By Ossi Turunen, Bournemouth University

Alongside tagging Atlantic salmon and brown trout one part of the project carried out by the SAMARCH team involves mapping out the type of habitat the fish are living in on certain long term river reaches. This work is continuum to a PhD project carried out by Jess Marsh.

The habitat mapping involves taking measures of channel width, water depth, flow velocity, substrate composition and in-stream plant cover. These measures are taken from a total of 50 evenly-spaced quadrats across a 100m reach. After the measurements an invertebrate kick sample is taken with the aim of covering the different micro habitats on the reach.

Measuring and documenting the habitat features

Taking invertebrate kick sample

After this the site is electro-fished for the minimum of three times in order to get a realistic estimate of the density of the fish populations. The fish are tagged and released back into the river as normal. The aim of this work is to find out what kind of chalk stream habitats Atlantic salmon and brown trout parr prefer, if there are inter-specific differences to these preferences and how to manage the preferable habitats in the future.