Fat Neck Trout?

[Bamboozle]

In the last week I have caught two trout in two different streams that had a noticeable bulge directly behind their head or gill slit. When I caught the first fish I thought it had swallowed something big and had yet to digest it completely; although the bulge appeared on both fish to be above the stomach area as I understand it to be.

In both cases the trout in question were brown trout, healthy and wild not bigger than 12" caught from streams. Here is a picture of trout #2.



Does anybody know what may cause this or have you seen it before?

[Vinny]

Bamboozle,

Here in New Mexico back in the 70's and 80's we had "Stunted" Trout that looked like the trout in your picture. These fish had the heads and tails of a 12 incher on an 8 inch fish. These fish faught harder than 8 inch fish (they actually had the power of a 12 inch fish). The Game & Fish identified these fish as "Stunted" caused by low water and/or fish overcrowding in small places.

Vinny

[garyj147]

Bamboozle,

One possibility is that the fish may have scoliosis. I have seen this phenomenon in fish before; since I primarily work with warmwater species, I have seen more of it in bass and crappie than I have in trout. However, I have witnessed scoliosis in some stocked trout.

[billknepp]

Have not seen any Hunchbacked trout, but I have caught a good many that have had anomalies. Such as a crooked or twisted spine. both Rainbows and Browns, I just chocked it up to injuries during stocking...I have not encountered this on wild trout waters...

I know that fish are placed into the streams from bridges as buckets are dumped right off of bridges....Seen this a few times...Do not know if that is standard practice???..and I would hope not...

[Bastion]

I have noticed trout on our local streams that have larger heads in proporsion to their bodies, which i assumed were just older trout who live in smaller streams that could be overpopulated.

I have also noted some trout in our streams that have gill plates that do not fully cover the gills. A couple of us think this is some desease the trout has contracted when younger and we think these fish should be killed to prevent the disease transferring to healthy trout. Does anyone know what may cause this?

[Lew]

I know that fish are placed into the streams from bridges as buckets are dumped right off of bridges....Seen this a few times...Do not know if that is standard practice???..and I would hope not...


I don't think dumping fingerlings off a bridge would hurt them much. They stock mountain lakes from airplanes without harming them to any signigicant degree. There are other ways that fish can be injured however, and I feel that twisted spines etc. could be the result of rough handling, narrow escapes etc. I think the dowagers hump is probably a deformity that hasn't resulted from injury. My 2/100ths.

[James Smith]

Having worked at a trout hatchery in another life, my guess would be that these are hatchery raised trout that have a genetic anomaly and very probably came from the same batch of fry. It was VERY common to see "distorted" trout many with two heads, etc and part of my job was to cull these out as fry since they almost always die in a short while anyway. Something as subtle as what you point out would be rather difficult to detect in fry and since it was not a life threatening anomaly. they went on to grow up and were stocked.

Just an semi-educated guess.

Jim Smith

[Bamboozle]

James Smith:

Considering both fish came from Class A Wild Trout streams where NO stocking takes place and both fish exhibit markings consistent with wild trout here in PA; I would be willing to bet there is no chance either fish was stocked.

Additional info:

The bulge was between the gill opening and the front edge of the dorsal fin so it really wasn't an enlarged head or skinny body, (depending on how you view it).

The first fish I caught was from a relatively decent sized stream with good flow and deep holes. The second trout was from a very small mountain stream. I caught about 9 fish from the small stream and all but two were Brook Trout and none had any deformities I could see. I fish the larger stream all the time since it is 10 minutes from my house and all the Brownies look just fine except the one from last week.

Could it be a pre-spawning thing since they were both Brown Trout which spawn in the fall?

[cajundood]

Scoliosis (curvature of the spine) can be caused by many things. See:

http://www.blackwell-synergy.com/doi/ab ... .tb00718.x

Vertebral column abnormalities in brown trout, Salmo trutta L.
SARAH L. POYNTON. Journal of Fish Diseases, Volume 10 Page 53, January 1987

Download the .pdf journal article, there is a picture of a brown trout with similar deformaties

[Bamboozle]

cajundood:

Unfortunately I cannot access that PDF because a subscription is required. I also sent an e-mail to the PA Fish & Boat Commission to get their input.

Thanks, there are two votes for scoliosis so maybe that is it. If anyone is interested I'll summarize the Fish Commission's response if and when I get it.