Just as with people, bass need stability to successfully raise their families. That’s not easy to achieve for even the most responsible of largemouth parents.
That’s because the whims of nature and the needs of man often complicate or even deny conditions necessary for a strong year class.
“Anglers need to be aware that White River fisheries are cyclical. They are going to have their ups and downs,” said A.J. Pratt with the Missouri Department of Conservation.
The fisheries biologist was speaking specifically about Beaver, Table Rock, and Bull Shoals and all impoundments in general. But even natural lakes can prove a hostile place for bass in their first year.
By contrast, what conditions will yield a strong year class? B.A.S.S. Times asked fisheries experts to explain, especially for reservoirs, which receive most of the angling pressure.
Not surprisingly, stable weather and water for the spawn and immediately after rank at the top. If few fry survive, then a year class is all but eliminated.
“If nests are shallow enough, then extreme cold and storms can force the males to abandon them,” said Gene Gilliland, B.A.S.S. National Conservation Director. “Smallmouth and spotted bass are less likely (than largemouths) to be affected because they nest deeper.”
Also, depending on the timing, wind from those storms can destroy shallow-water nests or break up the fry school, making the tiny fish more vulnerable to predation, according to Mike Maceina, a fisheries professor emeritus at Auburn University. Additionally, the turbidity it creates can make finding food much more difficult.
“Mortality is very high for a week or two after the spawn anyway,” Maceina said. “Mostly it’s predation, but fry will die in two or three days if they don’t eat. That’s why each nest will have 2,000 to 3,000 eggs.”
In reservoirs, falling water levels can be just as damaging as foul weather.
“They can fluctuate greatly from year to year and that can make for some weak year classes,” Pratt said.
“But on the opposite side, if you get a lot of rain and the water stays up for an extended period, then you have good habitat (along shoreline) and an influx of nutrients,” the Missouri biologist added. “That can produce a good population.”
Low, stable water also can enable a good spawn. Sometimes, though, it will be more nutrient-poor than high water. Consequently, fry either won’t survive or grow as quickly into robust fingerlings. Still, good year classes are possible during low water, Maceina said.
Meanwhile, water moving quickly through a reservoir can be harmful, the fisheries professor explained. “When you have a high exchange rate, then it’s more like a river. You have more turbidity and food is blown out.”
In natural lakes and some reservoirs, aquatic vegetation provides both food for the young fish and refuge from predation.
“That’s one of the most consistent factors for guaranteeing good reproduction,” said Maceina, adding that too much can be nearly as harmful as too little.
Gilliland agreed. “If you have too much cover, little bass will stay in there and keep eating bugs on the plants,” he said. “Then in the fall, the plants will die back and the fish will be only 2 inches long. They’re much more likely to get eaten.”
Shifting to a fish diet early in the summer, can enable young of the year bass to grow to 6 or even 8 inches by fall, greatly enhancing their chances of surviving the winter.
“If you are going to grow big bass, it needs to happen quickly,” Maceina said. “The growth advantage occurs early in life.”
During winter, meanwhile, cover in deeper water can help young bass, especially the smaller ones, escape being eaten.
“Shallow-water cover is critical right after the spawn,” Gilliland said. “But they can’t stay there in winter because the water is too cold. That’s why it might be a good idea to make brush rows instead of brushpiles.”
Fisheries managers wait until the following spring to gauge the strength of a year class. “You want to see them through their first fall and winter,” Gilliland said.
“And size will vary hugely. As with any population, you are going to have a bell curve. Some grow like rabbits, and some are runts. The majority will be in the middle.”
Considering all that a young bass has to endure during its first year, it’s a good thing that a strong year class isn’t necessary annually to maintain a healthy fishery.
“Every several years, you need a good spawn,” Gilliland said. “Bass have long lives compared to other fish. Missing a year class is not a huge hole in the population for a fish that lives 10 years or more.
“But if you have two or three (poor year classes) in a row, then you have a bigger hole and anglers will see that. It will show up three or four years down the road in fewer quality fish.”
Additionally, bass are an adaptable and determined species, foul weather and fluctuating water levels notwithstanding.
“Bass will spawn in a lot of different places, in a lot of different depths,” the conservation director said. “And not all of them spawn at the same time. Usually, there are enough successful nests to maintain the population.