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TEXAS PARKS AND WILDLIFE COMMISSION

NOVEMBER 7, 2013

TEXAS PARKS AND WILDLIFE DEPARTMENT
COMMISSION HEARING ROOM
4200 SMITH SCHOOL ROAD
AUSTIN, TEXAS 78744

COMMISSION MEETING

MR. DAUGHERTY: Good morning, Commissioners. For the record, my name is Dan Daugherty. I'm one of the research biologists at Heart of the Hills Fisheries Science Center with our Inland Fisheries Division and I'm pleased to be here this morning to provide you guys this update. I apologize in advance because I'll be pointing at this screen back here because it's the only one that we all can see from time to time.

I know a number of you are new to the Commission since the last briefing, which I believe was in November of 2010; so I just wanted to begin by briefly mentioning why Alligator Gar are really an important fisheries resource here in Texas. First, the species has undergone a significant range reduction. You can see in blue the historic range encompassed 14 U.S. states and the Gulf Coast of Mexico. Yellow you see here is the current distribution of the species, including eight states in the U.S. and the Gulf Coast of Mexico.

So most of the Midwest drainages they're now extirpated from. Fortunately, Louisiana and Texas are two definite stronghold states for Alligator Gar that remain in the United States; but really what makes Texas unique is that we have continued trophy fishing opportunities in Texas. Louisiana, while they're ubiquitous throughout the state, they are commercially fished and remain recreationally unmanaged. So we're the only state that really provides both a large number of populations and the trophy fishing quality.

So in an effort to keep that trophy potential here in Texas, we began managing Alligator Gar actively in 2009 with the institution of the one per day regulation. Within our Inland Fisheries Division, we prioritized Alligator Gar as a species for research and management and we identified the particular data needs that we really needed to address going forward with our management, what the critical data needs were.

Some of those are what I'm going to talk about today. They include estimating harvest, quantifying reproduction of Alligator Gar in our systems, understanding habitat use and movement patterns in our systems, and determining the appropriate geographic scale of management. That's a new area that we're getting in to, and I'll talk about that at the very end.

To this end, we've conducted a number of experiments in a number of systems, number of studies, special management projects with our management staff, research projects within our research program to address these data needs and that's what will be the focus of the talk today. So the first thing I want to talk about was estimating harvest. The first thing you need to do though is to put harvest into some kind of context so we know what is sustainable. So the first thing we had to do was develop a population model and so what we're doing is taking information like life span, the rate at which the fish die, the growth rate of the fish, and then also harvest, fecundity, the number of eggs produced, the survival of those offspring, so on and so forth and we put that into a population model and if we keep everything constant except for harvest, we can simulate what happens when we change harvest on the population.

And you'll see here in this picture -- well, I'll come back here. You have time and years here across the X axis and the number of fish in the population across -- along the Y. The three trajectory lines that you're seeing on that graph are showing the change in population abundance at three different harvest rates and those are 5, 10, and 15 percent. You can see that if we harvest at 5 percent per year, the population is able to maintain itself. Essentially, that's a harvestable -- sustainable harvest rate.

Whereas when you increase harvest to 10 and 15 percent, we see appreciable declines over time in those populations and we're talking at 10 percent harvest, that's about a 50 percent decline in fish numbers over a 25-year period and at 15 percent harvest, we talking about over a 70 percent decline over a 25-year period.

These are very low harvest rates. When you think about bass, you think about Crappie, you think about other species, catfish, typical harvest rates for those species are 20 to 50 percent. So we're showing really very, very sensitive -- that Alligator Gar are very, very sensitive to overharvest and so maintaining a sustainable harvest level is very important.

So given that graph was showing us that our harvest goal was 5 percent or less, that was a rate that was sustainable. With that, we can now go out into the populations and determine what our harvest rates are currently and how we do this is typically tag release return studies and you can see in that upper picture, that's an Alligator Gar with the -- with what's called Floy tag or a spaghetti tag and we go out and we tag a large number of fish, release them back into the population, and then solicit our anglers at -- through the media and through boat launch signs such as you see in the lower picture, to report tag returns -- or to report catches of those tagged fish back.

And so for every 100 fish that we have tagged out in the population, the number of fish that come back reported from anglers gives us an idea of harvest or exploitation. We've conducted those estimates in three systems -- the trinity, both in the Middle Trinity and the Lower Trinity; the Middle Brazos; as well as Choke Canyon Reservoir. And you'll that all of our current rates of harvest are below that 5 percent threshold that we were talking about before. The Trinity is 2 to 4 percent, Brazos is right around 2 percent, Choke Canyon is at 2 percent.

So currently, we believe that our one Alligator Gar per day limit is effective at the current rates of harvest. However, that doesn't mean that future harvest rates are going to continue to increase. We know that our popularity of our fisheries is increasing. Excitement and popularity of Alligator Gar as a species, as a destination fishery in Texas. We know that our current -- our harvest levels in the future may continue to rise, so it's very critical that we continue to monitor harvest rates as we progress in time.

