Gar Science

For GASS members, gar are more than just targets. We recognize that they are fascinating and frustrating creatures. We want to know more about their ways not just to catch more, but because knowledge of this wonderful fish is immensely satisfying. Getting accurate, scientific information helps gar anglers to better enjoy their sport. Our Official GASS Science Advisor is Jamie Ladonski, a biologist from the Field Museum in Chicago. Jamie received his Bachelor of Science in Fisheries and Wildlife from Michigan State University and his Master’s degree in zoology from Southern Illinois University. He is a member of the American Society of Ichthyologists and Herpetologists, the North American Native Fishes Association, the Illinois State Academy of Science, and the Indiana Academy of Science. We’re excited to have Mr. Ladonski in GASS. Send your questions for our Science Advisor to

Q: Do gar see in color?

A: Teleosts (higher fishes, basically all our local fishes except sturgeons, gars, and bowfin) all have well-developed color vision, as most anglers know. A 1983 publication by Burkhardt et al. suggested that gars and bowfin have anatomical structures in the eye similar to teleosts, indicating they also have color vision. The bowfin seems to have a slightly more "advanced" anatomy, and may have more well-developed or more complete color vision than gars, but the anatomy of the eye in both groups indicates they do see color.

Q: At what water temperature do gar become active?

I have information about their optimum temperature, but I couldn't say when the gar season begins. In terms of spawning temperature, our data suggest shortnose gar start spawning at around 60 F, which was late April in the southern Illinois area. Other researchers have found spotted gar spawning in Missouri when the water temperature was 68 F, and longnose starting to spawn at 59 F in Wisconsin, 63 F in New York, and 68 F in Oklahoma. So gars generally start spawning when the water temps are in the low to mid 60s.

Q: Just got a picture and a message from a Manhattan KS gar angler who's been landing longnose to 54" in a stream at 34 degrees. On a jig with no bait, no less. Mike Faulkner of OK also catches gar when there's a bit of ice on the river. Would you expect fish to be as active in 34 degree water up North here as they are in 34 degree water further south?

A: Good question. As far as the water temp goes, I'd be interested to see what the pattern of water temps has been for the whole winter. Surely temps in the north have been colder (for longer) than in the south. If so, I would think the fish in the north would be more sluggish, since they've been dealing with colder temps longer. I know 34 degrees is 34 degrees, but there is a difference between living with it for three months compared to one month. But the habitat will probably affect the fish just as much as the temp. If the guys in KS and OK are fishing areas that don't have good winter refugia (or if they are fishing in the refugia), they are hitting fish that are "trapped" and will probably catch quite a few since many of the fish in the area will be concentrated in those spots. I'd be interested to know what kinds of areas those guys are targeting and how they produce during the summer.

Q:How can GASS members estimate the age of the gar they catch?

There is really too much variability between age and size to accurately estimate the age of the fish you catch, with the exception of the first two to three years. Beyond that point, growth rates slow considerably and two fish of similar size can be dramatically different in age. Just as a quick example, we had 22-inch shortnose males ranging in age from 2 to 7, with similar variability at other sizes. Another problem is that females live longer than males, and so have different growth rates. This means that in order to even attempt to estimate the age of the fish you've caught, you'd also need to know the sex. But with gar, there are no obvious external differences between males and females, like there are with salmon (for example). Some researchers (Johnson and Noltie) have looked into ways of sexing gars based on physical measurements of the bodies (fin lengths, girth, etc.), but these are somewhat impractical for the casual angler to record these measurements, then plug all the numbers into a formula. The best you could do as far as age goes is to know maximum, or near-maximum, ages and sizes for the three most common species (longnose - 22 years, 72 inches; spotted - 18 years, 44 inches; shortnose - 13 years, 32 inches), and estimate based on your catch.

Q: Generally speaking, fish grow bigger in lakes than in rivers. Is this true of gar, too? Has research been done to compare growth rates of gar in rivers vs. gar in lakes?

