Hippocampus histrix 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Syngnathiformes Syngnathidae

Scientific Name: Hippocampus histrix
Species Authority: Kaup, 1856
Common Name(s):
English Spiny Seahorse, Thorny Seahorse
Taxonomic Source(s): Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds). 2016. Catalog of Fishes: genera, species, references. Updated 2 August 2016. Available at: (Accessed: 2 August 2016).

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2cd+4cd ver 3.1
Year Published: 2012
Date Assessed: 2012-05-11
Assessor(s): Wiswedel, S.
Reviewer(s): O’Donnell, K. & Foster, S.
Hippocampus histrix was previously listed as Data Deficient but new information from trade surveys, and international trade data made available since the listing of seahorses on Appendix II of CITES in 2004, has allowed us to suspect a population decline of at least 30% over the last 10–15 years and that these declines are suspected to continue into the future. There are also concerns about habitat destruction and capture of seahorses as bycatch throughout the range of H. histrix. For these reasons, this species is listed as Vulnerable under criterion A.

Using data from the CITES Trade Database, it was found that this species is widely traded in both the live and dry trade throughout it's range and that trade is continuing (Evanson et al. 2011, UNEP-WCMC 2012a). Historical trade surveys report trade in this species from the mid 1990's in various parts of its global range (McPherson and Vincent 2004, Meeuwig et al. 2006, Perry et al. 2010) and even at this stage, interviews with fishers and traders reported declines in availability of seahorses in some countries (McPherson and Vincent 2004, Perry et al. 2010). Together this information demonstrates that there has been substantial pressure on wild populations for well over 10 years and that these pressures are continuing.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Hippocampus histrix is relatively rare but widespread throughout the Indo-Pacific (Lourie et al. 2004).
Countries occurrence:
China; French Polynesia; Indonesia; Japan; Malaysia; Mauritius; Micronesia, Federated States of ; New Caledonia; Papua New Guinea; Philippines; Réunion; Samoa; South Africa; Tanzania, United Republic of; Tonga; United States (Hawaiian Is.); Viet Nam
FAO Marine Fishing Areas:
Indian Ocean – western; Indian Ocean – eastern; Pacific – western central; Pacific – northwest; Pacific – eastern central
Additional data:
Lower depth limit (metres):20
Upper depth limit (metres):1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There is little information on population levels and trends for Hippocampus histrix but it can be suspected that population levels are decreasing due to exploitation for international trade, coupled with high levels of bycatch and habitat destruction of H. histrix's primary habitat, seagrasses. 

In parts of its range fishers and traders have reported declines in the availability and/or size of seahorses. For example, in 1998 and 1999 in Malaysia and Thailand, surveys of both fishers and traders reported declines in the availability of seahorses including H. histrix (Perry et al. 2010)There are also reports of general seahorse declines in the Philippines (O'Donnel et al. 2010). In East Africa, surveys of fishers and traders in 2000 documented declines in seahorse availability and size, which included H. histrix (McPherson and Vincent 2004). Currently, trade in this species is extensive with annual reported volumes exceeding 200 thousand individuals annually between 2004 and 2010 from a number of countries throughout this species' range (Evanson et al. 2011, UNEP-WCMC 2012a). Trade in seahorses, is expected to continue into the future as the demands for traditional medicines increase due to their increasing popularity in both the developed and developing world (Robinson and Zhang 2011). 

General seahorse population declines within H. histrix's range are suspected as a result of habitat degradation and declines in seagrasses (Marcus et al. 2007, Short et al. 2011), and mortality from intense trawling bycatch (Baum et al. 2003, Giles et al. 2006, Perry et al. 2010) - and indeed these threats are known to occur throughout this species' range (FAO 2001, Perry et al. 2010). 

Since trade is reported for several different parts of this species' range and that the threats facing this species occur throughout its range, it is suspected that these declines are occurring globally for H. histrix. It is conservatively suspected that the rate of decline has been at least 30% for the past 10–15 years and that this decline is expected to continue into the future.
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Hippocampus histrix is often found at depths between six and 20 m (Lourie et al. 2004) but may also be found deeper than this (Kuiter 2000). This species is found on a variety of substrates including sponges, weedy rocky reefs, soft corals but mainly on seagrass beds (Lourie et al. 2004, Kuiter 2000).

All seahorse species have vital parental care, and many species studied to date have high site fidelity (Perante et al. 2002, Foster and Vincent 2004), highly structured social behaviour (Vincent and Sadler 1995), and relatively sparse distributions (Lourie et al. 1999) - all traits which make seahorses vulnerable to exploitation. There are however some traits, such as small body size, fast growth and high fecundity that may make seahorses more resilient to exploitation (Morgan 2007). However a specialised life-history coupled with a dependence on shallow habitats that are subject to extremely high fishing pressure, and the fact that seahorses do not move very much and are thus easily captured, means they are very vulnerable to over-exploitation. The importance of life history parameters in determining response to exploitation has been demonstrated for a number of species, including seahorses (Jennings et al. 1998, Foster and Vincent 2004).
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):2

Use and Trade [top]

Use and Trade: Hippocampus histrix is one of the six seahorse species most often reported to CITES as being traded internationally (Evanson et al. 2011). This species is traded both live, for the aquarium trade as well as dry, for use in traditional medicine. Although this species has a spines on its body, which is considered undesirable in the traditional medicine trade (Vincent, 1996), there are large numbers of dried specimens traded. 

