Think Out Loud

OSU researchers find sharks in Puget Sound for the first time

By Stella Holt Dupey
Aug. 5, 2024 4:17 p.m. Updated: Aug. 5, 2024 8:34 p.m.

Broadcast: Monday, August 5

Big Fish Lab researchers process sevengill sharks on the Oregon State University research boat.

Big Fish Lab researchers process sevengill sharks on the Oregon State University research boat.

Courtesy of OSU/Maia Insinga

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Last week, researchers from Oregon State University documented two shark species in Puget Sound for the first time. They found a broadnose sevengill shark and the critically endangered tope shark. The presence of these large predators in the sound may mean that the ecosystem is changing to fit the needs of the sharks, which could have other effects. Taylor Chapple, assistant professor and head of the Big Fish Lab at OSU, joins us to share more about his team’s findings.

This transcript was created by a computer and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. Last week, researchers at Oregon State University (OSU) documented two shark species in Puget Sound for the first time. They found a broadnose sevengill shark and the critically endangered tope shark. The presence of these large predators in the Sound is seen as evidence that the marine ecosystem is shifting as the ocean warms, which could have other knock-on effects. Taylor Chapple is an assistant professor and the head of the Big Fish Lab at OSU. He joins us now. Welcome to the show.

Taylor Chapple: Thanks, Dave. Thanks for having me.

Miller: Can you first just describe these two sharks? First of all, the broadnose sevengill shark?

Chapple: Sure. The broadnose sevengill – I guess, by its name kind of gives it away – has seven gills; most species of sharks have five. And so we think that they’re actually one of the more sort of ancestral species of sharks that we have around. And they sit sort of on top of food chains. The same way that we think about white sharks, these big predators in systems, these sevengills are actually a more prolific predator than even white sharks that you’ll see on “Shark Week” and things like that. So they’re a sort of a coldwater, slower moving, but important predator in systems.

Then the tope, or we call it soupfin – there’s a bunch of different names for it – they’re sort of a middle-of-the-road predator where they’re eating smaller anchovies, and sardines, and other sharks, and fish like that. So these are really key species for healthy habitats, which is really interesting that we found them in the Sound recently.

Miller: Why did your team start to look for them in the Puget Sound?

Chapple: So, like most people, my lab spends some time on social media. And with some collaborators from different agencies, [we] came across a few fishermen that had caught a few species that were pretty abnormal. So that was the soupfin and the sevengill. We contacted those fishermen. We wanted to find out if that was sort of an anomalous thing or [if] that was something that they were catching more often, and found out that they had been interacting with those animals more often than just a one-off. So that’s what really got us thinking about the presence of these animals in a place that’s hundreds of kilometers, hundreds of miles away from where anyone’s ever seen them before.

Miller: Any scientists have confirmed, in other words.

Chapple: Yes, correct.

Miller: So how do you go about, then, seeing if you can do the same thing? How do you catch a shark?

Chapple: It’s actually not as easy as it seems – I think they make it look easy on TV. But they’re really discerning predators, so they usually know what they’re interested in and what their prey species are. We went out into the southern parts of the Puget Sound, down near Shelton and Olympia, and put a series of baited lines down. That’s a technique that we use along the coast for these same species, so we know them to be effective. And we spent multiple days and multiple hours on the boats in order to catch these animals. So we would use a small piece of bait, and a few hooks at a time, and just wait – a lot of time waiting.

Miller: But you did find numerous examples – I guess this is the word – of the sevengill. And it was one tope shark?

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Chapple: Yes. So we spent about 10 days on the water and found nine sevengills – mostly males and one small female – and also one tope shark. And I think the tope shark was an interesting one for us because we usually target the larger sharks. The tope go for a smaller hook than we typically use. So my guess is that there’s many more of those in the water than we were able to find. We’re actually changing up our methods a little bit more to find more of those tope in the Sound.

Miller: In the big picture, what do you think the presence of these sharks in Puget Sound tells you?

Chapple: Well, we’ve got a license plate in Oregon coming out that’s shark-themed and it has the tagline “Vibrant Ocean.” And I think that’s really important because the sharks play this critical role in the ecosystems, the same that a lion does on the Serengeti where they help maintain the sort of the homeostasis of the balance of an ecosystem. So when we have new predators coming in – soupfin and sevengill – it suggests that there’s a change in the regime, or there’s some type of change within the system that’s happening that allows these predators to sort of come in and manage the system.

