Dr. Bob Ellis & Erica Burgess: Goliath Grouper Recovery & Regulations

Full transcript of the Tom Rowland Podcast, Episode 603 with Dr. Bob Ellis and Erica Burgess.

Introducing the Goliath Grouper Season

Tom Rowland: Okay, we have an exciting podcast today all about the Goliath Grouper. I know a lot of people are very excited about that. I have Erica Burgess and Dr. Bob Ellis, both of the FWC. Is that correct?

Dr. Bob Ellis: Mhmm. Yep.

Tom Rowland: Erica, why don't you tell us what your responsibilities are?

Erica Burgess: Well, thanks, Tom. I appreciate you having us. My responsibilities are in the Division of Marine Fisheries Management for FWC. I'm a section leader for analysis and rulemaking, and my staff includes all the regional biologists who are spread throughout the state to engage with recreational and commercial anglers. We cover all state waters fisheries, so think redfish, snook, sea trout, scallops, and lobster. That's the purview of my shop.

Tom Rowland: Okay, all right. And Bob, Dr. Fish Counter on Instagram?

Dr. Bob Ellis: Yeah. Hi, Tom. Hi, Erica. Great to be here today. I'm a research scientist with the Fish and Wildlife Research Institute. I work at the headquarters in St. Petersburg, and we have field offices all around the state. I work in the marine fisheries biology group, so our job is to study the biology of the marine fish that are under the purview of FWC. Within FWC we have a bunch of different groups doing research, and our job is really to fill in gaps anywhere there's a biological question about a species. So we end up doing a lot of life history, age and growth studies, and we've increasingly been getting into habitat science — looking at where fish are, what types of habitats they use, and where they're moving to. So we do a lot of movement ecology. We're heavily involved in acoustic telemetry, where we tag fish and listen to where they move up and down the state.

Acoustic Telemetry and Tracking Florida's Fish

Tom Rowland: That's fascinating. What, if you don't mind, before we get started on Goliath — what fish are you acoustically tagging and studying right now?

Dr. Bob Ellis: Sure. We have projects going on tarpon and snook, looking at juveniles. We're tagging juveniles in retention ponds and their upland habitats, and using acoustic telemetry to tell us when they're leaving those habitats to egress into the estuary. We have a couple of studies looking at juvenile Goliath Grouper inshore, and other species like sheepshead and spotted seatrout. We have some studies going on in the Indian River Lagoon looking at how water releases out of Lake Okeechobee — when that water pulses down the St. Lucie River — affect how those fish respond to those changing, fluctuating conditions. We're also using acoustic telemetry to try to assess discard mortality in hogfish offshore. We know that increasingly hogfish are being caught during the wintertime, especially on hook and line, and we're trying to figure out if an undersized hogfish gets thrown back, how often it survives. We use pinger tags, some with a pressure sensor, that can tell us where in the water column the fish is, so we can see whether the fish just lies on the bottom dead or resumes its normal activity. And most recently we just started a big three-year cobia project in the Gulf of Mexico, looking to see, as cobia move up the west coast of Florida, whether they're sticking around year-round or migrating to the western Gulf or back to the Keys and vice versa.

Tom Rowland: Yeah, I'm really interested in the acoustic telemetry because I did another podcast with the scientists at FIU who were doing a jack crevalle study, and they talked about getting a ping from Louisiana. With the internet and everything, you're getting pings that you wouldn't know were happening before, because all of these things are tied together now. I thought that was fascinating. When you do studies like that, does that information ever become public?

Dr. Bob Ellis: It does. There are cooperative networks — one in the Gulf of Mexico called iTag, and one for the Atlantic Coast called FACT — and we're members of both. The way the technology works is I put out a receiver that can listen to any tag made by that company, so I might be listening for hogfish but pick up a cobia that someone else tagged last week. Those networks help us get in touch with the scientists who tagged the fish so we can get them the data. One of the issues with some of this data is the time lag — for example, the receivers we put out off Tampa Bay, we only need to retrieve them once a year, so those might have detections from over a year earlier. At the FACT network we're trying to automate a lot of that data sharing, so twice a year we'll update all the detections and people will be able to go species by species and see where different things are moving. We're hoping to roll that out later this summer.

Tom Rowland: That'd be cool. I'm fascinated by the movements — like that jack crevalle that goes all the way to the Mississippi River. When you're out there fishing, you wonder where a fish came from, especially something like a tarpon — an old fish. What has this fish seen in its lifetime? That little bit of data helps you understand that. So the purpose of today's show is to talk about the Goliath Grouper. As many of the audience knows — and you both were instrumental in this in some way — there was a point where the Goliath Grouper fishery was totally open. If you go to the old Keys restaurants, you see pictures of giant Goliath Groupers; people called them jewfish back then and would eat them. Then something happened and there was basically a moratorium — no fishing for them at all. And now, as of late this year, there's a new season, and I'm not sure if there's ever been another season between the closure and now. There's a trial, permit-only season — a limited season for a specific size and a specific number — and that's what I want to get into today. Does anybody know the history of the Goliath and the regulations?

The 1990 Moratorium and the Long Road to Recovery

Erica Burgess: Sure, I'll launch into this. From the 1950s through the 1980s, Goliath Grouper were targeted both commercially and recreationally, with the recreational fishery picking up more in the eighties. During that time the fishery became overfished, so severely that in 1990 FWC closed the fishery to harvest, and the Gulf Council and the South Atlantic Council followed suit. FWC controls fisheries in state waters — zero to nine miles in the Gulf, zero to three miles in the Atlantic — and the councils had authority beyond that out to the international waters line, roughly 200 miles. They closed the fishery because it was at a point where we could not sustain harvest. There was no goal set for what would happen at a certain milestone, and no discussion of when the moratorium would end. It stayed in place, and a few stock assessments were conducted over the years to try to determine how much rebuilding had occurred, since the population slowly started rebuilding during the closure. Unfortunately, those assessments — which Bob can speak to — didn't pass peer review. A peer panel of scientists said there wasn't enough information to really say what was going on with the stock. It wasn't bad science, it just wasn't enough science, so the fishery remained closed. Beginning in 2017, the FWC commissioners wanted to understand where the fishery stood and asked staff what was happening — should it remain closed, how is the population doing — and that set us on the path to today. Not much happened from a management standpoint between the 1990 closure and that point.

Tom Rowland: So what was the beginning of the decision to consider a season?

Erica Burgess: First, it's just asking questions. Some of the research Bob and others do helps answer those questions. We got to a point where we realized we will likely never be able to do a traditional fishery stock assessment, so we had to set new metrics. But not being able to get a traditional assessment doesn't mean we can't ask whether harvest could be sustained. So that was the question to staff: can harvest be sustained?

Tom Rowland: And the decision was — possible?

Erica Burgess: The response was, it's possible — at a conservative level, at this point we could consider a harvest.

Tom Rowland: Bob, tell us why a traditional census couldn't be done on this fish.

Why a Traditional Stock Assessment Wasn't Possible

Dr. Bob Ellis: The way a traditional stock assessment works is it takes a bunch of different types of information and tries to resolve what all those data streams are telling you. You get information from the fishery itself — commercial landings, estimated recreational landings (which has undergone a big change in recent years to improve accuracy) — basically a trend over time of how many fish are being landed. We also do fishery-independent monitoring, both here at FWC and through NOAA Fisheries — basically scientific fishing. One issue with relying only on the fishery to tell us the trends is that fishermen get better over time: GPS has gotten better, outboard motors have gotten bigger, we can access more fish and get back to the exact same spot over and over. If you just rely on those trends, it might tell you everything is fine even though you're increasingly targeting a smaller population of fish. So we also do scientific sampling, spreading out effort equally and conducting the same kind of fishing effort year after year, and use computer models to resolve those trends over time. We also know about the biology of the fish — how long they live, the age structure of the catch. Every so often a fish that comes into the fish house, someone pulls an otolith, the ear bone, and we get an accurate age. So we know the age structure of the population, and we can use that to figure out how many eggs a given number of fish at a given age produce, and how many new fish we'd have the next year. We use those data streams to help resolve where we think the trend in the fishery is — going up, going down, or stable — and then use the biological information to predict the next few years, usually three years at a time.

Tom Rowland: Got it. So a regularly harvested fish, like a snapper or a tuna, you have tons more data available, but with a fish that's completely catch-and-release, no-kill, none of that landings data is available to you. You have to choose a different way to assess it.

