Hippocampus mohnikei 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Syngnathiformes Syngnathidae

Scientific Name: Hippocampus mohnikei Bleeker, 1853
Common Name(s):
English Japanese Seahorse, Lemur-tail Seahorse
Hippocampus japonicus Kaup, 1856
Taxonomic Source(s): Lourie, S.A., Pollom, R.A. and Foster, S.J. 2016. A global revision of the seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): Taxonomy and biogeography with recommendations for future research. Zootaxa 4146(1): 1-66.
Taxonomic Notes: Both Hippocampus mohnikei and H. japonicus were described from Japan and examination of their type specimens shows them to be the same species (Lourie et al. 2016 - Appendix J). Specimens from elsewhere in the Indo-Pacific morphologically conform to H. mohnikei, and differ genetically (e.g. Japanese and Vietnamese specimens differ by an average of 2.25%—648 bp, CO1, BOLD 2016), indicating that there is the possibility of cryptic species within what we know as H. mohnikei.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2cd+4cd ver 3.1
Year Published: 2017
Date Assessed: 2016-09-27
Assessor(s): Pollom, R.
Reviewer(s): Ralph, G.
Hippocampus mohnikei is a coastal marine seahorse that inhabits seagrasses, mangroves, oyster beds, and  mussel farms along the coast of continental Asia from southern India to North Korea and Japan. The species is exploited both as a targeted species and as bycatch and subsequently traded for use as curios, aquarium pets, and in traditional medicines. In addition, seagrass and mangrove habitats are declining globally as a result of human impacts, especially in Southeast Asia. Fishers have reported substantial declines in seahorses in several places across this range. Given that previous declines were reported, more recent data are only available for one locality but still show declines, and that pressures on habitat have not ceased and may be accelerating, overall it is suspected that declines of at least 30% have occurred for this species over the past 10 years and that these declines will continue into the future. Therefore this species is listed as Vulnerable under criterion A2cd+A4cd.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Hippocampus mohnikei inhabits waters from the Gulf of Mannar, India, to North Korea and northern Honshu, Japan (Aylesworth et al. 2016).
Countries occurrence:
Bangladesh; Cambodia; China (Fujian, Guangdong, Guangxi, Hainan, Hebei, Jiangsu, Liaoning, Shandong, Tianjin, Zhejiang); Hong Kong; India (Andaman Is., Andhra Pradesh, Orissa, Tamil Nadu, West Bengal); Indonesia (Sumatera); Japan (Honshu, Kyushu, Nansei-shoto, Shikoku); Korea, Democratic People's Republic of; Korea, Republic of; Malaysia (Peninsular Malaysia); Myanmar (Coco Is., Myanmar (mainland)); Singapore; Sri Lanka; Taiwan, Province of China (Taiwan, Province of China (main island)); Thailand; Viet Nam
FAO Marine Fishing Areas:
Indian Ocean – eastern; Pacific – northwest; Pacific – western central
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):Unknown
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:Unknown
Lower depth limit (metres):10
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:To date there have been no dedicated underwater surveys or population estimates for Hippocampus mohnikei. Trade surveys undertaken by Project Seahorse in the 2000s indicated substantial declines (30-68%) in seahorses within the range of this species (Giles et al. 2006, Perry et al. 2010). Hippocampus mohnikei has been observed and reported extensively in bycatch and targeted trades (Aylesworth et al. 2016). In Cambodia, fishers reported catch declines from 30 seahorses per month in 2010 to 5-10 seahorses per month in 2014 (an 88% reduction if extrapolated to 10 years) (Aylesworth et al. 2016). In addition, seagrasses and mangroves are declining globally and such losses may be contributing to declines in H. mohnikei (Polidoro et al. 2010, Short et al. 2011). Given that previous declines were reported, more recent data are only available for one locality but still show declines, and that pressures on habitat have not ceased and may be accelerating, overall it is suspected that declines of at least 30% have occurred for this species.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:UnknownPopulation severely fragmented:Unknown
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:UnknownAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Hippocampus mohnikei inhabits areas with seagrasses (including Zostera spp., Halophila ovalis, Thalassia hemprichii, and Enhalus acoroides), mangroves, oysterbeds and mussel farms (Aylesworth et al. 2016). One study has examined planktonic juveniles of the species that range in size from 6.0–65.3 mm (standard length) (Kanou and Kohno 2001). These juveniles were found in plankton tows from May–January. Young from 15–34 mm SL showed high gut fullness and had consumed small crustacean prey including Oithona davisae and Penilia avirostris. In contrast, large planktonic individuals ≥35 mm showed low gut fullness, preying on larger but less abundant prey items such as species of Brachyura. As in other seahorses, H. mohnikei is ovoviviparous, and males brood the embryos in a pouch prior to giving live birth (Foster and Vincent 2004).  Their breeding season appears to occur from May to September in the Japanese portion of their range (Otsuka et al. 2009).
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):1-2
Movement patterns:Unknown

Use and Trade [top]

Use and Trade: Hippocampus mohnikei is targeted and caught as bycatch and subsequently traded live for the aquarium trade or dried for use as curios or in traditional medicine throughout much of its range (Vincent et al. 2011, Aylesworth et al. 2016).

Threats [top]

Major Threat(s): Hippocampus mohnikei is threatened by overexploitation (through targeted catch and as bycatch) and seagrass and mangrove habitat loss as a result of coastal development and pollution, destructive fishing practices such as trawling and the use of dynamite, and the effects of climate change including increased sea surface temperatures and frequency of storms (Waycott et al. 2009, Polidoro et al. 2010, Short et al. 2011, Aylesworth et al. 2016). It is thought that in combination these ongoing threats are likely to result in range-wide declines of at least 30% in the H. mohnikei population over three generations.

Conservation Actions [top]

Conservation Actions: The entire genus Hipppocampus is listed on Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), effective May 2004. H. mohnikei is listed (as H. japonicus) as Vulnerable in the 1994 Viet Nam Red Data Book (Lourie et al. 2004). It’s not clear whether the species occurs in any protected areas.

Citation: Pollom, R. 2017. Hippocampus mohnikei. The IUCN Red List of Threatened Species 2017: e.T41005A54907304. . Downloaded on 19 July 2018.
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