Thursday, July 17, 2008

Tyee Test Fishery primer

Some Members had questions about what exactly the Tyee Test Fishery is, so we've prepared this little primer. Hope it helps. Let us know if you have any questions.
There's the boat pictured in action.

The Tyee Test Fishery:
Where: lower Skeena river, near an old railway siding called 'Tyee'
When: generally from June 10 to August 24
Who: contracted gillnetter
Doing what:
-gillnetter does sets at slack tide periods at the same time every day since 1955
-the total catch of each species is standardized to a catch per hour.
-the Index (catch per hour for that day) is derived by averaging the catches of the two to three sets made each day
-the daily Index figure is then expanded by 245 to arrive at the estimated number of fish entering the river that day
-relative abundance and timing for other species, including steelhead, is determined by comparing the calculated indices for a given year to those recorded in previous years
-all salmon are killed and kept
-all steelhead are released (according to DFO sources 2007) **now corrected to: all dead steelhead are actually kept by the contractor and presumably sold**
-longterm average mortality rate: about 50% for steelhead
-steelhead catch ranges from approx. 200 in a poor run year to 1200 in good run year
-steelhead catches/mortality by Tyee was never added to the commercial harvest rate calculations using the Skeena Management Model

- only longterm model of its kind to estimate sockeye escapement numbers and compare relative abundance of other species
-is only an 'estimate'
-is not a very scientific way of collecting solid information as too many natural variables cannot be accounted for such as; high water, low water, water temperature, water turbidity....etc.
-operates 'upstream' of the commercial fishery providing only an 'after the fact' look at commercial impacts
-seems to be developing a habit of over-estimating the sockeye run strength
-no ones come up with something better

** some confusion over whether all steelhead dead or alive are released...needs to be confirmed

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