0:00:00.9 John Sheehan: You can always tell an oceanic whitetip shark by its characteristic fins, the distinctive white patches on their tips, giving them their name, but also by their shape.

0:00:09.8 John Carlson: They're like big giant oars. In fact, the scientific name Carcharhinus longimanus in Latin means large or long hands. These guys have really big, broad paddle like fins with a whitetip on the end.

0:00:23.9 JS: And while once they were abundant to the point of even being considered pests. Now after decades of population declines due mostly to bycatch and long-line fisheries, such as tuna, oceanic whitetips are listed as threatened under the Endangered Species Act.

0:00:37.7 JC: The situation looks very bad, particularly in the Indo-Pacific region. The population could have declined by up to 99%. But in the United States, in the Northwest Atlantic, we do have declines 80 to 90% potentially. If things don't get better in the foreseeable future, then this species will be endangered of extinction.

0:00:57.0 JS: This is Dive In with NOAA Fisheries. I'm John Sheehan. And today, we're discussing oceanic whitetip sharks and a forthcoming recovery designed to help this species back from the brink. NOAA Fisheries creates recovery plans for species listed under the Endangered Species Act, which marks its 50th anniversary in December. My guest is one of the developers of the Oceanic Whitetip Shark Recovery plan, Dr. John Carlson, a research fish biologist at the Southeast Fisheries Science Center.

0:01:17.2 JS: Dr. John Carlson, welcome to Dive In with NOAA Fisheries.

0:01:19.4 JC: Thank you. It's really good to be here.

0:01:21.8 JS: So John, let's talk about oceanic whitetip sharks. Give us some background. What are their population's like?

0:01:28.3 JC: Yeah, Oceanic whitetip shark is, it's a pelagic species. That's a species that's found in the open ocean pretty far offshore. But in some cases, depending on the oceanographic conditions, like if the water drops off very quickly as you get away from shore, like in The Bahamas, you can find them close to shore. Tropical subtropical conditions generally between the tropical of Cancer and the tropical of Capricorn is the majority or the main part of their range. They prefer temperatures between 75, 76 degrees up to about 81, 82 degrees. But it's interesting in some of the more recent research that we've been doing is they generally don't like temperatures above 82, 83 degrees. So although they like warmer water temperatures, there is a thermal limit to what they prefer or what they can withstand.

0:02:13.3 JS: So that's going to become more and more relevant as waters get warmer.

0:02:14.0 JC: Exactly. And that's one of the things we have on our radar is as climate change influences sea surface temperature, we don't exactly know what's gonna happen right now, whether they're gonna shift their distribution become deeper. It's one of those questions that we have as we move forward with research for these animals. They do on occasion travel. Like for example, off the east coast of the United States. In the summertime, they'll follow the Gulf Stream north. In fact, interestingly, the first time I ever saw an oceanic whitetip was when I was in college and I was fishing for tuna in the Hudson Canyon off New York. And just as the sun was going down when we started chumming for tuna, I saw an oceanic whitetip shark fin at the surface.

0:02:54.5 JS: Oh Wow. And they were ones very abundant.

0:02:58.6 JC: Yes, they were. In fact, if you go back and look at some of the historic accounts, like from some of the early fishery surveys back in the 1950s and in the 1960s when they were searching for tuna grounds for fishermen. And if you go back and you read those old reports, it's so interesting because they weren't catching a lot of tuna. They were catching a lot of oceanic whitetip sharks. So much so that they were a pest. There are accounts of scientists actually throwing sticks of dynamite off the back of the boat to deter oceanic whitetip sharks. They were that abundant in the '50s and '60s.

0:03:33.1 JS: And so what has happened? Because today, they are not.

