Pelagic Longline Fishing Gear: A Brief History and Review of Research Efforts to Improve Selectivity

Abstract

Pelagic longline gear had several independent evolutions, but the most widespread form appears to have been originally developed by the Japanese as early as the mid-19th century. Technological developments such as polyamide monofilament line and modern fishing vessel construction have resulted in the evolution and expansion of this gear type as the primary worldwide method of commercially harvesting large pelagic fishes such as broadbill swordfish and tunas. Although the adaptability of the gear through changes in materials, lengths, and deployment strategies has resulted in generally high selectivity for many target species, the bycatch of protected species by pelagic longlines is considered a global problem in the conservation effort to sustain populations of sea turtles, sea birds, and some istiophorid billfishes (sailfishes; spearfishes; marlins). Recent research on the modification of pelagic longline fishing strategies uses this inherent adaptability of the gear to avoid or reduce the mortality of bycatch species. This is an alternative to the traditional management strategy of closed areas, which fishermen view as less effective and generally more restrictive (limiting) with respect to target catches. This work with academic partners and commercial fishermen has resulted in the development of bycatch reduction strategies which include safe handling and release gear and protocols, use of circle hooks in place of traditional J-style hooks, restrictions on gangion and mainline lengths, and corrodible hooks.