DF,

Good question. I can't think of any particular reason for there not being jack sockeye or chum, which normally mature at age 4, with some 3 and 5 year olds. Jacks are usually 2 year old coho or chinook. In that case one might say all pinks are jacks (or not) because pinks are 2 years old at maturity. In order for a pink to return as a jack, I guess it would have to return at age 1.

Hey, I thought of a possible reason. Pinks, chum, and sockeye TYPICALLY make a migration circuit that is far off shore compared to chinook and coho, and maybe they can't get from where they are in the middle of the ocean to their natal streams when they are age 1 or 2? Ah, but there are jack steelhead, and they have similar far off shore migrations, so maybe that hypothesis doesn't work. Or maybe it does because steelhead migrations stay farther north (cooler water) than pink and chum.

Keep those thinking caps on boys and girls. Curious minds want to know.

Sincerely,

Salmo g.