Dr. Bob Ellis: Exactly. We don't have landings data — there's no fishery, so we don't have that fishery data coming in. We do have some biological data; that's our job — we understand the reproduction, the age and growth. We also have a little information from alternative sources. One of the better ones for Goliath Grouper is the Everglades National Park creel survey, which has been going on for a very long time and is a pretty robust dataset, but it only tells us about the juvenile population. We also have diver data — we use the REEF Environmental Education Foundation's diver dataset, which we think is pretty robust, because if you're diving on a wreck or a reef, the fish are pretty obvious. But the problem is this data can only give us a relative estimate of where the population is. Up until the moratorium we could get an absolute number using traditional stock assessment metrics — we could predict how many we could take. As soon as that stopped, we could only rely on where we think we are relative to that point. Based on the data we had in 1990, we estimated the Goliath population was down to around 5% of what it was before we started fishing for them — pre-1950s, before we started collecting fishery data. That's a very serious depletion, and that's why we needed the moratorium: sustainable fishing just wasn't possible at that point. Since then we've done a couple of stock assessments and been able to say, relative to that 5%, the population has recovered. But we can't get an absolute number — we can't say you can take a thousand tons next year, like we can with something like red snapper, where we have tons of data. We know the population is doing better; we just don't have the ability to say we can sustainably remove this many fish and be super confident about it.

Tom Rowland: Gotcha. So I'd assume the initial question of whether we could take any fish sustainably is probably brought on by the public saying, wow, there are a lot of Goliath Groupers here, they're eating all my fish — or divers saying there used to be one here, now there's twelve. Is that where the question of a season starts, or am I wrong?

Erica Burgess: Certainly public interest played a role in this. As the population rebuilds, the number of interactions between anglers and Goliath Grouper increases, and it was that increase in interaction that angered a lot of anglers. They feel they're in direct competition with Goliath Grouper. Now, Goliath Grouper eating all the fish on the reef — the science doesn't really support that statement. However, those interactions where a Goliath will take advantage of a fish on a line are occurring, and occurring more frequently.

Tom Rowland: Sure. Yeah, obviously you're going to have anglers speak out and divers speak out — positively or negatively — bringing attention to the fact that there are more or fewer of a certain species, and that might start the questioning of whether there are too many, or not enough, and whether we can take them. The Goliath Grouper is interesting because divers love them — it's an absolute home run. If you take somebody diving and they see a fish literally as big as the car sitting in their driveway, they're never going to forget it. So all the dive operations want the Goliath Groupers there. Then the fishermen — the same thing happens: you take someone out, they're getting the fish of a lifetime, and boom, it gets eaten right by the side of the boat. How long do you sit there feeding the Goliath Groupers before you have to move? It makes their job harder because they found the fish but can't catch it, so they get angry while the divers are happy. That makes for a controversial fish. So a lot of people have asked me why, if there are so many big ones, this season would open with such a small size limit.

Setting the Slot Limit and the 200-Fish Quota

Tom Rowland: I'm sure it's based on science, but a lot of people want me to ask: it seems like we'd go after the giant ones, but what is the limit? It's 24 to 36 inches — is that right?

Erica Burgess: Yes, 24 to 36 inches. There was a straw man proposal put out in 2017 for a hundred fish at a larger slot, and we got feedback on that.

Tom Rowland: Feedback from the public, or from other scientists?

Erica Burgess: From the public and from our commissioners. We held about 17 public workshops around the state in 2017, had multiple commission meetings, and people wrote in comments. The amount of input on Goliath Grouper from the public dwarfs any other species I've worked on with the agency. We took in all that feedback and thought about not just who wants harvest and who doesn't, but what people were saying about which fish could be harvested, and what our management goals are as an agency. We know that to keep rebuilding the population we need as many large spawning adults in the population as possible. We're also trying to fill out the top end of the age structure, so we need older fish. Bob, what age are we estimating they reach in the population right now?

Dr. Bob Ellis: We have limited data, but the population definitely appears to be somewhat truncated toward younger ages. The harvest moratorium started in 1990, so it's been about thirty-two years — it's possible there are some really big, old ones out there. The oldest fish we've aged, since 2007, was around 30 years old. Most of the fish we get otoliths from come from our program where basically any time a dead Goliath Grouper is reported to us, we send biologists to get as much data as we can, and the data suggests we don't have a lot of older, larger fish in the population — not as many as we'd like. That's part of the reason for the slot limit Erica mentioned.

