Publication Abstract

The impact of trapping and tagging on the timing of continued seaward migration of wild Atlantic salmon (Salmo salar L.) smolts

The impact of trapping and tagging on the timing of continued seaward migration of wild Atlantic salmon (Salmo salar L.) smolts

W.D. Riley, A. Moore, I.C. Russell, I.C. Davidson, R.J. Cove and M.J. Ives

The decline in salmon, Salmo salar L., stocks in the North East Atlantic has been partly attributed to poor natural survival in the marine environment (Friedland, Hansen & Dunkley 1998). As a result, the marine survival of Atlantic salmon is being monitored in a number of rivers (Potter & Crozier 2000), and estimates of return rates are reported annually to the International Council for the Exploration of the Seas (ICES), North Atlantic Salmon Working Group. One technique that is widely used to study marine exploitation and survival of salmon is the tagging of migrating smolts with coded wire tags (CWT). While efforts have been made to quantify the effects of using electronic tags on fish before behaviour investigations (Moore, Russell & Potter 1990; Adams, Rondorf, Evans & Kelly 1998; Martinelli, Hansel & Shively 1998; Thorstad, Økland & Finstad 2000), no studies have reported the short-term effects of trapping, handling, anaesthetising and tagging with CWT on wild Atlantic salmon smolts migrating in their natal streams, despite suggestions that these techniques may have a negative impact on survival (Hansen & Jonsson 1988; Hansen 1988; Moffett, Crozier & Kennedy 1997; Crozier & Kennedy 2002). Therefore, there is an urgent requirement to assess commonly used population marking methodologies, particularly on wild smolts, to determine any potential bias in the estimates of marine mortality in monitored salmon stocks.

This paper describes the results of a study to investigate the short-term impact of these techniques on wild migrating smolts, with particular reference to their subsequent movements and run-timing immediately after release back into their natal stream.

The study was carried out between 2004 and 2006 in the River Ceiriog, a tributary of the Welsh Dee in North Wales.

Reference

W.D. Riley, A. Moore, I.C. Russell, I.C. Davidson, R.J. Cove and M.J. Ives (2007) The impact of trapping and tagging on the timing of continued seaward migration of wild Atlantic salmon (Salmo salar L.) smolts. Fisheries Management and Ecology,14(4): 287-290

W.D. Riley*, A. Moore*, I.C. Russell*, I.C. Davidson, R.J. Cove and M.J. Ives*

Fisheries Management and Ecology,14(4): 287-290