Groundbreaking model used in trout count

Experts are counting insects on the Mataura River to determine trout habitat needs by using a model considered the most sophisticated in the world.

Cawthron Institute fresh water fisheries scientist John Hayes and fresh water ecologist Karen Shearer, with Environment Southland and Fish and Game, are looking at macroinvertebrate (insect) numbers on the Mataura River to advance their knowledge of trout habitat needs.

The group is using a bioenergetics foraging model, the first of its type to be used on a river of this size, to calculate the number of brown trout in the river.

The model links fish growth with other variables providing a clearer picture of the environment.

The model had only been used in a research context in New Zealand before on a stream smaller than the Mataura, so it was exciting to be able to apply it, he said.

The model was the most sophisticated in the world and at the forefront of applied science.

Such research was important for regional councils as the predicted increase in demand for water from the Mataura catchment could have detrimental effects on the brown trout numbers, Mr Hayes said.

The Southland Times