (Shirakihara and Shirakihara 2002); 289 (CV=19%) in Omura Bay (Shirakihara and Shirakihara 2002); 3,743 (CV=24%) in Ise/Mikawa Bay (Yoshioka 2002); 3,387 (CV=33%) in Chiba/Sendai Bay (Amano et al. 2003); and 7,572 (CV=17%) in the Inland Sea (Shirakihara et al. 2007; most of the estimates were summarized in IWC 2006). For the Inland Sea subpopulation, Kasuya et al. (2002) recorded a decline in density of 18-100% for 18 tracklines surveyed in 1976-78 and again in 1999-2000. The declines for 11 of these tracklines were statistically significant. Using abundance indices calculated by multiplying the density indices (no. individuals/cruise distance) and area size of each stratum, an overall decline of 69% is inferred over the 22 years between the two sets of surveys (Toshio Kasuya pers. comm., January 2007, data from Kasuya et al. 2002). There were estimated to be at least 217 (CV= 21-150%) finless porpoises in Hong Kong waters (Jefferson et al. 2002a). Surveys in western Korean waters (Yellow Sea) in the early 2000s estimated 21,532 (CV=39%) finless porpoises in offshore waters and 5,464 (CV=20%) in inshore waters (Zhang et al. 2005). The Scientific Committee of the International Whaling Commission (IWC) viewed these estimates as minima (IWC 2006, p. 223). Smith (2006) estimated that there were 1,382 (CV=55%) finless porpoises in the coastal waters of Bangladesh. Based on surveys from 1984 to 1991, Zhang et al. (1993) estimated that there were about 2,700 porpoises in the Yangtze River, while Zhou et al. (2000) estimated that only 700 remained in the lower reaches between Nanjing and Hukou between 1989 and 1992. Wang et al. (2000) concluded that finless porpoise abundance in the Yangtze River had declined considerably and that there could be fewer than 2,000 animals (although this was not based on a rigorous assessment). There are no abundance estimates of finless porpoises in the Arabian (Persian) Gulf, along the Indian Ocean coasts of Iran or Pakistan, or in Chinese marine waters other than Hong Kong (IWC 2006). .
Population Trend:	Decreasing

Population:

These porpoises are small and cryptic and therefore difficult to survey. Estimates of abundance have been made for only a few areas (Jefferson and Hung 2004, IWC 2006). Estimates from the early 2000s are available for five subpopulations in Japanese waters, distinguished on the basis of skull morphology and mtDNA variability (Yoshida 2002), as follows: 3,807 (CV=16%) in Ariake Sound/Tachibana Bay (Shirakihara and Shirakihara 2002); 289 (CV=19%) in Omura Bay (Shirakihara and Shirakihara 2002); 3,743 (CV=24%) in Ise/Mikawa Bay (Yoshioka 2002); 3,387 (CV=33%) in Chiba/Sendai Bay (Amano et al. 2003); and 7,572 (CV=17%) in the Inland Sea (Shirakihara et al. 2007; most of the estimates were summarized in IWC 2006). For the Inland Sea subpopulation, Kasuya et al. (2002) recorded a decline in density of 18-100% for 18 tracklines surveyed in 1976-78 and again in 1999-2000. The declines for 11 of these tracklines were statistically significant. Using abundance indices calculated by multiplying the density indices (no. individuals/cruise distance) and area size of each stratum, an overall decline of 69% is inferred over the 22 years between the two sets of surveys (Toshio Kasuya pers. comm., January 2007, data from Kasuya et al. 2002).

There were estimated to be at least 217 (CV= 21-150%) finless porpoises in Hong Kong waters (Jefferson et al. 2002a). Surveys in western Korean waters (Yellow Sea) in the early 2000s estimated 21,532 (CV=39%) finless porpoises in offshore waters and 5,464 (CV=20%) in inshore waters (Zhang et al. 2005). The Scientific Committee of the International Whaling Commission (IWC) viewed these estimates as minima (IWC 2006, p. 223). Smith (2006) estimated that there were 1,382 (CV=55%) finless porpoises in the coastal waters of Bangladesh.

Based on surveys from 1984 to 1991, Zhang et al. (1993) estimated that there were about 2,700 porpoises in the Yangtze River, while Zhou et al. (2000) estimated that only 700 remained in the lower reaches between Nanjing and Hukou between 1989 and 1992. Wang et al. (2000) concluded that finless porpoise abundance in the Yangtze River had declined considerably and that there could be fewer than 2,000 animals (although this was not based on a rigorous assessment).

There are no abundance estimates of finless porpoises in the Arabian (Persian) Gulf, along the Indian Ocean coasts of Iran or Pakistan, or in Chinese marine waters other than Hong Kong (IWC 2006).
.

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	The finless porpoise is found mainly in coastal waters, including shallow bays, mangrove swamps, estuaries, and some large rivers. However, it can also occur in shallow waters (< 200 m deep) quite far from shore (up to 240 km). It appears to have a strong preference for waters with a sandy or soft bottom (Jefferson and Hung 2004). In Hong Kong waters, groups of finless porpoises spend about 60% of their time at or near the surface (Jefferson et al. 2002a). In Japanese waters, they prefer shallow depths (<50 m) and close proximity to the shore (< 5 km). In the shallow East China Sea, however, proximity to the shore is not as important (Amano 2002). Small fishes, cephalopods, and crustaceans (mainly demersal species) form the diet of finless porpoises (see Jefferson and Hung 2004).
Systems:	Freshwater; Marine

Habitat and Ecology:

The finless porpoise is found mainly in coastal waters, including shallow bays, mangrove swamps, estuaries, and some large rivers. However, it can also occur in shallow waters (< 200 m deep) quite far from shore (up to 240 km). It appears to have a strong preference for waters with a sandy or soft bottom (Jefferson and Hung 2004).

In Hong Kong waters, groups of finless porpoises spend about 60% of their time at or near the surface (Jefferson et al. 2002a). In Japanese waters, they prefer shallow depths (<50 m) and close proximity to the shore (< 5 km). In the shallow East China Sea, however, proximity to the shore is not as important (Amano 2002).

Small fishes, cephalopods, and crustaceans (mainly demersal species) form the diet of finless porpoises (see Jefferson and Hung 2004).

Systems:

Freshwater; Marine

Threats [top]

Major Threat(s):	Finless porpoises, like other phocoenids (Jefferson and Curry 1994), are extremely susceptible to entanglement in gillnets, and large numbers have been, and continue to be, killed in many parts of their range (Jefferson et al. 2002b). Finless porpoises are caught in nets along the India and Pakistan coasts, and off the Malay Peninsula, although there is no estimate of the magnitude of such catches. In Japan they become entangled in a variety of types of fishing gear. Changes in fishing methods may have reduced the incidental catch in some areas such as western Kyushu (Kasuya 1999), but substantial numbers are still being taken in gill nets and other fishing gear (J.Y. Wang pers. comm., January 2007). A total of 114 specimens were collected in Japan during 1985-1992 from western and north-eastern Kyushu including parts of the western Inland Sea (Shirakihara et al. 1993): 84 of them had been killed incidentally in fisheries, 25 had been found dead on the beach or in the sea, and there was no information on the other five. Fisheries that killed the 84 porpoises employed bottom-set gill nets (58), surface gill nets (17), trap nets (7), trawl nets (1) and drifting (ghost) nets (1). Such fishing gear is common in Japan and probably kills finless porpoises off other coasts, although usually such catches remain unreported. Yang et al. (1999) reported that finless porpoises were the most frequently captured cetaceans in fishing gear along the Chinese coast and estimated that more than 2,000 were taken in 1994, mainly in trawl, gill, and stow nets. In the waters of western Taiwan, including the Matsu and Chinmen Islands (western Taiwan Strait), a considerable number of finless porpoises are taken in trammel nets, trawl nets, stow nets, and other gear (J.Y. Wang pers. comm., January 2007). Given the numbers and types of net fisheries in Chinese coastal waters (e.g., Zhou and Wang 1994; Yang et al. 1999), there are serious concerns about the level of bycatch of this species. Although illegal, electric fishing has become widespread in the Yangtze River during the last decade, and it probably kills porpoises outright and contributes to the depletion of their prey (Reeves et al. 2000). In some parts of their range, there is an aversion to eating finless porpoises (Kasuya 1999; J.Y. Wang pers. comm., January 2007). However, the species is taken as bycatch and sold for human consumption on the Korean peninsula (IWC 2000). From an analysis of the species composition of odontocete products in Korean markets during 2003-2004, it was estimated that the true catch of finless porpoises in Korean waters during this period was probably about four times the officially reported catch of 142 animals (Baker et al. 2006). As a coastal species, the finless porpoise is also affected by habitat loss and degradation, boat traffic, and pollution. The extensive modification of coastlines for shrimp farming and rampant harbor (and other) development throughout Asia (including the Arabian Gulf) means that there is less habitat for finless porpoises (Reeves et al. 2003). Porpoise habitat in the Yangtze River system has been degraded by water development, including the Gezhouba and Three Gorges dams and about 1300 smaller dams in tributaries (Liu et al. 2000; Smith et al. 2000). Sand mining is intensive in Poyang Lake, until recently a stronghold for Yangtze finless porpoises (B. Taylor pers. comm., January 2007). Although pathology related to contaminant exposure has not been reported in finless porpoises, pollution is considered a potentially serious threat (Kasuya, 1999; see Kannan et al. 1989; Iwata et al. 1994, 1995; Parsons and Chan 1998; Le et al. 1999; Minh et al. 1999; Parsons 1999; Jefferson et al. 2002b). The number of reported small cetacean strandings in Hong Kong has increased in recent years, partly due to increasing public awareness of local cetaceans, but also possibly due to escalating levels of human disturbance and pollution (T.A. Jefferson pers. comm., January 2007). Vessel collisions, especially involving high-speed ferries, may be a particular problem for porpoises in Hong Kong (Parsons and Jefferson 2000). The causes of an apparent decline in porpoise numbers in the Inland Sea of Japan are not fully understood but include incidental mortality in fisheries as well as various forms of habitat degradation (IWC 2000, 2006). Parts of the coastal regions of the Inland Sea are highly developed and industrialized so the associated threats of habitat loss and pollution are suspected to have had some (undetermined) level of impact