Tom Rowland: Do we have any data from other sources — like fish that have lived in aquariums, or old scientific samples — that would show the record age or how long a Goliath Grouper might live?

Dr. Bob Ellis: The oldest one we've aged was 37 — a pre-moratorium fish. In the late eighties — unfortunately, Cletus, the Goliath that used to live at the Florida Aquarium in Tampa, passed away about a year ago. We were able to age him, and it came out basically as expected — he was in his late twenties.

Tom Rowland: That's funny, man, because even a small one of those fish just looks old to you — though compared to a tarpon, not that old. What's the full age of the oldest tarpon we know of?

Dr. Bob Ellis: I'm not sure — pretty old, I think in the fifties.

Tom Rowland: Fifties? I'd have thought even more, sixty or seventy, but I have no idea, really. Everybody always talks about how old tarpon are. A four-hundred-pound Goliath Grouper leads you to believe it could be older, but maybe they just grow faster and get really big.

Erica Burgess: Yeah, that's one of the fascinating things about fish. How old do you think an 18-inch tripletail is?

Tom Rowland: I'd think very young.

Erica Burgess: One year.

Tom Rowland: A triple tail looks very old at that size. A mahi, on the other hand, looks pretty young — and I know that's one of the fastest-growing fish in the ocean, so even a big twenty-pound mahi isn't very old at all, right?

Erica Burgess: Right — the maximum age we'll see in the fishery is around four years for mahi. Those bull mahi, if you come across one, are likely only four years old. The longest they can live, we think, is seven to eight years, but most don't reach that age because they're harvested before then.

Tom Rowland: Yeah, everyone likes those. Okay, so let's go to the specific number chosen for the Goliath Grouper — the size and the count. I see you're trying to protect the larger fish. What led to this specific slot limit?

Erica Burgess: The slot limit is based on wanting to protect the oldest fish, but also concerns related to mercury. Twenty-four to thirty-six inches — we know Goliath Grouper, like any long-lived, large-bodied marine animal, will accumulate mercury over time, similar to other large groupers, tilefish, and mackerel. That was an additional consideration for the size limit.

Tom Rowland: I certainly didn't consider that as a factor, but it makes sense. And why 200?

Erica Burgess: Like Bob said, we don't have a stock assessment that can tell us we can safely take a certain number of fish without threatening continued rebuilding. Based on the life history of Goliath Grouper — late to maturity and long-lived — and the abundance indices from the surveys Bob mentioned, we put that information together and decided that a conservative number allowing some harvest without threatening rebuilding would be about 200 fish within this slot limit. The size of the fish targeted affects how many you can take — if you're focusing on younger fish you can take more; if the fishery targeted larger fish, the allowable number would be much lower.

A Citizen-Science Permit Program

Tom Rowland: Okay. And there's a cost associated with this — it's like a hunting permit, right? How do you decide on the cost?

Erica Burgess: This is unique, because we're going to make everyone who participates a citizen scientist. Along with the permit and the tag, we're going to request that you submit data to us, just like with a deer hunt — you'll report size, location caught, and other information useful to Bob's research to understand the fishery better. We're also going to request a clip of the fin — we'll provide a kit to clip the fin, store the sample, and mail it back to us — and we'll use that as part of our genetic studies to better understand the number of individuals in the fishery and the diversity of the stock's genetics. Part of the fee pays for that analysis.

Tom Rowland: Bob, would there be any reason to have a disposal site for the head, so you could get the otoliths and a good idea of the age of a fish of this particular size? Or why wouldn't that be something you'd try to get?

Dr. Bob Ellis: In terms of otoliths, it's not particularly valuable to us for this program. A 36-inch fish, based on our age curves, is anywhere from four to seven or eight years old — there's variation, but that's not particularly useful for something like a stock assessment. We're really paying more attention to the bigger, older fish to make sure we're seeing those in the population. One thing that could be useful is a diet study — besides physically looking at what's inside the stomach, we can do stable isotope analysis, taking a plug of muscle tissue and looking at the relative ratio of different elements, which tells us something about where the fish sits on the trophic chain, the food web. We're pretty knowledgeable already about what's going on for this size class — a 36-inch fish is right about when the majority will leave the estuary and move out to the reefs offshore. Maturity happens probably a year after that egress from the estuary, at somewhere between about 120 and 150 centimeters.

