The Importance of Baseline Health Surveillance Efforts in Freshwater Fish Conservation Using the Threatened Iberian Leuciscids as an Example

Freshwater fish species are experiencing the highest decline among vertebrates in this century. Although a great effort has been made to identify and tackle threats to the conservation of this taxa, several knowledge gaps still exist particularly for noncommercial endangered species, including considerations regarding fish health status. These species face deteriorating environmental conditions in their natural habitats that may lead to stress and increased risk for infectious disease outbreaks. Establishing health surveillance is crucial to identify and predict physiologic disruption in fish populations. Additionally, information retrieved may be used to direct targeted efforts to contribute to improving the conservation status of these species. We used threatened Iberian leuciscids as a case study to discuss the current knowledge regarding their health surveillance and to suggest recommendations for the establishment of practical health assessments that can benefit conservation plans for these species and be implemented in threatened or endangered freshwater fish species plans globally.