Development of Non-Lethal Methods for Health Assessment of Free-Ranging Fish Populations

Use of non-lethal methods to quantify indices of animal health are important tools used for management of terrestrial and aquatic wildlife. Many species of interest are endangered, or used as sentinels of ecosystem health. In Florida, health assessments of the Florida manatee (Trichechus manatus latirostris) and bottlenosed dolphin (Tursiops truncatus) are conducted annually in several important geographic areas. Typically these events involve a lead investigator and multiple collaborators from state and federal agencies as well as multiple universities. Historically these types of investigations have not been carried out on free-ranging populations of fish. During the summer of 2011 we will be conducting a pilot study with a protected red drum (Sciaenops ocellatus) population to determine applicability of these techniques to fishery science. Development of a reasonable health assessment protocol has to begin with a definition of “health” and clear articulation of questions or specific concerns pertaining to the population of interest. The most basic protocols typically involve collection of body weight and morphometric data, and collection of blood for complete hematology and serum chemistry profiles. During field restraint of many mammalian species a portable clinical analyzer is used to monitor blood gasses, acid-base balance and electrolyte changes. These units have been used on fish, but not as a means of clinical assessment during field sampling. Fluorescein dye has been used to assess traumatic injury in fish caused by handling, and clearly demonstrates areas of mucus damage or scale loss that are not visible to the unaided eye.  We plan to use both of these methods to develop restraint and handling protocols for adult fish that will minimize damage to the animal during sampling. Ancillary tests used to define “health” in a population include identification and description of resident microbial or parasite populations on fish, serology to assess exposure to specific pathogens of interest, and collection of tissue for contaminant analysis. These can be used to develop baseline data on key species in sensitive environmental areas and will enhance our collective ability to make good management decisions and identify trends as these ecosystems are impacted by development, climate change and other natural or human-mediated events.