0:03:36.9 JC: I mean, as we talked about in their fins, their fins are very valuable in the Asian fin markets to make sharked soup. Because of the large size, the density of the fin raises within the oceanic whitetip fins makes them very valuable for the market. In fact, 50, 60 US dollars per kilogram or per pound or some of the values that oceanic whitetip shark fins would fetch. Now, although they were never really targeted, most of the pelagic fisheries are targeting tuna and swordfish, what we would call them is desirable bycatch. Meaning if they caught an oceanic whitetip, they weren't gonna let it go. They were gonna cut its fins off and save it for that particular reason. So what had happened was, in the '80s when the fin markets really started opening up, oceanic whitetips were a desired bycatch. So anytime that one was caught, the fins were lopped off. Now sharks can't recover from that type of unregulated fishing practices where sharks are community harvested and harvested and harvested. They can't recover like a tuna or a swordfish. Oceanic whitetips don't reach sexual maturity to probably around eight years old. They give birth every other year. They're not giving birth to millions of little babies. They're giving birth to four to eight pups or individuals at a time. So that is not the same productivity that you would see in like a tuna.

0:04:52.1 JS: And we should note that in the United States, shark finning has been banned for a very long time. And despite these bans overall on shark finning, oceanic whitetip sharks continued to decline.

0:05:07.0 JC: A lot of it was too late. I mean, they had already slipped off a cliff, so to speak, and were already on a severe decline before a lot of these regulations kicked in. Now that being said, we do have some very strong outside the Endangered Species Act, strong regulations that are implemented through what are called our regional fishery management organizations or RFMOs. These are countries that have signed a treaty together. They were primarily designed around regulating tuna and swordfish. But because sharks are such a prominent bycatch that regulations haven't implemented and Oceanic whitetip, it's one of the most strongest is that these sharks can no longer be landed. They're what's termed a prohibited species. So that's very strong regulation, which also ties in with the listing under the US Endangered Species Act.

0:05:53.2 JS: Yeah. And that's led to this oceanic whitetip recovery plan.

0:05:58.1 JC: Yes. Yeah. Once the species has been listed, whether it's threatened or endangered, we are required, NOAA fisheries is required to develop a recovery plan. And one of the misconceptions that people don't understand about the goal of the ESA is to get the species off the ESA. It's not to keep it on in perpetuity. We wanna get the animal recovered. And that's the purpose. It's the tool the most, one of the strongest tools to recovering species that are either threatened or endangered with distinction.

0:06:24.9 JS: Yeah. So it's not just a list of actions that you have to now do, but it's also benchmarks on, like these are targets we have to hit.

0:06:32.8 JC: Exactly, exactly that. And it's called recovery criteria. The most robust way we can measure if the population is recovering is through a stock assessment. This assessment takes information on catch on how many are being harvested. It takes information on abundance. It takes information on the biology to develop a model to provide us not only with the status currently, but also project into the future on given fishing mortality is this, this is how long the population is gonna take to recover. However, now that they are prohibited, we're not getting catch information for these animals anymore because they're not supposed to be caught. So in the absence of catch information, we've also developed alternate methods to measure whether recovering is occurring. And one of those is just looking at in particular abundance. We have tools in our kit, we have observers that go on our commercial fishing vessels that record information on bycatch.

0:07:26.3 JC: And the way we measure abundance. One of the things that I'm very envious of is like some of my colleagues that are botanists. If a forest is cut down and you wanna recover plant X, you can just go into the forest and count 1, 2, 3, 4, 5, 6, 7, 8. We can't do that in the ocean. It's a big place. So a lot of times we'll rely on what we call relative abundance. For example, a long line, a pelagic long line may set out 10,000 hooks. And what we record over time is there may be a hundred oceanic white tips caught per 10,000 hooks. So we look at that trend over time to see if per 10,000 hooks, are we seeing more? That is one tool that we're using to measure recovery. Now that being said, there's not a lot of data that comes in from various parts of the world.

