Tuna carrying radio active material across Pacific | Pacific Beat

Tuna carrying radio active material across Pacific

Tuna carrying radio active material across Pacific

Updated 16 July 2012, 11:41 AEST

Back in May we reported radioactive material being carried by tuna from near Japan's crippled Fukushima power plant, all the way across the Pacific to the US.

One of the scientists doing that research was Stanford University's Dan Madigan.

Now he wants to know what other species are carrying radioactive material across the Pacific.

Presenter: Wayne Shields

Speaker: Dan Madigan, Stanford University

MADIGAN: It's very regional, regionally dependent, and dependent on the species themselves. There's actually a lot of information available online about seafood being caught off Japan, where as you would imagine the levels are the highest. As far as I know no animal, including the bluefin that we measured off California in 2011, were close to the safety limits of either the US or the Japanese government. So according to limits as we mentioned in our first reported findings, according to those safety limits they shouldn't be that concerned and that's not talking about seafood off Japan, which is more complicated. However it became clear, and part of the reason that we're going forward with the research, is that people don't necessarily feel comfortable about any radioactivity being in their food, especially radioactivity that came from something like a failed power plant. So one thing we realised from the public response was that people want to know what's in their seafood, whether it's considered safe value or not, that's one of our motivations for continuing this work.

SHIELDS: Ok so just explain your next research project and how that continues on from the first bit of research that you've already completed?

MADIGAN: Sure, so in 2011 the fish we measured because we didn't know what we'd see and we weren't really convinced we'd see anything we only measured 15 fish, and what was amazing was that we found it in all 15 bluefin tuna that we looked at. These were known from their size to be migrants from Japan, so they had only by the nature of when we sampled them and how long it takes them to cross the Pacific, we know they'd only been in the water around Japan for at most two months, probably less, maybe less than a month. So our big simple question was what will bluefin look like that migrate over this year that have spent their entire life from egg stage growing up in the waters off Japan? The concentrations of radioactivity had decreased, but the amount of time the animals have to spend in that water before they make their long migrations has increased. So we really don't know what to expect. And there's many other species that use those waters off Japan and migrate long distances, and as of now none of them have been looked at, and again people really want to know what species are carrying this radioactivity and which aren't, and that's what we're trying to do.

SHIELDS: Ok so give us an idea of what other species you'll be testing?

MADIGAN: Sure so we're actually going forward with a much larger project on the bluefin, so we're doing Pacific bluefin again. This time we'll look at multiple year classes, and interestingly bluefin migrate only from the west Pacific, in waters around Japan and ... to the east Pacific, so any fish caught in the east Pacific has come from Japan at some point in its life. So part of this project is to learn more about this species itself, not just say how much radiation is in the fish from a consumer standpoint, but also which fish came from Japan and which fish have been hanging around California waters for a while. So our bluefin project is greatly expanded and that's thanks to the More Foundation and Noah is sponsoring that research. What we're trying to build is another broader project and that's the one that looks at multiple species. There's some species that we know migrate from Japan and end up in different areas of the Pacific. Examples of those are salmon sharks, which are a cousin of the Great White, look a lot like the Great White shark. They end up in Alaska and some seem to hang out in the east Pacific, some from the west, the extent to which they mix is unknown, the amount of which they pick up radiocesium is unknown, no salmon sharks tested off Japan did have radioactivity. So we'll be testing salmon sharks in Alaska, for that matter salmon as well, make entire trans-Pacific migration as well as migrations from Japan to Alaska, so we're measuring levels in salmon. Two other species known to make the migrations across the entire ocean are albacore tuna, which have not yet been measured and blue sharks travel across the Pacific.

SHIELDS: Ok as well as the testing that you'll be doing for the radioactivity, you're actually going to be getting a fairly good indication of the migration patterns of these species, which is something that hasn't been done before, is that right?

MADIGAN: That's right, I mean for some of the species different approaches have been used to look at their migration patterns, and that's how we know to target certain species across the Pacific. Electronic tags, the top program, TOPP, in the Pacific taught us a lot about migrations of a lot of these animals, and traditional tagging studies where you basically put a plastic tag in an animal and later it's caught and you find out basically where you released it and then where it went, have taught us that some of those species I mentioned like salmon, blue sharks, albacore, the bluefin, that they cross the Pacific. Other animals we're looking at their migration patterns are less known, and there's the possibility here that we'll find out for the first time that certain species make migrations across the entire Pacific ocean.

SHIELDS: Dan how are you funding this research, who's paying for it?

MADIGAN: So as I mentioned the kind of large-scale bluefin project and that's focussing on bluefin in the northern Pacific ocean, is the More Foundation and Noah have gone ahead and funded this work. We're working on getting the multi species work funded now. Interestingly from the bluefin perspective a large group of fish in terms of their individual size go and show up off New Zealand and are fished off New Zealand and they're mixed in with the southern bluefin tuna, which you're probably familiar with in Australia. No one knows, they're considered one population, but no one really knows when those giant bluefin move from the northern Pacific down to waters off New Zealand. And no one knows if they go back and forth or if once they're in New Zealand they stay there. And that's important for understanding bluefin tuna. So that's one interesting story and we're looking at sea turtles, seabirds, whales, for a lot of these species the mixing extent to which they mix and whether or not they come from Japan and in what numbers is unknown. So that's what the multi species project is focussing on and that's what we're actually actively trying to raise money for now. There's a relatively new, I think it's somewhere in the range of one to two years old, funding site called petri dish, so that petridish.org, and we actually just launched our project on that site. And it's a really cool idea what they've done. Their idea is instead of applying to grant agencies in the traditional fashion, it allows the public to go on this website, check our scientific projects, find one that interests them and contribute. And we really found after our first study we were overwhelmed by the public response, and it was clear that people want to know more about what's going on and this is a chance for them to put a contribution of their choice, a small or a larger contribution towards figuring that out and doing a solid comprehensive study of lots of different species. So that's what we're doing and Petri Dish reached out to us and we just launched our project on there, so I'm encouraging anyone who's interested in this story to go on that site. And we really want people to focus on and let us know the animals that they are interested in; whether it be ones they eat or ones they just like, so it could be sea turtles or whales, because you really like sea turtles or whales. Or it could be albacore because you eat a lot of albacore, it's really up to you. And the nice thing is that the people who contribute are kept up to date with the work, they're basically already directly taking part in the work and depending on how much you contribute you get something from the researchers, whether it be a thank you letter from all the researchers, other forms of swag like t-shirts, framed photographs of your study animal of choice, there's kind of a wide variety there and you can check that all out on the site too.

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