Height and spread of the Danish seine

Abstract

Height and spread of trawls is successfully measured by the wireless "Scanmar" system. Several experiments made by fishermen have shown that this system will not work on the Danish seine. A modified version of the "Scanmar" system have been tested for geometrical measurements on the Danish seine. During May 1987 a total of 11 valid hauls were made by two different types of Danish seines on fishing grounds in Northern Norway. Hauling and fishing procedures were carried out as in the normal, commercial fishery. The measurements clearly demonstrated that it is possible to control the geometry of the Danish seine throughout the haul by this modified version of the "Scanmar" system. In addition to read the height and spread of the net, it was possible to detect whenever a rope got fastened around rocks, and to see when it loosened again. Signals from the height and spread sensors were lost for shorter periods during the haul. Using this (modified version of the) system, the skipper will get continuous information about the geometry of the Danish seine, and thereby know exactly when to start hauling the ropes and when to change the hauling speed, in order to keep a steady/continous closing of the wings.