Fisheries science: Mid-water Surveys

Acoustic surveys

Pulses of acoustic energy are sent into the water and the energy that is reflected back is read, much in the same way that sonar works. Acoustic surveys are often paired with trawl surveys where scientists can collect data on biomass and species presence to help with converting the acoustic signal to biomass.

Gillnets

Gillnets are typically deployed in the mid-water zone. The thin netting is nearly invisible to fish and will capture certain sizes of fish of multiple species as they swim into the net.

Purse seine

Used to catch aggregations of fish. A group of fish is circled with a large net then the leadline (at the bottom) is brought together to effectively close the net before it is hauled onto the boat.