Likely, as climate change in different waters open to different species, we’re seeing an influx of things like anchovies into the Sound – and that’s a perfect prey species for the tope. So we actually started to see, in about 2014, this increase in anchovies in the Sound. And that coincides with some of the first records from the recreational fishermen of these tope sharks. It’s a sign of change, but it also can be a sign of health. So if you imagine having these big predators in your system, there has to be a fairly healthy system to be able to support them. Having sharks in any ecosystem is really a good sign for the health of that system in general.

Miller: All of these things are so complicated in terms of the web of connections here, in terms of prey, and predator, and food for the anchovies, and what was the food for the things that the anchovies ate … and on and on. But, why is it that anchovies started showing up nine years ago or so?

Chapple: Well, we think it has to do just with water temperatures. Historically, sardines and anchovies would have this back-and-forth about cold and warm water. I think what we saw in 2014 was this big anomalous event called the blob, which is this huge pocket of warm water that was off of our coast, and it really switched the systems up, our broad systems. It brought tuna in way closer. It actually, in California, brought juvenile white sharks up much further north than they typically go. So it was that same sort of event that we think changed the system over to a warmer regime inside the Puget Sound, and that’s what brought those anchovies in initially.

Miller: Once the sharks are here, I imagine they won’t only eat anchovies or sardines. What might this mean for, say, Chinook salmon in Puget Sound, which are already threatened?

Chapple: I think your comments earlier about how complex these interactions are is quite appropriate here. I guess I’ve focused a lot on the tope so far, but the sevengill, they’re a much higher-level predator, so they’re eating things like marine mammals – sea lions and harbor seals. When you want to get into the interactions, we know that sea lions and harbor seals are eating millions of salmon smolt outgoing and then the adults coming back in, and there’s tons of evidence of the interactions that they have with salmon. It’s complex because you’ve got that sevengill that now may be predating on a few harbor seals or sea lions during its period in the Puget Sound, so that’s going to release a bunch of predator pressure on outgoing salmon smolt or incoming adults. So it really almost is going to realign, or has the potential to realign some parts of the system. It’s one of the things we just have to kind of sit and wait.

One of the cool things that we do with these different species is, when we have them on the boat, we actually hold their stomach contents onto the boat. We put water in their stomachs and basically make them puke up into a bucket, so we can see what they’re eating. It allows us to say, what effect are they having in this system? And I will say that, so far, we haven’t seen salmon in their stomachs yet.

Miller: I don’t think this will hurt your feelings to tell you what you probably already know, which is that on our show, and just in general, when I see various media, I’m a lot more used to hearing about marine mammals like whales, or dolphins, or orcas, or sea lions, as you just mentioned, than sharks, than the big fish – which is the title of your lab. I’m curious if that mirrors a similar emphasis in academia on the West Coast?

Chapple: One hundred percent. There are known publications, scientific publications, coming out of the state of Oregon. There’s only a few in the state of Washington on sharks. Even though we’re home to 15 species off the Oregon Coast and 12 off the Washington Coast, they’re incredible parts of the ecosystems on par with marine mammals, but they definitely haven’t gotten the attention.

Miller: How do you explain that?

Chapple: Well, I think there’s a few parts of that. One is that, for the most part, even though the tope shark are critically endangered globally – they’re up for ES listing right now, the endangered species listing – there’s very few federal funds available to support shark research. So it’s hard, expensive work; the single tag that we put out is $8,000. So it’s tricky to do without those funds.

The other thing is that they’re cryptic by nature, so finding these animals is tricky. I like to joke with my marine mammal colleagues… I have a lot of them that I respect greatly. But I would say, you’ve got it easy. Your animals have to come to the surface; ours don’t. So there’s a lot of similarities and the role that these animals play, but there’s definitely been a disparity in what we know and how we think about them in our ecosystems.

Miller: Taylor Chapple, I look forward to talking again. Thanks very much.

Chapple: Thanks so much for having me.

Miller: Taylor Chapple is an assistant professor and the head of the Big Fish Lab at Oregon State University.

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