Underwater visual census for seahorse population assessments.

1. Introduction
1.1. Why Is It Important To Assess Populations of Seahorses?
Apart from their intrinsic worth, these fishes are unusual and valuable for a number of reasons
including their unusual biology, economic value, medicinal properties and conservation

• Reproductive Behaviour: Seahorses (genus Hippocampus) exhibit the most highly
specialized paternal care of any animal: they incubate young in brood pouches. Some
seahorse species also exhibit rare sexual fidelity, called monogamy, to only one partner
(e.g. Hippocampus whitei, Vincent & Sadler 1995).

• Anatomy: Seahorses are voracious predators that lack scales, teeth and stomachs. They
have binocular vision, tube-like snouts, bony plates and unusual grape-like gills. Their
fins are reduced in size and most species lack a caudal fin, relying on dorsal and pectoral
fins for propulsion. Seahorses grasp holdfasts with prehensile tails and remain stationary
during long periods of time.

• Ecology: Seahorses contribute significantly to food web dynamics in seagrass
communities (Tipton & Bell 1988), and form an important component of their coral,
mangrove and estuarine ecosystems.

• Economics: Some seahorses provide income for many subsistence fishing families and
sell for high prices. Seahorses are also used in the live aquarium fish trade and as dried
curiosities or souvenirs (Vincent 1996).

• Medicines: Seahorses and pipefishes are used extensively as traditional medicines to
treat a range of ailments. The use of these fishes for medicinal purposes is recognized by
the World Health Organization.

• Conservation: Seahorses are important as attractive species around which we can rally
support for a wide range of marine conservation issues, from habitat destruction to
overfishing to bycatch. These fishes can therefore be used as an educational tool – and
seahorses are themselves recognized as threatened, or of conservation concern.

Curtis, J., Moreau, M., Marsden, D., Bell, E., Martin-Smith, K., Samoilys, M. & A.C.J. Vincent (2004). Underwater visual census for seahorse population assessments. Project Seahorse, University of British Columbia, Vancouver. https://projectseahorse.org/wp-content/uploads/2021/06/Underwater_visual_census_seahorse_Population_Assessment.pdf