Underweight Bass- Causes?

[Mastermarsh]

Tonight while fishing I hooked into a very nice bass at first glance. After not much of a fight I got the fish to the boat and noticed something severely out of sorts. The fish was 22 inches long, had the mouth and head of a 8 pound fish but only weighed just under 4 pounds. The fish was very thin for its size and it seemed to be very low on energy.

I was thinking that either the fish is at the end of its life, it had lost a ton of weight spawning (the spawn is just ending here), or it was sick. Has anyone ever experienced anything like this?

[Turkey sandwich]

Sounds like post spawn weight loss.

[soflabasser]

There are many reasons why a bass might  be underweight. The bass could be sick, might not have enough fish to eat for various reasons,etc. One reason some bass are underweight is that some bass swallow soft plastics often and this causes bass problems digesting it's regular prey. There's many pictures online showing underweight bass cut open revealing many soft plastic lures inside of them.

[BareHook]

Or possibly too much competition or bass over population in that particular pond, all the smaller fish may be eating up all the prey.

[Red Bear]

id guess its either worn out and not yet recovered from the spawn or theres too much competition for food in that body of water and that fish isnt getting its fill...

[the reel ess]

Could be a male fish that has grown larger than average. Could be there's not enough food at this particular time, but there was for most if the fish's life. Could be a genetic freak.

It could the the balance is out of whack with the majority of the forage fish (bluegill) getting too big for bass to eat and in turn, eating some of the food the bass would normally eat. Once a pond gets into this condition, it's very hard to correct because you have to remove a large number of both species to return it. And if you're fishing someone else's pond, they usually look at people taking their fish as theft. I've seen the Pond Boss shocking fish up to remove them and restore balance.

Some ponds stay in balance on their own, but most don't. I fished a place recently that nobody takes fish out of. The average bass was over 2 lbs. I caught a 3. And the owner said the largest to ever come out of it was 12 lbs. He has an 8 on the wall. I feel certain it has a healthy self-sustaining balance of predators and prey.

[Team9nine]

Not a post-spawn thing - that fish is on its way out. Here's a good piece by I-F contributor Ralph Manns on the subject:

Big Headed, Skinny Bass: Why?   

By Ralph Manns

Bass and other fish live in a very hostile environment. On average, 20 to 40 percent of all adult bass die every year. Very few live more than five or six years. That's why any fish that reaches lunker size is rare and should be released . Bass waste-away and eventually die for many reasons.

Disease kills some. There are many fungus and bacterial diseases in every bassing water, just waiting to find a host in slightly weakened condition. And now we know there is at least one virus out there that attacks stressed bass. Even careful catch and release stresses bass, but fish are also stressed just by the processes of normal living. They race for food and lose to a faster or closer bass.

Many bass accumulate burdensome parasite loads. Practically everything a bass eats bring with it some additional parasites that then set up housekeeping inside a bass' guts, liver, eyes, skin, and muscles and sap its energy. Tapeworms steal food, and a wide variety of parasitic flukes nest in various tissues, reducing the fish’s ability to function at full strength. The older the bass, the more parasites it usually contains. A few flukes migrate into a bass' eyes and live there. These often blind the bass, even though the damage isn't always visible externally.

Bass live in a competitive environment. They aren't perfect predators, they merely function well enough to survive. Prey are equally efficient escape artists, and bass don't catch food every time they feed. If a lot of bass try for a limited amount of catchable food, the may get insufficient food if they are not able to compete at full strength.

Preyfish seem abundant to anglers, but in most lakes, even our best bassing waters like Toledo Bend, they are usually in a population that is fairly well balanced. The number of prey and predators tends to come to equilibrium, with neither too many nor too few predators or preyfish. The result is that any bass that is only at 90 percent physical capacity tends to starve. It takes a lot of visible shad to support the full population of bass in a water like the Bend.

The result is that in most healthy bass populations there are always a few fish that are in some stage of dying. They are either sick with diseases or parasites (or both) or injured and can't compete well enough and are slowly starving to death.

Almost nothing is know about the effects of aging on bass, but some lunkers stop growing, waste away and die. Apparently, just like in humans, some organs just stop functioning as well if a bass gets too old or too fat. My wife caught a 29.5 inch bass at Santee_Cooper years ago with a huge head and skinny body that only weighed 9 pounds. We saw a 16-pounder from the same lake on the wall that was the same length. It was obviously declining. Since then I've seen many bass of various sizes that were on their way out.

Anglers often think bass with one eye out, or obviously blind, can feed effectively with lateral line alone. In a normal lake environment this is NOT true. Bass need full vision to feed effectively in competition with other, healthy bass and to catch elusive prey that can both see and sense that the bass is near. Other fish beat them to any prey that come within catchable range and they slowly starve. When anglers catch a fat, blind bass, its almost always because the fish was only recently blinded and its slow decline isn't yet visible. At Falcon Lake, on the Texas/Mexico boarder, underwater brush is often covered with thorns. Anglers frequently catch healthy-looking blind or one-eyed bass there, as the fish injure themselves chasing prey. But, few of these fish live long or continue to grow.

