Determining heterosporis threats to inform prevention, management, and control

Project manager: Paul Venturelli

Description: Heterosporis was first discovered in Minnesota in 1990 and has since been detected in approximately 30 waterbodies and is considered a disease of emerging concern in Minnesota. This disease is caused by the parasite Heterosporis sutherlandae, which damages the skeletal muscle of susceptible fish and renders them unfit for human consumption, and can result in direct mortality. H. sutherlandae can infect up to 40% of the individuals in a wild population of game or bait fish and there is no known treatment.

The primary objective of this project is to provide an initial estimate of threat that heterosporosis poses to the harvestable biomass of yellow perch in Minnesota, and establish timelines for population-level impacts.

We will develop a population model of yellow perch and couple this model with a disease model that describes H. sutherlandae dynamics as well as a generic population model that describes the dynamics of other fish hosts. We will use the model to estimate the threat that heterosporosis poses to yellow perch harvest in Minnesota, and prioritize future empirical research for improving model predictions. The overall project (Phases 1 and 2) will generate advice related to heterosporosis spread prevention, monitoring, control, and management; and establish a framework for approaching other invasive species that are relevant to Minnesota.

Project start date: 2015

Estimated project end date: 2017

Progress:

Researchers have developed a model that combines bioenergetics and population dynamics to model perch in the absence of heterosporosis, and are now coupling this with the disease sub-model. In late 2015, researchers conducted field work in Leech Lake, Cass Lake, and Winnibigoshish Lake, where they sampled 1,221 fish. In 2016, they sampled an additional 821 fish from Leech Lake in winter, spring, and summer in order to determine if heterosporosis varies seasonally or with size, sex, or species. These samples are now being processed. Going forward, researchers will be conducting infection trials in the MAISRC laboratory to determine temperature impacts, spore shedding rate, and infectivity of the disease.

Updates: