A large, opening-closing midwater trawl for sampling oceanic nekton, and comparison of catches with an Isaacs-Kidd midwater trawl

Abstract

A new midwater trawl for sampling deepsea nekton from discrete depths is described. Its mouth area is about 50 m2. The trawl body is lined with small mesh netting and terminates in a 5-net opening-closing codend device. Problems of delayed flushing of animals into the codend and of entanglement of animals in the netting were not acute. Compared to a 5.4 m2 Isaacs-Kidd midwater trawl, this trawl catches many more individuals and species of fishes and larger sizes of some fishes and cephalopods. This net will be most useful in sampling sparsely populated mesopelagic and bathypelagic waters