Hippocampus comes is targeted by fishers supplying a substantial trade in seahorses for medicinal and aquarium uses. This species is also incidentally caught (bycatch) in other fisheries and affected by habitat degradation. Given that H. comes is among the most commonly traded seahorse species, particularly for ornamental display, fishers' and traders' evidence of declines in seahorse availability raise concern (Vincent 1996) for this species.
Hippocampus comes has been studied in situ in the central Philippines since 1995, as part of a conservation program in an area where this species is of considerable economic importance (Vincent and Pajaro unpubl. data). The longevity of these animals is estimated as 3.2 years (Meeuwig unpubl. data), and they first mature at about one year old. Generation time therefore must be somewhere between 1 and 3.2 years. Declines under criterion A must be considered over 10 years, as this is undoubtedly longer than three generations. Fishers in Bohol, central Philippines, reported a decline in mean catch per unit effort (CPUE) from 24 seahorses per night per fisher in 1986–1990 (Vincent and Pajaro unpubl. data) to 2.9 seahorses per night per fisher in 1996–1999 (Vincent et al. in prep.). From these numbers, we can estimate an 84% decline in CPUE from 1991–2001 if we assume a linear decline between 1986 and 1999.
Other fisheries targeting H. comes occur in other areas of the Philippines, including Quezon, Iloilo (Panay), Bantayan Island (Cebu), and Surigao del Sur (Mindanao). H. comes are also caught incidentally in pushnets in shallow water, as well as occasionally in trawls from deeper water (Pajaro unpubl. data). Declines of varying severity have been reported in Quezon for H. comes specifically, and in most other areas of the Philippines and Southeast Asia for seahorses as a group (Vincent 1996, Vincent and Perry unpubl. data). Decline in and fragmentation of H. comes' coral, seagrass, and mangrove habitats throughout its range may lead to declines in populations in addition to those caused by the fisheries and trade. Damage to coral reef ecosystems by dynamite and cyanide fishing have been well documented, particularly in the Philippines. Land-based activities such as forestry often lead to increased siltation in surrounding marine waters, thereby smothering coral reefs and seagrass beds. The fishing gears used in seagrass beds often result in substantial trampling by fishers (Pajaro unpubl. data).
A precautionary listing of Vulnerable is warranted, inferring overall numeric declines of 30–50%. The more severe population declines in Bohol are unlikely to be representative of the species throughout its range. Fishing pressure in the central Philippines is particularly high and the reefs that comprise a major habitat are particularly accessible. Even in the central Philippines, H. comes in other habitats, such as seagrass meadows and deeper soft bottom habitats, are much less heavily targeted.