Pacific's bigeye stocks critically depleted.

Transcript

New figures on tuna populations in the Pacific show that the region's bigeye stocks have been critically depleted.

Research by the Secretariat of the Pacific Community is to be presented to the Western and Central Pacific Fisheries Commission, or Tuna Commission, which meets early next month in Majuro in the Marshall Islands.

The research co-ordinator for the SPC's Oceanic Fisheries Programme, Dr Shelton Harley, says they found that bigeye numbers are now less than 20 percent of what they were before the species was fished.

SHELTON HARLEY: SPC is responsible for providing the scientific advice on tunas in the Western Pacific. Essentially what we're trying to do is provide an estimate of how many tuna are in the water and how many is safe to take. But the expanse of water is quite large, we're talking an area from Japan in the north to Hawai'i, down to French Polynesia and across to Tasmania and we're also, across that area, looking to integrate information on fish catches, sizes, fisherman success, for a period of over sixty years, so it's a lot of numbers and takes a long time to crunch them

DON WISEMAN: This was achieved, effectively by a lot of computer work in your office there in Noumea?

SH: Yeah, essentially we set up our own little farm of computers, essentially anybody in the office who's away or overnight we harnessed their computing power to crunch the numbers.

DW: You've completed this process now and some of it's highly critical, I know there've been concerns for a long time about the state of the fishery but you're particularly concerned about what's happened with bigeye and this is down dramatically on what it was before it was being fished. Just how dramatic?

SH: Bigeye tuna is a species that people have been concerned about for several years, it used to just be taking large fish by longliners for sashimi, but in the last twenty years when purse seiners started fishing, small fish were being caught in these large purse seine nets. So you could say we've started burning the candle at both ends and now today we believe bigeye tuna are down 80 per cent and by that I mean there's only 20 per cent of the spawning bigeye that were left before fishing started.

DW: So what does that mean for the fishery?

SH: Well the Tuna Commission which is responsible for managing bigeye tuna last year set out a limit for bigeye tuna and a limit is essentially a point that you don't want to go near and now bigeye is either at or slightly below that limit so what it means for the commission is that they now need to act to take some management measures to help move bigeye away from that level but what we've seen last year in the fishery is that the longliners who are catching the large ones, their catches are way down, the lowest catches we've seen for fifteen years.

DW: It would seem that the message is that there's got to be no fishing for quite some time of bigeye.

SH: Well what we have to do is find a way primarily to avoid catching them in the persane fishery. Because in the persane fishery which we're trying to catch skipjack, which is in good health, we catch these small amount of bigeye which is essentially part of the problem so that's probably one of the key tasks for the commission now will be to look at some ways to reduce this unwanted by-catch of bigeye tuna in the persane fishery.

DW: And as you say as far as skipjack goes that's doing ok but it is down though still, quite significantly.

SH: The skipjack catch is actually, last year, the highest on record but the population is down at the lowest level that we've observed however it's still much healthier than bigeye tuna. We estimate that there is essentially half of the skipjack population remaining that would be there if we weren't fishing and for a fish population that you're out there exploiting, 50 per cent is actually a pretty good place to be.

DW: Less so for yellowfin but you're relatively happy with those figures?

SH: Yeah, yellowfin is part way between skipjack and bigeye in terms of its shape. Biologically it's probably not too much of a concern, but again the biomass is going down and so the commission is going to have to be mindful of what is going on with yellowfin. But an added to dimension to yellowfin is while the overall stock is viewed to be healthy, some of the countries that live in the south such as New Zealand, Niue and some of the others are seeing less and less yellowfin, so they're concerned as well.

DW: I don't know whether you get into answering the environmental questions or the sustainability questions that come out of this but one of them has to be that a lot of the fishery has to be just put into abeyance for a significant period of time - which of course I guess is never going to happen - if they want it to recover properly.

SH: Well the main focus I think for the commission this year will be coming up with first, some measures to try and rebuild the bigeye stock. I think that's going to be critical. The other area which they need to act upon is to stem the increase in new purse seine vessels that are coming in. The purse seine fishery was the second highest on record at 1.9 million tonnes and there are just more and more boats being built so I think it's going to be very critical for the commission to take some steps to essentially put a cap or a lid on that purse seine fishery, otherwise the potential risks to skipjack are real.