Fishing is permitted year-round in the park, from 30 minutes before official sunrise to 30 minutes after official sunset. The park allows fishing in all streams EXCEPT
the following stream and its tributaries upstream from the point described:
Lynn Camp Prong upstream of its confluence with Thunderhead Prong.
This stream is closed to fishing to allow fish to repopulate following restoration work. For the exact location, consult the appropriate USGS 1:24,000 Quadrangle Map available at park visitor centers. Detailed information, including a complete list of regulations and a map of fishable park waters, is also available at any visitor center or ranger station.
Seems to be closed on the website. No one ever claimed the park made the best maps
You could always just show up at the trailhead next Wed and give it a shot, although it might not be good for Steve Moore's blood pressure.
I can see headlines now "Fisheries students nab Chemistry professor" or "Brookies Breaking Bad"