Those four records read like reservoir-edge forage and possible seasonal concentration water rather than proof of an open, practical creek fishery. No fishing guide lists Cockle Creek specifically; Reel Adventures Fishing Charters covers Duncan Lake at the lake and charter level, not this creek. No hatch report or fishing log for the creek itself turned up either.
Documented food and forage here is
kokanee and
sculpin. Duncan Reservoir itself adds zooplankton and mysid shrimp as kokanee food, plus
chironomids,
leeches and shoreline
terrestrials, and fry where the creek connects through to the reservoir. Where legal and away from spawning fish, that points to small sculpin and fry streamers, a sparse
Woolly Bugger or
Balanced Leech,
chironomid patterns fished near still or soft margins, and general small-stream nymphs and dries:
Prince,
Hare's Ear,
Pheasant Tail,
Elk Hair Caddis,
Adams and
Stimulator.
Reservoir drawdown and spawning gravel
BC Hydro's Duncan Reservoir monitoring has recorded kokanee shore and alluvial-fan spawning around the reservoir, and found that sampled shore redds in earlier years were mostly dewatered by reservoir drawdown. Duncan Reservoir itself runs low-productivity and phosphorus-limited. Give shallow gravel and any spawning fish near the creek mouth a wide berth, and keep food-web expectations modest.