Prime salmon feeding areas of Cook Inlet - in the Knik Arm and Turnagain Arm. Of course that area has the largest concentrations of salmon in the Inlet. 

If you exclude the middle part of the Inlet, where the Kenai and Kasilof rivers are home to huge returns of salmon. 

Funny how the National Marine Fisheries Services pardons 125,000 fathoms of gillnets spread across the Inlet as no obstacle to Belugas health and well-being. 750,000 feet of gillnet, close to 150 miles in the center part of the Inlet, of course can't be contributing to a decline in Beluga. Access to their primary food source could never impact these whales. 

When the commercial fishing fleet is out in full force, of course it doesn't disrupt the number of salmon entering the rivers. Just ask any Anchorage or Mat-Su dipper who rides home from the Kenai with an empty cooler when the commercial nets are out. No connection whatsoever.