University of Missouri researchers Brian Johnson and Dr. Doug Noltie compared populations of longnose gar from Weaubleau Creek and Harry S Truman Reservoir in central Missouri. They found that fish from the reservoir (=lake) had higher growth rates during the first four years of life than fish from the creek (=river). This difference was probably due to the presence of more food (gizzard shad) in the reservoir than in the creek. However, after age 4, growth rates between the creek and reservoir did not differ. The reason for this is because the fish reached sexual maturity by age 4. Before that point, most of the fish's energy goes toward growth. But once a fish becomes sexually mature, most of its energy is put towards reproduction, and its growth rate slows dramatically. Basically, the reservoir fish were maturing sooner, but once they matured their growth slowed and the creek fish caught up.

Q: Has research been done that shows the effect of gar populations on “glamour species” populations?

A: I attempted to address this question a bit in my thesis. I found many sources from 60,70, and 80 years ago describing what a nuisance gars as a whole are, and in truth, many of those sentiments are still held today by most anglers and biologists. Still, I found much research that shows that while gars do eat the occasional young bass, nongame species (such as minnows) make up a large percentage of their diet. Much of the problem is in how you define “game species”. I don’t know if I would include panfish (bluegill, crappie, etc.) in that category, since populations of those fish don’t usually require the type of management that bass, walleye, or pike requie (stocking, length limits, closed seasons, etc.). Many of the studies found gars feeding on various panfish, as well as invertebrates such as crayfish. One thing that can get overlooked when talking about predation is that the limiting factor is usually not how good the predator is at catching its prey, but how bad the prey is at avoiding being caught. That holds true with gars as well as any predator. Gars will eat whatever prey are easiest to catch, and that can vary from one body of water to another. Some species of fish may be easier to catch than another, and fishes as a whole may be easier to catch than crayfish. The point is, if a young bass is going to be eaten by a gar, it would probably stand just as good a chance of being eaten by a larger bass, or a walleye, or pike, whatever. It’s not that the gar is a “super predator”, it’s just that the young bass (for example) can’t stay out of harms way.

Q: Are the ranges of shortnose, spotted, and longnose gar diminishing?

A: While not federally listed as threatened or endangered species, all are somewhat restricted regionally. Shortnose gar are protected or listed as “special concern” in Montana, North Dakota, and Ohio. Spotted gar are likewise protected in Ohio, as well as Kansas and Kentucky. Keep in mind there are numerous reasons for listing a species as threatened or endangered. Species on state lists are often put on those lists because the range of the species in that state is very restricted and may have always been that way. While a threatened or endangered species deserves protections regardless of the reason it is listed, in cases like this it should be noted whether the species is actually declining or if it is historically rare.

Q: What is the spotted gar's primary food? I have caught several, and although many sources say they feed primarily on shad, I find a majority of spotted gar in my area with crawdads in their stomachs. Also, what is the alligator gar's primary food, and what size range of this food do they eat?

A: Generally speaking, longnose gar tend to feed more on fishes, spotted and shortnose tend to eat greater percentages of invertebrates like shrimp, crayfish, and insects (although fishes still dominate their diets), and alligator gar seem to be scavengers as much as predators. One study on alligator gar in the gulf coast of Mississippi reported stomach contents to include fishes, a chicken, hooks, wire leaders, and a heat indicator from a diesel engine. I've read a similar report for alligator gar in Texas. As far as size range, most of the fishes in the stomachs of the alligator gar in the Mississippi study were 20-32 centimeters (about 8-12 inches).

Q:What are the "crocodile gar" often available for sale on eBay?:

A1:Gar breeder Bruce writes that these fish are captive bred and are a hybrid. He crossed a Florida shortnose gar with a true alligator gar and called them crocodile gar due to their apperance.