0:08:12.6 JC: So one of the things we're looking at now more is electronic monitoring, putting cameras on boats, because as we talked about earlier, these are very easy to identify. A camera, oceanic whitetip being brought up on board. A camera's gonna identify it, no problem. And ironically, my colleague Chelsea Young and I, who's at the Pacific Islands Regional Office, we're working with the Nature Conservancy last year, they have a very big program for electronic monitoring of vessels in the Indian Ocean and in the Indo-Pacific. Because a lot of these boats, if you look at them, you're like, I'm gonna go for two weeks and see on that. So they've been trying to put cameras on board the boats. And to speed up the process 'cause it's a lot of video you gotta go through. They were working with Microsoft to develop artificial intelligence to identify oceanic whitetips through the, all that video, through that thousands and thousands of hours that, boom, speeds up the process.

0:09:02.7 JS: Yeah, absolutely. And that's a really great example of innovations that you're using to sort of make up this data gap. Are there any other sort of examples of like technology taking up the slack?

0:09:14.8 JC: Oh, definitely. You know, on the subject of cameras, one of the models that we're developing, it's a baited remote underwater video and it's what it's called is a BRUV. It looks like a small Christmas tree without all the branches. And what it has on it are cameras. And what you do is you hang a box of bait below the cameras, the bait attracts the oceanic whitetip into the camera, and you can record video of the numbers of oceanic whitetips over say a certain segment of time, an hour that the camera's out there floating in the ocean. Now what we've done right now is it's been very simple. We've been using GoPros and the GoPros are working really well. But my colleagues who actually are here at the Panama City Lab who've done some more advanced stuff with stereo cameras and lasers, we wanna use these stereo cameras now, which will not only give us the number of oceanic whitetips, but it'll also give us size because of the lasers and will get more refined video with these stereo cameras because they'll get different angles.

0:10:11.8 JC: And one of the things that we're noticing, we've talked earlier about the, that characteristic whitetip on their fins. It looks like the fin pattern or the white pattern on the fins is identifiable to a particular animal. So with the new cameras, we can start identifying individual animals, which will get us an estimate of the population size. So the BRUVs are very easy to transport. You can use them off of 20 foot vessels if you really need to. They're cheap, I shouldn't say cheap. They're cheaper than running a big, huge survey with hooks and baits and stuff off a big NOAA White ship. So this shows a lot of potential because not only can we use them in areas in the United States, but we can work with small artisanal fisheries in say, Sri Lanka or in some areas in the Pacific Ocean that we can't get a big NOAA to, but we potentially can deploy these off their smaller contract vessels.

0:11:08.9 JC: So that's one way looking at video. Now another thing that's showing a lot of promise is environmental DNA or they also call EDNA. Everything has DNA. When a shark poops, that poop has DNA when skin loss off their bodies, that has DNA in it. So I've been working with colleagues at the University of South Mississippi to potentially use environmental DNA to go to, we're gonna test it first in an area like off Kona, Hawaii or in The Bahamas where we know oceanic whitetips are. If we can detect oceanic whitetip environmental DNA in the water using water sampler bottles, we may able to deploy this technique into various places around the world. Again, a very portable scientific method. And that'll help us identify potentially where high areas of occurrence are for oceanic whitetips.

0:11:57.9 JS: Are sort of low tech solutions a part of this? I know in Hawaii, not too long ago, they banned wire leaders because of the impact they were having on whitetips.

0:12:08.6 JC: Right? I mean, that's another major aspect of the recovery plan is we want to reduce fishing mortality. So there's two ways we can do that. One is the first thing is you prevent them from being caught on the hook if they are caught on the hook. The second is trying to increase the survivorship. So once you release them, the shark has the best chance to survive being caught on fishing gear. When they're being caught on the hook, one of the significant factors that affects their survivorship is wire leaders, because generally when they're caught on wire leaders, they don't live as well as if they're caught on a monofilament leader, that wire leader gets down their throat, causes a lot of internal damage, the shark generally doesn't survive very well being caught on wire leaders. So this was something the industry in Hawaii took the initiative among themselves, which is huge to ban wire leaders. It was a very important conservation step, which was led by the industry, which was great.

