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Thread: Predictions for 2009 sockeye runs on the Kenai Peninsula

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    Default Predictions for 2009 sockeye runs on the Kenai Peninsula

    Are there any ways to predict the run for 2009? For example with the Kenai and Kasillof sockeye can they look back at escapement numbers for the year class's that spawned the fish that are going to be returning and make some estimates?

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    Forum Admin Brian M's Avatar
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    Yes, there are ways to predict the runs, and in fact F&G releases their forecasts every year before the run gets under way. I'm guessing Nerka could help here by shedding some light on when the forecasts are publicized and how big of a margin of error they're usually dealing with.

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    I do look forward to seeing the forecast, because then I know what the run won't be. All in good fun, (but not far from the truth)

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    yukon, have you got a better way to predict and forecast?

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    Nope, take it easy Grampy. All in good fun. Geez..........

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    I did not mean to start anything here guys. I was just wondering how predictions are made. F&G do a great job considering no one is ever happy. they do thier best and thats all anyone can ask. Back to the question are there any ways they can predict a runs strength?

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    Quote Originally Posted by kgpcr View Post
    I did not mean to start anything here guys. I was just wondering how predictions are made. F&G do a great job considering no one is ever happy. they do thier best and thats all anyone can ask. Back to the question are there any ways they can predict a runs strength?
    Go to the source for a start, lots of info here, free for the taking with no barbs attached!.

    http://www.cf.adfg.state.ak.us/region2/ucihome.php

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    been there done that just not much on future predictions. That is an awsome site however! Tons of great info

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    Quote Originally Posted by kgpcr View Post
    been there done that just not much on future predictions. That is an awsome site however! Tons of great info

    Good. If you looked thru the historic forecasts, you'll notice they are usually released to the public in December.......

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    I was just wondering how they come up with the predictions.

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    Default let is a brief over-view.

    The forecast are made differently for each species. However, for chinook and sockeye they have a common element. The historic record is used to make relationships between the components of the adult return. For example a four year old sockeye returning in one year (age 1.2) can be used to predict the number of five year old fish (age 1.3) to return the next year.

    This is done by plotting the four on five year relationship and getting a statistical fit. This can be done for a number of combinations. When you combine the freshwater portion you can run 1.3 (one freshwater three salt total five year) against 2.3 ( two freshwater and 3 salt six year old fish) and so on.

    In addition to using adult data you can use fall fry numbers to predict the return for Kenai River sockeye salmon. The fall fry numbers can be used to make relationships to future adult returns. This also can be done with smolt numbers if you have them - Kasilof River sockeye has a reasonable data set.

    In addition, one can just use the parent year spawners to predict the total return based on production models like a Ricker curve. Then the average age combination is used to make predictions by age class.

    Finally, a combination of methods can be averaged to get a best fit model. For example after a number of years forecasting there can be correction factors added to reduce known bias or error. For example if one has predicted forecast for a number of years and all those forecast are low by 20% then one can still use the method and correct it by 20%.

    Each year is somewhat different in what method is used since the fits to the data set change with each additional year of return. So one year a fit may be great and the next the data set is not so great.

    Hope this helps.

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    Thanks Nerka! It sure does help!

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    I'm going to throw something out about management in general in response to Yukon's joke and the what some folks think. Not saying your comment wasn't funny yukon is kind of was.........but so was Gramps response. See from my limited understanding a LOT of management is done by feel, guess, and combinations of data. Some folks will bring that up as an arguement in what they believe management should be doing. Well in most cases there are other alternatives but they are very expensive and the question of who pays for them comes up. So then the same folks don't want so much money spent. I bet if you did multi million dollar smolt studies combined with better at sea sampling and more netting recapture studes we would have better estimates.

