Last updated January 11, 2018 at 10:30 am
A simple policy to save dolphins being accidentally caught up in or killed by fishing nets developed in South Australia could save the lives of thousands of dolphins worldwide.
In purse-seine fishing a net is set from a boat to encircle a school of fish and then drawn together, like a purse string, to prevent fish from escaping from the bottom of the net. It’s the main fishing method used for fishing in the open ocean.
In the 1960s tuna fishing in the Pacific Ocean killed hundreds of thousands of dolphins when a technique called ‘dolphin fishing’ was used. Fishers would deliberately chase and net groups of dolphins that were associated with tuna. Fishing practices changed in the 1990s and reduced the number of dolphins killed substantially.
Today, most if not all fisheries do not deliberately target dolphins, but there are still accidents occurring where dolphins are encircled or killed in nets. Just over a decade ago researchers estimated (from observed samples) that 423 dolphins were killed in nets during the 2004-05 sardine fishing season in South Australia. This was discovered when an independent observer program was set up and found much higher rates of dolphin interactions, including deaths, than was being reported in logbooks. This discovery had a huge impact on the industry as the South Australian Government shut the fishery for two months and threatened to close it permanently unless a solution was found to reduce dolphin impacts.
Industry and scientists worked together to implement a very simple new Code of Practice that boils down to two parts. First, before a net is set a crew needs to search for signs of dolphins around the boat, and if dolphins are detected, to delay setting a net until they’re gone. Amazingly this simple step was not done prior to 2004. This simple act alone reduced the incidence of dolphins getting encircled in nets by 85 per cent. Secondly, if a dolphin does get detected in the net before it’s brought up onto the boat, the release of the dolphin becomes the number one priority of the fishing operation and the net is opened. This has reduced dolphin deaths by 97 per cent. The only dolphin deaths were associated with two dolphins that were tangled in the outside of the net.
These simple changes, backed up with a lot of industry training and education, could easily translate to other fisheries around the world suggest the researchers. The procedures are simple and not very expensive to implement.
Over the course of the last decade, the discrepancy between the rates of dolphin interactions reported in logbooks versus when an independent observer is present on the boat have dropped, reflecting a big change in the culture of the industry where there is now an increasing attitude of stewardship of the oceans.
The original research about the impact of this code of practice was published in Marine Policy.