0:13:00.7 JS: And, and cooperation with with industry is obviously amazing. I feel like this effort needs a lot of cooperation internationally.

0:13:09.7 JC: Yes, cooperation internationally is one of the biggest challenges that we have because in many cases, the threat is greater overseas than it is in US waters. So cooperation with national governments, but also working through these regional fishery management organizations that I mentioned is gonna be a critical element of our recovery plan. And actually it is outreach. A lot of the work that we're doing with US fishermen is teaching them safe release guidelines. When a shark is caught, what's the best way to maximize that when you cut it loose, it's gonna live. So some of those techniques that we're developing in the US, we're gonna try to carry forward into some of these international bodies going, look in the US, we found out that this is the best way to increase survivorship. We'd like your fishermen to start doing this as well.

0:13:54.0 JS: And what does success look like? What are the thresholds that you have to reach in order to say like, we've done it?

0:14:01.2 JC: Yeah. We have several different criteria under that, depending on the methodology that we're using. For example, if we are... We do have a stock assessment, what we've looked at is virgin biomass or un fished biomass. This is what the size of the population is before fishing mortality starting, causing the population to decline. Bringing that back to a proportion, we know we're never gonna get there. You know, we wanna be reasonable. The population will never get back to 100% how it was before fishing took place, because fishing is gonna occur regardless. So we looked at what the stock assessment was telling us, and one criteria is if we can get that population back to about 30% of what it was like before the population was exploited. And that population has to continue to show recovery for two generations of its lifespan. That's about 20 years. And that's based on the animal's life history, things like how often they reproduce, what's their age maturity, how long do they live, and that from that we get an estimate of their generation time. So two generations is about 20 years.

0:15:02.4 JS: And so what other criteria are you looking at, to gauge success?

0:15:08.5 JC: One of the issues as I mentioned earlier, is we may not have a stock assessment available just for reasons that we might have not have the data might not be feasible. So we've looked at alternate ways to look at recovery and one of those is looking basically at relative abundance. You know, number of oceanic whitetip sharks per 10,000 hooks. Now if we track that over time, if we see a rate of change of about 12% over those two generations, 20 years from the time they were listed, that's an indication of recovery. Also, some of those alternate techniques that I talked about, the cameras, the pelagic BRUVs. If we have an estimate of number of sharks per hour of video footage, that's also a rate that we can use to look over time. So these are some potential tools in our toolbox, not relying strictly on the stock assessment, because as I said, the data might not be available for it, it might not be feasible for some parties or countries to conduct that type of assessment. 'cause it's a very data rich modeling approach and it's the most robust, but it needs a lot of data to make it work.

0:16:07.4 JS: Which again, it's very, very challenging given that they're sharks, given that they're highly migratory in nature. It's super challenging.

0:16:15.9 JC: Oh, it is. It is. Like, like we had said, it's a large ocean out there. It's an international species that likely more of the threat is by overseas fleets rather than US fleets. 'cause we, the United States has some of the most robust and stringent regulations for our shark industry. Other places unfortunately do not have that type of regulation or enforcement for that matter, even if they have some of the more stringent regulations like protected areas. I mean, there's some big huge protected areas out there in the Pacific Ocean, in the Indian Ocean. However, if you don't have the, the tools or the resources for enforcement, it's kind of moot.

0:16:54.4 JS: Dr. John Carlson, thanks so much.

0:16:58.2 JC: You're welcome. It's my pleasure to talk about probably one of my favorite sharks. So it's been a great pleasure for me to have this time with you.

0:17:06.0 JS: Dr. John Carlson is a research fish biologist at the Southeast Fishery Science Center. You can learn more about Oceanic Whitetips at our website, fisheries.noaa.gov, where you can also find the latest news from around the agency or sign up for one of our newsletters. I'm John Sheehan and this has been Dive In with NOAA Fisheries.