Kelp, Seagrass, Crabs, and Conservation along California's Coastline with Dr. Brent Hughes, Sonoma State University Professor & Marine Biologist

Dr. Brent Hughes takes us on a fascinating journey through California's coastal ecosystems, revealing the unexpected ways sea otters transform their environments. As an Associate Professor at Sonoma State University with a background spanning from the center of landlocked Kansas to the rugged Pacific coast, Hughes brings unique perspective to marine conservation.

The conversation explores how foundation species like kelp, seagrass, and salt marshes create the physical structure that supports entire ecosystems. Hughes shares his groundbreaking discovery that sea otters prevent coastal erosion by consuming burrowing shore crabs – research so significant it earned the cover of Nature magazine. These "crab condos" weaken marsh banks, but when otters remove the crabs, the marshes stabilize. It's a perfect example of how restoring natural food webs can solve environmental problems that human intervention struggles to fix.

California's sea otter population faces a precarious future, stalled at just 3,000 individuals despite historical numbers likely reaching 20,000-30,000. The culprit? What Hughes calls the "white shark gauntlet" preventing otters from expanding their range north or south of central California. His research suggests San Francisco Bay alone could support twice the state's current population, reveali

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Chapters

• 0:00 Introduction to Resilient Earth Podcast
• 1:40 Meeting Dr. Brent Hughes
• 3:58 Foundation Species and Coastal Ecosystems
• 8:43 Sea Otters' Impact on Ecosystem Health
• 18:43 Sea Otter Population Challenges
• 28:46 Kelp Forest Restoration Efforts
• 37:31 Conservation Strategies and Coastal Protection
• 47:31 From Kansas to Marine Ecology
• 54:50 Kelp Recovery and Coastal Stewardship

Transcript

Leigh Anne Lindsey: 0:10

Welcome to the Resilient Earth Podcast, where we talk with speakers from the United States and around the world about the critical issues facing our planet and the positive actions people are taking, from the tiniest of actions to the grandest of gestures, so that we can continue to thrive and survive for generations to come. Leigh Anne Lindsey, producer and host, along with co-hosts and co-producers Scott and Tree Mercer of Mendonoma Whale and Seal Study, located on the South Mendocino and North Sonoma Coasts. The music for this podcast is by Eric Allaman, an international composer, pianist and writer living in the Sea Ranch. Discover more of his music, animations, ballet, stage and film work at ericallaman. com. You can find Resilient Earth on Spotify, apple and Amazon Podcasts, iheartradio, youtube, soundcloud and wherever you find your podcasts.

Leigh Anne Lindsey: 1:40

On this last episode of Season 1, scott Mercer drives the conversation with Dr Brent B Hughes, associate Professor in Marine Biology at Sonoma State University in Santa Rosa, california. He has a PhD from UC Santa Cruz and has co-authored numerous abstracts, papers, technical reports and books. His research interests are community ecology, marine ecology, conservation, coastal ecosystems and food webs. Research in his lab seeks to determine the processes that affect the stability of coastal ecosystems. The research is focused on coastal habitats like seagrass, salt marsh and kelp, also known as foundation species, which provide valuable ecosystem services, yet they are threatened by human activities. We'll get into that conversation now. I'm Leanne Lindsay. Thank you for joining us in this last episode of Season 1 on Resilient Earth Radio and Podcast. We'll be back with more episodes in the coming months. With me today is Scott Mercer of the Mendenoma Whale and Seal Study, and he's going to be our host today.

Dr. Brent Hughes: 3:00

Great. Hi Scott, hi Brock, how are you Doing well, Thank you.

Leigh Anne Lindsey: 3:06

And Scott and his wife Teresa, or Tree Mercer, are the co-creators of this show too. They're co-producers, co-hosts, but normally I kind of run the show. But today, because Scott has done a lot of study on whales but also seals and otters, and I just wanted to make sure that, because of your vast experience and all the papers you've written from the coastlines up in British Columbia down to Monterey, that Scott join us in asking you some of the top questions. But welcome to Resilient Earth Radio and Podcast.

Scott Mercer: 3:41

Thank you.

Leigh Anne Lindsey: 3:42

All right, Scott, all yours.

Scott Mercer: 3:44

Thank you, Professor Hughes. A term that I found in your material that I was reading yesterday was foundation species. Just for people who aren't familiar with that, could you explain what that is? I think I know what it is. Could you explain what that is?

Dr. Brent Hughes: 3:58

Yeah, yeah, you could probably imagine what it is A foundation species. We typically kind of think of them as habitat forming species. Now, a foundation species doesn't have to be a habitat forming species, but that's oftentimes what we think about. And in the ocean, especially here in California, it's going to be kelp, it's going to be seagrass or it's going to be salt marshes. Those are the foundation species of the ocean. You know, if we move up to land, it's the redwoods, it's the oaks in the grasses that form the grasslands. And so, a foundation species. They're well known to create positive species interactions. So a lot of ecology, especially historically, has focused on negative species interaction, like predator-prey, who-e2, herbivores, diseases, parasites. You know these are all negative things, but my lab and a lot of my research focuses on the positive interactions that result in functioning ecosystems. At the foundation, the base of it are these foundation species.

Scott Mercer: 5:06

Okay great Thanks. So it's somewhat different than a keystone species, right yeah?

Dr. Brent Hughes: 5:11

yeah. So if we think about a habitat-forming species like kelp ray or seagrass, you know that's a lot of biomass A keystone species. On the other hand, in an ecosystem has a very low overall biomass, but its effects to the ecosystem are disproportionate to its biomass. Example a well-known keystone If you weighed everything in the kelp forest, the sea otter would be like 0.0001% of the entire biomass of the kelp forest. But its effects are huge and that's a keystone.

Leigh Anne Lindsey: 5:53

Right, this is a good time too, scott and Dr Hughes, just to let you know where we are too. We're just over on the coast from you. Now, you're located near Sonoma State University, is it?

Dr. Brent Hughes: 6:07

I'm a professor at Sonoma State University. You know we are 20 miles from the ocean, sonoma State. We are in a coastal watershed though, the Russian River watershed, and you know you might be like. Well, why are they doing marine science at Sonoma State? Why are they doing marine science at Sonoma State?

