One of the findings of a study investigating and trialling new tools to reduce risk of seabird net captures in trawl fisheries shows the number of seabirds captured in the New Zealand deepwater fishery has decreased markedly in the last decade.
The findings were presented by the New Zealand Deepwater Council’s Ben Steele-Mortimer an international forum on 15 May. Experts from around the world met at the forum in Edinburgh to discuss the latest developments in reducing accidental seabird captures in fishing gear.
Steele-Mortimer’s paper shows the number of seabirds caught in the southern squid trawl fishery, verified by Ministry for Primary Industries independent observers, has halved in the 10 years to 2020.
The Agreement on the Conservation of Albatrosses and Petrels (ACAP) Seabird Bycatch Working Group will meet over three days in Scotland and includes members from governments, NGOs, academic institutions and the seafood industry.
Its member countries and territories include Australia, Brazil, Chile, Ecuador, France, New Zealand, Peru, South Africa, Spain, the United Kingdom, Uruguay, and Vanuatu. These countries which are signatories to ACAP have agreed to work together to conserve albatrosses and petrels in particular, both within their national territories and in areas beyond national jurisdiction.
In this country a Net Capture Programme was established in 2019 by the Southern Seabirds Trust, which includes industry and the World Wildlife Fund, and the Seafood New Zealand (SNZ) Deepwater Council, which represents New Zealand’s deepwater fisheries, to investigate, innovate and trial operational approaches to minimise net captures of seabirds at sea.
The focus of New Zealand’s presentation was on the southern squid fishery due to its high observer coverage (more than 80 percent of all trawls have been observed by government observers over the past 10 years) and its overlap with the breeding season and range of many seabird species.
The arrow squid fishery, the second largest in New Zealand by volume after hoki, is largely based on the stormy waters of the Stewart Snares shelf and the Auckland Islands in the Southern Ocean, with other smaller fisheries off the Otago coast and on the Chatham Rise. The squid fisheries have become more efficient in the last 20 years since 2003. The same quantity of squid is caught with 50% fewer trawl tows, which reduces the seabirds' exposure to danger by half.
The ocean environment in the southern squid fishery is known for its hostile conditions (Roaring Forties and Furious Fifties) due to its exposure and proximity to the Southern Ocean. Down here, large swells above three metres are very common, and the relatively shallow shelf makes for difficult seas even in summer. Over two-thirds of the time, wind speeds are between 38 and 50 km/h, and frequently exceed 50 km/h (Meteoblue – Auckland Islands).
The southern squid fishery overlaps with the foraging range of many seabirds, notably due to the proximity of breeding areas of sooty shearwaters (Puffinus griseus approx. 10 million pairs) white-chinned petrels (Procellaria aequinoctialis 200,000 pairs) and two mollymawks or small albatross species, white-capped and southern Buller’s (Thalassarche cauta and T. bulleri – approx. 95,000 pairs and 12,000 pairs respectively).
These foraging birds which have aggressive feeders around fishing vessels, end up interacting with fishing gear.
Consequently, the Deepwater Group, now the Deepwater Council, placed considerable focus on reducing the risk of seabirds interacting with mobile fishing gear, with warp (cable) mitigation equipment, effective fish waste management and dedicated operational procedures.
Steele-Mortimer says there is no silver bullet in ensuring the birds’ safety, it is more a matter of incremental reductions.
“Skippers, shore staff, fisheries and conservation managers and MPI observers have all played an important part in reducing the interactions of seabirds with fishing gear,” he says.
Tori lines made from colourful streamers to deter birds from striking the wire warps attached to the net have long been in place, as has delayed offal disposal
“We are always innovating, and investigating new ways to reduce interactions even further, we have looked at high-pressure water sprayers, noise and strobe lights but these were found to be impractical or ineffective,” Steele-Mortimer says in the seabirds study.
The New Zealand ACAP presentation, co-authored by Richard Wells, notes that seabirds are attracted from up to 10 km away. Possible cues include sight, the sound of engines and winches when hauling, smell and other seabird activity.
“It’s very difficult to reduce seabird attraction to fishing vessels, our effort is better placed at reducing interactions when they are in the vicinity of the vessel and the fishing gear,” the paper says.
“It was found a key risk is the pooling area immediately astern of the vessel where birds can enter the net mouth or become entangled in the mesh.
“Turning the vessel to close off this space and sinking the gear quickly has proved to be effective at minimising the time birds have access to the trawl net.”
The majority of birds caught in the net are petrels and shearwaters, where they are at risk of drowning.
Albatrosses occasionally get caught inside nets but more often get caught up in the net mesh from outside of the net.
Deepwater Council general manager Aaron Irving says that minimising interactions and reducing risk to seabirds has always been a priority for the seafood industry.
“Our people do not want to interact with birds or other species for that matter when they are fishing, and that is why they do all they can to reduce vessel interactions,” he says.
“Since 2005-06 when Deepwater Group first started the total estimated number of reported seabirds captures in the squid fishery by the deepwater fleet has fallen by 60 percent from 1,213 to 481 seabirds in 2019-20.[i]
“Capture rates and trends do fluctuate to some extent, but importantly the trend continues to travel downward.
“We all want to see that number continue to drop. How cool would it be if we could bring the risk of net captures all the way down?”
“It has been a long journey, and while we are not there yet, we are determined.“
Aaron Irving, Seafood New Zealand Ltd – General Manager Deepwater
022 472 7040 [email protected]
[i]https://protectedspeciescaptures.nz/PSCv6/released/birds/squid-trawl/all-vessels/eez/2019-20/
