Traditional mesh trawl nets certainly do their job when it comes to extracting marine resources from the seas but they have several major drawbacks: they damage the catch; and they can harm and even kill undersize fish as well as larger unwanted marine animals such as sharks and rays that are thrown back. Then there's the tendency for trawlers to discard excess target catch rather than face fines upon returning to shore. Now, humble PVC resin may deliver a major advance to what is a 150-year-old technology and solve all of these problems in one fell swoop.
Dubbed Precision Seafood Harvesting, the technology does away with traditional trawl nets and, instead, sees fish contained and swimming comfortably underwater inside a large flexible PVC liner where they can be sorted for the correct size before being brought on-board the fishing vessel. The break-through design of the harvesting system greatly increases protection for small fish that can swim free through 'escape portals.'
Once on deck, the fish are still swimming inside the liner, in perfect condition, meaning fresher, more sustainable fish for consumers and higher value products for fishing companies using the technology. At thia point, large non-target fish (by-catch) as well as any undersize fish still present can be released unharmed.
Precision Seafood Harvesting represents the future of sustainable fishing according to its developers, a consortium of New Zealand-based fishing companies: Aotearoa Fisheries; Sanford; and Sealord who are investing NZ$26 million in the project with matching funding from the New Zealand Government under the Primary Growth Partnership program. Scientists at Plant & Food Research (Auckland, New Zealand) are partnering with the fishing companies to develop and trial the technology on commercial fishing vessels.
| Giant PVC trawling tube has escape portals for undersized fish. |
Alistair Jerrett, from Plant and Food Research says "One of the objectives is to make sure that any animal that reaches the surface, if we can't select it out underwater, is delivered back to the sea unharmed." He says this is true for bigger animals as well, like rays, sharks or any animal that is inadvertently captured. "In terms of selectivity we design everything to make sure unwanted animals are discharged as fast as possible at depth - we don't want them to even see the light of day."
Sealord CEO, Graham Stuart believes Precision Harvesting is an opportunity for New Zealand to 'lead the world with another great kiwi innovation'. "Seeing Hoki [blue hake] landed from a depth of 300 meters, alive and in fantastic condition is remarkable and will totally change how our fish are brought to market."
Sanford, Sealord and Aotearoa have been actively trialing the new technology on their fishing vessels for the past six months. Vessel Manager at Aotearoa Fisheries, Nathan Reid says fisherman onboard their vessels are excited about the condition of the fish when they are landed. "Replacing old trawl technology is really important for the industry. We're going to see better stock recruitment and better stock in the water - it's better for everyone."
