This topic usually comes up some time after they release the regs. It usually comes up because antlerless is almost never defined at the beginning of the section for elk, it is however defined under the actual definitions section, this year it is on page 16.
http://wdfw.wa.gov/publications/01496/wdfw01496.pdfAntlerless is defined as "Deer, elk, or moose without antlers; doe and fawn deer and cow or calf elk and moose are considered antlerless."
They use this term in season regulations to dictate what can be hunted. It differs from any elk in that spikes and elk with points would still be prohibited.
Saying "anterless only" means cow and juvenile only, nothing with any visible points is legal.
Saying something like "anterless or 3 pt minimum" means no spikes or 2 points. Cows and juveniles with no visible points, and mature bulls with 3 points or more on at least 1 side are fair game.
Saying "any elk" means exactly that, you could shoot any elk, regardless of sex or maturity.
If they defined this the same way they do every other term and listed it at the beginning of the section they could save some folks some confusion and frustration. Maybe it's just their way of making you read the whole pamphlet.