Genetics and a Close-Kin Mark-Recapture Study

Dr. Bob Ellis: Again, in terms of biological data, we don't think these are reproductively active fish at this size, so we won't get estimates of fecundity from them. The genetics is really where it's at — we're attempting to answer a couple of questions right now with genetics related to Goliath Grouper. One is just to look at the genetic diversity, which can tell us something about that relative baseline. Any time you shrink a population down to around 5% of its carrying capacity, you really need to start worrying about genetic diversity — you can start getting mutations that persist in the population that aren't beneficial. That's something we've been looking at for the past few years, and the data we have suggests that diversity is continuing to increase, to a point where we probably don't need to worry about it — we've moved through that bottleneck, which is one thing that helps us make the determination for a harvest. We're seeing positive signs in the genetic diversity of the population. The other thing we can do, if we get a suitable number of samples, is a close-kin mark-recapture analysis, where we get samples from juveniles through this harvest program and from adults through other programs, and try to match parents to offspring. If we know how many samples we had of each group, and how many matches we made, we can do some pretty complex math to back-calculate how many adults there needed to be in the population. It's an alternative way for us to get at that absolute abundance number. It's going to be a little difficult — the sampling we need is quite high. This harvest opportunity is going to get us part of the way there, and we're working on other ways to get the rest of the way. It's going to take a few years — at least three years of collecting this data each year — so it's a pretty big task, but we're going to try.

Tom Rowland: So the data you're collecting on the adults — is that fin clippings, and is that from recreational anglers or just scientists?

Dr. Bob Ellis: Both. We have scientists collect fin clips, and we also have a number of charter guides in the catch-and-release fishery who help us out. We can get anglers on our special activity license to actually land the fish and get the fin clip for us. We've been doing that for the past few years to answer those genetic diversity questions, and at the same time using that data to calculate how much sampling we'll need for this close-kin project going forward. So it's a lot of citizen science, basically.

Tom Rowland: With that program, do you want fin clips from any size fish, or are you targeting big ones or little ones specifically?

Dr. Bob Ellis: All of the above.

Tom Rowland: Are they providing you a fin clip and an overall size estimate — on tape, or just eyeballing it?

Dr. Bob Ellis: As a scientist, basically what I tell these guys is the more information you can give me, the better. If you've got a tape measure in centimeters, I'll take it. If you pull it up to the side of the boat and estimate it was six feet long, that's fine too. Same thing with location — if you want to give me your honey hole, I'll take it. Otherwise, "four miles out of John's Pass" is fine too.

Tom Rowland: Do people have to apply to be in that program? What would they need to do to participate?

Dr. Bob Ellis: Absolutely — you'd just have to get in touch with me directly. My email is Robert.Ellis@myfwc.com. We're trying to focus on people who are more active in it — if you're catching one or two a year, we'd love your help, but we're really after people catching ten to a dozen every few months, and there are plenty of people in Florida who fall into that category. So yeah, we can use all the help we can get.

Tom Rowland: That's fantastic, because even from a fishing perspective, or from the perspective of someone who wants to see the fishery stay open, the only way that happens is more data. We don't have data coming in from commercial fishing or from harvest, so you've got to get the data somewhere to make a scientific decision about whether you can take more, less, or whatever.

Looking Ahead: What Comes After This First Season

Tom Rowland: As we embark on this season with these 200 fish, what does the future look like? What has to happen for there to be another season next year — could it be 400, could the size be larger? What does it look like from a management perspective?

Erica Burgess: I won't pretend to have a crystal ball. After this first season we're going to evaluate how the program went, potentially tweak some things like what we want folks to report, but we'll take this one year at a time. We're purposely being conservative — we're opening a fishery that's been closed for thirty-two years. It was fished down to 5% of what it was before, so we're celebrating the fact that we're able to reopen this fishery, but we want to do it right.