Dr. Brent Hughes: 6:24

And what I tell students, as soon as they get into my marine ecology class the first day, I show them a map in the proximity of Sonoma State to all these different ecosystems. So you know, within an hour I can be at a kelp forest. I can be at the biggest estuary on the West Coast. I can be at a tiny estuary on the West Coast. I can be in the Rocky Intertidal. I can be at a kelp forest. I can be at the biggest estuary on the West Coast. I can be at a tiny estuary on the West Coast. I can be in the Rocky Intertidal. I can be at sand dunes, I can be in the salt marsh. So you know, it's the proximity to all these great ecosystems that really makes the position of, geographically, the position of Sonoma State pretty unique.

Leigh Anne Lindsey: 7:06

And where I'm at too, is just right across from you on the coast in the Sea Ranch. And we're right, you know. Greater Fair Lawns is off our coast and Delmar Landing Marine Preserve is right there, and then Scott and Tree are up by the Point Arena Lighthouse.

Dr. Brent Hughes: 7:21

Oh fun.

Leigh Anne Lindsey: 7:22

So they study the Mendocino and Sonoma coasts and they studied the East Coast as well for about 13, 14 years now, right, scott?

Scott Mercer: 7:33

We've been out here for our 14th year trying to count gray whales. Especially challenging this year with the decline in numbers and the days that would go by when we used to have like let me call it a whale stampede. We'd just be looking at whitecaps this winter, and the spring hasn't been much better.

Dr. Brent Hughes: 7:53

A lot of mortalities of gray whales. We have a few people studying whales at Sonoma State right now. I can't speak too much to the whales since I'm not counting them or studying them, but yeah, it seems kind of tragic.

Leigh Anne Lindsey: 8:05

Yeah, scott just brought on somebody from the Marine Mammal Center down in Sausalito and Josie Slothauk, and so we just did an episode on the gray whales and the whales that have perished in the San Francisco Bay. Scott, was it gray whales or humpbacks?

Dr. Brent Hughes: 8:22

Oh, grays Grays. Yeah, I've heard this, I believe, from Josie I met really recently. This is, yeah, kind of where I was really alerted to the mortality events of the gray whales and you know what's the cause? I think that's TBD.

Leigh Anne Lindsey: 8:42

Yeah, some of the emaciated whales too, and then the vessel strikes. But here in Sea Ranch there was even a whale on the beach the other day. Oh really yeah.

Dr. Brent Hughes: 8:52

My lab works at Sea Ranch, and do you know exactly where that?

Scott Mercer: 8:57

was? Yeah, it was on a walk-on beach on Sea Ranch. It washed in. On Saturday Cal Academy came up here. They hadn't understood that the whale was still free-floating. It's wedged in some rocks in there. But they didn't come with wetsuits. Apparently I didn't go down Enough. People were down there and the photos I saw. I wouldn't call it immature. That opens up too much footage for what it might be. But it was a, a young, the younger humpback. Sure it was floating on its back but apparently fluke shots weren't available it was kind of kind of a mess yeah, it's.

Dr. Brent Hughes: 9:36

It's hard, maybe hard to idea if it's flipped over.

Scott Mercer: 9:40

Yeah it was right upside down, with the ventral pleats open and the sun beating down on the body.

Dr. Brent Hughes: 9:46

Oh yeah, and they deteriorate pretty fast, or at least when they get beached. I hear that.

Scott Mercer: 9:52

The tongue had already opened up like a small blimp. It made the whale look like it had been beached. Do you?

Dr. Brent Hughes: 9:58

know if any sharks were. Well, not because of that whale.

Scott Mercer: 10:03

Well, it's funny, not funny, but the last time humpback washed in was just north of us, just north of Point Arena, but the beach right on the it's right at Point Arena and Sarah Grimes and my wife and I, Tria and I were down there with Sarah on the beach it's Manchester Beach and we were working around it and each time we came down in the morning the next day there'd be more bite marks out of the area. The whale was sort of in the water, not in the water, yeah, Like half and half. Well, one day there were people down there and had their kids in the water.

Dr. Brent Hughes: 10:45

Is it still around? I mean, like these are actually things I'd like to know, because you know we want to avoid, we dive and so we actually want to avoid those areas when you have a dead whale floating around.

Leigh Anne Lindsey: 10:59

Because of sharks. Yeah, yeah exactly.

Dr. Brent Hughes: 11:01

We don't want to be near it. So then we bite marks on it yeah, not the new one.

Leigh Anne Lindsey: 11:07

Well, scott and Tree were in actually a documentary a couple of years back that a couple of Berkeley students had created and it was called Washed Ashore, and data has changed since then, but it was a very good documentary on what happens along our coastline from Baja up to how far was it, scott? Was it all the way up to Washington State?

Scott Mercer: 11:32

The UME was yeah, the documentary stopped with us, started in Baja and ended with us, the two of us sitting on a cliff out there.

Leigh Anne Lindsey: 11:41

By the Point Arena Lighthouse right yeah that's where it ended. That made a big splash at the Mendocino Film Festival. Everybody cheered when they saw the lighthouse Scott go ahead with the questions that you've got about sea otters, because this question does keep coming up in talks that you give Well there's a question I wanted to ask Dr Hughes for a moment here when I was looking at your website last night.

Scott Mercer: 12:04

There's a question I wanted to ask Dr Hughes for a moment here when I was looking at your website last night. There's a photo of you with clams You're kind of in the mud, and then there's another one where it looks like you're whispering to a shark. What is that you're holding?

