We present the first synthesis of the life history and ecology of seahorses, compare relationships for seahorses with other marine teleosts and identify research needs. Seahorses occurred primarily amidst temperate seagrasses and tropical coral reefs. Population densities were generally low, ranging from 0 to 0Á51 individuals m À2 , but reached 10 m À2 in some patches. Inferred life spans ranged from 1 to 5 years. Seahorses consumed live prey and possibly changed diet as they grew. Growth rates are poorly investigated to date. Reproduction and mating systems are the best-studied aspects of seahorse ecology. The relationship between size at first maturity and maximum size in seahorses conformed to that for other marine teleosts. All seahorse species were monogamous within a cycle, but some were polygamous across cycles. Direct transfer of clutches to the brood pouch of the male fish made it difficult to measure clutch size in live seahorses. After brooding, males released from c. 5 to 2000 young, depending on species and adult size. Newborn young measured from 2 to 20 mm in length, which was a narrower size range than the 17-fold difference that occurred in adult size. Newborn body size had no relationship to adult size. Both eggs and young were larger than expected among marine teleosts, even when considering only those with parental care, but brood size at release was lower than expected, perhaps because the young were more developed. The size of adults, eggs and young increased with increasing latitude, although brood size did not. Considerable research is needed to advance seahorse conservation and management, including (a) fisheriesdependent and fisheries-independent abundance estimates, (b) age-or stage-based natural and fishing mortalities, (c) growth rates and age at first maturity, and (d) intrinsic rates of increase and age-or size-specific reproductive output. Current data confirm that seahorses are likely to be vulnerable to high levels of exploitation. # 2004 The Fisheries Society of the British Isles

This article analyses the pressures on seahorses and explores conservation responses. It focuses on seahorses (Hippocampus spp.) but also considers pipefishes and seadragons, especially where they can fill gaps in seahorse knowledge. The charisma of many syngnathids can make them good flagship species for threats and solutions in marine conservation. The article combines a synthesis of published literature with new data on the trade in seahorses for traditional medicine, aquarium display and curiosities. Most traded seahorses come from trawl by-catch, although seahorses are also targeted. The total extraction is large, tens of millions of animals annually, and unsustainable. A first review of the effect of habitat change on syngnathids raises many questions, while suggesting that some species may cope better than others. The combination of pressures means that many species of syngnathid are now included in the IUCN Red List of Threatened Species or national equivalents. In addition, seahorse exports from 175 countries are limited to sustainable levels under the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora. Possible conservation measures include marine protected areas, fisheries management, select aquaculture ventures, trade regulation, improved governance (particularly) and consumer engagement.

Nomenclatural clarity is vital for the collection, dissemination, and retrieval of natural history information, which itself is necessary for effective conservation and management of species. Seahorses (genus Hippocampus) are small marine fishes that in many cases are heavily exploited and suffering severe population declines worldwide, leading to conservation concern and action. Here we provide a brief history of seahorse taxonomy, and attempt to clarify seahorse nomenclature by reducing redundancy and exposing areas of disagreement in need of further study. We provide an annotated list of the 41 species we currently recognize as valid, and describe their geographical distributions to offer a solid foundation for future research and conservation efforts. We base our conclusions on available morphological, genetic and distributional data, re-examination of the relevant literature, previous examination of almost all original type specimens, familiarity with many thousands of other live and dead specimens, and photographs of seahorses. This work should lead to greater taxonomic clarity by highlighting known research gaps and by ensuring that each species designation is justified by robust and defensible taxonomic protocols. Such clarity should facilitate greater efficacy in management and conservation.

ABSTRACT1. In principle, the database generated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) offers an unparalleled opportunity to analyse trade in species of conservation concern.2. The value of the database is assessed in the context of trade in 47 species of seahorse (Hippocampus spp.), all of which are included on CITES Appendix II. This listing requires that all 180 Parties to CITES (member Parties) limit exports to levels that do not damage wild populations, ensure they are obtained legally, and report their trade to CITES.3. An evident need for greater universal compliance with CITES reporting requirements was identified. The most glaring problem was a substantial mismatch in species and volumes between export records and import records, indicating that neither dataset is complete nor reliable.4. The evaluation also showed that Parties should increase compliance with CITES requirements to record all trade shipments, provide units for exports (e.g. individuals, kilograms) and identify exported taxa to species, perhaps supported by automated checking of entries.5. The challenges with the CITES trade database were more evident for the global trade in dried seahorses than the smaller and more easily-tracked trade in live seahorses. Nonetheless, CITES' data from 2004-2011 revealed a seahorse trade involving millions of animals, tens of species, and scores of Parties.6. CITES data have also proven invaluable in supporting CITES reviews of how Parties are implementing the Convention for seahorses, and in generating consequent action for their conservation.

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