By Bianca Nogrady
The iconic ‘prawn on the barbie’ is as much a feature of the Australian summer as thongs, cricket and sunscreen. But in recent years, prawn fisheries – like many other marine-based industries – have become much more conscious of the environmental impact of their trade, and one of the biggest issues they are grappling with is bycatch.
To find a solution, the industry collective NPF Industry Pty Ltd (NPFI) has taken the unusual approach of going straight to the men and women on board the Northern Prawn Fishery (NPF) fleet to ask for ideas.
With a target of a 30 per cent reduction in bycatch, the NPFI has offered $20,000 in prize money to whoever can come up with the most successful methods of reducing bycatch.
“We wanted to engage the people on the water – the skippers and fleet managers and crew – to get their ideas, because they do come up with great ideas,” says Adrianne Laird, project officer with the NPFI. One promising design has come forward already, with early trials showing a reduction in bycatch of between 30 and 85 per cent. Kon Triantopoulos, a retired skipper and now a net-maker for A Raptis & Sons, has developed ‘Kon’s Covered Fisheyes’, a modification of an existing bycatch-reduction device.
Adrianne Laird says most of the bycatch is small fish, crabs and syngnathids – creatures that are a similar size to prawns but poor swimmers, making it difficult for them to escape the prawn nets. They are trapped in the net with the prawns, and have to be brought aboard the ship, sorted and discarded.
The amount of bycatch varies enormously across the prawning sector, largely because of the different types of prawns and catching methods used. Banana prawns tend to swim up into the water column, which makes them easier to catch. Tiger prawns lurk on the seabed, so the nets must skim along the bottom to stir them up. These characteristics are reflected in the amount of bycatch. In banana prawn fishing, it can range from just five per cent of the overall catch, while in tiger prawn fishing it can be as much as 80 per cent.
Despite this, there is little evidence that fishing is having a negative impact on the populations of bycatch species in the NPF. The few species that might be vulnerable to impacts on bycatch are closely monitored through the NPF scientific and crew member observer programs.
The NPF prides itself on having achieved certification by the Marine Stewardship Council in 2012 – testament to its high level of sustainability – and reduction in bycatch is an issue it wants to address. Public demand for sustainable product also makes fishers keenly aware of public attitudes towards issues such as bycatch.
“Fishers have addressed the problem of the big creatures like turtles and sharks and rays through the turtle excluders,” Adrianne Laird says. “But the little stuff gets through those bars and the battle now is to try and stop that or provide an easy way for them to escape.”
The other challenge with bycatch reduction devices is that they must let only the bycatch out, not the prawns. At most, the industry will tolerate a 2.5 per cent loss of prawns. Any more than that and the device becomes a hindrance.
In the quest for user-generated solutions, the first step was to identify suitable ‘tests’ for any new ideas. The NPFI wanted to make sure this was done properly from the start. Working with CSIRO, NPFI developed a trial guide that gives skippers a method to follow to test the new devices and record the results in a standardised fashion.
“We needed to be able to show that there was some influence and that it would be worth putting under a scientific trial,” Adrianne Laird says, pointing out that a proper scientific trial is rigorous, thorough and not cheap.
Any device or strategy has to be tested over a period of time, in different conditions and different locations, as well as rotated around the four nets of a typical prawn trawler, to ensure that any variations in bycatch are not the result of other factors.
Already, this approach has delivered a potential winner. Kon’s Covered Fisheyes include a cone-shaped insert that fits inside the fish-eye. This creates an area of low water flow, which makes it easier for the bycatch to swim into it and escape, says Michael O’Brien, manager of the Tropic Ocean Prawns fleet. The device is a modification of a bycatch reduction device already approved by the Australian Fisheries Management Authority (AFMA), called a ‘fish-eye’.
“When you see the ones that we use now and then you see what Kon’s designed, you see how simple it is,” Michael O’Brien says. “The other thing that Kon did was to put two in a net. Instead of just putting one in, he put one in further down the net end, and another further up the codend, and again, it’s making what we had better.”
The device has just completed formal testing in the tiger prawn fishery in the Gulf of Carpentaria, and everyone is excited about the results.
“The skipper who trialled this device was keen to start using it immediately, before it had even been formally approved, because he could see the benefits from it,” Michael O’Brien says. “It’s really exciting because it looks like we might have found a winner and will come home strongly with it.”
The trial of Kon’s Covered Fisheyes was supervised by AFMA observers in June 2016. Analysis of the catch shows the device is achieving an average 40 per cent reduction in small bycatch, with a less than two per cent loss of prawns.
For Adrianne Laird, hearing the trial results was a moment of truth. “The first night, Mike rang me and he said the worst result was 30 per cent bycatch reduction, the best was 85 per cent and they caught just under 400 kilograms of tiger prawns and only lost six kilograms of prawns all up. I was so excited and these great results continued night after night,” she says.
The other advantage of the device is that it is lightweight and small. Bulky or heavy devices could create a problem for crew, particularly in rough weather conditions.
“That’s key as well – to have something that’s simple, easy to use, and not just reduces bycatch, it’s also safe for the crew to use,” Adrianne Laird says.
While this device looks promising in the Northern Prawn Fishery context, that doesn’t necessarily mean it will work for all prawn fisheries around Australia or internationally. Michael O’Brien says industry has tested some devices used in prawn fisheries overseas, but they didn’t work as well in Australian conditions.
“A lot of bycatch reduction devices are built and suitable for particular fisheries, with particular environments and particular types of fish being caught,” he says. “Ours being a tropical hot water fishery, it will probably react differently in South Australia.”
The approach of crowd-sourcing ideas from those working on the boats has proven so successful that it is likely to be taken up elsewhere. Michael O’Brien says the level of engagement across the NPF was incredibly high, with everyone involved going above and beyond the call of duty to resolve the issue of bycatch.
Adrianne Laird, firstname.lastname@example.org