Taxonomic notes: All Black Sea specimens examined thus far have been genetically identified as Hippocampus guttulatus, with no evidence of a separate species (Woodall 2009). This supersedes previous suggestions that a new and different species or subspecies inhabits the Black Sea.

Hippocampus guttulatus is primarily a species of European waters. The species is present along the Atlantic coast from the UK, Ireland and Netherlands to the Mediterranean Sea. Distribution continues into the Mediterranean Sea and the Black Sea (Lourie et al. 2004). Exact locations of populations are unknown, but it is expected that seahorses occur at low densities all along the coastline (L. Woodall pers. obs.).

Generally, seahorse density is patchy (Foster and Vincent 2004) and at most locations they are rare, but they can be abundant locally (Curtis and Vincent 2005, Woodall 2009). Wherever data are available, seahorse populations appear to be declining (Foster and Vincent 2004, Vincent et al. 2011). 

There is no global estimate of H. guttulatus population size and no global assessment of population trends. However there are two locations where long-term datasets are available and another where population dynamics have been assessed through interviews.

In the Ria Formosa (southern Portugal), the H. guttulatus population decreased by 94% from 2002 to 2007 (Curtis and Vincent 2005, Caldwell and Vincent 2012). More recent surveys at this location revealed that the population size is possibly increasing again (M. Correia pers. comm.). No cause for the population change has been confirmed, but benthic macrofauna habitat changes recorded in the area have been shown to result from anthropogenic stressors (Gamito 2008) and this may be related to the declines in seahorse numbers. 

In the Thau Lagoon (Southern France), H. guttulatus populations have fluctuated each year, however no long term trend has been observed (2005–2009) (Louisy 2011). In the Arcachon Basin (Western France), interviews suggest that the population distribution is very patchy, but to date no trend has been established due to lack of consistent data collection (2005–2011) (Grima 2011).

Anecdotal evidence is available in other locations, but without exhaustive surveys and systematic data collection. In Mar Menor, (Southern Spain), Voiotias, (Greece) and Varna, (Bulgaria) the population size of H. guttulatus fluctuates greatly each year (2005–2011) (anecdotal evidence compiled by L. Woodall, Project Seahorse). In other coastal sites populations have both decreased (Badalona, Spain- J. Ortiz, SASBA,  in. litt.; Malaga, Spain- P. Cabrera, in. litt.; Galicia, Spain- S. Valladares, in. litt) and increased (La Herradura, Spain- P. Cabrera, in. litt.). It is therefore difficult to generalize on population trends for this species throughout its range.

Hippocampus guttulatus are mostly found inhabiting small home ranges in shallow coastal waters, lagoon systems and estuaries (0.5–15 m; Curtis and Vincent 2005,Curtis and Vincent 2006, Garrick-Maidment and Jones 2004, Woodall 2009) but there may be seasonal migration to deeper waters (30 m+) (Boisseau 1967, Garrick-Maidment 2007, Garrick-Maidment and Jones 2004). Adult H. guttulatus use varied habitats, of all sediment types, macroalgae and seagrass and in addition are often observed on artificial structures using them as holdfasts (Curtis and Vincent 2005, Franco et al. 2006, Garrick-Maidment and Jones 2004, Louisy 2010, Woodall 2009). 

In the Ria Formosa adult H. guttulatus are associated with complex habitats, including Zostera marina, Ulva spp., Codium spp. and artificial structures (Curtis and Vincent 2005). However this species is seen in different habitats such as rocky areas, sand/silt ripples, sessile invertebrates and sponges in other locations such as the U.K, Bulgaria, Spain, France and Greece (Garrick-Maidment and Jones 2004, Louisy 2010, Woodall 2009). As an ambush predator, H. guttulatus has a wide dietary range that mainly comprises Amphipoda, Anmura, Decopoda and Mysidacae (Kitsos et al. 2008, Gurkan et al. 2011) and thus is associated with highly productive habitats.

Hippocampus guttulatus are seasonal breeders (approx. March to October) with a temperature limited mating and gestation period of around 21 days (Boisseau 1967, Curtis 2007). Predicted annual fecundity is about 900 young and is correlated with fish size, but the size of the male brood pouch is inferred to be a limiting factor for both sexes (Curtis 2007).

In the Ria Formosa, newborn H. guttulatus are about 12 mm and are seen in adult habitat at 96 mm. Males are mature at 109 mm, reproduce at 125 mm and live for approximately 5 years (Curtis and Vincent 2006). Juvenile H. guttulatus (<96mm) are rarely observed during surveys (Curtis and Vincent 2006, Louisy 2010, Woodall 2009). They spend the first weeks of life as plankton, but nothing more is known about them until recruitment at 96mm (Boisseau 1967). Juvenile development ex-situ is determined by water temperature, food availability and condition at birth (J. Palma pers. comm.).

