Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Catfish mouth gapes/panfish prey sizes

I figured I would take some records on our recent fishing trip to post results of what was caught. Esshup if you need to move this to the correct forum page or thread be my guest, just wasn`t sure where to put this. Gape is side to side.

Blue Catfish:
Length. 20" Weight. 2.8lbs Gape. 2"

Length. 20" Weight. 2.7lbs Gape. 2"

Flathead Catfish:
Length. 22" Weight. 4.8lbs Gape. 3"

Length. 23" Weight. 5.12lbs Gape. 3 1/8"

Length. 23" Weight. 4.2lbs Gape. 3"

Length. 30 1/4" Weight. 11.6lbs Gape. 4 1/8"

Length. 34" Weight. 16.2lbs Gape. 5 1/2"

Length. 36 1/2" Weight. 22.10lbs Gape. 6 1/8"

Later this week as I fish out our catfish ponds I`ll add on data records. Hopefully more CC.




I really wanted to sit down and measure live bg/hybrid bg we were using, but rains were moving in and it was either measure or fish and I chose the latter.
Give some scale on the different sizes we used. The container was holding 130 at that point.

Interesting stuff. I have been wondering about CC mouth gap data recently. Please keep posting as you get it and I will add my CC data as I catch them.

Hey old buddy.....When is the fish fry for all those catfish fillets!

Always welcome Bill, looking forward to getting those FHC belly's in the fryer.

While this is on FHs and not BC and there is some gape difference it's not a lot.

North American Journal of Fisheries Management
Article: pp. 198–202

Gape:Body Size Relationship of Flathead Catfish
Joe E. Slaughter IVa,,1 and Brad Jacobsonb
a) Georgia Department of Natural Resources, Wildlife Resources Division, 2065 U.S. Highway 278 SE, Social Circle, Georgia 30025, USA
b) Arizona Game and Fish Department, Region IV, 9140 East 28th Street, Yuma, Arizona 85365, USA

Abstract.

The flathead catfish Pylodictis olivaris is a highly piscivorous ictalurid native to central North America whose range has been extended throughout much of the United States. With this range expansion, many populations of native fishes have experienced declines in the number of individuals due to direct predation by flathead catfish. Previous evidence suggests that flathead catfish are opportunistic feeders and may be the least gape limited of North American freshwater piscivores. To better understand the size of prey vulnerable to flathead catfish, we measured gape dimensions for individuals of various sizes to determine the maximum size prey a flathead catfish can kill based on its gape limitations. Our results show the relationship of total length to horizontal and vertical gape and the relationship of flathead catfish total length to the total lengths of ingestible-sized prey of different body shapes. Furthermore, comparisons of the body depth of three common fish species to the gape dimensions showed that no size of largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, or gizzard shad Dorosoma cepedianum would preclude predation by flathead catfish. Our results support the assumption that the flathead catfish is one of the least gape-limited piscivores.

I can always tell what catfish is biting on my live bait. CC seem to peck and do short burst runs with a BG. BC seem to strike hard, running with BG like something was going to steal it away from them. FHC are the easiest to tell as it's one hard bite then a slow steady pull of line.

CC mouth gape:

4# 3 oz.
20"
Gape 2"


By the way-- no definite signs in the stomach that it had been recently feeding on BG. There were what looked like green seeds, the size of small peas and very hard. I assume it was the by-product of eating/chasing some kind of forage.

Guys - Wow! This is great information about catfish mouth size and body length. Thanks for taking time to make the measurements and post the results.

Male and female CC mouth gap similar for any given length of fish? I am wondering whether the data should specify male vs female.

I have always assumed the wide headed CC are male and the narrow headed CC are female. Is that correct?

Bill, IMO male CC seem to have darker pigment, larger head compared to the body size with two large knots on either side above the eyes. They also seem to have way more yellow fat content then a comparable sized female fillets. Female with smaller head that stays portioned with weight down the body, except when full of eggs where the belly will be disportioned.

When fish farms raise catfish for spawning they often use head shape as one feature to sex the catfish.

This is a very interesting topic. In May 2011 I finished a 1/3 acre put-and-take pond.

It is for HBG, CC, HSB and some RES, I tried trout two winters ago, but couldn't get them out because the other fish were so much more aggressive at taking bait and lures.

Anyway, I've mostly been hand feeding all three of my ponds this season so I can see what my fish are looking like.

Interestingly, I've noticed that the catfish in the put-and-take pond have two distinctive mouth shapes. It is easy to see when they go into their "vacuum cleaner" mode of sweeping the surface for pellets with their gapes wide open. I've put batches of 25-each, 4-inch CC, into the pond each season since May 2011. The 2011 class is now about 18-22 inces. The 2014 class is 8-10 inch. I don't see this year's class eating yet.