Dr. Brent Hughes: 12:17

So that clam one, that was a moment of serendipity, kind of caught with a you know, a digital camera in me. It's a funny story. That was from Alaska, southeast Alaska, prince of Wales Island. We were working on a project up there that was focused on sea otter recovery and how it would impact not only the ecosystems but the people, specifically the indigenous communities, and for me it was kind of my group. We were really wanting to know well, what is the seagrass like in areas where sea otters have recovered versus not recovered, and we made this discovery around 2013 or so in California that sea otters, much like they, have these positive impacts to kelp forests by consuming urchins. They can also be hence the term keystone. We found that they could be keystones in seagrass beds in central California. Now, that is specifically one estuary, elkhorn Slough, which is you know it's a significant estuary in Central California. You know it has about 20, currently about 20 hectares of seagrass, which is you know, it's a good amount for California. But in Southeast Alaska there's about 10,000 kilometers of shoreline that are covered with seagrass, so it's a much bigger area and the sea otters were just expanding like crazy and we started looking at the seagrass itself and saying like okay, simple question do we see more seagrass or healthier seagrass in areas with sea otters versus not sea otters? That was kind of the working hypothesis and the way it works, the food web. It's somewhat similar to California's food web in some ways, but in some ways it's different. And one big way that it's different is that they have in Southeast Alaska the clams. The clam populations are just, especially in the intertidal zone, are just dense, and so that picture that my grad student at the time, jessica Saavedra, took of me was I said it was serendipity because we showed up to our site to look at our seagrass at this one site that had not really experienced significant sea otter recovery by that point and there was a black bear on the beach and the protocol is if there's a black bear on the beach you can't get off the boat to go do the work.

Dr. Brent Hughes: 14:59

We have protocols to kind of try to scare, spook the bear to get off the beach so we can go do our work. This bear was so stubborn so we were just sitting there on the boat and the tide went out and so the boat was literally high and dry. Eventually the bear left and we were just stuck there. So I just started. I said, hey, jessica, let's just start digging in the mud like we're a sea otter. And so that was me digging in the mud. I kind of used the shovel, but really I just used my hands.

Dr. Brent Hughes: 15:28

Sea otters dig with their paws to get these clams. That's what I dug up and it was just like, oh my gosh, well, look at all these clams, which is really important for the indigenous communities. Right, they want to protect those clams. But what we found was that the grass, the seagrass itself and the clams kind of compete for space in the mud. Right, a nice, healthy seagrass bed will put on big, thick rhizomes and all these root hairs, and so there's this competition below ground. And so what we found was that by the sea otters removing all these clams, it actually stimulated more growth and bigger biomass of the plants of seagrass. And so that was kind of the aha moment, that kind of really kind of helped us, guide us to figure out well, what are they doing in this ecosystem? There are good things and there are bad things, the bad being the just almost wholesale removal of these clam beds, the good being that you get bigger seagrass, which ends up benefiting the fish.

Dr. Brent Hughes: 16:38

That's the story behind that one, the shark one I don't know what it is. It's probably us doing leopard shark sampling in Drake's Estero I believe that's where it came from. I had a student, Alyssa Cooper, one of my first students, who was interested in the role estuaries play for supporting leopard shark nurseries. What we were finding is in California that the leopard sharks yeah, they'll use estuaries as kind of nursery grounds, and Drake's Estero in particular, we think, is a major nursery ground for leopard sharks. And so Alyssa was just doing studies.

Dr. Brent Hughes: 17:20

And it's cool when you do the shark studies, you know these leopard sharks are beautiful animals.

Dr. Brent Hughes: 17:26

I think they're the most beautiful animals on the planet and so you catch them in a net and then we're trying to figure out well, what are they eating? You catch the shark, you flip it over, kind of like we were just talking about the whale. You know, if you flip the shark over, it goes into a state of what's called tonic immobility. It basically falls asleep when it's flipped over and this might sound brutal and stuff. But then we put in a hose and pump water through it. It doesn't affect the animal but it kind of forces it to throw up and regurgitate everything it just ate, and then we collect that. We collect its vomit, then bring it back to the lab and identify, well, what the heck was this thing eating. So we can we can actually figure out what it was eating without having to watch, you know, and try to track. That's really hard in a in a very turbid estuary. So yeah, that was a from a leopard shark study, I believe yeah, I was staring at that.

Scott Mercer: 18:22

It had a shark's face. It it was the opposite, the other end. I couldn't quite figure out what that was, but it was clearly a shark face. When I blew the picture up, you could see the uh. Look like I had a camouflage shirt. I was curious as to what you were holding there.

Dr. Brent Hughes: 18:40

Yeah, yeah, and it might've been like I my waitaders. I might have had my waders on, and they're camouflaged too, so yeah.

Scott Mercer: 18:49

Everybody who's been to Alaska has a bear story or a story that might have been a bear story.

Dr. Brent Hughes: 18:59

Luckily on this island there are no grizzlies. They're interesting black bears stories. You know we're always kind of. They love being on the beaches. You know, either they're foraging there or whatever. Yeah, we're often competing for space on the beach with the black bears in Alaska.

Scott Mercer: 19:17

I went kayak fishing around the Tikchik area. Each night we went out. There was eight interconnected lakes in this Tikchik area. Each night we went out, there was eight interconnected lakes in this Tikchik. Well, it's Alaska's idea of a state park. It's like a million and a half acres from one end to the other, so we had plenty of room to kayak around in.

Scott Mercer: 19:38

And one night I went out fishing and I was pulling an Arctic char into the boat, the kayak, and then I figured there wasn't enough room for me in the char. So I was paddling back into the beach and throwing the char up on the sand and then I realized that I was going to have to go get it. My party was back where we had our tents, so there was really nobody between me and where my group was friends that I brought with me it was one of the fastest dashes I ever made to pick up some trout off a beach Getting back to the kayak and then we cleaned and cooked everything back there. Well, the next morning we woke up and there were grizzly tracks right up to the edge of our tents and then it turned around. I decided not to mess around. I turned around and went back into the woods. So good.

Dr. Brent Hughes: 20:29

That's wild. Oh, yeah, you know these. Yeah, you spend enough time in the outside, in nature, doing these things. You know you're gonna have encounters every once in a while and you know, luckily we have all the safety protocols. You know for what happens. You know if there's a white shark spotted or a bear being spotted, you know it's actually good to talk about this stuff because then we can approach science especially, you know, for us a lot more safer. And so, yeah, these are, you know, good stories to share.

