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Bass Biology
The Art of Raising Bass - Mother Nature gets a Helping Hand
By Wayne Gustaveson

March/April 1999

Raising bass in a hatchery is more of an art than a science. That's a nice way of saying we humans would like to have more control over bass than we do. Rainbow trout have been completely domesticated for years, making them cookbook-easy to raise. Eggs and sperm are hand-stripped and the rest of the hatching process is done in trays and raceways. The only job for trout is to produce the eggs. Trout have even been selectively programmed to spawn when the eggs are needed instead of when the fish want to spawn. If eggs are needed in the fall then fish that spawn later in the year are selected as brood fish. After several years of selecting late spawning fish as parents, the kids automatically spawn later. Wild rainbow trout naturally spawn in the spring but in hatcheries they have been selectively induced to spawn in the fall since that is when the progeny can be used most efficiently in the stocking program.

Stubborn Bass Make Great Parents

Persnickety bass are having none of that. They spawn only in the spring and then only a few eggs at a time. The prolonged spawning nature of female bass prevents them from being hand stripped. Most of the eggs are not ripe at one time. Bass eggs are adhesive, which irritates hatchery managers who want to uniformly spread out eggs so they do not touch. Clumped eggs are prone to destruction from fungus that quickly develops on unfertilized eggs and then spreads to healthy ones. With trout eggs the dead ones are picked daily, reducing fungus problems which allows viable eggs to thrive.

Bass are caring parents who spawn fewer eggs per capita and depend on a high survival rate for species perpetuation. Most other fish species spawn large numbers of eggs and then leave the kids to fend for themselves. A smaller percentage of fry surviving to adulthood is enough to complete the grand scheme for species that do not care for the young.

The artful part of raising bass in a hatchery is allowing the fish enough initiative to produce the needed fry but then circumventing the process just enough so maximum production is reached. Bass are placed in a pond with enough shallow water to entice males to build nests. But a wild nest is hard to work with so males are given an artificial nest to use. The fish are tricked into using the artificial nests by their innate desire to spawn on rocks. The pond is lined with plastic so no rocks are found except those placed in the artificial nest.

The Artificial Nest

The nest has a window screen bottom within a two-foot square wood frame. One-inch sized rocks are placed in a separate hardware cloth basket, which rests on top of the window screen. Eggs spawned on the rocks hatch in about three to five days, depending on temperature. Newly hatched fry are transparent yellow wigglers that work their way deep into the rock pile. Rocks provide natural protection while the fry are most vulnerable. With the artificial nest box the natural wiggling action places the fry under the rocks but on top of the window screen of the nest frame.

So That's Why We Call 'Em Black Bass

As the fry grow and develop, they take on a black pigment. They wiggle in the rocks for another three to five days until they develop swimming ability. The proud papa guards the nest heroically during this critical stage of development and wise hatchery managers let him do it. But once fry swim they become very difficult and time consuming to capture. Black fry are harvested just before swim-up by removing the box of rocks. Fry are then left exposed on the window screen and can readily be washed out of the nest frame and moved to a plankton-rich, predator-free nursery pond where survival is enhanced. Virtually every young fish is given a chance to survive with this method. In the wild, predation begins immediately as the fry swim up, despite the best efforts of the male to protect them from harm.

Play It Again Sam

When a bass nest is destroyed, the innate (genetically programmed) response by the tenacious male is to make a new one. When one batch of fry are harvested from the hatchery pond the nest is removed overnight. When the nest reappears the next day, papa bass begins tidying up and preparing to do the whole thing over again. Females still only produce a few eggs for each individual spawn, which makes them available every few days during the entire two-month spawning period for males in any stage of the spawning cycle. If wind action or other natural disasters destroy a nest, the male can always find a female to share his new nest. Nature has worked out a marvelous process for the bass that need ideal circumstances in order to bring off a good nest of fry. Bass get many extra chances each spring if the first nest or two go bust.

The hatchery manager uses the male's natural drive to build nests to get maximum production out of each fish. Bass are not allowed to waste valuable production time guarding the swimming fry, as they do in the wild. Since the fry are not allowed to swim in the pond and the nest is removed, the male is immediately put back into fish production when the nest reappears. The world record bass, in my opinion, is one prodigious fellow in our hatchery pond that produced eight different nests of fry in one spring spawning period. He was my hero.

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