These are nets that will usually encompass the entire “cage system” around the outside and underneath to protect the grower nets and the stock within from large predators such as seals and sea lions.
This larger mesh net can be seen in this photo hanging down from the corner of a 14-cage system along the outside corner of the walkway.
Barge Tarps are smaller than plankton tarps and are used to wrap the entire underside of a floating structure usually once it arrives at a new site. By wrapping it tightly and pumping out as much water as possible the living organisms will soon die of oxygen starvation and begin to rot and fall away from the barges hull. After a few weeks the tarp can be removed and the rotted dead fouling can be allowed to fall away and then the bottom of this float is effectively disinfected of organisms from another site that may possibly have harboured harmful pathogens or a virus that could otherwise cause problems to the new stock grown at this new site.