Trawls are commonly used to collect fish in fisheries research.  They are also a very common way of fishing commercially for pelagic species (like the Russian trawlers we are seeing fishing for mackerel).  The trawl being used to capture the post-smolts is not huge like those on a commercial vessel and is designed to stay on the surface.  The post-smolts tend to be in the top 3 meters of the water column.  Fishing right at the surface reduces our bycatch as well.  The trawl is towed for anywhere from one to five hours in specific areas to target the post-smolts.  

The net coiled coming off…

The net going out…the teal line is filled with floats to keep the net on the surface.

Floats are attached to the mouth of the net to keep it on the surface.

Large steel doors keep the net open as it is trawled.

The cod end of the net coming on board.

Emptying the cod end of the net…filled with post-smolts.