Leigh Anne Lindsey: 21:01

You mentioned too the Elkhorn Slough down there just off. It's in inland from Moss Landing.

Dr. Brent Hughes: 21:09

Yeah, so it's just right. It's the heart of Monterey Bay. It's an interesting estuary because the mouth of the estuary sits at the head of the Monterey Bay Submarine Canyon. It's a great place because you can study kind of deep sea dynamics too. I don't necessarily do that, but you can just pull in right out of the harbor of Moss Landing and you're in a canyon, and so it's been great for not only estuary studies just because of the access, but also places like the Monterey Bay Aquarium Research Institute, one of the world leaders in deep sea ecology. Monterey Bay Aquarium Research Institute one of the world leaders in deep sea ecology yeah, just the benefit of having that canyon sitting right there is cool, and then you can even look at how these ecosystems are connected too.

Dr. Brent Hughes: 21:55

A lot of what gets produced in Elkhorn Slough, which is a very nutrient-enriched ecosystem, actually makes its way down into the canyon. The connection here is, you know all these row crops of like lettuce and strawberries and Brussels sprouts they require a lot of nutrients. That ends up getting into Elkhorn Slough and it stimulates a lot of algal blooms, of green algae in particular, and that green algae ends up making its way down to the canyon and actually subsidizes invertebrate communities down in the canyon. So there's actually a linkage from the Salinas Valley strawberry all the way down to the canyon and in the deep sea in the Monterey Canyon. So there's these really neat ecosystem connections there too that you can study, and it's kind of a rare thing to be able to do that.

Scott Mercer: 22:48

You know most people study the deep sea have to go, you know, far away, and so it's cool when it's just you know it's just right there your documentary, the film Zach Cliver, you met you sent me a link to it again and I had seen it on one of the nature shows a few years ago. The whole thing about Elkhorn Slough was really new to me and interesting, but what I found kind of even funny to watch was the crabs on the side of the bank. So you talk a little bit about that. It reminded me of like they were all living in high rises, it seemed to be a bummer high rises.

Dr. Brent Hughes: 23:24

We call them crab condos and you know crabs are a very natural part of, you know, especially estuaries, coastal systems. If they're left unchecked by predators they can be very damaging to marshes and this was really well described on the East Coast in New England, salt marshes.

Scott Mercer: 23:46

Can I interrupt you for a second? Yeah, if you don't mind. What is the genus and species of these, since they're green? Are they Carcinus manis?

Dr. Brent Hughes: 23:57

Yes, so there's a couple of crabs that we've been studying in around the marshes of Elkhorn Slough. One is the European green crab, Carcinus manis, the other one, which is a native crab, it's the striped shore crab, Pachygrapsis crassipes, and it's kind of like two different stories. The European green crab, at least in Elkhorn Slough, don't really use the marshes, they use kind of the areas just below the salt marsh, and what we found was that the sea otter loves eating those European green crabs, which are these really notorious invaders, especially on our coast. We think the invasion started in San Francisco Bay. It made its way down to Elkhorn Slough in the late 80s and it's slowly been moving its way up the coast and now these green crabs are in Alaska, and these green crabs are known to eat other native crabs, native species, oysters, so they have kind of these really harmful effects that are not desirable. What we found in Elkhorn Slough is that the sea otters are really good at keeping those population numbers down, and so that was a big finding, because we've also been finding that in places like Bolinas Lagoon, for example, eradication by humans is almost it doesn't work. In fact sometimes it does the opposite effect. You try to eradicate and you actually end up getting more green crab. This is another example of restoring a food web leads to these positive benefits to the ecosystem. In this case it's invasion resistance.

Dr. Brent Hughes: 25:36

Now these other crabs, the native crabs, which are smaller than green crabs, the striped shore crab they do use the salt marshes and they do burrow into the salt marshes and into the banks and create these crab condos, which you know is basically Swiss cheese, and they eat the roots of the salt marsh because that's where all the good nutrients and sugars are, and they destabilize the banks. And so what we found as we're chasing these sea otters around, the big discovery was made where we found that they were using salt marshes, they were eating these crabs around salt marshes, they were hauling out the pups, the mothers were putting their pups on the salt marsh to rest while they would go get the Pachygrapsis crabs, the striped shore crabs. And over time what we found was by them removing these shore crabs, they started stabilizing the banks. And so in Elkhorn Slough there's been this big problem with erosion.

Dr. Brent Hughes: 26:41

Over the last 80 years or so, the banks of the estuary have just been eroding away. There was about 50% loss of salt marsh because of this erosion. The sea otters pretty much stopped the erosion. There's still a little bit of erosion happening, but by just removing these crabs they were able to really solidify those banks and slow down to the erosion to the point where it almost is non-existent. That was a huge finding, not just for the sea otter but really all of nature, where we're thinking about eroding systems and how predators can affect the geomorphology of aquatic ecosystems. The big analogy here is the gray wolf reintroduction to Yellowstone. There's a lot of documented positive effects. None of it was experimental. So we were the first ones to really experimentally test. So we put cages out on the banks to keep out sea otters of certain areas to test this hypothesis that sea otters can slow down erosion, and that study took about 12 years but we just published it last year in Nature and it got the cover of Nature, which was really exciting for us scientists.

Dr. Brent Hughes: 28:00

Number one magazine there for us scientists.

Leigh Anne Lindsey: 28:00

Number one magazine there.

Dr. Brent Hughes: 28:02

Yeah, yeah, it's the top science publication in the world, and so that ended up being another big discovery. So it's basically, if you can conclude it, all what we've found with the sea otter is expect the unexpected, and there's a long history with why we're just now seeing them using salt marshes. It's because they've been in a state of recovery. They were almost hunted to extinction in California To the point, in the early 1900s it was thought they were extinct until about the 1910s, 1920s, something like that A population of about 50 animals was discovered off the Big Sur coastline, and so since then our population of sea otters has been expanding north and south, but it's been a slow expansion.

Dr. Brent Hughes: 28:51

Ecology basically started in a period where a lot of animal hunting was almost concluding because we had hunted almost all the, especially the marine mammals.

