2024 Program Grants: Clarifying the Protocol for the Successful Rearing of Ambystoma dumerilii Larvae
The critically endangered Achoque (Ambystoma dumerilii), endemic to Lake Patzcuaro in central Mexico, faces threats from habitat loss, pollution, invasive species, and overexploitation. AArk’s Conservation Needs Assessment recommended ex situ management as vital to this species’ survival, especially during its vulnerable larval stage, which currently experiences up to 50% mortality. With AArk’s 3-year grant, the team, hosted by Universidad Michoacana de San Nicolás de Hidalgo, will refine larval rearing protocols, improving survival rates for A. dumerilii. Soft releases into Lake Patzcuaro are also planned from year 1, with the microchipping of at least 20% of the released individuals and monitoring until adulthood.
Grantee:
Rodolfo Pérez Rodríguez | Universidad Michoacana de San Nicolás de Hidalgo
One of the main lakes in central Mexico is Lake Patzcuaro, since it is home to a remarkable wealth of freshwater organisms. In addition to its high degree of endemism, these organisms represent millenary fishery resources that were decisive in the establishment and development of pre-Hispanic cultures around the lake (Orbe-Mendoza et al., 2002; Toledo et al.,2008).
The Achoque, Ambystoma dumerilii, is one of the four paedomorphic species of the genus that are micro-endemic. Like its congeners, A. dumerilii has been continuously exploited for consumption by local communities from pre-Hispanic times to the present day in Lake Patzcuaro. Unfortunately, at present, factors such as land use change, pollution, global warming, overexploitation, introduction of exotic species, emerging diseases, and excessive extraction of natural populations have caused the collapse of amphibian populations globally, the latter being considered the main cause of the population decline of Achoque in Lake Patzcuaro (Frías-Alvarez et al., 2010). This has placed A. dumerilii in a special protection status (NOM-059-ECOL-2010), while the IUCN red list presents a Critically Endangered status (IUCN 2020).
One of the actions for the conservation of this species is ex situ management. However, although in the last four years ex situ management has been carried out in different colonies of this species in Mexico, it has been detected that the critical stage is the first two months after hatching: it can present up to 50% mortality. It has been observed that this mortality is mainly associated with the lack of adequate food at these stages, water quality due to excess of nutrients and high temperatures, in addition to a high incidence of attacks when the larvae density is high. On the other hand, for the third and fourth months, although there is a lower mortality, it continues to occur mainly due to factors associated with water quality and the occurrence of cannibalism, both factors associated with food and density.
The purpose of this project is to develop a management plan for the larval stage of A. dumerilii, in order to obtain a better development and higher survival rate (about 80%) through the following objectives:
- Establish an adequate feeding process during the Ambystoma dumerilii larval stage
- Enable a post-water filtration system from the public network that guarantees good quality
- Enable a module for larval development that allows optimal temperature control
- Establish a monitoring protocol for the chemical parameters of the water to guarantee optimal quality during the larval stage
- Determine an optimal density of larvae to achieve greater survival and better development throughout the larval stage
- Design and build a prototype culture system to increase the capacity tohandle a greater number of larvae of different sizes
- Evaluate a soft release stage through the implementation ofa process of acclimatization and conditioning of juveniles in mesocosms.
The aim is to obtain a survival rate of 80% of larvae during the critical stage, and to have conditioned and acclimatized juveniles to be released. In addition, we intend to develop a larval management plan for the management and development of larvae of this species.
