By Ed Melvin October 12th, 2020
Editor’s note (from source, sustainablefisheries-uw.org): This post is the first part of a two-part series aimed to bring you behind the scenes of an emerging fishery technology. The first post comes from the perspective of a scientist—it explains the Hookpod technology and its conservation benefits. The second post is written by a fisherman who describes his experience with an emerging technology implemented in the 1990’s. He offers his thoughts on how the new Hookpod technology would impact and benefit fishermen. These two posts are an example of stakeholder perspectives that fishery managers consider when making decisions.
Seabird bycatch in longline fisheries is a major conservation concern throughout the mid to high latitudes of the world’s oceans. It has been linked to declines and poor recovery of seabird populations and is the primary at-sea threat to albatross and petrels. Seabirds are attracted to fishing vessels to forage on discharged offal and used baits; they can become hooked and drown while foraging on baited hooks as they sink during longline deployment. Research published in 2011 estimated the annual mortality of seabirds attributable to world longline fisheries – demersal and pelagic – at 160,000 to 320,000 birds.
Among seabirds, albatrosses and petrels pose the most acute conservation concern due to a life history that is highly sensitive to adult mortality. Albatrosses are long lived, have a protracted pre-breeding life stage, and produce only one egg annually, or biennially. Although many albatrosses and petrels face threats on land at their breeding colonies, adult mortality at sea has the most influence on population trajectories and recovery. Albatrosses spend most of their lives foraging over vast expanses of the mid to high latitude oceans where they overlap with multiple fisheries. With 70% of 22 species threatened with extinction, albatrosses are the most threatened of any bird family. In response, several international agreements were established to characterize and stem mortality in longline fisheries including the United Nations Food and Agriculture Organization International Plan of Action for Reducing the Incidental Mortality of Seabirds in Longline Fisheries and the Agreement for the Conservation of Albatrosses and Petrels (ACAP). In addition to negative effects on seabird populations, seabird depredation of baits from longline hooks can increase fishing costs and compromise fishing efficiency. In some fisheries, seabird bycatch unchecked can lead to lost fishing access and negative perceptions of the fishery and reluctance throughout the supply chain to purchase the catch from high bycatch fisheries.
Seabird bycatch in longline fisheries is managed by requiring fishermen to use technical bycatch prevention measures and temporal and spatial limitations on fishing. Traditional best practice measures include deploying some combination of: a bird-scaring line (streamer lines or tori lines), using fast-sinking, weighted branchlines, and setting longlines at night. These measures are more difficult to apply in pelagic longline fisheries, because unlike bottom longlines, pelagic longlines are suspended from surface floats that can tangle with bird-scaring lines. Long (20 to 40 m) branchlines (monofilament line running from the longline to the hook) with weights positioned near the hook can pose a danger to crew as longlines are retrieved, while setting lines at night can compromise the catch rates of some species, limit fishing opportunities, and be unsafe.
New regulations in New Zealand, which came into force earlier this year, allow fishermen setting surface longlines (pelagic) the option to use hook-shielding devices like the Hookpod as a stand-alone alternative to traditional mitigation measures. This new legislation allows New Zealand to conform to revised conservation measures of the Western Central Pacific Fisheries Commission (WCPFC) that now include hook-shielding devices as an option to traditional measures to protect seabirds from mortality in pelagic longline fisheries. These regulatory changes also conform to revised best practice advice of ACAP. Through its Seabird Bycatch Working Group, ACAP evaluates and recommends best practice seabird bycatch avoidance measures for application to fisheries worldwide. It defines hook-shielding devices as those that “encase the point and barb of baited hooks to prevent seabird attacks during line setting until a prescribed depth is reached (a minimum of 10 meters), or until after a minimum period of immersion has occurred (a minimum of 10 minutes) that ensures that baited hooks are released beyond the foraging depth of most seabirds.” It is important to note that hook-shielding devices are designed specifically for application to the long (20 to 40 m) monofilament branchlines specific to pelagic longline fisheries, which target swordfish, tuna and tuna like species. Two hook-shielding devices were assessed as having met the specific performance criteria of ACAP: the Hookpod and the Smart Tuna Hook. At this time only the Hookpod is available commercially and meets New Zealand environmental standards.
Hookpods are available in two models: the Hookpod LED, which is heavier (60g) and includes a light emitting diode for fishermen who use lights (light sticks or electric) to attract fish, and the 48g Hookpod Mini without the LED for fishermen who prefer more flexibility with lighting. Both are a polycarbonate capsule that encases the barb of a baited hooks which is released via a pressure release system at a predetermined depth beyond the reach of seabirds.