Dr. Brent Hughes: 29:06

We had hunted them all, and so when ecology started, it was like all these populations of marine mammals were super duper small, and then we thought, oh well, this is just how it is, this is the baseline and we were wrong. This is the baseline and we were wrong Because as these animals start expanding their populations and there's protected areas like Elkhorn Slough where humans can't access we're seeing they're really unraveling themselves and their true what we call the niche breadth, their ability to use different ecosystems, their ability to use different ecosystems. There's been a period of discovery over the last 15 years, just kind of following these animals around and letting them tell us what they're doing and what they're capable of doing, and that's been, I think, really exciting. Then you know, the conclusion with the sea otter is expect the unexpected and wherever they go, there's going to be change. So for a scientist, if you're guaranteed change, it's really exciting because you know that's what we were really kind of trying to figure out. Well, what's driving change? Either good or bad.

Scott Mercer: 30:14

Yeah good, back in 1974 or 5, I worked that Cal Fish and at the time it was Cal Fish and Game Sea Otters Population Survey and my station was out on Point Sur, which at that time the Navy was in charge of. So I got out there about an hour early. I was driven out there and began counting from the land and then a couple of fish and wildlife people were going to fly over and that was one of the tests on what you're missing or how many you think you're seeing with all the kelp floating around. But a few weeks later I got the conclusion of the survey. Once the statisticians got done. The population at that time was a little over 1,500. They come up with. Well, what is it now? I can't really get it.

Dr. Brent Hughes: 31:06

It's 3,000 in the entire state. It's about doubled.

Scott Mercer: 31:11

And it was doubled in a lot of decades. What?

Dr. Brent Hughes: 31:13

year was that, scott, about 74 or 5. Yeah, so it's doubled since then. So that's 50 years, yeah, and you might be like yay, doubled. But it sits at this threshold of 3,000, where it's actually a threshold. That was kind of established by the US Fish and Wildlife Service, who manages the sea otter, and they established for the Endangered Species Act this threshold of 3,000 animals. The population has been stuck there for at least 10 years, so it's not necessarily growing, it's not going down, it's just stuck at 3,000. They need to go, either move north or south. That's their only option At either end, which is Santa Barbara and south of San Francisco, that's where the range limit is north and south. At both ends of those are very significant great white shark populations. We call it the white shark gauntlet that the sea otters just can't get past.

Dr. Brent Hughes: 32:18

We will see sea otters pop up in San Francisco or sometimes Drake's, estero or Tomales Bay. They usually are males, so that doesn't do anything for the population and they'll stick around, usually for a couple weeks, and then they'll take off, knowing that there are no mates here. There might be plenty of food but no mates, and they'll try to go, you know, swim back down. Oftentimes these otters are coming from, like Santa Cruz or Monterey. Some will make it back, a lot of them, don't, you know probably because they get eaten by something or starved to death or whatever it might be.

Dr. Brent Hughes: 32:56

The problem is that you need at least one female and a male to expand the population. That's been the big problem, we know. In San Francisco Bay alone, historically, there was probably 10,000 sea otters. So just that one estuary, you know, had tripled the amount of sea otters that we currently have in the entire state. The true number, what we call the carrying capacity, how many sea otters could be supported in the state, you know, is probably 20,000 to 30,000 sea otters. We're, you know, at the state where it's just, they're just not really recovering. The big risk for the sea otters, like if there's a big oil spill or a big disease event, the population's still in kind of jeopardy, and so therefore, it's listed under the Endangered Species Act as threatened Not endangered, but threatened.

Scott Mercer: 33:46

Yeah, after what happened in Alaska with the Exxon Valdez, just wipe out this population along here very quickly.

Dr. Brent Hughes: 33:54

Oh yeah, yeah, and that's the fear, at least from the sea otter conservation perspective.

Scott Mercer: 34:00

Yeah, some of the stories I heard from the medical people who worked with the otters who were soaked in oil when they got them internally, when they did a necropsy on them.

Dr. Brent Hughes: 34:12

They're just falling apart inside, yeah yeah, yeah, the sea otter did not fare well and that was probably I think it was basically the last species to really start recovering after that oil spill. You know, it took 30 years or whatever, and they might still be recovering to some degree and so, yeah, that was devastating. Really kind of highlighted how impactful the oil spills can be, for the oil spills can be.

Leigh Anne Lindsey: 34:45

I mean there's discussions right now in our government to open up oil drilling off of Sea Ranch Gualala Point Arena. This whole coastline.

Dr. Brent Hughes: 34:51

Yeah, you know, I think the community, if the community doesn't want that, you know, the community really needs to band together and voice their opinions.

Leigh Anne Lindsey: 35:01

Yeah, there was an open comment period there for a while, until June 16th.

Dr. Brent Hughes: 35:06

Oh, really yeah Okay.

Leigh Anne Lindsey: 35:07

It wasn't widely, you know.

Dr. Brent Hughes: 35:10

I didn't even hear about this, I didn't even know.

Leigh Anne Lindsey: 35:12

News announcement, nothing like that. I mean. I shared it on social media. Richard Charter of the Ocean Foundation had put together a website where to go to sign up and report what you feel to the government, but that closed already June 16th, so we're waiting to see what happens with that. But we can still do something, even though that comment period has ended, and it's important that those that feel that we should be extractive and go after these limited resources, the damage that it can cause to the marine systems and fishing and tourism along our coast.

Dr. Brent Hughes: 35:57

That's not good. Yeah, it's hard, especially when the kelp forests are already struggling, really struggling. There's a lot of different types of communities in that region, from fishing to residential, to the indigenous communities. Yes, the Kishaya Banapomo Indians.

Leigh Anne Lindsey: 36:18

They're right here, they're all around us the Kishaya.

Dr. Brent Hughes: 36:21

Yeah, and I don't think that would be desirable for them, I would imagine. Well, it happened before a totally different time. You know, with the Point Reyes in the you know the 60s right, there was that debate of turning it into a suburb of San Francisco and the community really banded together to put a stop to that and then they got a national park out of it. Yeah, that's unfortunate.

