Skinny Fish, Big Reason

By Bob Lusk

Sometimes, things are not always as they seem. As biologists, we sometimes get locked into a comfortable little box and miss something when we hear the same questions over and over.

A fishing pond manager from Odessa, Texas, Larry Hensley has been a pond owner for years. His family ranch, outside Brownwood, Texas, has several ponds and a five-year-old 35-acre lake--not just any lake, mind you, but one that was well-thought-out and designed. Because he's a stickler for details, Hensley worked with a nearby fish expert to design, oversee construction, and then to stock the lake. He did it "right."

Biologist Bob Lusk and Bass Pro
Shops' Dan Hoy dissect the 21-inch
bass, looking for clues into its poor
body condition.

Hensley called world headquarters late one September with a problem. It seems some of his bass were "skinny." For the most part, he said, "The fish are healthy, but occasionally we catch a long fish that's exceptionally thin."

Normally, when clients say they are catching a few long, thin bass, it means they are catching bass on their last leg of life, old-timers in decline, but not in a five-year-old lake.

That Saturday in September when Hensley called, I asked him to put the fish on ice and send it to me overnight. He headed to the store in Brownwood the next day to buy some blue ice and a Styrofoam chest to ship the fish. While there, he happened to bump into the fish guy who had stocked the lake. He got a 30-minute dissertation on why his fish were skinny. Ordinarily, the information would have been right on... if you prefer "box" thinking.

"Not enough food, too much vegetation, need to harvest 'slot' fish" was the thoughtful fish guy's advice. However, he missed this one. Why? Because he stayed inside his comfortable box.

Photos force all of us out of our boxes. When questioning Hensley, I knew the majority of his fish were healthy. From his field notes, relative weights of his bass were decent. It was just an occasional fish that was abnormal. Keep in mind that a 21-inch bass should weigh more than five pounds in order to have reached 21 inches. When Hensley told me he had a 21-inch bass that weighed less than three pounds, I knew there must be an issue. However, I thought the issue was limited to several individual fish, rather than the entire population, since relative weights of other fish were normal. That's why I asked him to ship the fish.

My mission was to autopsy this fish and see if there was something obvious. If not, then I would have him ship the next fish straight to a fisheries pathologist to check for diseases.

I started by using a sharp fillet knife to open the gut cavity of the fish and cut it back to see what was going on inside the fish. As I made the first cut, the fish's stomach rolled out. It was packed tight. I cut the stomach and pulled out four soft-plastic baits, all in varying degrees of digestion.

This fish had had a fetish for soft-plastic baits and ate them. The baits effectively had blocked the fish's digestive system. It wasn't that this bass couldn't eat, because its stomach could certainly handle more volume. But, with its digestive system blocked, it couldn't digest and pass any of its natural food. Consequently, the fish was starving to death.

All its organs looked pretty good. Its liver was normal color, with a moderately low number of grubs. Its heart was fine. Kidneys were a little distended-looking. Its swim bladder was much larger than normal, taking up considerable room in the gut cavity, but that probably was because the fish was in survival mode and struggling to maintain its equilibrium, plus it had been in an ice chest for 24 hours.

Here is the fish and the soft-plastic baits that were found in
its stomach.

Bottom line: There was only one reason this particular fish was so thin. It had lost almost 50 percent of its body weight because it couldn't digest food.

Oh... there was one other pertinent fact. There wasn't a hook anywhere inside this fish--just four plastic baits.

When I called Larry and emailed the photos, he was amazed. He also said all those baits had started off as watermelon color. They turned that funky green inside the fish. He also told me he never throws used baits overboard. He did say it wasn't unusual to lose a bait when fishing--a fish often pulls the soft plastic off the hook.

While I am certainly not ready to call this a "problem" because of one or two cases, I do think it's wise to pay attention. For now, don't throw any soft plastics overboard. Toss them elsewhere for proper disposal.

Reprinted with permission from Pond Boss Magazine (www.pondboss.com).

About the author. Editor Bob Lusk has 30+ years of practical field experience in the art of lake and pond management. He is a fisheries biologist with a bachelor's degree from Texas A & M University in wildlife and fisheries sciences, fisheries management.

My thanks to Charlie Bruggemann for bringing this story to my attention in the first place.