Injuries caused by the invasive armoured suckermouth catfish Pterygoplichthys sp. in three captive Antillean manatees Trichechus manatus manatus

Abstract

Background. The interaction between Pterygoplichthys and Florida manatee (Trichechus manatus latirostris) was recorded approximately 13 years ago in Florida, United States. In Mexico, this interaction has not been documented neither in the wild nor in captivity. Until now it was supposed that Pterygoplichthys attach to manatees to forage the epibiota of the skin without causing any damage. However, some behaviour displayed suggests pain, stress, and discomfort when these fish attach to the manatee’s skin. Goals. To determine if the skin wounds found in three captive manatees are associated with the presence of Pterygoplichthys in the facilities where they are housed. Methods. By trawling a large artificial lagoon (AL) for three consecutive days, every six months for two and a half years we decimated the local population of Pterygoplichthys; in the management pool (MP), fish were removed manually. Additionally, we reduced the time individuals spent in the management facilities by releasing them into the AL. Results. Total disappearance of the skin wounds was achieved in three years, due to their decreased interaction with the catfish (both through the reduction of the population of Pterygoplichthys and of the time spent by the manatees in the MP). Conclusions. Injuries were caused by the fact that manatees lived in a small space, without food available for the catfish, which caused an increase in the frequency and aggressiveness of the encounters. Therefore, we recommend creating and implementing strategies to reduce Pterygoplichthys populations in places where manatees inhabit, because in the future the wounds they cause could be a potential threat for the long-term population viability of the endangered Antillean manatee.