Leigh Anne Lindsey: 36:49

Now, scott, you have brought up a couple of times how reintroducing sea otters along the Mendocino, sonoma Coast could be almost impossible. I wanted you to talk with Dr Brent Hughes about that.

Scott Mercer: 37:08

Yeah, when I've given a talk here since two years ago, suddenly I don't know who lit the match, but there was all this talk here about bringing sea otters in and people. Well, it was before the abalone diving and so forth harvest ended. The divers, as you can imagine, were not too keen on the idea, and other people were, and. But just a matter of pointing out that there's no place for the otters to go here, yeah, kind of put a high blush on that.

Dr. Brent Hughes: 37:42

Yeah, right now, especially given the state of the kelp forests, you would think that or at least I do that if you want to grow a population or put sea otters somewhere where they're not currently, the estuaries are the places to go. The estuaries up here in Northern California are a lot more stable than the kelp forest. They have a ton of food and habitat and the most know sea otter restoration program that has existed for california has been in the central coast in elkhorn slough. When the monterey bay aquarium rehabilitates their sea otters and puts them so, they take stranded juvenile sea otters that lost their mom. They get raised by a surrogate mother at the aquarium to learn how to be a sea otter and eat and hunt and they get put back in Elkhorn Slough and now because of that, elkhorn Slough has the highest concentration of sea otters in the state of California and there's now populations in Elkhorn Slough that have never seen a kelp forest. They just stay in the state of California and there's now populations in Elkhorn Slough that have never seen a kelp forest. They just stay in the slough. There's a lot of healthy ecosystems, estuaries in particular, like Drake's, estero.

Dr. Brent Hughes: 39:08

We did some modeling work and, looking at Tomas Bay. We found that those two systems could support about 300 sea otters. We've done some modeling work for San Francisco Bay this is all published, by the way too for San Francisco Bay, using the current kind of habitat availability, not the historic, because a lot of things have changed in the Bay we believe that the San Francisco Bay could support currently, in its current state, about 5,000 to 6,000 sea otters, which would essentially triple the population of california. I totally agree. You know, like the kelp forest, like I want to put a sea otter out here in the kelp forest there are, there's very little kelp and all the urchins are starving to death. Um so, uh, you know the prey would be would not be all that great, but in the estuary it's a totally different story.

Scott Mercer: 40:00

Yeah, when you were talking, I thought of the Garcia River I don't know if you're familiar with that here off of Point Arena.

Dr. Brent Hughes: 40:08

Yeah, a little bit.

Scott Mercer: 40:10

That seemed to be something positive you could say about bringing sea otters back in the area, when you were talking about elkhorn slew and how I haven't done much trudging or any trudging up and down um, that river bank. Yeah, a couple of birding friends off and on, but um, you know just how that compares. And the other thing a few years ago leanne was off to your northwest. There she, she, took herself on a birthday trip. You went kayaking up one of the rivers, I don't know was it the Albion or one of those up north.

Leigh Anne Lindsey: 40:43

Oh, I was just about to say Big River up by Mendocino.

Scott Mercer: 40:47

You wrote on Facebook or to me that you'd seen a lot of sea otters up in there and I said, no, I don't think so.

Dr. Brent Hughes: 40:52

I said why they're river otters, river, otters River otters, river otters yeah, river otters can be tricky, you know they could. You know the river otter is cool and the river otter got a really bad name too, because they should be, you know, river slash, coastal otters or something. Because river otters can basically can feed on the same exact things that sea otters can feed on Mussels, clams, crabs. But they're also unlike the sea otter, which is a horrible fisher. Sea otters are terrible at catching fish, to the point where fish are really not even part of their diet, but the river otters are good at catching fish. So the river otter diet is just insane. It includes both terrestrial, aquatic, marine animals, but there's distinctions between the two. You know, the river otter is about a third of the size of the sea otter. River otters also don't float on their backs like the sea otter, so a good telltale sign if you think it's a sea otter, you'll know if it ends up floating on its back at some point, because that's something that the the river otters just don't do and it's actually kind of fun to think about. Well, you know, if sea otters made it up here, what would that mean for the river otters? You know, I don't think they would be impacted at all, because their diets are so broad that they would just ship their diets to whatever we saw.

Dr. Brent Hughes: 42:18

Saw it with the leopard sharks in Elkhorn Slough. The leopard sharks in the 70s and before the sea otters came back to Elkhorn Slough, were primarily eating crabs. They resurveyed the sharks. To compare the 70s to the 1990s, which was about a decade and a half after the otters came back to the estuary and the leopard sharks were now eating all fatting keeper worms, which are, these? Just big worms that burrow into the sediments but are a much more difficult prey item to get than, like a red rock crab or something like that. So the sea otters, yeah, they are usually the dominant predator when they move into their ecosystems and it causes the food web to kind of totally change, and I would imagine it'd be the same for the river otters too. Yeah, absolutely.

Scott Mercer: 43:11

When Leanne put that on Facebook I think it was I told her no and why. But at the time I thought well, I'm pretty sure there isn't a remnant population up here and I don't think a couple have made it up here. But never say never.

Dr. Brent Hughes: 43:31

Well, you know, it was a couple years ago. Two or three years ago a female showed up in Drake's estero. That was a tagged female, meaning the monterey bay aquarium had tagged it and came swam up from monterey and she was in the estero for about two weeks. We had people watching her feed, forage on and and it was guess what crab and it was really exciting because we're like, okay, if she just stays there and then a male shows up, then that's the start of a population. That was the first female that we've seen up here and the females have a very small home range. They don't move very far from where they're born. It's usually, on average of, you know, less than six kilometers they'll move in their lifetime. So they have a small home range. The males, especially juveniles, will just swim wherever. It was really exciting there for a minute and then we lost the signal or the aquarium lost the signal and I don't know where she ever ended, but that was for two weeks. It was a very exciting time at Drake's Estero.

Scott Mercer: 44:41

You get a merit badge for going across the bay.

Dr. Brent Hughes: 44:44

Yeah, she deserved one yeah.

Leigh Anne Lindsey: 44:48

Could you tell us just in these last few minutes? Here too, I'd like to know what courses you're teaching there at Sonoma State University and what some of your plans are going forward.