Tom Rowland: I think that's a good way to describe it — celebrating that you're opening the fishery, because a species has to rebound to a certain point to sustain harvest, and that's to be celebrated. This fish was literally kind of like the buffalo out west, or the bison, where it was so low you could count individuals, and now it's back. That's fantastic, and really to be celebrated. Now, how does something like the fish kill that happens on the west coast — the Okeechobee-related situation — play into the decision? Everybody saw the pictures on Instagram of giant Goliaths washed up on the beach. You said scientists went to those fish and got whatever data they could. But when you're thinking, okay, we're only going to take 200 fish this entire year, and then an event like that happens where obviously lots of fish were killed — how does that factor into continuing forward with the plan, or deciding maybe nature did the work for us and we need to reassess? At what point do you look at natural events like that as part of the equation?

Erica Burgess: One of the things we track — and we've mentioned a few times — are these surveys that give us a relative index of abundance, whether it's the reef survey or the creel survey in Everglades National Park. We can actually see how natural events cause changes in those survey results — there was a cold-kill event that caused a huge drop in the time series, and then it came back up afterward. So we can see these things happen. As far as how we respond to things that happen a year out, or a few months before, we are responsive to things that happen in the environment. I think the best example is the catch-and-release regulations that took effect for parts of southwest Florida following the 2017 through 2019 red tide, for snook, redfish, and sea trout. We do have the ability to use executive orders to revise regulations in between regular cycles, but until an event happens, I can't say how we'd respond.

Tom Rowland: Understood. Same thing kind of happens out west when the rivers get too hot, and they put what's called a hoot-owl restriction on the rivers — it's not safe to catch and release, so you can only fish between certain hours. And FWC has that authority, right? You could make these changes anytime based on whatever you deem necessary?

Erica Burgess: Yeah, it's not our favorite way to manage fisheries — we don't like to be reactive — but we have that avenue open to us.

Life Cycle: Spawning, Mangrove Nurseries and Offshore Migration

Tom Rowland: Gotcha. Bob, let me ask you some questions about the Goliath Grouper, because I think they're just a really cool fish. You find them in really shallow water and in really deep water — sometimes big ones inshore and little ones offshore. But for the most part, you mentioned there's a size, around 36 inches, where they leave the inshore areas and move offshore. Can you tell us anything about where these fish are spawning, or born, and how they're getting into these shallow-water areas? What does the life cycle of a Goliath Grouper look like?

Dr. Bob Ellis: Sure. Spawning happens in the fall, late summer to early fall — generally the new moons of August and September tend to be the peak. They really like these high-relief structures, so a lot of times nowadays that means shipwrecks. It makes for an incredible diving experience, jumping in the water and swimming up to a wreck and seeing a hundred fish bigger than you — southeast Florida has become an international destination for that. On the flip side, it makes the fish very vulnerable to overfishing, because they aggregate in predictable ways at predictable times of year — if you wanted to, you could go collect a hundred adults just by going out on the September new moon, knowing exactly where the fish will be. That's part of what happened to them historically, and it's a similar story for other grouper species — Nassau grouper is the classic example of massive overfishing tied to predictable spawning aggregations.

Dr. Bob Ellis: They spawn on the new moon, the eggs take about twenty-four hours to hatch, and the larval fish drift for about thirty days. What I think is super cool — I learned this early on at FWC talking with a colleague who studied mostly estuarine fish — is the timeline: they spawn at the new moon of September, and thirty days later is king tide season in south Florida, the highest tides of the year, flooding the mangroves right when those larval fish are drifting in and settling out. It's a neat little story of evolution. They're basically obligate to those mangrove nurseries for at least that first year — you probably won't see one until it's about a foot long, hiding back in the flooded mangroves. Then they spend the next three to eight years before they hit about a meter in length. Some of the data we've collected on inshore movement suggests the egress happens after a cold front — we've seen this four or five times now, where a cold front comes through, water surface temperatures dip, and a three-foot-long tagged fish suddenly appears offshore. From that point they're mostly offshore — something we're still learning, especially on the west coast, possibly a function of the distances involved, though we do tend to get big adults living in the mouths of estuaries too, again around high-relief structures like bridge pilings. Once offshore, these fish are generally pretty resident — they don't move around much once they find a home structure they like. I've got colleagues who know when one of my tagged fish has moved into their site because their receiver suddenly has pages and pages of data. Once they mature — around four and a half to five feet long, about 150 centimeters — they start making migrations, and some of the acoustic telemetry data suggests that's tied to the lunar cycle as well. We start seeing them move around July, picking up cues probably from water temperature and lunar cycle that it's time to find a spawning aggregation. Some of the fish we tagged on the east coast moved quite far — we had one fish, five years in a row, whose home reef was up in southern Georgia, and it swam all the way down to Jupiter for those spawning aggregations each year, predictably there in time for the August new moon.

