Largemouth Bass Biology: Everything You'd Want to Know

Largemouth Bass: Basic Biology

Largemouth bass are a species of black bass, in the family Centrarchidae, most commonly found in the United States. They also thrive in many different environments and can be found all across North America, Mexico, Japan, South Africa, Europe, Guam, Lebanon, New Zealand, and the Philippines. While they are found all over the world currently, this is not their native range.

Largemouth bass are historically known to be found in much of Eastern North America, Canada, and Northern Mexico, everywhere else they were introduced by humans. They are primarily a warm water species that thrives in lakes with aquatic vegetation. They can have many different color patterns based on the water qualities, habitat, and time of year they are caught.

For instance, the fish in Florida are much darker in color than the fish found in upstate New York.

This is due to the dark nutrient rich water found in Florida, whereas upstate New York has much colder, deeper water. The color pattern just depends on the surrounding environment in which these fish attempt to match. This matching color pattern is, paired with their large mouths, is what helps to make them proficient ambush predators.

Largemouth Bass Feeding Characteristics

Possibly the most notable characteristic that largemouth bass are known for is their large jointed mouth. This large mouth enables these fish to use the power of suction to capture their prey. They will lay in wait in or around cover and utilize the water suction that their mouth creates when they open it to pull the prey into their mouths. In lakes with large populations of shad and other open water forage fish, the largemouth populations will school up and spend their lives following these baitfish. Their voracious feeding habits coupled with upturned mouths and eyes located on top of their heads makes largemouth bass excellent at feeding upward in the water column. For this reason, largemouth bass will mostly be found below the schools of baitfish they are foraging on.

The diet of a largemouth bass varies extremely depending on what can be found in the water they’re located in at any given time. Largemouth bass are extremely aggressive and are very opportunistic when it comes to finding their next meal. They have been found with snakes, birds, small rodents, other bass, crayfish, frogs, and various other items in their stomachs.
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As a general rule of thumb if they can fit it in their mouths there is a strong chance that they will take a shot at it.

The overall length that these fish can grow to is also dependent on the climate to which the body of water is in. In colder temperate climates, it is harder for these fish to grow to “trophy class size”, as the colder weather slows their metabolism. Warmer climates will grow overall larger average sized fish, as well as larger trophy sized fish. As a general rule of thumb females are always larger than their male counterparts, at the same age. This is because the larger a female is, the more eggs that she can carry. It is also easier for her to avoid predation by being larger, making the eggs more secure. While a male can be much smaller and still carry millions of sperm cells.

To break this down in a manner that makes sense, we’ll divide this section into pre-spawn, the spawn, and post-spawn. Most people generally associate the spawn with springtime. In reality there is more that goes into it than that. It has a lot to do with the weather conditions and the moon phases.

Largemouth Bass Movements: Pre-Spawn

Pre-spawn begins as the water temperature begins to rise to around 45-50 degrees, as it rises toward the peak spawn temperature of 55-60 degrees Fahrenheit. As the water warms up it triggers a response in the largemouth bass.

This response is one that is hard wired into their DNA as the urge to reproduce. While all animals have different responses to this urge, it triggers largemouth bass to leave the comfort of deeper water and move toward the shallow water in which they will lay their eggs. This shallow water provides the light, oxygen, and habitat required by the eggs for the most successful nest possible. This movement toward shallow water is what anglers everywhere are dreaming of all year and left reminiscing when it is gone.

It’s not as simple as it sounds however, just because the largemouth bass are now extremely shallow does not mean anyone can catch them. Shallow can be a relative term however. It all depends on the water clarity of the body of water.

In a crystal-clear lake, the fish might be in 5 or 6 feet of water. While in a very turbid, or “muddy” lake, the bass might be in 2 or 3 feet. It all depends on where the bass feel safe and comfortable. That being said, largemouth bass don’t just spawn anywhere, there are many other factors that come into play.

Specifically cover, bottom composition, and bottom contour. When largemouth bass push up to spawn, they are moving from areas of deeper water into areas of shallow water. In order to do this, they need travel routes. This can be creek channels, ditches, or just up main lake points as they travel from the main lake to the backs of the pockets. These travel routes provide the easiest access for fish as the make their annual movement.

Largemouth Bass Movements: The Spawn

The spawn usually begins with the first full moon after the water temperature begins to reach between 50-60 degrees Fahrenheit. This is when largemouth bass will start to push up into shallow water. The full moon creates a large amount of light at night that leads to an increase in nocturnal fish activity. This generally is why many anglers are left puzzled as they encounter large numbers of fish on “beds” when the water temperature is still in the mid to high 40’s. They are up and searching for areas with hard bottom composition in order to create their nests, which are commonly referred to as “beds”.

Often times the bed will be built around overhead cover, such as lay downs or docks. This cover helps to conceal the fish as they guard the eggs on the nest. This is undoubtedly the most vulnerable point of the year for a largemouth bass, so they try to make their nests as concealed as possible. That being said you will often times find fish making nests in the most obvious of places. I once pulled up to fish a lake and a male had made a nest next to the dock at the only boat launch in the area.

