Trawling

Trawling is the most important method of harvesting fish in New Zealand waters. It involves one or two boats towing a very large net, either on the bottom (for fish such as orange roughy, dories & cardinal fish) or a lesser depth, called mid water trawling (for fish such as hoki).

The net consists of several parts. Strong steel cables (referred to as warps) connect the net to the trawler. The net is held open by two large trawl doors (or trawl boards) which act as hydrodynamic kites, and stop the mouth of the net from closing. The weight of the boards also determine the depth at which the net will operate.

Fish enter the net through the mouth and then make their way to the other end, called the "codend". This part of the net contains the smallest mesh size. The size of this is controlled by law. Undersized fish are able to swim through the mesh unharmed.

Pair trawling is used on smaller boats and at shallower depths. One of the lines from the net is passed to a second trawler and the two boats tow in tandem, using the distance between them to assist in keeping the mouth of the net open. Prior to hauling the net in, the line is passed back to the first boat, and the net is hauled onto one boat.

For information on bottom trawling click here »