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[fish4]

so over the years regardless of the ##'s there has always been some info posted on the Sockeye situation put nothing this year WHY

[danielk]

Is this what you’re looking for ?

https://frasersalmon.ca/wp-content/uploads/2023/03/2023-Forum-2-Day-2-FR-SK-and-PK-Escapement-Planning-Forum-2023-03-01.pdf

[Darko]

Is this what you’re looking for ?

https://frasersalmon.ca/wp-content/uploads/2023/03/2023-Forum-2-Day-2-FR-SK-and-PK-Escapement-Planning-Forum-2023-03-01.pdf

does p50 6.1 million pinks, mean 50% chance of that many returning?

[Roderick]

does p50 6.1 million pinks, mean 50% chance of that many returning?

I don't think so.  The p50 is just the middle of the bell curve, so it has the highest probability but probably not 50%.  It depends how tight the curve is. The p25 and the p75 have an equal probability of happening, as do the p10 and p90. 

I hate stats lol. 

[RalphH]

I don't think so.  The p50 is just the middle of the bell curve, so it has the highest probability but probably not 50%.  It depends how tight the curve is. The p25 and the p75 have an equal probability of happening. 

I hate stats lol. 

does p50 6.1 million pinks, mean 50% chance of that many returning?

sort of,  it splits the forecast range in half and basically means the chances are 50/50 actual return will be 6.1 million or higher (or lower). Alternately the p10 of 3.247 million means there is a 90% chance it will not be lower and the p90 of 11.591 means there is a 10% chance the actual will be higher. Clear as Fraser River water in June?

it's not a bell curve

[Roderick]

I bow to your status as expert on everything Ralph.

[RalphH]

Aren't you cheeky in this heat.(LOL)

I don't know anything close to everything but I am pretty good at entering search parameters into google.

I believe it is more like a cumulative frequency graph. This may help;

https://www.dnv.com/article/terminology-explained-p10-p50-and-p90-202611

It's also important to know these are not real numbers but forecasts. They do plug real numbers into their model ( which is a mathematical formula)- like estimates of actual fry migrations  and they have a range of actual returns of adults. They may adjust them for other factors such as expected ocean survival based on what the conditions are or were in the 2 years they were out there.

Important to know the pink forecasts often are so far off actual returns as to be close to worthless. I did check some series of them once and they were typically off by 30 to 100%, IIRC. Usually the really big return years have much higher actual returns than the forecast. You can find the numbers of the Pacific salmon Commission website if you are interested.

[RalphH]

so I had a quick look and for 2013 through 2019 here are the actual vs pre-season forecast from the final weekly management report - so not the final numbers but very close


        Actual (millions)      Forecast (millions)
2013      26                        8.9
2015     6.2                      14.5
2017     3.7                       8.7
2019     8.9                         5


in each year the error was very high often much higher than the pre-season forecast. So don't put a lot of stock in the pre-season foreast. They usually don't have a good idea what the run will be until the last half of August.

[Roderick]

Well, if you are one of those people that actually likes stats, you can always read this:

https://publications.gc.ca/collections/collection_2021/mpo-dfo/fs70-7/Fs70-7-2021-038-eng.pdf

[RalphH]

Well, if you are actually one of those people that actually likes stats, you can always read this:

https://publications.gc.ca/collections/collection_2021/mpo-dfo/fs70-7/Fs70-7-2021-038-eng.pdf

LOL I was looking at that maybe 20 minutes ago

[Roderick]

You know what Mark Twain said.  “There are three kinds of lies: lies, damned lies, and statistics.”

Still true.

[RalphH]

personally I took  at least half a dozen university level courses in statistics or that involved statistics and I don't think that's true. I don't think Twain thought that was true either. It was the same sort of witticism he issued  on a world wide speaking tour to pull him self out of bankruptcy and said "everyone complains about the weather but no one does anything about it". A statistic is a number. You can't anymore say a median or a mean is a lie than you can say 2 + 2 = 4 is a lie. However people do use statistics to fabricate lies. Politicians of various stripes and business leaders in particular.   

[Roderick]

We are certain that 2+2=4 but with stats there is never certainty, only probability.  These guys use stats to predict the future and are wrong most of the time... but are never actually wrong because they only stated a probability.  It's a logical way of getting it wrong, while still being right. 

[RalphH]

well I don't agree in the sense that you capture only a small part of the issue in a forecast. Probability itself is a certainty and all math is an abstraction.  Forecasts are based on a model of reality so are not a reality in themselves. There is the potential to leave out many things (variables) that can effect the result. Pink salmon runs are highly variable on the same cycle. It's not like sockeye where they are 4 cycles and some runs have 5 year old and 3 year old returning adults which smooths the run difference to an extent.  Someone  on here once said (it may have been WMY) that DFO doesn't really care much about the pink salmon forecast. It's a low $ fishery. They don't forecast or even count other pink runs like the Squamish and Indian for example. Still they have to do it because of the Pacific Salmon Treaty and the the Fraser River pink run is shared with the US. What really matters is the summer test fisheries. They determine how many fish be caught

[clarki]

so over the years regardless of the ##'s there has always been some info posted on the Sockeye situation put nothing this year WHY

Maybe because the PSC Fraser River Panel just had their first meeting of 2023 today…

Reports here: https://www.psc.org/publications/fraser-panel-in-season-information/