Dr. Brent Hughes: 45:01

Yeah, so Sonoma State. I teach a variety of primarily ecology classes. Currently I teach well. This semester I'll teach an upper division ecology course. In the spring I teach marine ecology and then I teach a variety of graduate courses, primarily in statistics and coding. Ecology is turned into a very statistic-heavy field. Making sure the students have the tools that they need when they go into the workforce is really important, especially how to manage data, how to analyze data, things like that. My courses are, especially when I teach ecology. They're heavily geared towards getting students into the field and getting those experiences. So experiential learning experiences and what better place to do it than the Sonoma County and Marin County too? I take my students. All you know it's all about learning the ecosystems and natural history behind our local ecosystems. So it's a fabulous you know opportunity for me to be able to teach in an outdoor setting.

Leigh Anne Lindsey: 46:11

You should connect with Scott and Tree too, I was thinking.

Dr. Brent Hughes: 46:14

That'd be great. Yeah, no, we're always looking for people to connect with in the field. A lot of our trips, you know, we take to Point Reyes and to the Sonoma Coast. We, you know, we go to Carmet Beach to go to the Rocky Intertidal. We'll go up to Fort Ross to learn about all our kelp forest restoration work that we do up there and marine mammals as well. So, yeah, it's all about kind of providing these experiences, which is kind of how I get really fired up about teaching.

Scott Mercer: 46:43

Yeah, absolutely, have you met Richard Charter. I don't think so I don't think. So he's in Bodega Bay, and what's the name of the group he's with?

Leigh Anne Lindsey: 46:55

The Ocean Foundation. He's a senior fellow there for about 30 years oh geez.

Dr. Brent Hughes: 47:00

Okay, I should probably know him.

Scott Mercer: 47:02

He's a great community resource in politics especially.

Dr. Brent Hughes: 47:05

Absolutely what's going on there yeah.

Scott Mercer: 47:07

Conservation ecology.

Leigh Anne Lindsey: 47:09

He's a force to be reckoned with that Richard. Charter.

Dr. Brent Hughes: 47:14

Well, I'll have to look him up for sure We'll get you connected too. Okay, that'd be great. Yeah, I've worked with the ocean foundation in the past on various projects, but it's been a while, so, yeah, it would be great to get connected with them what got you down this path?

Leigh Anne Lindsey: 47:31

I just wanted to understand more about your background and who you are and how you ended up here.

Dr. Brent Hughes: 47:38

Well, I like to say I'm the most famous marine ecologist from the state of Kansas.

Scott Mercer: 47:48

From the Hall of Fame huh Middle of the country.

Dr. Brent Hughes: 47:51

I grew up in Kansas, Kansas City suburbs. My mom is actually from a town called Lebanon, Kansas, which is the geographic center of the United States. You can't get further away from an ocean if you tried.

Leigh Anne Lindsey: 48:04

I heard about this.

Dr. Brent Hughes: 48:05

Yeah, I graduated from a college in the Midwest called Truman State University, which is in Missouri. I got a bachelor's degree there and in my final semester there you know, there's all these posters in the hallways kind of advertising different courses and I saw a course that was offered by the University of Oregon at the Oregon Institute of Marine Biology for summer post-baccalaureate courses in marine ecology and marine animal behavior. I'm like, well, I have nothing to do. This sounds like fun. I've only been to the, you know, spent, you know, maybe 10 days total in the ocean, all on the East Coast at beaches.

Dr. Brent Hughes: 48:47

And so I drove out to Oregon in my Jeep and got there and it was, you know, the very first day of class. We went to the Rocky Intertidal and I thought I was on a different planet and so I was already hooked. And then I, you know, just talked to my professors there. I'm like asking them, like you can get a job just counting these things. They're like, yeah, that's what I do. And then, right there, in about five minutes, I knew that what is what I wanted to do with the rest of my life is marine ecology, and so I had to move back to midwest, save up some money and then I moved back out and went uh enrolled at moss landing marine labs for for my master's and then that led to a ph at UC Santa Cruz and a postdoc at Duke and Friday Harbor Labs in Washington, and then eventually I got the job offer at Sonoma State in 2018. I've been in California since 2021, primarily in Santa Cruz, and then the last eight years or so I've been up here in Sonoma.

Leigh Anne Lindsey: 50:01

Thank you for that. I was actually wondering about those green crab. You mentioned something about how eradication efforts sometimes boomeranged. How could that happen?

Dr. Brent Hughes: 50:13

You know I can't tell you the exact way it happens because I wasn't a part of that study but a colleague of mine named Ted Grosholtz who's kind of one of the green crab marine invasion experts on our coast. They wrote a big paper in the Proceedings of the National Academy of Sciences on it. You would have to ask him about the mechanism because I can't just tell you off the top of my head.

Leigh Anne Lindsey: 50:40

It's okay. I just thought I was curious. I was thinking really excited, no, I'm curious too.

Dr. Brent Hughes: 50:45

I don't know if it's like you know. They get in the trap and the females release, you know, all their eggs I have. No, I'm not exactly sure what the mechanism is, but it was surprising and it was like, dang well, what's the solution now?

Leigh Anne Lindsey: 50:59

Because I was listening to Sheila Seamans. She's the executive director of the Noyo Center for Marine Science and she was saying how you've got to try different things because sometimes what you think might be a good conservation or restoration tactic actually has the opposite effect.

Dr. Brent Hughes: 51:15

Yeah, it happens, I'd heard that before. Yeah, it happens. And then so, modern day conservation, it's all about adaptive management, right? So you have a goal it might be restoration, it might be, you know, shoreline protection, whatever and you implement, you know the plan, and then you assess and if it doesn't work, then you go back to the drawing board. Yeah, so that's kind of a lot of how conservation?

Leigh Anne Lindsey: 51:46

works these days and ergo why statistics are important.

Dr. Brent Hughes: 51:49

Exactly, since we can't count everything.

Leigh Anne Lindsey: 51:55

We're so dependent on statistics. That's why, scott and Tree, what you guys do, you're providing data all the time.

