Reproductive management of the Orinoco river dolphin Inia geoffrensis humboldtiana in Venezuela

Abstract

The Orinoco river dolphin Inia geoffrensis humboldtiana is included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. The International Union for Conservation of Nature Red List used to categorize the Orinoco river dolphin as Vulnerable; however, it is now considered Data Deficient because current information about threats, ecology and the population are limited and out of date. The Red Book of Venezuelan Wildlife categorizes the species as ‘vulnerable’, and the Venezuelan National Biodiversity Strategy and Action Plan identifies ex situ conservation actions for threatened species. The distribution of this river dolphin in Venezuela extends from the Casiquiare canal, upper/mid-/lower Orinoco River, tributaries, through the delta, where its populations are threatened by the deterioration of habitat, illegal hunting and accidental capture in fishing nets. Captive-breeding programmes for cetacean river species worldwide, including the Orinoco river dolphin, have led to an increase in knowledge about reproductive parameters and biological data, which is helpful for future conservation planning. Detailed husbandry manuals and management procedures, which were insufficient at the time the data were collected, are of vital importance for the sustained survival and reproduction of this species ex situ, especially if the conservation status should change from Vulnerable to Critically Endangered. Valencia Aquarium, Venezuela, housed Orinoco river dolphins for 41 years, from 1975 onwards. In 1994 a reproductive group was established with one male and two females. Over the next 22 years (1994–2016) eight calves were born. The following report details the prenatal management, birthing events, lactation periods, and sizes, weights and survival of the young.