Salmon

At the present time the Atlantic Salmon is at risk and the Trust will seek to promote and support schemes that will ensure the survival of the Salmon in the River Dee and to increase its abundance.

Dee Stock Assessment Programme (DSAP)

The Dee Stock Assessment Programme is a long-term monitoring and research programme for salmon and sea trout on the Welsh Dee. The programme began in 1991 with the completion of a head-of-tide fish trap at Chester weir designed to capture adult salmon and sea trout migrating up-river.

Trapping at Chester Weir along with a number of other activities (e.g. net and rod fishery censuses, smolt trapping & microtagging, juvenile electrofishing surveys, automatic fish counting) make the Dee one of the most intensively monitored rivers in England and Wales. Along with the Tyne, Tamar and Lune, the Dee is one of four ‘index’ monitored rivers supported by the Agency’s national fisheries monitoring programme.

Together, the monitoring activities on the Dee produce several key outputs describing stock and fishery status e.g. adult run strength and timing, age and size composition; catch, catch per unit effort (CPUE) and exploitation by rod and net fisheries; spawning escapement and egg deposition; indices of juvenile abundance.

These outputs are used to develop scientific understanding and inform and direct fisheries management. This occurs at a National as well as a local level; e.g. providing evidence to support byelaw changes and facilities to monitor their success, contributing information to national R&D initiatives, producing annual returns on stock and fishery performance to ICES (International Council for the Exploration of the Seas).

Trapping and tagging at Chester Weir

Trapping at Chester Weir is carried out throughout the year, but not continuously (i.e. the trap is operated around 60% of the time). Most fish caught are measured for length, a proportion are also weighed, and scales are taken for ageing purposes.

A main aim of the programme is to estimate numbers of adult salmon and sea trout entering the river each year. As it is not possible to trap and count all fish, run size is estimated in-directly using tag-recapture methods.

Salmon are tagged using T-bar or Floy tags and recaptured upstream by anglers who are paid a reward for each tag returned. An angler logbook scheme is used to feed back results from the programme and helps encourage reporting of tagged fish. The salmon tagging programme also allows estimates of angling exploitation on groups of fish entering at different times and of different sea age.

Few sea trout are caught by anglers, but many fish are recaptured back at Chester trap in the year following tagging. As screening for tags does not rely on anglers, this allows much smaller (Visible Implant) tags to be used on sea trout.

In the last 11 years, annual run estimates of salmon and sea trout at Chester weir have averaged 5,600 and 8,800 fish respectively; around 20-30% of these fish have been trapped.

Smolt trapping and tagging

Trapping and microtagging of wild salmon smolts began in 1993 - fishing in late April / May on the lower main Dee and Ceiriog (a major tributary).

The main objectives of the programme are to estimate (i) smolt return rates back to Chester Weir and (ii) exploitation by the marine fisheries - principally the Irish fishery.

In 2000, a new trapping device - a Rotary Screw Trap (RST) - was fished in May (in collaboration with the Centre for Environment, Fisheries and Aquaculture Science) and captured around 3,400 salmon smolts (only 30 sea trout smolts). Little smolt trapping was possible in 2001 because of restrictions imposed by the ‘foot and mouth’ outbreak, but the programme has continued since.

Designed by
M W Thrussell

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