The thing I've noticed is that some have a wide flat gape, while others have a smaller almost-round gape. We'll start harvesting some of the larger ones starting next week. It will be interesting to see if I can sex them based on their gap.

I've not noticed this in my BG/LMB/CC/HSB pond, but I will start to look for it now.

Ken

Hey Bill, thanks for posting this:



Because of this thread, and particularly Bill's note, I did a little more searching. On this site I found this note:



We're never to old to learn something new.

Thanks all.

IIRC Theo Gallus did a measurement survey and found that Males had a larger mouth than females. There was some correlation to body length in regards to mouth gape.

I think there is an error (maybe oversight) in the Quoted description above provided in the link by Dan Ashe that said "It is fairly easy to distinguish the sex of a channel catfish. Males usually have a broad muscular head that is wider than the body. A sexually mature male also has dark mottled gray splotches on the underside of the jaw and the abdomen. Female channel catfish have two vents, one to release urine and the other connected to the oviduct to release eggs."

To get specific, technical, and correct the female channel catfish has three ventral openings: the anus, the genital pore, and the urinary pore - 3 vents. The male has two vents; the anus and the genital vent for sperm release. The correct distinction between the male and female urogenital vents/pores is male's pore is on a papilla whereas the female's urinary genital pore/openings are in a slit without a papilla. To accurately sex the fish experienced fish squeezers use the tip of a pencil or similar item to probe the opening to detect presence or absence of the papilla. A common less accurate way to distinguish sex of CC is when the CC is mature the males have the broad muscular head wider than the body, a darkening of the body color and grayish color ('splotches') under the jaws. In contrast females has smaller heads, lighter body color, and have a distended abdomen at spawning time.

Another reference that I have says the female has a tubular nature of the genitalia. During spawning season the folds of skin that are on each side of the urinary and genital openings are raised and divided by a groove.

The erroneous sex distinction information in the link Catmandoo provided was provided by "Dan Ashe is a fisheries biologist with Texas Parks and Wildlife Department. He has worked out of the Jasper, Texas field office since 2005 helping to manage east Texas reservoirs including Sam Rayburn and Toledo Bend. Dan has also worked as fisheries biologist in Puerto Rico, California, and Alaska but now calls Texas home." Just because you are a fisheries biologist or other trained worker (even doctor) it does not mean one should not double check their information.

We are planning to harvest CC starting the end of July. I will gather as much info as I can as well. I am hoping to also get some data on stomach content vs mouth gap.

Although there might be difference between a male/female gape of the same length, does it really matter? I think the collective knowledge (average or the upper size gape for each length) is more important. If one wanted to know this mouth gape size to control a species, etc, I think they would say when catfish get to this size they need to be controlled or the catfish will do so-n-so. Would we ever really say something like when males get 18" and females are 21" , do such and such ??? OR... if it is only a 12" female it should be returned but keep a 12" male... this goes against what most advise.

Like Bill mentioned, I think stomach contents along with size and gape are more important.

Thanks for the info snakebite. I'm putting a catfishery together in attempt to decrease my carp numbers and this info is very helpful.

CC:
27", 7.9#, male
Gape: 4" x 3"

Caught on a Roostertail.

CC:
19" 2.5#, Male
Gape: 3" x 2"
Stomach contents: pure pellet food.

Questions and observations:
Would Gape on catfish be measured from side to side? ( I am assuming it this way because of Snakebite's pics above).

LMB would be top to bottom?

On this CC, it was 3" wide when open and at the lips. However, looking further into the mouth, the CC seemed to have a cartilage structure(jaw bone?) that diminished down in size. It was actually 2" at this point, but a whole 1" back into the mouth. Would this not be what really is the restriction of what a CC could swallow?

Some CC data

Mouth Gap (MG) measured horizontally

From our pond:

F 17.5 inch 1 lb 12.5 oz MG 1.6
F 17.0 inch 1 lb 10.0 oz MG 1.5
F 18.5 inch 2 lb 6.0 oz MG 2.0
M 18.4 inch 2 lb 4.5 oz MG 2.3
M 18.8 inch 3 lb 0.0 oz MG 2.6

Stomach contents were NIL. Not surprising as I have been feeding pellets heavily lately in prep for harvest. Fishing was done at feeding time.

From Lake:

F 26.0 inch 7 lb 8.0 oz MG 3.0

Stomach content was green goop

Whoa....

http://www.fishforums.net/index.php?/topic/391688-big-blue-catfish-eats-big-carp/

It's amazing how fast a large Blue cat can strike. It does appear that the last second in the video it realizes it can not swallow it and releases the buffalo.

Channel Catfish --

Length - 13" Gape - 1.25"

Length - 19" Gape - 1.75"