Can someone explain the OTF index.
I'm totally guessing it's Offshore Test Fishery???
from Nerka's post
Here you go. This was posted by Nerka in one of the management thread. Best description I've seen on OTF. Hope it helps. If you post more you will get access to that forum.
4. Offshore index - One cannot use daily index points for anything meaningful unless they run for a few days low when they start to impact the model for total run.
I just talked to ADF&G and the total run projection is for 4.4 million if the run is on time. If it is late just a few days the estimate goes up significantly. The forecast is for 5.5 million so the run could be underforecast but certainly not in trouble. It just means ADF&G will cut back in fishing the Kenai section to make the escapement and not fish more than the 1/2 mile in the Kasilof section. Remember when the set nets fish only 1/2 mile the drift fleet does not fish.
However, back to the OTF program. It is an averaging program which means it makes projections for the total index for the year and then uses a fish passage rate to make the estimate. So lets say the OFT total index is 1000 on 15 July for the season and that is the 50% point of the return. The projection for total index points would be 2000. Now on 15 July if the fish counted to date - catch, escapement, and residual in the district number 2000000 that means each index point represents 2000 fish. If one has a projection of 2000 index points the total run estimate would be 4 million.
So , one day would not change the shape of the curve very much and even a couple of days of low counts would not do it. Also, since the passage rate is estimated after each fishing period low counts could be compensated for by high passage rates. Therefore, for anyone to say the counts are low and the run is in trouble is not correct.
Last edited by Akbrownsfan; 07-23-2008 at 10:23.
Reason: make it work for this thread
That clears it all up... Clear as the water in the lower Kenai. Thanks for the reply though. We spent 4 hours with two nets in a boat on the Kenai and came home with 15, a bit slow.