The lastest counts:
OBSERVATIONS:
Stamp falls counting facility has been fully operational since September 2.
During the past 9 days Chinook adult numbers have ranged from 320 to 914. Coho adults have
ranged from 234 to 925 and Sockeye adults have ranged from 33 to 841. Total escapement
through Stamp Falls to September 22 is 10,436 Chinook, 12,874 Coho and 32,468 Sockeye.
Sockeye escapement through both Great Central Lake and Sproat Lake counters requires
further analysis at this time. No additional data is available at present.
Stamp Falls enumeration has been fully operational so far with no shut downs.
River flows have increased over the past few days and are above average for this time of year.
River temperature has cooled to 15oC and is below recent years average.
2010 EXPECTATIONS:
Sockeye: For 2010, the initial forecast return of Somass sockeye was 600,000. The
escapement target for this run size is 371,000, giving an expected surplus of 229,000 sockeye
available for catch. Expected stock composition was about 57% Great Central, 43% Sproat
sockeye. Expected age composition was about 55%, 35%, 9%, and 1% for age 42, 52, 53 and 63
adults, respectively.
Chinook: Approximately 43,000 Somass Chinook are forecast to return to Barkley Sound and
Alberni Inlet in 2010. The predicted adult age composition is 27%, 41% and 32% of 3, 4 and 5-
year olds, respectively. Given the age composition, about 33,800 spawners are required to
meet the 57.2M egg target for the system. Therefore, about 9,000 Somass Chinook are
available for harvest in the ‘terminal fishery’ from Alberni Inlet seaward to Barkley Sound.
Coho: For the 2007 brood year, 415,000 coho smolts plus an additional 227,000 unfed fry were
released from the Robertson Creek Hatchery and there were about 38,000 natural spawners.
Given the forecast survival rate of Robertson Creek/Somass Coho for the 2007 brood year is
low at less than 1%, the total expected return to Somass system is about 10,000 to 15,000.
However, there is considerable uncertainty in the survival rate forecast, and models predicting
the survival rate of the wild WCVI coho indicator (Carnation Creek) are much higher (e.g.
~10%).
Chum: Pre-season forecasts for chum returns are highly uncertain. Over the last few years,
returns of WCVI chum have been well below long-term averages and this trend is expected to
continue in 2010.
PROGRAM OVERVIEW:
Fish counting operations on the Somass system are run by the Hupacasath First Nation in
collaboration with DFO.
To estimate the escapement of Somass Sockeye, automatic fish counters are installed at the
Sproat and Great Central fishways in mid-May. Twice weekly visual calibrations are used to
validate counter data as well as to determine species and age (jacks versus adult) composition
of escapement. A portion of the Sockeye escapement is biologically sampled at the fishways.
Of interest are age at return, *** ratio and fecundity. For Henderson Sockeye, escapement is
estimated through a series of swim surveys of the main spawning habitat (Clemens Creek and
nearby beach habitat). These surveys are conducted in September and October.
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Counters are removed from the Great Central fishway in early September when Chinook begin
to migrate upstream. After this, all salmon passing through the Stamp Falls fishway are counted
by trained and experienced observers. They identify fish to species, estimate the portion of
jacks by relative size and estimate the portion of marked (adipose fin clipped) fish. Migration
through the fishway is videotaped for later verification of daytime real-time counts and species
identification and for enumeration of night-time migration. Real-time observations are typically
greater than 95% accurate for counts, species identification and mark rate.
Below, are a series of figures that express 2010 escapement observations relative to average
escapement timing from 1999 to 2009 for Chinook and Coho. Although informative, in some
years observed escapement rate relative to average escapement timing may be a poor
indication of final run abundance. In contrast to ‘run timing’, (the return of Chinook/Coho to
Alberni Inlet) escapement timing tends to be more variable. It is influenced by the impact of
fisheries and environmental conditions, such as river temperature or flow.