Salmon gender

During the salmon run we have a daily count of fish, males and females. I want to determine if there is an equal probability each day of getting an equal portion of males and females. Our new proposed system will count fish but wont determine gender. I want to know if I can assume they are in equal proportion. Help!


Omega Contributor
Do you have any historic data on gender proportions or resources on what to expect? What would you do with the results?
I have seven years of data. I intend to install a bioacoustics system that can accurately count the fish but cannot identify gender. I would like to make an assumption on the proportion of male to females.


Omega Contributor
Were your prior 7 yearrs of data (e.g., sampling) comparable to the new data (sampling technique)? Or will there be differences which make generalization inappropriate between the two sampling techniques?
No, the methods should be comparable, its just that the new technique cannot ID gender. Over the course of seven years there were 1253 males and 1202 females. I want to know if I can reasonably apply this proportion to the new count. Thanks for your time on this.


New Member
That's not really something statistics can answer for you.

If the proportion of males is relatively constant over those 7 years, then I would say that you might expect a similar proportion. One could even calculate some kind of estimate of the interval based on historical data.

However, this assumes the situation with respect to sex does not change. I know nothing about salmon, but if something could cause the proportion of males or females to increase, you would have no way of nothing if that were the case.

Maybe you could combine your new system with a random sample of the salmon? Here statistics might help establishing a confidence interval for the proportion.
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New Member
To put it in other terms, could there be any reason for any given year for the proportion not to be similar?

And out of curiosity, why is it important to know the proportion?