Longline fisheries operations may catch a lot of fish, but they also sometimes catch endangered seabirds such as albatross. Several years ago, a group of marine conservationists began work on a product that was designed to keep the birds from getting caught. It's known as the Hookpod, and a recent international study has concluded that it really works.
In a typical longline fishing setup, there's a main line that extends out horizontally from the boat, with individual branch lines hanging down vertically from it. At the end of each of those branch lines is a baited hook.
The problem occurs when the lines are being deployed, and the bait has yet to sink all the way down. Albatrosses will dive in and grab it, getting the hook stuck in their mouths and subsequently drowning.
Made out of polycarbonate, the spring-loaded Hookpod is attached to the branch line, and encapsulates the barbed end of the baited hook. As long as the hook stays in relatively shallow water, the pod remains clamped to it. Once it reaches a depth of at least 10 meters (33 ft), however, a pressure-activated mechanism in the pod causes it to open, releasing the hook and exposing its barb. At that depth, albatrosses won't be going after it.
The now-open Hookpod still remains attached to the branch line, and can be reused many times. As an added bonus, each pod also contains a fish-attracting LED, to take the place of the chemical glowsticks often used by longline fishermen.
The study was conducted over a four-year period (2011 to 2015), and incorporated 18 separate at-sea trials which took place in the waters of South Africa, Brazil and Australia.
A total of 59,130 experimental branch lines were observed, approximately half of which were equipped with Hookpods. Of the 25 albatrosses that were caught on those lines, only one was caught on a pod-equipped hook. That translates to a bycatch rate of 0.8 birds/1,000 hooks using traditional methods, as opposed to 0.04 birds/1,000 hooks using the Hookpods.
Additionally, the pods didn't have a negative effect on the catch rate of target fish species.
A paper on the research was recently published in the journal Animal Conservation.
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