Our statistical analysis enabled fisheries managers to make a decision about which method was the most effective at reducing the number of albatross killed in trawl fisheries.

Albatross interactions with trawl warps

Globally, albatross populations are in decline because they are killed by fishing operations. For albatross populations to recover, these fatalities must be reduced. In trawl fisheries, the warps (cables that connect trawling gear to a vessel) can strike and kill albatross that are feeding behind the vessel.

Finding the best device

In 2006, legislation was introduced requiring that all trawlers over 28 m in length, fishing in New Zealand waters, use mitigation devices. These devices keep birds away from the danger zone under the trawl warps at the vessel’s stern. Three different devices were permitted by the legislation, but no data existed on which one was the most effective.

An experiment was planned to identify the best mitigation device, with representatives from the Ministry of Fisheries, the Department of Conservation, WWF-New Zealand, the fishing industry and research organisations working collaboratively. They had a simple question: which device worked the best?

Despite plenty of hearsay about how effective each mitigation device was, it wasn’t clear where the truth lay. Dragonfly worked together with other stakeholders to provide the necessary analysis and make a clear recommendation to fisheries managers.

Statistical models show a clear winner

The statistical models demonstrated that streamer lines behind the vessel were by far the best way to keep the birds away from the warps. The analysis showed a 90% reduction in bird strikes when they were used.

Since the experiment, the use of streamer lines has increased and a decrease in the bycatch of white-capped albatross has been observed. This work has also contributed to international recommendations for reducing bird strike behind trawlers.

I was impressed by Dragonfly’s ability to bring a quantitative approach to this real world issue.

Research relating to fisheries management typically doesn’t produce tidy datasets, but Dragonfly routinely works through such difficulties with aplomb.

From the design phase to the final analysis, they linked results back to objectives and consistently produced strong, defensible outputs and delivered value for money. I also appreciated the sense of a research partnership that working with them engendered.

Johanna Pierre
Marine Conservation Services, Department of Conservation