The next thing I wanted to talk about was quantify and reproduction and what we really need to know related to that is how often are Alligator Gar spawning, how variable are those spawning events from year to year, and what kind of factors, environmental factors, in the system are influencing the success of those year classes or that reproduction effort in a given year.

And so over the last few years, we have developed the techniques. I'm not going to talk in great detail about this because I don't have time, but we've developed the techniques to be able to accurately age Alligator Gar and when you can accurately age Alligator Gar, you can take a sample of fish, you can age each individual fish, and you can put that -- you can put that into a year class. So a three-year-old fish caught in 2013 was produced in 2010. So we can put -- you take a sample and you can compartmentalize each individual based on the age into what year class it was part of.

And what you're seeing here is essentially an age distribution that's compartmentalized into what year those fish were produced and so the larger -- you start to -- you can take this and turn it into a reproductive success measure. So the larger bars are showing years there was really good reproduction going on. The small bars, obviously very weak production going on. Somewhere in the middle is an average over time.

And so we've done this for the trinity River. We've aged over 100 fish in that system and there's some really interesting data to point out in this illustration, which I'm going to talk about now. The first thing I would like to call your attention to is this is a 46-year chronology. So the oldest fish that we've aged in this sample was 46 years old and that's bringing you back into the 1960s. And what you can see first is there are 17 missing bars on that graph out of the 46 years. So 37 percent of the time, either reproduction did not occur or reproduction was completely unsuccessful. So four out of every ten years, Alligator Gar in the Trinity River, based on our samples so far, have not had successful reproduction.

The next thing I would like to point out is that if you look kind of over time --

COMMISSIONER JONES: Say what you just said again. I'm sorry. Just say that statistic.

MR. DAUGHERTY: The last point?

COMMISSIONER JONES: Yeah, one more time.

MR. DAUGHERTY: Okay. There's 17 missing year classes on here. If you look at the graph, there's 17 times where there's no yellow bars. So what that's telling you is, is that based on our sample, no reproduction -- either no reproduction occurred in that year or the reproduction that did occur was unsuccessful. So four out of every -- that's 37 percent of the time, which is roughly four out of every ten years on average.

COMMISSIONER JONES: Okay.

MR. DAUGHERTY: The next thing I would like to point out is that if you look over time, trends and time, you see that prior to 1990, we had a rather abundant string of strong year classes. From 1964 to 1990, there was -- there were nine strong -- very strong year classes produced. If you look in the 23 years since then, which is roughly about the same amount of time, we're talking about two and particularly one really strong year class produced in 2007.

So what that's telling us is that in recent history, we've had frequently less strong reproduction. The last 20 years or so has been really supported by one strong year class of Alligator Gar in that system. The other thing I pointed out was it's important for us to look at influential factors of things that we think are influencing the spawning success of Alligator Gar.

One thing that we noticed is there appears to be some pretty strong links to hydrology in the system or how often the system is flooding or water levels in the system. You can see here is a couple illustrations in recent history. 2007 was that very strong year class that I talked about that's pretty much supported the population over the last 20 years in terms of new recruits to the stock. That was the year we had very high water levels in the spring and spring is the spawning time for Alligator Gar. We show that as a very strong signal in the population age distribution. However, the years that follow -- '09, '10, and 2011, drought years we're all quite familiar with that. We have very, very, very little production of Alligator Gar. So it alludes to strong links between hydrology and reproductive success of Alligator Gar.

The next study that I want to talk about, which also has some links to hydrology, is a habitat moving -- habitat and movement study that we conducted in the Lower Trinity River in 2009. The Lower Trinity River being, just for clarity, being the Livingston Dam tail race to the Coast. So 180 kilometers or 110 miles roughly of river there. We tagged 51 fish with these telemetry tags you can see in this picture. That allows us to follow the fish around in the system for the duration of the study, and we did that for a 22-month period.

And what we found, a lot of the behavior and movement that we saw of fish, habitat use behavior and movement that we saw for the fish that we had tagged was really related to flows. And so there's another, you know, mention of hydrologic links. In normal -- under normal flow conditions, main channel pool habitats, so the deeper water. You can see here in yellow on these channel bends and so on and so forth, were very important habitat for Alligator Gar. An individual would move between pool habitats over a home range of roughly 37 miles of river or roughly a third of the river reached.

The interesting thing was in the winter in the cold water period, those fish would also use main channel pools during normal flow conditions; but they would select a single pool and pretty much spend the entire winter there. So it shows the importance of these pools for over wintering habitats. Fish are very lethargic. Probably not moving around, not feeding. These are areas that are providing them protection from current and so on and so forth at those low metabolism periods.

During high flow, we saw a completely different pattern of habitat use. As you can see in the picture, those fish would use the highlighted habitats in yellow. When the water would -- when the water levels would increase and the banks would flood, it would flood old channels like this Oxbow lake here in yellow. Those fish would move out of the main channel and utilize those Oxbow habitats or off on the floodplain. And what those really provide is velocity refusal. The velocity in the main channel of the river under flood conditions is very, very high. Those fish would move to the off channel areas where the flow rates were reduced. Another thing important in terms of reproduction is when those flow rates occurred in the spring and those habitats would flood in the springtime, they provided important connections to optimal spawning habitat and in this inset picture, you can see what really kind of constitutes optimal spawning habitat for Alligator Gar.