A2: I looked through my references more extensively last night for info on hybrids. I wasn't able to find any real mention of it anywhere. Sounds like an area rich for study!
Jamie continues: I was talking with one of the grad students at SIU recently about those hybrid gar that were on eBay a while back. He is working on a genetic study of gars so I asked him about gar hybrids. He said he hadn't run across any mention of it, and has over 400 papers in his library! Pretty thorough.
And he continues to research the question: I talked to Brooks Burr about those "crocodile gar". He mentioned that Larry Page (formerly at the Illinois Natural History Survey, now at the Florida Museum of Natural History) told him the longnose in the Mobile River basin and in Florida look very different from those in the midwest. They were hoping to get tissue to include in Brooks' student's study. A new species? That's a big jump, but it is cool nonetheless.

A3: As far as hybridization, there was a paper published about that just last year: "Hybridization between Longnose and Alligator Gars in Captivity, with Comments on Possible Gar Hybridization in Nature", by Steven J. Herrington, Kurt N. Hettiger, Edward J. Heist, and Devon B. Keeney, Transactions of the American Fisheries Society 2008; 137:158-164.

Here's the abstract:

Although hybridization occurs widely in fishes, it has never been recorded in gars. Here, we describe the first known hybrids of the longnose gar Lepisosteus osseus and alligator gar Atractosteus spatula from four specimens spawned in an aquarium containing multiple gar species. Genetic analyses of cytochrome b and tyrosinase sequences and a microsatellite locus indicated that the four specimens were hybrid offspring of a female longnose gar and a male alligator gar. The combination of physical appearance, meristic counts, and mensural measurement ratios further discriminated the hybrids from each parent and supported the conclusion of hybrid origin. The four hybrids had body coloration and transverse scale rows similar to those of longnose gar, a snout length and shape intermediate between those of longnose and alligator gars, and two rows of teeth on the upper jaw as are seen in alligator gar. This conclusive evidence of intergeneric hybridization in the gars may provide insights into phylogenetic relationships in Lepisosteidae and hybridization theory and may explain unsubstantiated reports of gar hybridization in nature and the pet trade.

Q: Is it only alligator gar that have two rows of teeth?

A: No. This is a characteristic of the genus Atractosteus, shared by alligator, Cuban, and tropical gars. This is one trait that separates Atractosteus species from Lepisosteus species (which lack a second row of large teeth).

Q: OK, then. Are the Cuban, tropical, and alligator gar one in the same fish, with just minor variations due to location?

A: They are different species, separated mainly by skeletal (specifically, skull) characteristics along with gill raker and scale counts.

A. spatula (alligator gar) vs. A. tropicus (tropical gar)
spatula = 58-62 lateral line scales, 49-54 predorsal scales; tropicus = 51-56 lateral line scales, 43-48 predorsal scales.

A. spatula (alligator gar) vs. A. tristoechus (Cuban gar)
spatula = 59-66 gill rakers on first arch, outside row; tristoechus = 67-81 gill rakers on first arch, outside row.

A. tristoechus (Cuban gar) vs. all other Atractosteus species
A. tristoechus skulls lack enameloid patterns on the dermal roofing bones of the skull (all other Atractosteus species have these patterns)

Regarding tropical vs. alligator gar, Monty Millard of Costa Rica writes:
Our master guide (British) has fished the Rio Fio for 14 years. I personally think these gar from the Rio Frio are alligators not tropical. He has caught them to 80 pounds in the Nicaraguan basin and much larger ones are reported. The gar that I have caught and seen are similar to those I use to net in OK and TX. Geewhiz, could they twist a net!!! :-)) I think some genetic research is due. A simple fin clip is all that is necessary for DNA analysis. We fish out of San Carlos often also, in the San Juan and the Rio Frio all the time. All gar I have examined have two rows of teeth. Therefore they could only be tropical gar or the alligator gar. Reported sizes exceed that for the tropical gar. I will be looking at some of the information that Glenda Kelly (biologist for the IGFA) sent (heads, snout measurements). I still feel these are alligator gars. However no one else agrees. I will be talking more with Kelly at the tarpon symposium. Still need some genetic work...simple to do with fin clips. Just a matter of finding a lab with a bit of free time. I should have electrofishing gear soon so a more complete examination of the gar...and others will be easier.