Hippocampus guttulatus adults have low dispersal and limited migration (Caldwell and Vincent 2012). This reduces their ability to colonize new areas, recolonize old ones, and in addition reduces their ability to move when habitat becomes unfavourable. H. guttulatus, consistent with other seahorses, has a genetically monogamous mating system, at least within a breeding season (Woodall et al. 2011), and this may reduce their reproductive potential if their partner is removed from the population (e.g. caught). However H. guttulatus matures at an early age, has rapid growth rates, and a short generation time, traits which suggest that it may recover rapidly when direct (e.g., exploitation) and indirect (e.g., by-catch and habitat damage) effects of disturbance cease, but may be vulnerable to extended periods of poor recruitment (Curtis and Vincent 2006).

No specific targeted fisheries are known in Europe for H. guttulatus. There may be exploited populations in Africa but the extent of the species' range in this region is unconfirmed. International trade is required to be documented as sustainable, as H. guttulatus is listed on CITES Appendix II. There were just four records of international trade in H. guttulatus reported to CITES between 2004–2010 for the purpose of conservation research (UNEP-WCMC 2012a). Seahorse species are, however, often misidentified (L. Woodall pers. obs.).

Hippocampus guttulatus are sold as curiosities and good-luck charms when obtained as by-catch, (France and Portugal; L. Woodall, pers. obs.) and are collected occasionally under permits for display in local public aquariums (Portugal and France; L. Woodall pers. obs.), it is unlikely that these activities threaten the species globally.

The major continuing threat to H. guttulatus is habitat degradation and disturbance through direct anthropogenic activities such as coastal developments and the effect of fishing gear (e.g., trawls and dredges) (Caldwell and Vincent 2012). As it is a shallow coastal species it is extremely susceptible to anthropogenic activities. Habitat degradation through climate change continues across H. guttulatus geographic range, and H. guttulatus, like other small coastal fish, is also threatened by pollution from shore side run-off and ships (Islam and Tanaka 2004).

Seahorses are caught both intentionally and incidentally in Portugal, and sold for curiosities or into the live aquarium fish trade (J. Curtis, in litt. to P. LaFrance). They are also caught incidentally in Italy, France, Spain and Croatia (J. Curtis pers. comm. to P. LaFrance). The volume of this trade is unknown, but without appropriate management this trade might represent a threat to the species.

• 7.3 Other ecosystem modifications
• 5.4.3 Unintentional effects: (subsistence/small scale) [harvest]
• 11.1 Habitat shifting & alteration

The entire genus Hippocampus was listed in Appendix II of CITES in November 2002 with implementation of the listing in 2004. Hippocampus guttulatus has been listed under OSPAR, European CITES, (Curd 2009) the Bern Convention and Barcelona Convention (Abdul Malak et al. 2011) .

Regionally, it is listed as Near Threatened in the Mediterranean (Abdul Malak et al. 2011) and Endangered in Croatia (Jardas et al. 2007). In the Black Sea region, it is listed as Endangered by Turkey, Vulnerable in Georgia and the Ukraine, and Least Concern in Romania (Yankova 2012). The species is listed in National Red Data Books in Bulgaria, France, Portugal and Slovenia (Yankova 2012). H. guttulatus is protected by the UK Wildlife and Countryside Act of 2008 (DEFRA 2008) and is a UK Biodiversity Action Plan priority species (JNCC 2010).

Further research on this species biology, ecology, habitat, abundance and distribution is needed. Long-term monitoring is required for this species across its geographic range focusing on population trends, harvest level trend and habitat trends.

• 1.2 Resource & habitat protection
• 4.3 Awareness & communications
• 1.1 Site/area protection
• 2.1 Site/area management
• 5.2 Policies and regulations
• 4.2 Training

Hippocampus guttulatus retains its 2003 classification of Data Deficient.

There is some evidence for a large (94%) decrease in population census size from one location (Ria Formosa, South Portugal) (Curtis and Vincent 2005, Caldwell and Vincent 2012), but no consistent trends have been observed and trends throughout the species' range are unknown; this is partly due to a scarcity of information. Thus, based on a lack of data, this species cannot be reliably categorised on a global level.

Urgent population assessments and long term monitoring programs across its geographic range are required to assess the global extinction risk of this species. In addition there are, at present, no data as to the extent populations are exploited in Africa. Current research ongoing in West Africa will hopefully elucidate this situation.

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