Tom Rowland: Do we have other fish like that, or could that be an outlier? Are there other fish that show big movements like that on the west coast or elsewhere?

Dr. Bob Ellis: Those really big movers are probably outliers — we had a handful of fish tagged in that same project that never left the Jupiter area; they were year-round residents. Why one fish swims four hundred miles a year and another swims four miles a year, I have no idea — just a pretty cool aspect of their biology. We do have some movement data from the Gulf suggesting similar movements of a hundred to two hundred miles, from around central Gulf Florida down to offshore Naples, which is where a lot of the Gulf aggregations tend to be — again the prime location, since if you're a piece of plankton it probably takes about thirty days to go from fifty miles offshore of Naples to a flooded mangrove in the Ten Thousand Islands.

Tom Rowland: Yeah, that's super cool. Those fish, I find really interesting — they go from being really small, probably eating shrimp, and the ones around the mangroves eating crabs and small lobsters, to basically eating anything that'll fit in their mouth. They love permit, and permit are big and hard to eat — it takes a big fish to eat a permit like that. You were talking about where they sit on the food web — when they're small they're probably lower on the food web and then it increases. Can you explain that a little?

Diet: Crabs, Not Reef Fish

Dr. Bob Ellis: Sure. This is a tricky point, because this is where some of our scientific information tends to diverge a bit from a lot of anglers' experience. We have direct evidence from reaching into stomachs and pulling out what they've been eating, and it suggests that reef fish — groupers and snappers particularly — play a pretty small part in their overall diet, something like 10 to 15%, across the entire life cycle. Their diet is dominated by crustaceans. When they're in the mangroves, they're really focused on crabs — we hear from the crabbers about how the little ones follow the crabs up onto the mud flats and end up in their crab traps. Then they move offshore as they grow, and what we found in those offshore adults is that the thing pulled out of stomachs most often were demersal crabs like shame-faced crabs and box crabs, which bury themselves in the sand away from the wreck or reef. That's the Goliath's natural food source — they move out onto the sand flats and hunt for buried crabs.

Tom Rowland: Are they tailing like a bonefish, or bashing into the bottom to get at a buried crab?

Dr. Bob Ellis: I've never seen it, but I would imagine that's what it looks like.

Tom Rowland: It's interesting that with so many divers around these fish all the time, even someone like you hasn't seen that behavior. But I can tell you, if you're throwing a crab against the mangroves trying to catch a redfish and you catch a Goliath Grouper instead, they eat them — they really like them. And when they come in, they cough up all kinds of other crabs.

Dr. Bob Ellis: Yep. And in addition, we find a lot of slow-moving prey — burrfish spines, stingrays, occasionally a turtle. What we really don't find is swift-moving fish, something that can swim away. These aren't high-level predators — they're not a tuna chasing down a mackerel. They're opportunistic, eating whatever is easiest. If you're at a wreck with nobody fishing on it, a buried crab isn't going to swim away from you. But it becomes the easiest thing to eat when a boat shows up, starts fishing, and starts throwing back an undersized mangrove snapper that's trying to swim back down to the reef — all of a sudden that little fish is the easiest thing to eat, and that's where we start to get into these negative interactions. Because these are resident fish that don't move around much, fishermen tend to fish the same spots, and that's sort of a recipe for disaster — more and more negative interactions, people unintentionally feeding the Goliath Grouper. It's this weird intersection of biology: they're opportunistic, trying to eat the easiest thing, and we're serving it up to them. We're pretty confident in our stomach-content analysis because we've backed it up with the stable isotopes. Unlike a lot of fish — a gag grouper or red grouper is maybe a better example, because they actually switch, eating increasingly more fish as they grow larger, so their place on the food chain ratchets up as they get bigger — the Goliath's is pretty stable, because a blue crab isn't in the same place on the food web as those offshore crabs. If that's your dominant diet, you're not going to change that much through your life cycle. That's what we see: the adults have a relatively low place in that trophic food level, based on the stable isotope analysis, which backs up what we're pulling out of the fish's stomachs.