Skinny bass with large heads are normal in most bodies of water, as long as they remain a small part of the total bass population. If most of the bass appear underweight, there is a gross imbalance of prey and bass numbers or a rampant disease is effecting most of the fish. These are stunted, sick bass, and should be removed from the population and eaten if apparently in good health and retention is legal. Catch and release of such fish is not beneficial or appropriate in almost all waters.

[Mastermarsh]

Thanks guys, I'm fishing a chain of impoundments that don't seem to have any shortage of baitfish for the bass to eat, as every other fish is quite healthy. It was just this particular fish so I'm inclined to agree with you @Team9nine, as the fish was very lethargic.

During an internship I where I studied lake trout populations in Canada it was actually fairly common to catch very large fish with undersized bodies. Because of the different tissue types when the fish couldn't sustain its mass, the body shrank & the head would stay the same size. Pretty interesting article since I never knew bass reached this age in my lake.

[fishballer06]

Not to discredit what Team9 said, but female fish do lose a fair bit of weight during spawn. For example, I just caught this fish 3 weeks ago. She was 22 3/4" and only weighed 3.6 pounds. We caught 3 other smallmouth this day that were over 20" and all of them were skinny and lethargic during the fight. The water temperature was around 70* that day, and the weekend before the water was around 62*.  I fish this particular lake a good bit. Back in October/November I caught a few other smallmouths in this lake that were in the 19-22" range and most of those were in the 4 to 4.5 pound range and were very scrappy during the fight and had very chunky bellies. So I'm betting that this fish had lost a pound or so during the spawning process.

 

Without actually getting a scientific study done or seeing visual problems on the fish (parasites, etc.), it's hard to say. Seeing as you're in Michigan (and me in PA), it's a very good chance the fish was post spawned out. 

 

[Glenn]

I've seen this several times, and discussed it with the Pond Boss, Bob Lusk (world renowned bass biologist and pond management guru).  The fish was on his last days.  Sad to see, but normal so long as it's a rare occurrence on the same body of water.

[roadwarrior]

Several years ago I caught a "ghost fish" at Pickwick. If it were healthy the bass would have had a mature weight of at least six or seven pounds, but this sucker was gone and didn't weigh a pound. It was scary and I didn't touch the thing. I lifted it at the hook with pliers and manipulated the release. The fish swam away...

 

[Team9nine]

A couple other thoughts while were on the topic. Ask about any biologist and they'll tell you that most bass anglers almost always overestimate how much a female bass will weigh when getting ready to spawn. You've likely heard it before, "If only I had caught her when she was ready to spawn, she would have weighed xx pounds." In reality, the average female bass only carries eggs which weigh about 4-6% of her total body weight. At the very high end you might be looking at 8-10%, but that would be the exception in most cases, on most waters. The point being, a healthy female fish that measures in that 20-22" range and might normally be expected to weigh 4.5-6 pounds isn't going to be carrying around 2-3 pounds of eggs. It's much more likely to only be 4-8 ounces at best, most of the time. As such, assuming she completely spawns out her eggs, she will only decrease her overall weight by that same amount.

Now, if you are seeing or catching quite a few fish with big heads and skinny bodies, then you most likely have a food/feeding issue, most likely a shortage of available food, and this can be seasonal on the same body of water. In other words, they look fat and healthy at some point in the year, but many months later, they are looking light and skinny. Some waters simply don't have a good enough (or diverse enough) food supply to keep bass fat and healthy all year long. And yes, it could be a case where several factors combine to make fish unusually thin, but by and large, a single isolated incident (like @Mastermarsh indicated in his response) is most likely a sick and dying fish, while skinny or thin fish being more the norm on your waters is probably a food or environmental issue.

-T9

[OCdockskipper]

Isn't post-spawn weight loss in females a combination of dropping the eggs & not eating for a while?  

I caught this female off a bed in the late part of the spawn this year, she was 23" long & weighed 5.4 lbs.  She wasn't grossly thin & she put up a good fight, she just didn't have that fat stomach you see on prespawn fish or later in the year when they have fattened up.  Based on the other large fish I have caught on this lake, I would have expected her to be about a pound or so heavier if her frame had been filled out.

 

[Hog Basser]

This one was about 20.75 inches and 3.45 lbs., which is way underweight.  She looks pretty decent from this perspective, but when I held her up, you can tell she's skinny.  I use the relative weight chart I found in the lake management section articles on this site.  You want fish to at least be in the upper 80's to low 90's on RW, but this one came in at 65.71.  Cause is probably not enough forage for her to eat in the lake, although other factors come in too.  This was post-spawn (right after).  I'm working on culling unhealthy and smaller fish to increase size on the bigger ones.  Sometimes if they are underweight (stunted) too long, they will never reach their full potential.  

