Bike in as far as you can (not sure if the regs have changed) as the sectiion to Bryant Creek shelter is a long (and VERY boring) hike. My suggestion if hiking is to do the extra kms and go through Sunshine Meadows, much more scenic!! Or if you are wealthy, fly in and hike out. Just my opinion... Sorry, I have no info on the fishing in the area, but there have been people posting info regarding the Assiniboine PP area previously. "Fly Fishing the Canadian Rockies" is a great reference (though somewhat outdated). Here what it says for the Marvel area:
Marvel Lake - Cutts to 75 cm
Lake Terrapin - Cutts to 40 cm
Lake Gloria - Cutts to 50 cm
Mavel Pass Lake - Devoid
Owl Lake - Brooks to 35 cm
Bryant Creek - Cutts to 35 cm
Spray River (Upper) - Cutts to 30 cm
Watridge Lake (AB) - Cutts to 50 cm
Leman Lake - Cutts to 70 cm
Belgium Lake - Cutts to 35 cm
Palliser Lake - Devoid
Back Lkae (BC) - Devoid
For each lake listed there are some details, i.e., access info, etc., included (too much to write up)
P