Salmonid assessment
Radio tracking salmon
A national assessment of the status of the salmon resource in
England and Wales is undertaken annually, using the Pre-fishery
Abundance and National Conservation Limit Models originally
developed by Cefas (Potter et al., 2004), and reported to
ICES. The total pre-fishery abundance (PFA) of salmon (the
number of salmon alive on 1st Jan of their first sea
winter) from English and Welsh rivers is estimated to have declined
from over 350,000 in the 1970s to around 150,000 in the past 10
years, despite substantial reductions in exploitation both in
homewater and distant water fisheries. However, the reduction
in exploitation means that there has been a less severe decline in
the spawning escapement, from about 130,000 to about
80,000. Spawning escapement has also been buffered to some
extent by an increase in the proportion of smolt emigration at an
earlier age.
The status of individual river stocks in England and Wales is
also evaluated annually against the stock Conservation Limits (CLs) and Management
Targets (MTs) in line with the requirements of ICES and
NASCO. The 'management objective' for each river is that the
stock should be meeting or exceeding its CL in at least four years
out of five (i.e. >80% of the time). Egg deposition
requirements have been derived for each of the 64 main salmon
rivers in England and Wales, and estimated deposition each year can
be compared with these values. There was a slight decrease in
the proportion of stocks meeting their conservation limits over the
period.
Details of these assessments are provided in an annual reports
prepared by Cefas and the
Environment Agency.