[wyattcollins00]

Yes the same thing was going on with a bass I caught.

It was 25" and had a huge head but only weighed 3 1/2 lbs.

[Bass Turd]

On 6/15/2016 at 6:55 AM, soflabasser said:

There are many reasons why a bass might  be underweight. The bass could be sick, might not have enough fish to eat for various reasons,etc. One reason some bass are underweight is that some bass swallow soft plastics often and this causes bass problems digesting it's regular prey. There's many pictures online showing underweight bass cut open revealing many soft plastic lures inside of them.

 

 

[soflabasser]

17 hours ago, Bass Turd said:

 

 

 

Thank you for posting this video, I have seen this video before and have seen bass with soft plastics coming out of the mouth or their anus. Lots of bass fishermen fish with senkos down here and many of those bass fishermen do not realize that bass can(and will) swallow senkos.Goes to show that these soft plastics aren't as safe for the bass as some may think.

[Smokinal]

On 6/15/2016 at 10:15 AM, Team9nine said:

Not a post-spawn thing - that fish is on its way out. Here's a good piece by I-F contributor Ralph Manns on the subject:

Big Headed, Skinny Bass: Why?   

By Ralph Manns

Bass and other fish live in a very hostile environment. On average, 20 to 40 percent of all adult bass die every year. Very few live more than five or six years. That's why any fish that reaches lunker size is rare and should be released . Bass waste-away and eventually die for many reasons.

Disease kills some. There are many fungus and bacterial diseases in every bassing water, just waiting to find a host in slightly weakened condition. And now we know there is at least one virus out there that attacks stressed bass. Even careful catch and release stresses bass, but fish are also stressed just by the processes of normal living. They race for food and lose to a faster or closer bass.

Many bass accumulate burdensome parasite loads. Practically everything a bass eats bring with it some additional parasites that then set up housekeeping inside a bass' guts, liver, eyes, skin, and muscles and sap its energy. Tapeworms steal food, and a wide variety of parasitic flukes nest in various tissues, reducing the fish’s ability to function at full strength. The older the bass, the more parasites it usually contains. A few flukes migrate into a bass' eyes and live there. These often blind the bass, even though the damage isn't always visible externally.

Bass live in a competitive environment. They aren't perfect predators, they merely function well enough to survive. Prey are equally efficient escape artists, and bass don't catch food every time they feed. If a lot of bass try for a limited amount of catchable food, the may get insufficient food if they are not able to compete at full strength.

Preyfish seem abundant to anglers, but in most lakes, even our best bassing waters like Toledo Bend, they are usually in a population that is fairly well balanced. The number of prey and predators tends to come to equilibrium, with neither too many nor too few predators or preyfish. The result is that any bass that is only at 90 percent physical capacity tends to starve. It takes a lot of visible shad to support the full population of bass in a water like the Bend.

The result is that in most healthy bass populations there are always a few fish that are in some stage of dying. They are either sick with diseases or parasites (or both) or injured and can't compete well enough and are slowly starving to death.

Almost nothing is know about the effects of aging on bass, but some lunkers stop growing, waste away and die. Apparently, just like in humans, some organs just stop functioning as well if a bass gets too old or too fat. My wife caught a 29.5 inch bass at Santee_Cooper years ago with a huge head and skinny body that only weighed 9 pounds. We saw a 16-pounder from the same lake on the wall that was the same length. It was obviously declining. Since then I've seen many bass of various sizes that were on their way out.

Anglers often think bass with one eye out, or obviously blind, can feed effectively with lateral line alone. In a normal lake environment this is NOT true. Bass need full vision to feed effectively in competition with other, healthy bass and to catch elusive prey that can both see and sense that the bass is near. Other fish beat them to any prey that come within catchable range and they slowly starve. When anglers catch a fat, blind bass, its almost always because the fish was only recently blinded and its slow decline isn't yet visible. At Falcon Lake, on the Texas/Mexico boarder, underwater brush is often covered with thorns. Anglers frequently catch healthy-looking blind or one-eyed bass there, as the fish injure themselves chasing prey. But, few of these fish live long or continue to grow.

Skinny bass with large heads are normal in most bodies of water, as long as they remain a small part of the total bass population. If most of the bass appear underweight, there is a gross imbalance of prey and bass numbers or a rampant disease is effecting most of the fish. These are stunted, sick bass, and should be removed from the population and eaten if apparently in good health and retention is legal. Catch and release of such fish is not beneficial or appropriate in almost all waters.

Interesting that he doesn't even mention the possibility of soft plastic in fish. I believe this is more the case than anything else and a bigger concern than most think. jmo

[NCbassraider]

Sounds like a post spawn female.  Pictured is a female I caught last spring post spawn.  She was so skinny but stilled weight 5lbs 2 oz.  Probably a 6 1/2 lb pound bass when up to normal weight.

 

Did yours look like this