For the inhabitants of a Nebraska farm pond, the ability to survive seems miraculous when analyzing how many different ways a fish can die.
On a calm spring or summer afternoon, Nebraska farm ponds look anything but treacherous. They are peaceful places to take a kid for an afternoon of bobbers and hooked fingers, or to steal an afternoon nap on the water’s edge. Below the surface, however, ponds are a place of death and destruction where mothers and fathers eat their own children and survival on a daily basis is close to miraculous.
Just as it is on land, there is a pecking order to the underwater world – adult bluegill are bigger than minnows, adult bass are bigger than bluegills, etc. – but the limited types of food sources and the accompanying competition for them often muddies this pecking order. Young fish of all species compete against each other to eat the same plankton they require until they grow large enough to eat other foods, and young fish of even the largest species are fair game for almost any other fish that happens to be bigger at a given time.
However, each year reports emerge from around the country about enormous largemouth bass, some in the 20-pound range, being caught. While bass in Nebraska do not grow this large – the state record weighed 10 pounds, 11 ounces, and a five-pound largemouth bass is recognized by the Nebraska Game and Parks Commission as a “Master Angler” trophy – there were still 374 Master Angler largemouth bass reported to the Commission in 2008 and probably many more caught that were never reported. Quite often, many anglers even fail to take a picture of a lunker largemouth or, for that matter, any other trophy species they catch.
Yet it takes, on average, 10 years for a Nebraska bass to reach Master Angler size. Ten years of survival in a habitat that can be quite inhospitable at times. For purposes of illustration, the following uses largemouth bass to examine the daily struggles all fish have in their attempt to reach adulthood. Only by learning about and understanding these struggles can an angler truly appreciate the trophy fish that is caught, whether it be a six-pound bass, 1½ pound bluegill or 20-pound channel catfish. If anglers knew how rare those catches were, and what each of those Master Angler fish had to do to grow to that size, they would report every catch, release every trophy back into the water, and consider themselves quite fortunate to have spent a few seconds with a species who has excelled in the “fish eat fish” world of survival of the fittest (and luckiest).
The Top-Tier Prey
In Largemouth Bass, by Don Oster, the author states that between 5 and 10 bass are likely to survive to reach 10 inches in length from a nest that hatches between 2,000 and 12,000 eggs. Largemouth bass typically nest once per year after they reach 12 inches in length, which in Nebraska may not happen until their second or third year of life. After they hatch, bass fry feed primarily on zooplankton and insect larvae, but they do so in direct competition with a variety of other fish species, most notably bluegill.
As they grow, largemouth bass are not very selective with their prey choices and can thrive in a variety of waters. This flexibility allows the species to survive in 49 states, from canyon reservoirs in the western United States, brackish tidal sloughs in Louisiana, to Nebraska’s farm ponds. Bass eat insects, crayfish, frogs, lizards, snakes, other fish, baby birds and ducks, mice or anything else they think they can fit in their mouth. They can swim at speeds up to 12 miles per hour in short bursts, five times faster than an angler can retrieve a crankbait. Simply stated, they eat whatever food is available. Despite their voracity, however, they are also prey for other animal species. Six years ago I was walking down the edge of Louisville SRA’s Lake No. 2 and saw a two-pound bass pivoting above a nest of eggs as a group of bluegills, at least a dozen, surrounded the nest-guarding male on three sides.
A bluegill would dart toward the nest from the right, and the bass would swim toward the intruder, ushering it away while one, if not more, bluegills from the left would move in and start eating eggs. For each egg the largemouth tried to save on one side, he lost three more on the other. Within an hour the bass was gone, as were all the eggs he had been guarding.
Bluegills are one of many species that will feed upon other young fish. Northern pike, crappie, flathead catfish, channel catfish and largemouth bass will attack other fish species as well as their own. In addition, multiple bird species, including American pelicans, ducks, terns, grebes, egrets, great blue herons and kingfishers, eat largemouth bass. Cormorants, for example, can consume three to five pounds of fish per day. Even more threats come from land – turtles, snakes, minks, raccoons, otters and bullfrogs will all feed on fish if given the chance.
All of these predators help to account for the small number of largemouth bass that will survive to reach 10 inches. However, in research previously chronicled in the In-Fisherman book The Largemouth Bass, it was reported that largemouth bass most commonly consume prey that is 20 to 50 percent of their own length, and sometimes up to 70 percent. That means that some of these “safe” 10-inch largemouth bass could be eaten by their 20-inch brethren.
Aside from the predators in and around a pond, largemouth bass and other fish species must also contend with Nebraska’s chaotic weather. A summerkill can occur in shallow ponds that contain a large amount of decomposing organic material and excessive algae blooms. This organic material can enter the pond from the surrounding watershed as well as through duck, goose and grass-eating carp excrement, which, in large amounts, can raise the nutrient levels of a pond and create an algae bloom. While algae produces oxygen during the day, algae uses it at night or when the sun is not shining, lowering oxygen levels.
Winter can be just as dangerous. During this time of year, ice prevents atmospheric absorption of oxygen, so all the available oxygen has to come from plant photosynthesis or from oxygen already stored in the water. In order for that to happen, however, clear or even cloudy ice is needed to allow enough sunlight to penetrate down to the plants. If the ice is too thick or is blanketed with snow for an extended period of time, the plants may not receive enough sunlight to produce sufficient oxygen, resulting in a fish kill.
Three inches of ice, covered by five inches of snow, will block 99 percent of incoming sunlight. Remove snow from 30 to 50 percent of the pond surface or just in shoreline areas where submergent vegetation would be located beneath the ice, and fish have a much larger chance for winter survival.
The Ultimate Predator
While anglers love to catch big bass, many also love green yards and bugfree gardens. Insecticides, herbicides, fertilizers, petroleum products and domestic sewage often find their way into nearby ponds, lakes and rivers, and can result in fish kills. In addition, heavily-grazed pastures and row crops can allow silt to enter a body of water and increase its turbidity, making eating hard for largemouth bass and other sight-feeding fish species. Excessive amounts of sediment can also smother eggs in a nest when it is stirred up and then settles.
If fish can survive this multitude of variables, they can also die in the hands of an angler – either intentionally and ending up on a dinner plate, or unintentionally. Fish secrete a protective mucus coating which helps prevent fungal and bacterial infections. Anglers who do not wet their hands when handling fish decrease that fish’s chance for survival by making it more susceptible to infection.
Added to the already long and varied list, fish species can also succumb to extreme pH levels, spawning stress, and other bacterial infections. Mortality can also occur during the early spring when a fish’s disease resistance is low due to winter and pre-spawning stressors. In addition, if a pond is too shallow, fish will likely perish every winter. Yet if there is not enough shallow water in a pond, there will also be a lack of spawning areas for fish to reproduce. Simply put, there are a lot of ways to kill a fish.
Survival is a numbers game. If enough young largemouths can survive their spawn, using their coloration as camouflage and a pond’s aquatic vegetation as a hiding place, they may have a chance to reach adulthood. Once they reach adulthood, they may have the opportunity to reach Master Angler size if they win life’s lottery. At that point, they deserve two things: One, snap a couple pictures before releasing the fish and don’t be so worried about getting the next cast in the water as quick as you can. Two, release the fish. Five-pound largemouths don’t fillet very well anyway, and they deserve to swim again. They have definitely earned the right.
This article originally appeared in the July 2008 edition of NEBRASKAland Magazine. To purchase this issue, visit the NEBRASKAland Magazine Store.