Q: Are there pictures available of the gill rakers of tropical gar and the alligator gar? Where can I find information on the skull charateristics of gar?

A: There are diagrams of the gill rakers, and a wealth of information on the skull characteristics, in the following publication:
Wiley, E. O. 1976. The systematics and biogeography of fossil and recent gars (Acintopterygii: Lepisosteidae). Misc. Publ. Mus. Nat. Hist. Univ. Kansas 64: 1-111.

Q: Are gar eggs truly poisonous or is this an old fishers' tale that has been repeated so often that it has the illusion of truth?

A: I spoke with Ken Ostrand, lead author of the second paper cited below. He confirmed what I suspected, that the toxin has yet to be identified. He said it is a protein of some kind, and speculated it may even be an algicide or fungicide. He also said it may just be an old wives' tale, which many people have suggested. Adding to the mix is the fact that of the few studies that have focused on the subject (most of which offer just anecdotal reports), none describe the eggs as being toxic to other fishes. From an evolutionary perspective, this is significant, since fishes would be the most likely predators on gar eggs (not chickens, as some studies have used, and certainly not humans). In other words, why would egg toxicity evolve if it offered no protection against the most likely predators? So it may just be chance that the eggs cause sickness in birds and mammals. Or, as Ostrand suggested, converting the eggs to pellet form to feed to chickens, or even force-feeding raw eggs to mice, might involve changes in the biochemistry of the eggs which could cause an unnatural response.

Burns, T.A., D.T. Stalling, and W. Goodger. 1981. Gar ichthyootoxin - its effect on crayfish, with notes on bluegill sunfish. The Southwestern Naturalist 25(4):513-515.

Ostrand, K.G., M. Thies, D.D. Hall, and M. Carpenter. 1996. Gar ichthyootoxin: its effects on natural predators and the toxin's evolutionary function. Southwestern Nat., 41:375-377.

More about poisonous gar eggs:

I came across this page when I was searching for the toxin in gar eggs responsible for the severe illness my son and I encountered after consuming them. I caught and cleaned a 2' long gar in Laplace, LA. My Filipino mother-in-law who is visiting cooked the eggs. My son had 2-4 spoonfuls mixed with rice, I had 1/2 a plate or so at about 9pm.

At about 3am, I awoke to my son vomiting in the bed. We cleaned him up, and 5 min later again and again for about an hour or so followed by dry heaving. After all was "out" of him, he went to sleep.

I awoke at 7am with a slight stomach ache, ran to the bathroom, where I did not leave until 10:30am, violently vomiting, severe diarrhea, sweating profusely, cold, followed by so much dry heaving I thought something would implode. At about 10;30 or so, exhausted and semi dillusional, I staggered to my bed covered in sweat, laying there freezing and... the only way I can explain it... hallucinating. In my sleep until 3pm that evening, I had just crazy dreams.

I awoke at 3pm feeling a lot better, but still kind of "off". Here I am the day afterward, and I still don't feel 100%...I just feel weird, is the only way I can put it. My little boy is OK though compaining a little that his stomach felt "different". It was one of the worst sicknesses I've had. I read on this post that it might be a "old wives tale", but this needs to be put to rest. The eggs of garfish are extremely toxic and should never be consumed by anyone! I can speak from experience. The toxin is called gar ichthyootoxin. Bing it!

Our Science Advisor, Professor Jamie Ladonski writes:

Wow, that is something. I'm sending this to some of my other fishhead colleagues for their comments and will pass along their comments if they have heard similar tales. I remember talking to a fellow a couple years ago who did a little research on gar egg toxicity. He thought it might just be coincidence that they are toxic to mammals, as they don't appear to bother the more natural predators on gar eggs (fishes). Some coincidence, according to this poor fellow's tale!

Not something I'd like to experiment with, at any rate.

