Hey there... I can't speak for the south end of the Canal, but the north end is lousy with flounder. I haven't fished for them specifically, but I've caught a bunch while salmon fishing. I'm sure you can target them and do well, but I'm not really sure how to go about it.

Here's what I've found: most of the flounder I've caught have been from the depths-- over 40 feet. They've all taken herring or baitfish imitations such as Coyote spoons. If I wanted to go out tomorrow for flounder, I would use a bunch of small cut plug herring and dead drift with the bait a crank or two off the bottom. Fish shallow, and you're more likely to pick up sculpin and greenling.

You might be able to do well trolling artificials such as small spoons close to the bottom in the shallows or anchor and fish bait such as herring chunks or clam necks (which I've seen recommended) off three-way rigs. Fly fishermen tell me that they've caught a ton of flounder in the shallows fishing over mud and sand bottoms.

While I've been fly fishing for searun in some of the bays, I've seen starry flounder quite a bit.

Hope this helps because few things are as tasty as shrimp-stuffed flounder fillets.