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Nonselective fishing gears extract a great many small marine species, with limited documentation or assessment of their impacts. Among those species, seahorses (genus Hippocampus) are unusual because this genus has been the focus of scientific surveys and international trade regulation. Our review of published and unpublished data sources analyzed data on seahorse bycatch for five gear-type categories and 22 countries. The median catch per unit effort of seahorse bycatch across all five gear types was 0.96 seahorses per vessel−1day−1. Nonetheless, fleet sizes were so large that annual catches were estimated at approximately 37 million seahorses across our sampled countries. Fisher interviews suggested that seahorse catches were declining (although information on changes in effort over time were not available). Furthermore, international export data did not capture the magnitude of seahorses in bycatch. Our work emphasizes the importance of evaluating bycatch, even for taxa where reported daily catch rates are low.

Nonselective fishing gears extract a great many small marine species, with limited documentation or assessment of their impacts. Among those species, seahorses (genus Hippocampus) are unusual because this genus has been the focus of scientific surveys and international trade regulation. Our review of published and unpublished data sources analyzed data on seahorse bycatch for five gear-type categories and 22 countries. The median catch per unit effort of seahorse bycatch across all five gear types was 0.96 seahorses per vessel-1day-1. Nonetheless, fleet sizes were so large that annual catches were estimated at approximately 37 million seahorses across our sampled countries. Fisher interviews suggested that seahorse catches were declining (although information on changes in effort over time were not available). Furthermore, international export data did not capture the magnitude of seahorses in bycatch. Our work emphasizes the importance of evaluating bycatch, even for taxa where reported daily catch rates are low.

Seahorses (Hippocampusspp) are heavily exploited in Vietnam, but conservation and management measures are currently limited by the ambiguous taxonomic definitions of the genus in the region. Seven species of seahorse are identified in this paper as inhabiting the coastal waters of Vietnam. We used morphometric and DNA sequence data (from the cytochrome bregion of the mitochondrial genome) to delimit the species. Species descriptions are put forward and we provide illustrations and an identification key to the species. The species are provisionally assigned to Hippocampus spinosissimusWeber 1913, H. comesCantor 1850, H. trimaculatusLeach 1814, H. kudaBleeker 1852, H. kelbggiJordan and Snyder 1902, H. mohnikeiBleeker 1854 and H. histrixKaup 1856. The current level of confusion in seahorse nomenclature means that some of these distinct species in Vietnam (in particular H. spinosissimus, H. kuda, H. kelloggiand H. mohnikei) may have to be renamed once a comprehensive revision of the genus has been completed.