Major Threat(s):

Finless porpoises, like other phocoenids (Jefferson and Curry 1994), are extremely susceptible to entanglement in gillnets, and large numbers have been, and continue to be, killed in many parts of their range (Jefferson et al. 2002b). Finless porpoises are caught in nets along the India and Pakistan coasts, and off the Malay Peninsula, although there is no estimate of the magnitude of such catches. In Japan they become entangled in a variety of types of fishing gear. Changes in fishing methods may have reduced the incidental catch in some areas such as western Kyushu (Kasuya 1999), but substantial numbers are still being taken in gill nets and other fishing gear (J.Y. Wang pers. comm., January 2007). A total of 114 specimens were collected in Japan during 1985-1992 from western and north-eastern Kyushu including parts of the western Inland Sea (Shirakihara et al. 1993): 84 of them had been killed incidentally in fisheries, 25 had been found dead on the beach or in the sea, and there was no information on the other five. Fisheries that killed the 84 porpoises employed bottom-set gill nets (58), surface gill nets (17), trap nets (7), trawl nets (1) and drifting (ghost) nets (1). Such fishing gear is common in Japan and probably kills finless porpoises off other coasts, although usually such catches remain unreported. Yang et al. (1999) reported that finless porpoises were the most frequently captured cetaceans in fishing gear along the Chinese coast and estimated that more than 2,000 were taken in 1994, mainly in trawl, gill, and stow nets. In the waters of western Taiwan, including the Matsu and Chinmen Islands (western Taiwan Strait), a considerable number of finless porpoises are taken in trammel nets, trawl nets, stow nets, and other gear (J.Y. Wang pers. comm., January 2007). Given the numbers and types of net fisheries in Chinese coastal waters (e.g., Zhou and Wang 1994; Yang et al. 1999), there are serious concerns about the level of bycatch of this species. Although illegal, electric fishing has become widespread in the Yangtze River during the last decade, and it probably kills porpoises outright and contributes to the depletion of their prey (Reeves et al. 2000). In some parts of their range, there is an aversion to eating finless porpoises (Kasuya 1999; J.Y. Wang pers. comm., January 2007). However, the species is taken as bycatch and sold for human consumption on the Korean peninsula (IWC 2000). From an analysis of the species composition of odontocete products in Korean markets during 2003-2004, it was estimated that the true catch of finless porpoises in Korean waters during this period was probably about four times the officially reported catch of 142 animals (Baker et al. 2006).

As a coastal species, the finless porpoise is also affected by habitat loss and degradation, boat traffic, and pollution. The extensive modification of coastlines for shrimp farming and rampant harbor (and other) development throughout Asia (including the Arabian Gulf) means that there is less habitat for finless porpoises (Reeves et al. 2003). Porpoise habitat in the Yangtze River system has been degraded by water development, including the Gezhouba and Three Gorges dams and about 1300 smaller dams in tributaries (Liu et al. 2000; Smith et al. 2000). Sand mining is intensive in Poyang Lake, until recently a stronghold for Yangtze finless porpoises (B. Taylor pers. comm., January 2007). Although pathology related to contaminant exposure has not been reported in finless porpoises, pollution is considered a potentially serious threat (Kasuya, 1999; see Kannan et al. 1989; Iwata et al. 1994, 1995; Parsons and Chan 1998; Le et al. 1999; Minh et al. 1999; Parsons 1999; Jefferson et al. 2002b). The number of reported small cetacean strandings in Hong Kong has increased in recent years, partly due to increasing public awareness of local cetaceans, but also possibly due to escalating levels of human disturbance and pollution (T.A. Jefferson pers. comm., January 2007). Vessel collisions, especially involving high-speed ferries, may be a particular problem for porpoises in Hong Kong (Parsons and Jefferson 2000).

The causes of an apparent decline in porpoise numbers in the Inland Sea of Japan are not fully understood but include incidental mortality in fisheries as well as various forms of habitat degradation (IWC 2000, 2006). Parts of the coastal regions of the Inland Sea are highly developed and industrialized so the associated threats of habitat loss and pollution are suspected to have had some (undetermined) level of impact

Conservation Actions [top]

Conservation Actions:	The species is listed in Appendix II of CITES. Management measures are needed to reduce the threats on this species, especially those that result in incidental catches of the species in fisheries.

Conservation Actions:

The species is listed in Appendix II of CITES. Management measures are needed to reduce the threats on this species, especially those that result in incidental catches of the species in fisheries.

Citation:	Reeves, R.R., Collins, T., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2008. Neophocaena phocaenoides. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 20 November 2008.
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