Review of threatened Malagasy freshwater fishes in zoos and aquaria: The necessity of an ex situ conservation network—A call for action

Abstract

Madagascar's biota is characterized by an extraordinary species richness, with a high degree of endemism. The island's freshwater habitats harbor numerous micro‐endemic species, restricted to particular regions and thus particularly at risk of extinction, due to deforestation, overfishing, and introduction of exotic species. The present study investigates for which threatened Malagasy freshwater fish species ex situ populations have already been established, as a baseline to prioritize actions to develop an effective ex situ conservation breeding network. Populations in zoos and aquaria were primarily determined using the Zoological Information System. Of 173 fish species recorded from Malagasy freshwater habitats, 123 exclusively inhabit freshwater; 79 of these are endemic to Madagascar, and 50 are classified as threatened. Our survey found 21 Malagasy freshwater fish species kept in zoos worldwide, of which 19 are endemic and threatened (22 if counting species kept by private breeders). Nine of the 19 Malagasy freshwater fish species kept in zoos have successfully reproduced within the 12 months preceding our survey. The ex situ conservation activities for threatened Malagasy freshwater fishes thus have not improved significantly since the strong start in the early 2000s. More than half of the 50 threatened endemic Malagasy freshwater fish species (viz. 31 species) are not kept ex situ, including 11 species ranked as Critically Endangered. Based on these findings we call for a better distribution of offspring among institutions, including private breeders in the framework of citizen conservation initiatives; a closer connection of ichthyological field research in Madagascar with conservation breeding efforts to set up ex situ populations—both in Madagascar and abroad—of species not yet kept in captivity; and the development of effective, integrated in situ and ex situ conservation strategies.

Towards a DNA barcode library for Madagascar’s threatened ichthyofauna

“…As important conservation centers with global network activities, zoos contribute a great amount by preserving viable species populations which would be threatened with extinction due to the increased loss in natural habitats in the wild [ 69 ]. Most recently, a review of threatened Malagasy freshwater fishes in zoos and aquaria [ 15 ] highlighted the necessity of an ex situ conservation network. This complies with the One Plan Approach proposed by the IUCN SSC Conservation Breeding Specialist Group (CBSG), viz.…”

“…This complies with the One Plan Approach proposed by the IUCN SSC Conservation Breeding Specialist Group (CBSG), viz. the development of management strategies and conservation actions by all responsible parties for all populations of a species, whether inside or outside their natural range [ 15 ].…”

“…Of the 173 fish species listed from Malagasy freshwater habitats by Leiss et al [ 15 ], 123 are exclusive freshwater inhabitants, 79 of these endemic to Madagascar, and 50 classified in one of the threatened categories of the International Union for Conservation of Nature and Natural Resources [ 20 ]; of the threatened species, 6 are categorized as Vulnerable, 30 as Endangered, and 14 as Critically Endangered [ 20 ] (summarized in [ 15 ]). Of the marine species, 37 are considered to be endemic to Madagascar, and an additional 23 subendemic, that is, their distribution is restricted to Madagascar and adjacent archipelagos or submerged ridges [ 3 ].…”

“…Despite the presence of only three clades of primary freshwater fishes (cichlids, family Cichlidae; Madagascar rainbowfishes, Bedotiidae; Old World killifishes, Aplocheilidae), Madagascar's inland waters harbor a species richness comparable to other landmasses of similar size [12]. Early researchers interpreted this freshwater ichthyofaunal assemblage as depauperate [13] but Sparks and Stiassny [12] already listed as many as 143 native Malagasy freshwater fish species, and 26 new species have been scientifically named since [14,15]. The latest comprehensive checklist [3] lists 90 native freshwater species (defined as species where adults live mainly in this environment), as well as 28 introduced species (all from freshwater or transitional habitats), thus totaling 118 fish species occurring in Madagascar's freshwaters.…”

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

“…For example, among amphibians, 13 of the 34 species in zoos belong to the genus Mantella, a group of strikingly colored diurnal frogs, even though Mantella contains only 4% of Madagascar's amphibian fauna. Freshwater fishes, amphibians, and reptiles are highly suitable for targeted ex situ breeding and reintroduction programs (82)(83)(84)(85). For species in these groups and others with high levels of micro-endemism, such conservation programs continue to represent a major safeguard against extinction (86).…”