These back water areas, low velocity, flooded vegetation, that occurring during a warm water period in the spring when the temperatures are optimal for spawning are absolutely important. And likely, this is what the scenario was in 2007 when we produced a strong year class. Likely, these areas that you see in the picture now would be dry when we don't have high flow events.

The last thing I want to talk about is a new area of research for us that's come kind of as a result of some of the results of the studies that I've talked about already, is the management scale for Alligator Gar. I mean the question we're talking about specifically is at what geographic scale do we need to manage these populations?

We can use some of that information I just talked about to kind of illustrate why this is important. If you look at the distribution of the fish that we had tagged in our telemetry studies, so each of these little black dots that you see is a location that a fish was tagged in that study, tagged and released. We had essentially a Upper River Group and a Lower River Group and those fish pretty much stayed in the those areas for the entire 22- month study period.

So essentially, the Upper River fish never interacted with the Lower River fish. Conversely, the Lower River fish never really interacted with the Upper River fish. So one question we have is do we have distinct groups within -- along that river continuum such that we would want to be managing those groups independently?

The other interesting thing that we came across is these few fish that were tagged, I think there were six individuals total that were tagged in the very lower portion of the Trinity River, 78 percent of those fish ventured out into Trinity and Galveston Bay at some point during the study. That we thought was kind of curious since we think of Alligator Gar is a freshwater fish for the most part, they appear to be using the saltwater habitats. And so we started investigating this a little farther talking to the Coastal Fisheries folks and Coastal Fisheries, as you know, has a long-term gillnet data set that they collect in the spring and fall every year and low and behold, the gillnet efforts in Galveston Bay have netted over 2,000 Alligator Gar in the coastal habitats over the last 25 years.

And so we started looking beyond that. Well, what did we see on the other -- you know, all the bay systems. They've netted over 24,000 Alligator Gar in the coastal bays in the last 25 years. So there's a lot of Alligator Gar in our coastal habitats. Not just our freshwater rivers and reservoirs as well. And so in our lower river systems that are directly connected to these bay habitats, you know, we don't know how -- we don't know how the -- these river fish and these bay fish are interacting.

It may be that they are distinct populations. It may be that the river fish are utilizing habitats in the bay that are critical for the river populations to persist or vice versa. So we're very interested in trying to figure out what scale of management we should be working with here. Is it a whole system level or some localized level related to that?

So going forward, we're going to continue to monitor harvest of Alligator Gar. That's critical to maintaining our trophy fishery quality. We're going to work -- continue to work on determining the flow rates in our river systems that ensure periodic successful reproduction of Alligator Gar and the results of that study I just talked about, which by the way is going to be conducted in another system that we'll be able to characterize, we're going to do that in the Lower Guadalupe and San Antonio Bay system. That will address our needs to be able to understand managing at the proper geographic scale for Alligator Gar.

And with that, I really thank you for your time and interest and I'll be happy to answer any questions you have.

COMMISSIONER DUGGINS: Commissioner Scott.

COMMISSIONER SCOTT: Just a quick comment. Whenever y'all go to catch some of these and stuff, I grew up down there in that part of the world. I'd be interested in going out. I might drag another Commissioner.

MR. DAUGHERTY: Okay.

COMMISSIONER DE HOYOS: How old do these Gars get to be? What's their natural life pattern, I guess?

MR. DAUGHERTY: Well, interesting enough, a couple years ago there was one that was -- it was actually caught in a gillnet in Mississippi and they sent the -- well, let me back up a second. The way you have to age these fish is using the otoliths and so what you do is you have to sacrifice the fish and you essentially cut the skull open. It's essentially the inner ear bone, equivalent to the inner ear bone. Take that piece, take that structure out. You section it. You look at it under a microscope and they have what are called annuli, just like tree rings. And so you have to count up the tree rings and it gives you the age.

This fish I was speaking about in Mississippi was caught in a gillnet. I can't -- does anyone know the length on that? Nine, eight, close to nine feet in length, 346 pounds or something like that. It was just huge. And they actually sent the otoliths to our Heart of the Hills Fisheries Science Center to have it aged and we aged -- two individuals aged it. One aged it at 90 years old. One at 94.

COMMISSIONER SCOTT: Wow.

COMMISSIONER DE HOYOS: Wow.

MR. DAUGHERTY: So, yeah. Independent ages, so we know it was -- it was a geezer. There's no doubt about that. We have aged fish in Texas up to 60, but they are definitely one of the most long-lived fish out there.

COMMISSIONER JONES: A couple of questions. Have you done any study or are you doing any study of the fish in inland waters? Not rivers, but lakes --

MR. DAUGHERTY: Yes.

COMMISSIONER JONES: -- and ponds and whatnot?