I wish most NJ brown trout were 15". 15" is a huge wild fish anywhere in NJ, except for maybe the Delaware River. Most are closer to 7"-10".
Mulhockaway and Spruce Run Creek have good populations of wild brown trout, just like most cold water creeks in NJ. But most people don't want to bother fishing for tricky 8" fish that they can't keep.
There aren't many breeding browns moving in from Spruce Run Reservoir either. That fishery has been on the decline ever since the state stopped stocking Spruce Run Reservoir over 10 years ago. I think I've only seen one breeding pair in the last 3 years and those fish were so easily spooked and pre-occupied that they're nearly uncatchable.
If you're going to fish any of those creeks inthe fall or winter, please don't stomp through the water. You'll destroy the reeds and eggs.
This is what a typical adult wild brown trout looks like here in NJ:
This is what a spawning pair looks like:
