Better monitoring, better hooks—and less by-catch for Vietnamese fishers
An observer programme in Vietnam for C-hook trials on longline fishing boats, conducted from February to April 2017 as part of Vietnam’s Fisheries Improvement Project (FIP), has confirmed the feasibility of using circle hooks (or C-hooks) among tuna fishers in Vietnam. It has further confirmed how such hooks indeed reduce sea turtle by-catch—a serious problem in Vietnam, where very few historical turtle beaches now have viable populations—and how they may actually increase target yellowfin tuna catch.
This is stated in the report of the Vietnam Yellowfin Tuna FIP Coordination Unit (composed of representatives from WWF-Vietnam, the WWF-Coral Triangle Programme, and the Vietnam Tuna Association, VinTuna) on three observer trips from Dong Tac ward, Tuy Hoa city, Phy Yen province. The coordination unit provided technical support, while WWF-Vietnam, WWF-US, and industry partners, specifically international seafood suppliers Sea Delight and Anova, provided funding for the trips, on which a combination of traditional J-hooks and the newer C-hooks was used.
The report emphasizes that by-catch mitigation—in this case, particularly of sea turtles—is a key goal for better fisheries management in Vietnam. International trials, as well as a 2011-2012 study with WWF-Vietnam and the National Oceanic and Atmospheric Administration (NOAA), have already shown that replacing J-hooks with C-hooks can reduce sea turtle by-catch by as much as 85 per cent. The C-hooks have been under study by industry partners and stakeholders since 2011.
“The C-hooks are well-established as a proven technology to significantly reduce impacts at sea on this highly threatened or endangered species,” says Keith Symington, Marine and Fisheries Advisor of the WWF Coral Triangle Programme. “The effectiveness of C-hooks is especially relevant when considering that it is mature adult sea turtles that are essentially ‘off the hook,’ which means they are available for further mating and nesting. Saving just one adult turtle from bycatch mortality can translate into hundreds or even thousands of future eggs on the beach.”
C-hooks are also among the by-catch reduction and fisheries management measures recommended for non-member countries like Vietnam by the Western & Central Pacific Fisheries Commission (WCPFC), Symington adds, to conserve and manage highly migratory fish stocks in the area, including tuna.
Consultations and compromiseC-hooks come in several sizes; bigger ones make it easier to release sea turtles caught on hooks, but smaller ones, while still reducing by-catch, are generally perceived as better for securing fish, the report explains. Consultations with vessel owners and captains resulted in a compromise, where a median size 14 was chosen. VinaTuna and WWF also used a formula for calculating catch per unit effort (CPUE), or roughly, the effectiveness of a hook.
Although the sample size for this experiment (four boats, using a total of 49,350 hooks) is rather small to derive clear scientific conclusions from this single set of experiments, results were encouraging, and in line with the international scientific consensus regarding C-hooks. For yellowfin tuna fishing, the CPUE of the size 14 C-hooks was significantly higher at 8.65 kg/100 hooks, as compared to 5.93 kg/100 hooks for the J-hooks. The average size of tuna caught by C-hooks (47.3 kg) was also slightly bigger than of those caught with J-hooks (44.6 kg). No turtles were caught by the C-hooks for the duration of the trials. In contrast, two sea turtles were caught by J-hooks—and were successfully released alive.
Interestingly, the report supports earlier findings that C-hooks may actually make it easier to catch the target species, tuna: “The general consensus from past studies is that C-hooks (by virtue of their shape and ‘self-setting’ attributes) can actually increase catch rates on yellowfin tuna.”
The operative word is “self-setting,” says Symington. “In other words, once the fish bites down, it is easier to get a strong hold on it, and the fisher does not have to ‘yank’ on the line to get the hook to settle in.” It is not a new technology to fishermen, he reveals: “Polynesians have been using a type of C-hook for thousands of years! In fact, in the logs of Captain Cook, he mentioned the interesting-looking hooks of the Polynesians, and how effective they were at catching fish. Quite a lot of the Pacific fishing nations like Fiji have been using C-hooks for a long time—not so much because WWF asked them to, but because they are great at catching tuna!”
Although further trials are required, such a finding will certainly help in terms of “future buy-in and support from the fishing community, and may help alleviate some concerns that there would be negative economic impacts from C-hooks,” notes the report.
“Keep testing the hooks progressively with the direct involvement of fishermen, and continue outreach work with fishers, vessel owners and captains to show them these positive results,” suggests Symington, on how to further “sell” C-hooks to the fishing industry. Allowing fishermen to trade in their J-hooks for C-hooks, with industry support, would be another incentive. “Eventually, word of mouth about the hooks’ effectiveness—and that the fishers have nothing to fear—will spread among the community, raising the level of support to a tipping point.”
10 per cent permanent coverageThe observer programme was the other focus of the study, being another important element of the FIP Action Plan. The WCPFC is batting for permanent coverage of 10 per cent of all fishing trips; the goal, the report states, is a permanent observer programme for Vietnamese tuna fisheries jointly run by the national industry and the Vietnamese government for better data collection and, in the long term, for the fisheries’ sustainability.
For these trials, the report notes, candidate observers included staff members of the Research Institute for Marine Fisheries (RIMF) in Vung Tau, and local fishermen and boat staff who received training from VinaTuna staff on fish taxonomy and proper data recording.
“An observer programme provides the most reliable data on catch composition and figures on the landings of ‘target’ fish, such as tuna, marlin, and mahi-mahi, and ‘by-catch,’ such as turtles and sharks,” says Symington. “The data provides a means for calculating fishing effort, and provides fisheries managers with verified and accurate information on the fishing catch, effort, and practices. The programme is the front line of scientific research used to ensure sustainability.”
Observation also ensures that regulations such as WCPFC requirements are adhered to. “In this sense, observers are the ‘eyes and ears’ of management agencies charged with protecting our ocean resources. It is difficult work—they may go out for several weeks at a time, and observers can be treated harshly by crews.”
Ultimately, both an expanded observer programme and the mainstreaming of the use of C-hooks should be part of a national turtle by-catch mitigation programme. Other components, Symington adds, would be training of government technical staff and vessel captains in on-board observation protocols, knowledge exchange with other members of the Pacific community, and electronic logbooks and video monitoring to make such management fully electronic in five to 10 years.
Symington again references the aforementioned “tipping point” of ground support that must be reached. “We need at least a couple more at-sea tests and the dissemination of results, and we need government to set the policy foundation. But I think we are getting there.”