Tom Rowland: So with a fish like a Goliath — it's a big fish with a big body — if it eats a ten-pound jack crevalle or a ten- or twenty-pound permit, that's a nice snack. Does that hold it over, or does it burn through that fast? If it's a fish that eats primarily crabs, you'd think the metabolism might be a little slower, so a really big meal might hold it over for a couple of days.

Dr. Bob Ellis: I wish I had an actual number for you, but in general they do have a lower metabolism than something like a gag grouper or a tuna. I can't give you an exact figure, but my guess is if it eats a couple of fish from a fisherman, it's probably not going to go hunting that night.

Tom Rowland: Yeah, well, you'd think at some point — how many fish can it eat? But there are multiple fish down there that all look about the same size, so maybe they're just eating one and moving on. The divers would know more, since they actually keep their eyes on the fish — once one disappears out of view, the next one comes up, and it looks very similar to the last one. Who knows.

Closing Thoughts: A Milestone Worth Celebrating

Tom Rowland: But that's really cool. I think this is a good direction — I'm glad to see anything reopen, because it shows the public that these are considerations science and management are thinking about. I love that you call it a celebration — we're celebrating that we're opening this up. For fishermen who don't pay a lot of attention, you don't always know whether there's ever a chance something closed might reopen. I think this is a milestone, and some people were upset about it, but from the get-go I thought this was a good thing, that they're at least trying. It shows this is a topic of real interest to both science and management, not something locked away in a closet that nobody thinks about again. So I commend you for doing that, and hopefully the data from this, and the public reaction, is such that it continues — I think it's good. Is that the reaction you get from people, or is it really mixed?

Erica Burgess: We get mixed reactions — people in the same spot as you, and people on both ends of the poles. We're never going to make everyone happy.

Tom Rowland: Is that the most frustrating part of something like this, or is that even a consideration? Do you just go based on the science and make the best decision the science shows you, regardless? Where does public opinion or sentiment fit in?

Erica Burgess: Public opinion is a major factor in the commissioners' decision-making. We have a body of seven commissioners, appointed by the governor, entrusted with management of our resources. As staff, we advise them and bring forward recommendations based on science. We go out and gather public feedback, and we also propose options that might be in line with both the science and the public, and try to get to the sweet spot if we can. But there's such a range and diversity of opinion that the sweet spot might not suit everyone. Ultimately, though, we're charged with conservation of the resource — not just for today, but for tomorrow and the future — and our commissioners are passionate about that. But I can't give a presentation to our commissioners without them asking, so what does the public say? That matters a great deal to them; they want to know we've gone out, talked with stakeholders, and tried to find a solution that meets what people want and what the resource can support.

Tom Rowland: Well, great. I think it's got to be a hard job, both as a commissioner and as staff and as a scientist — thank you for doing it, all of you, because the resource — we're very fortunate in this country to have such an incredible resource, both on land and in the water, and that's not an accident. It could easily have been fished out, hunted out, overdeveloped to a point where we didn't have wildlife, but we're incredibly fortunate to have so much, and I believe that's because of good science and good management. So thanks for that, and really, thanks for coming on the show today. I know a lot of people had tons of questions, and this may just be the beginning of them — maybe we can do this again if everyone sends emails asking why I didn't ask this question or that one. I'm just trying to have a conversation and learn a little bit about this myself. I really appreciate you both coming on and being open and answering all the questions. So thank you — I appreciate it. If people wanted to send you an email, Bob, you put your email out — is there a way for people to get in touch?

Dr. Bob Ellis: Yeah, absolutely.

Tom Rowland: Erica?

Erica Burgess: Well, there's a general email you can send to — marine@myfwc.com. Contact us that way, and we'll get your question to the person who can best answer it.

Tom Rowland: Okay, awesome. And Bob, your email again if you want to give it out?

Dr. Bob Ellis: Sure — it's my name, Robert dot Ellis at, again, myfwc dot com. And, yeah, happy to answer questions directly, or if you send them to that marine address, Erica knows how to get in touch with me.

Tom Rowland: Okay, alright — well, thanks so much for this conversation. I learned a few things, and I'm sure other people did too. Thank you very much for your time — I really appreciate it, and I hope we can do it again.

Erica Burgess: Thanks, Tom.

Tom Rowland: Okay. Thank you.