my son is doing a sciene fair project on witch salmon has the most eggs anyone who can help thanks

I'm thinking the hens have the most eggs.

Sorry,just couldnt resist.
My guess would be fall chinook,if only because of shear size.
If your comparing salmon on a pound per pound basis then Iwould guess that the species that average a smaller weight would produce more eggs only because it would take more eggs and fish to deposit sufficient quantities to maintain a run.(In a natural environment)
Honestly this is just a guess though.Hit up Salmo G or Smalma about this question.they seem pretty darn knowledgable and could probably give you a much more factual answer.

I encourage your son to do a search on the internet to discover the answer for himself. Look for chinook, coho, sockeye, pink and chum salmon fecundities. Within a species there is variation in the number of eggs/female depending on the stock and size of the fish. He should find that chinook generally have the highest egg counts.

Tight lines
Smalma

That is an interesting question and the answer probably has to do with nature's estimate of each fish's survival rate. My guess would be spring chinook because they seem to be a fickle species which is prone to wild ups and downs in reproduction rates.

According to this web site:

ftp://www.streamnet.org/pub/fishfacts/pdf/fish_anad.pdf

it is the Chinook Salmon with up to 14,000 eggs laid while spawning. Hope this web page helps you out.