Probably a sockeye food fishery, although it is possible that a few summers were captured incidentaly.
The method used is called beach seining and is alot more sustainable than the gill netting done around these parts. If beach seines are executed properly unwanted bycatch can be released unharmed. The seine in the video was not selective. To handle fish properly in a beach seine the fish must be sorted in the water.
For one I have no problems with the practices displayed on the video as long as the resource is strong enough to handle a harvest of that magnitude.