April 2010 - More about poisonous gar eggs, from the Arkansas Game and Fish Commission weekly outdoor report:

HEBER SPRINGS – Not all fish eggs create caviar; some can be downright dangerous. A Cleburne County family discovered this after becoming violently ill upon eating the eggs of a long-nosed gar on April 5.

The eggs of some fish species are processed into expensive caviar, and fried fish eggs are a spicy appetizer in Indian cuisine. Even bluegill eggs can be deep-fried and served. But the eggs of all gar species are extremely toxic and should be avoided.

“My husband Darwin (Aaron) and brother-in-law Russell (Aaron) had gone spearfishing in Greers Ferry Lake and had gotten one gar,” said Tiffany Aaron. “My husband had heard that gar were good to eat, and we’ve always been a family that’s up for trying anything once.”

Mrs. Aaron said Darwin, Russell and her 10-year-old son, Carson, ate the gar and its eggs at about 8 p.m. that evening. Carson was the first to get sick, and began vomiting by 1:30 a.m. Russell became ill by 3 a.m., and Darwin followed suit at 5 a.m.

“The men were the only ones who had eaten the eggs, so I got online to find out more,” said Mrs. Aaron. “That’s when we found out they were poisonous.”

Carson was taken to Baptist Health Medical Center in Heber Springs where he was put under observation.

“My biggest question was what should we expect or watch for,” said Mrs. Aaron. “But the ER doctors didn’t have any experience with this sort of poisoning, and the Poison Control Center didn’t have any information. The one thing the doctors could tell me is that it was fortunate that my son began vomiting as quickly as he did to get the toxins out of his system.”

Lee Holt, an Arkansas Game and Fish Commission Fisheries Management Biologist conducting research on alligator gar, was contacted for more information about the type of toxin contained in gar eggs.

“I made a lot of calls to gar experts I knew from my research,” said Holt. “Our main concern was the type of toxin. There was one mention of it possibly being cyanide-based. The doctor at the emergency room explained that treatment for cyanide poisoning can be just as harsh as the toxin, so we needed to make sure before (Carson) was given any treatments.”

Holt said he found out that it was a protein-based toxin, so the harsh treatments could be avoided.

All three men recovered from the episode, but the effects of the poisoning lingered for three days.

“As it turns out, there’s so little information on the subject that researchers at Nicholls State University in Louisiana are conducting follow-up interviews about the family’s ordeal,” Holt said.

Solomon David of the University of Michigan and of writes:

I am a graduate student at the University of Michigan studying fish ecology; I have a fish website called for which I have several images of all seven species of gars...most of these are in captivity, but they may be useful in showing the diversity of gars and just general information for your site. If you are interested in setting up a link let me know, I welcome you to check out the site and all the gar images there. Just thought I would make the contact with you guys as I am a big fan of gars and love your site!

[Jan 2010 Update]

I have been developing a gar reference site in conjunction with other research units working on gar research. If you think it would fit, please feel free to post this on your site as it may help with people who are interested in gar ID and also the various places where gars are being researched. The site is and I have several of my photos up there plus some great illustrations by Joe Tomelleri and Emily Damstra.

Solomon David
Graduate Student, Resource Ecology and Management - Aquatics
School of Natural Resources and Environment
University of Michigan

Where to find the BIGGEST shortnose gar

Research from the University of Missouri's Jason C. Vokoun may lead gar anglers to a better catch of shortnose. In Shortnose gar foraging on periodical cicadas: Territorial defense of profitable pool positions (American Midland Naturalist 143, no. 1, Jan 2000), Vokoun reports on observations of feeding behavior of shortnose gar. He found that "the largest gar in each pool of an observed stream reach was positioned a the upstream pool lip." That position then would be a prime spot, able to be taken and defended by only the largest gar. So, when searching for those fat, five- or six-pounders in a stream, give extra casts to that area just below a riffle at the beginning of a pool. Vokoun also noted that during a emergence, shortnose fed exclusively on cicadas. Hooking one on a #4 treble and floating it along the surface would be a wise move during those times that cicadas are prevalent.

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