Trade in this species has been reported from countries throughout it's range including from as early as 1996 in Malaysia and Thailand (Perry et al. 2010), Kenya and Tanzania (McPherson and Vincent 2004) and Vietnam (Meeuwig et al. 2006). Since the implementation of the listing of all seahorse species on CITES Appendix II in 2004, there have been reports of approximately 200 thousand individuals traded annually between 2004 and 2010 and (Evanson et al. 2011, UNEP-WCMC 2012a). Given that a large proportion of the trade reported to CITES is only reported to the genus level, it is possible this volume underestimates the true extent of trade in this species (Evanson et al. 2011). In the CITES Trade Database, international trade in this species has been reported from many countries throughout its range including, China, Hong Kong SAR, Indonesia, New Caledonia, Philippines, Thailand and Taiwan (UNEP-WCMC 2012a).  In 2010, this species was selected by the CITES Animals Committee for the Review of Significant Trade following COP15 due to large amounts of potentially unregulated international trade (UNEP-WCMC 2012b). 

Although it was originally suspected that this species was only rarely traded live for the aquarium trade (Lourie et al. 2004),  large volumes of trade in live specimens have subsequently been reported to CITES, primarily consisting of wild-caught specimens originating in Indonesia (Evanson et al. 2011, UNEP-WCMC 2012a).

There is currently a national ban on the capture and trade of seahorses in the Philippines (Philippine Department of Agriculture 1998) - however field research in the area revealed that fishing continued in spite of the ban (O'Donnell et al. 2010, UNEP-WCMC 2012b). In 2001, all seahorses were listed on Schedule I of the Indian Wildlife Protection Act (Indian Ministry of Environments and Forests 2001), which effectively bans all trade in these species but again, illegal trade has been reported to be continuing in this country (UNEP-WCMC 2012b).

When looking at trade in H. histrix, it is important to note that this species name is often used as a label for any spiny seahorse from the Indo-Pacific and therefore may contain specimens of other species (Lourie et al. 2004).

Threats [top]

Major Threat(s): The major threat to Hippocampus histrix is international trade for the aquarium and traditional medicine trades. To supply this trade, this species is caught in both targeted fisheries as well as bycatch in other non-selective fisheries, particularly shrimp trawls (McPherson and Vincent 2004, Meeuwig et al. 2006, Perry et al. 2010). H. histrix has been reported in international trade since the mid 1990's and even at this stage, interviews with fishers and traders reported declines in the availability of seahorses (McPherson and Vincent 2004, Perry et al. 2010).

Even without demand for trade, this species is known to be a bycatch in the tropical shrimp trawl fishery and shrimp trawling is known to occur throughout much of its range and cause substantial damage to this species' habitats (FAO 2001, Perry et al. 2010). 

Indeed, this species' in-shore seagrass habitats are threatened throughout its range (Short et al. 2011). Major threats faced by seagrasses include; eutrophication, sedimentation, coastal construction, dredging and invasive species and these threats result in decline in and fragmentation of seagrass habitats (see Short et al. 2011 for an overview of threats facing seagrasses). It is reasonable to expect that all of these threats will continue into the future.

Seahorses life history and ecological traits may increase their susceptibility to these threats (see Habitats and Ecology).

Conservation Actions [top]

Conservation Actions: All Hippocampus species are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This means that countries who are signatories to CITES are subject to regulations on the export of seahorses. Countries are required to provide permits for all exports of seahorses and are meant to provide evidence that these exports are not detrimental to wild populations. However a lack of basic information on distribution, habitat and abundance means many CITES Authorities cannot assess sustainability of their seahorse exploitation and meet their obligations to the Convention.  The challenge is particularly large in that most seahorses entering trade are caught incidentally as bycatch and thus imposing export quotas would achieve next to nothing for wild populations. 

CITES has recommended a minimum size limit of 10 cm height for all seahorse specimens in trade (CITES Decision 12.54). This limit represents a compromise between the best biological information available at the time of listing and perceived socioeconomic feasibility.  But we urgently need information on wild populations to assess their conservation status and take conservation action, as well as refine management recommendations.  For example, evidence on variation in the spatial and temporal abundance of seahorses would enable areas of high seahorse density to be identified, as the basis for considering area restrictions on non-selective fishing gear that obtains Hippocampus species as bycatch.  An understanding of the technical and logistical feasibility of returning to the sea live seahorses taken as bycatch in various types of fishing gear would provide the basis for considering the feasibility of minimum size limits and/or other output controls. Establishing monitoring program of landings of seahorses at representative sites, taking into account different gear types and means of extraction and recording catch and effort metrics would allow us to assess population conservation status and develop management recommendations for various fishery types. 

Hippocampus histrix has been listed as Data Deficient in the Vietnamese Red Data Book.

Citation: Wiswedel, S. 2012. Hippocampus histrix. The IUCN Red List of Threatened Species 2012: e.T10070A16644674. . Downloaded on 17 January 2017.
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