Introduction

Electric Fishing Fry Index Survey

River Exe

January 2023

Hannah Winchester

Westcountry Rivers Trust is an environmental charity established in 1995 to restore, protect and improve the rivers, streams, and water environments in the region for the benefit of wildlife and people.

This report has been written and prepared by: Hannah Winchester

With contributions by: Phillip Turnbull BSc MIFM

Published by: Westcountry Rivers Trust

Rain Charm House, Kyl Cober Parc, Stoke Climsland, Callington, Cornwall, PL17 8PH.

Tel: 01579 372140

Email: info@wrt.org.uk

Web: www.wrt.org.uk

Charity no. 1135007

Company no. 06545646

© Westcountry Rivers Trust: 2023. All rights reserved. This document may be reproduced with prior permission of the Westcountry Rivers Trust

Executive Summary

Westcountry Rivers Trust (WRT) undertook electric fishing (EF) surveys throughout the River Exe catchment during the summer of 2022. A reduced programme of 52 Fry Index Surveys were performed in the River Exe catchment to complement the Environment Agency (EA) Water Framework Directive programme of electric fishing surveys. Notable omissions from the Fry Index Survey included the main River Barle and Little Exe, due to high density of EA sites in these tributaries.

This report focuses on the WRT performed Fry Index Surveys (FIS) and the historic 15 year data set. The summer of 2022 was the driest since 1995 as well as the second hottest year on record, which emphasised the importance of ensuring open and free migration for migratory salmonids, with the 2022 FIS data providing consistent evidence for the Strategic Exe Weirs programme.

The Danes Brook was a new addition to the River Exe FIS programme and was revealed to be highly productive for both salmon and trout. This indicates the Danes Brook as a productive and important tributary, and it is recommended the Danes Brook remain a regular survey area in the future.

Other notable salmon observations include two excellent sites on the main stem of the River Exe, a good site in the Iron Mill Stream and low numbers of salmon were found at the most upstream site indicating a good degree of penetration within this tributary. Trout production was most notable in smaller rivers where salmon production was poor, including the upper Quarme, upper Dane’s Brook, upper Batherm and Upper Lowman, and particularly the River Pulham which produced excellent trout results throughout. Conservation strategies, such as the Defend/Repair/Attack approach, can be applied on a sub catchment level with recommended fisheries management actions suggested to either improve or maintain salmonid habitat and numbers.

1. Introduction

Westcountry Rivers Trust (WRT) undertook semi-quantitative fry index electric fishing survey (FIS) of the River Exe catchment in July-September 2022. This was the 15th year of fish monitoring undertaken by WRT and forms part of establishing a long-term dataset of semi-quantitative fry numbers. A total of 52 sites were surveyed during the 2022 season across the catchment. This is a reduced programme compared to recent years as the Environment Agency (EA) conducted a catchment-wide electric fishing programme as part of Water Framework Directive monitoring. The Fry Index Survey sites were chosen to complement the EA programme and provide additional data for a more complete assessment of Atlantic salmon recruitment.

Sites were selected in order to direct the survey for maximum benefit to inform future works, as discussed with the River Exe & Tributaries Association (RETA). The River Exe has the most developed Fry Index Survey data set in the south west, and it is hoped this highly valuable baseline data will continue to be collected in future years. This will enable production of project development bids based on evidence, and ensure available resources are targeted according to up-to-date knowledge of the fisheries production in the catchment. The River Exe Tributaries Association have been key in undertaking some of the fisheries management actions in previous years.

Figure 1 Survey site location, River Exe, 2022