Report No SR3404/1

THE ALLEGED DECLINE OF BROWN TROUT POPULATIONS IN SCOTLAND AND NORTHERN IRELAND

SR3404/1

Jul 1993

EXECUTIVE SUMMARY

This document reports on the research into the alleged decline of brown trout (Salmo trutta) populations in Scotland and Northern Ireland, as carried out under contract to the Scotland and Northern Ireland Forum for Environmental Research (SNIFFER) between 1 March 1992 and 31 March 1993.

The quality and extent of currently available data relating to the status of trout stocks in Scotland and Northern Ireland is discussed, and examples of information from different sources are presented. The implications of these data, regarding the status of trout stocks across Scotland and Northern Ireland, are discussed.

Many factors are known to potentially impact upon trout populations and these are reviewed briefly, along with information on the concerns of Scottish anglers regarding perceived trout population declines.

Both the quality and availability of information from which conclusions regarding the status of trout stocks may be drawn is poor. Whilst there are examples of localised declines in specific areas, there is no conclusive evidence to support the notion of a serious widespread decline in stocks throughout Scotland and Northern Ireland. Equally however, the nature of the available information does not indicate that there is no cause for concern.

It is recommended that the originally envisaged Phase Two to this investigation is not undertaken. Instead, it is suggested that a database of electrofishing results is produced to provide baseline information against which future changes may be assessed, and that competition results from selected angling clubs be collated to provide more information on population trends in a series of selected catchments. In addition, it is recommended that research is undertaken to improve the potential for the use of electrofishing results for between-site comparisons of fishery performance and for indicating water quality impacts.

KEY WORDS

Brown Trout, Fisheries Management, Scotland, Northern Ireland.

Copies of the report are available from FWR, price 30.00, less 20% to FWR Members.