    The thing that brings this up is The feds had a small opener for cod. P Cod is driven as a fishery by both P Cod quota and halibut quota. The feds subtract the % of dead ones the fleet catches to get a handle on it. This is done by having biologists on the boats taking very small samples (300kg) and comparing that to the entire catch. Well only 30% of the fleet has biologists on board at any one time. IF that. So the guy who manages the gulf then compares it to "like" hauls from previous years. Uses mainly this years data when available and sometimes other years and sometimes a guess based on experience. Recently this P Cod season opened for a 5 day fishery. Well out of the 10-20 biologists on board the boats 8-15 got seasick and were new. So we had few seasoned people on board who collected somewhat represenative data. (I say somewhat as they is always some bias and variance).

    Well fishers are now mad as the halibut were subtracted from the quota. Did we have awesome data? No as most fished with no one watching and the ones who had biologists on board had new ones who where seasick. So the manager did the best he could. While many would have a problem with what/how he did it, I would ask what else would you do? Just not subtact any? That's wrong and illegal. We could put cameras on evey boat and somehow change laws to make boats bring back anything but no one seriously wants that.

    I guess my long winded, yet short for the subject is trying to bring up the point of we can all ask why, and if things could be better. But at the same time most likely someone has already thought of it, and couldn't find a different better way. Managers just like fishers, and sport fishers are people too. They are doing what they do as they believe in it.

    Hey Yukon just to be clear this was not directed at you, just spill over from the P Cod thing. I think you understand what I typed and likely would agree with most of it.

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    I totaly believe that the Fish and Game folks are doing thier best and you are correct it we had unlimited funds things would be different. They are doing the best they have with what they have. Perfect... No but then who is. I have two friends who are doctors. One trained at the Mayo Clinic and one at Johns Hopkins and they dissagreed on what antibiotic i needed when i got bronchitis on a fishing trip. Truth be told either one would have worked just fine but each had thier own opinion. Two people at the top of thier profession and different views. So it is with managing wildlife.

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    Oh I hear ya!! I had to re-wire my house and listening to the electrician I would have sworn he had a doctorate. Goes to show you almost any job is more complicated than laymen think. management to guiding to mechanics.

    Have a good night amigo!! I get to go home soon myself!

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    One thing we can do is evaluate how other east and west coast fisheries and countries like Canada and the Scandinavians predict and forecast their runs. Look at what works and what doesn't, learn from the past, and try to improve on it. Avoid the disasters. Use a conservative approach, keeping development and habitat loss in check. Grasp improved technology when we can. Ironically, other fisheries look to Alaska as an example that works. We just need to stay on track and keep moving forward. No matter how good we get at forecasting and predicting, Mother Nature will always be in charge and throw us the curve-ball. I don't put too much faith on predictions and forecasts, but rather actual in-season management. It's got to be the most complex fishery to manage there is. The only thing that might be as difficult to forecast and predict in Alaska is the weather.

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    guess and check
    I choose to fly fish, not because its easy, but because its hard.

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    Default Kenai sockeye forecast

    Talked with ADF&G biologist who does the forecast and while this is not official he indicated the total Kenai sockeye salmon return will be about the same as 2008. This is based on preliminary model results.

    So everyone should be prepared for closures and restrictions late in the season. Depending on how the run timing is the PU and sport fisheries downstream of the sonar could be regulated earlier than in 2008, depending of course on how ADF&G manages the commercial fishery.

    However, in any case this is not a good return. The 2008 return was right in line with the brood year interaction model.

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    Nerka
    I have a few questions for you. I do not wish to open a can or worms but i saw the prediction for the run this year 2008 was 3 million for the kenai and kasilof. Did we get a poor escapement due to a low run or to many harvested before they got in river? Again not wishing to open a can of worms just wondering.

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    Default 2008 comfish projections

    Just looked at the website for Comfish, Upper Cook Inlet Commercial take was @ 2.4 million as of August 18th. Sounds like the commercial take was pretty good. I have heard of gripes about dipnetters and sport fishers not being cut back the last week of July but 2.4 Million Salmon is a lot of new truck payments compared to my 89 Chevy pick up. Need I say more? Good night, Ken SCADA

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