Scott Mercer: 52:00

Yeah, we're trying to provide data. I was going to mention to Brent that I'm from New Hampshire, back in New England, so green crabs there are about as popular as athletes' foot. Yeah, I grew up being told to crush those when you see them. But that's also the same group of ancestors who thought pulling legs off a starfish was going to kill them. Yeah, instead of a population explosion yeah, they can fragment.

Dr. Brent Hughes: 52:35

Yeah, so the invasion first happened. Yeah, obviously on the East Coast and you know, moved west, we think with oysters and yeah, so that you know the spread of invaders is. You know usually we think of like boats and ballast water and stuff like that. But you know you can get it. You know the aquarium trade you know often could be a culprit for invasions. This case I believe it was the transport of live oysters to the west coast.

Scott Mercer: 52:58

Yeah, when the talk out here turned a few well, it was the transport of live oysters to the West Coast. Yeah, when the talk out here turned a few well, seven or eight years ago, to crushing urchins, then I said, well, I came from an area where pulling this or that apart was supposed to be a remedy too, and so you know, find out first about that. Yeah, hammers and smashing urchins, yeah.

Leigh Anne Lindsey: 53:18

These are the purple urchins. Yeah, these are the purple urchins you're talking about correct?

Dr. Brent Hughes: 53:21

Yeah, they must be, and so we do kelp forest restoration in Sonoma and Manasino. We work with the commercial urchin divers who are kind of not working right now because there's really not a fishery because of the kelp forest decline. Even though there's billions of urchins, they're just basically empty shells. We have the commercial urchin divers basically hand harvest these urchins. We don't smash. It's a very sensitive issue for some of the indigenous communities up here to smash native animals, and so we have the commercial urchin divers hand harvest. There was a big push to try to fatten them up after they're harvested and try to sell them on the market. It didn't quite work out. So, you know, as we planned it, so a lot of the urchins will get turned into compost For the communities we're working with. There's a positive you know aspect to that. You know, of removing, wholesale removal of urchins. We try to turn it into a positive thing. So yeah, we don't smash, but they do in Central California and they do in Southern California and elsewhere.

Leigh Anne Lindsey: 54:33

Well, they are up at Fort Bragg. The Watermen's Alliance are doing it in Casper Cove, yeah.

Dr. Brent Hughes: 54:39

Casper Cove is the one location in Northern California where there is smashing happening and that's a really community-driven effort there. Yeah, you know.

Leigh Anne Lindsey: 54:50

The indigenous are involved in that.

Dr. Brent Hughes: 54:53

Yeah, we kind of respect whatever they want. You know they're our partners on this stuff too, so we work with them and their belief systems and we think it's a good of success with our restoration, which is a really great thing, because we spent several years again failure going back to the drawing board, failure going back to the drawing. So we went back to the drawing board for about three years and we've just now kind of figured out really, you know, how to restore kelp and we've just now kind of figured out really, you know how to restore kelp.

Leigh Anne Lindsey: 55:39

Well, I was just at the Sea Ranch Lodge and looked out at Black Point and I was impressed to see this huge kelp gathering just to the south of Black Point Beach, right there.

Dr. Brent Hughes: 56:02

A place like Shell Beach and Sea Ranch. That kelp forest has actually been around since almost the kelp forest big decline and that's a really special site because, for whatever reason, the kelp has remained intact. So we have locations too across the coast where we are seeing persistent kelp beds. So it's not total destruction, right. There's still that 10% or whatever. That's kind of held on 5% yeah, maybe 5%. We're seeing a little bit of a rebound in the last year or two, just natural recovery, which has been also great. We hope that keeps on going.

Leigh Anne Lindsey: 56:32

Well, thank you Dr Brent Hughes from the Sonoma State University, associate professor, who's written tons of papers, abstracts, technical papers, and you've been studying this for the past two decades. Thank you so much for joining us today and our host, Scott Mercer of Mendenoma Whale and Seal Study. Any last words, Scott?

Scott Mercer: 57:00

Yeah, thank you for mentioning the fat ink keeper worm, Eurecus cowpaw. The name came back to me when you said that. What I did for two years down there was a feeding study feeding ecology study when I was a student of college in Marin, and after sitting outside for eight to 10 hours at a time and looking through a spotting scope we'll be in the Coast Guard jetty and one of the auditors came up with a fat ink keeper worm. It was like watching them pulling it back, Pull it back and it was stretch and stretch. Sometimes it was snapped and hit him in the face.

Scott Mercer: 57:33

And other times it wouldn't, the worm would win in the face, and other times it wouldn't, the worm would win. So that was a good memory, thinking of that.

Dr. Brent Hughes: 57:46

Yes, I've been able to observe lots of sea otter foraging around Elkhorn Slough on these fatty keeper worms and it's always hilarious.

Scott Mercer: 57:48

Yeah Well, it was the sea otters actually that got me from invertebrate zoology at College of Marin in San Francisco State into marine mammals. Oh, cool I'm so fascinated with them. I'd be sitting out there all day watching otters eat. You just look beyond them and gray whales be migrating and stella sea lions going the other way. It was a great time, learned a lot out there.

Dr. Brent Hughes: 58:11

Thank you for coming. It's like sitting on a rock for eight hours. You learn a ton.

Scott Mercer: 58:17

Like don't do it.

Leigh Anne Lindsey: 58:19

Scott and Dr Brent Hughes. Thank you so much for being with us here today on Resilient Earth Radio and Podcast and again we hope to connect with you in the future, at least you and Scott and Tree.

Dr. Brent Hughes: 58:34

Yeah, absolutely. This is fun. This is my first podcast ever, so thanks for letting me in, at least you and Scott and Tree. Yeah, absolutely. This is fun this is my first podcast ever.

Leigh Anne Lindsey: 58:59

Thanks for listening to the Resilient Earth podcast, where we talk about critical issues and positive actions for our planet. Resilient Earth is produced by Planet Centric Media, a 501c3 nonprofit, and Seastorm Studios Inc. Located on the rugged North Sonoma Coast of Northern California. Please support us by subscribing or donating to our cause.