CJ -
Not sure what is considered a "sizeable" coho this time of year. As supcop said this time of year the coho most commonly encounter are those resident fish - 2 to 4 #s.

That said while mooching in MA 10 last week I caught one unmarked coho that was pushing 6#s and lost a similar sized fish to a seal. Since I released the fish I can not say whether it was a large resident coho or part of the first wave of ocean fish. That said most years don't really expect to see many such fish for another 3 weeks or so.

Curt