In the animal kingdom it is not uncommon to see the male do most of the work in order to impress a female, largemouth bass are no different. Males will arrive to the shallows first in order to create the nest and keep it tidy until the female arrives. The male will use his tail and other fins in order to push and sweep away the sediment and silt to reveal the “clean” gravel. This gravel provides space for the eggs to fall into as a way to help protect them while keeping them oxygenated. The males may arrive weeks in advance, while the females will lurk out deeper waiting for the optimal conditions in which to lay their eggs.

This is due to the fact that the females are carrying the expensive part of reproduction. You may be asking yourself what does that mean? As a great professor of mine once said “Sperm is cheap”. Meaning that there is a lot more effort put into the production of eggs in a female than there is sperm in males. Thus, the females will stay in deeper water where there is more safety, while they allow the smaller males to do their grunt work until they are ready.

When the conditions are just right the females will pull up the beds that the males have created and begin to lay their eggs. As they lay their eggs the males will release their sperm onto the eggs. This begins the fertilization process within the eggs. The females are tricky though, they will not release all of their eggs at one nest.

They will release small amounts at different nests guarded by different males. This will help diversify their young in hopes to give them a better chance at survival.

After the females have laid their eggs into a nest, they will then begin their search for food to try and regain the weight they had lost during the spawn. Luckily nature has set it up so that the bluegills, brim, and shad all spawn after the largemouth do. These easy food sources act as a recovery for these stressed and very thin largemouth. While the females begin to recover, the males will continue to guard the eggs even after they hatch. The males must stick around to guard the eggs from predators, such as bluegills, various minnow species, crayfish, and even other bass. The males will watch over the fry until they reach around 1-inch in length. At which point the male will abandon them and oddly enough, eat any other fry he encounters. This prolonged overwatch the males provide helps to ensure that most eggs are able to make it through the fry stage.

The typical survival of fish eggs is between .01 – .05 percent, depending on many environmental conditions. This is why fish lay thousands of eggs. It acts as a means of ensuring the most possible young make it to reproductive age in the future. This will ensure the parental genes continue to be passed on. Overall, the spawn can last a few weeks, or over a month. It all depends on the conditions mother nature throws at these largemouth during any given year.

Largemouth can spawn multiple times if a nest fails, which can often happen as anglers remove them from their nest. This leaves their nest open and free for predators to snatch an easy meal. One study showed that after a male smallmouth bass is removed from the nest, great lakes gobies can clean the nest of eggs in 15 minutes. Groups of panfish pose the largest threat to largemouth bass nests. While the male is off chasing one, the rest of the group will move in and eat the unguarded eggs. The spawn is something that all anglers look forward to every year, while it is exciting, it is only one short part of the year.

Largemouth Bass Movements: Post-Spawn

That being said, after fish spawn they have one thing on their minds, food. These fish have to recover from the stress that they have endured during the spawn. Luckily for largemouth bass, both bluegill species and different species of shad have evolved to spawn right after them. It is likely that the largemouth bass that spawned early faired better than the ones that spawned later. Thus, creating populations of bass that spawn before the baitfish.

So, after the spawn the bass will disperse to follow different food sources. Some will chase the shad, while others will chase the bluegill species in your lake. If you have neither bluegills or shad, which is highly unlikely, then the fish in your lake likely feed on crayfish and other small baitfish. These fish will then follow similar transitions as the ones they moved in on and start to slowly fade out deeper into their summer patterns. It is important to note that not all the fish in your lake will do the same thing. Some fish will stay shallow, while others will move out deeper and some in between.

Largemouth Bass Movements: Summer

In the heat of the summer, largemouth bass must find areas of the lake that provide them with enough oxygen in order for them to survive. This can lead fish to only a couple of avenues. They can either move out to deeper, cooler water or they can move shallow and utilize the oxygen rich environment and shade that is given off by the aquatic vegetation in any particular body of water.

The warmer the water gets, the lower the amount of oxygen that it can hold. This is why anglers generally associate summertime fishing with deep water. That deeper cooler water is able to hold more oxygen, which is why these fish move there. This oxygen line is also known by the thermocline.

So, these fish will utilize these oxygenated areas during most of the day. This is why anglers find peak feeding activity in the low light periods of morning and evening. They are simply catching the fish that have pulled up into the shallow water that has cooled at night in order to feed. While most fish still feed during the day, in some lakes the temperature and pressure can create entire populations of fish that feed almost solely at night. For the duration of the summer months these fish will continue to use these deep and shallow water hideaways as areas to escape the threat of anoxia and overheating.

Summer fishing is often explained as very difficult when the water gets extremely hot. This is because the more a fish eats then the more oxygen it would use in order to digest the food. This leads to fish becoming very lethargic in order to conserve oxygen during the most stressful points of the day.

They will remain in these areas until the air begins to cool as the season changes to fall.

Largemouth Bass Movements: Fall

As the water temperatures begin to drop and the air starts to get a crisp feeling, it sends yet another signal to all the fish, including largemouth bass. This cooler water tells the fish one thing, winter is coming. This means they need to begin feeding up while the water is still warm enough for their metabolism to allow them too. This makes largemouth bass even more aggressive and opportunistic than they normally are, making them very susceptible to anglers.

This cooler water is also able to hold more oxygen which allows those fish that were out deep to now travel back up into the shallows to feed. Most species of baitfish and other forage fishes are also up shallow, creating prime feeding opportunities for an aggressive largemouth bass. The dropping water temperature that fall brings also brings what anglers refer to as the fall turnover.

This turnover is what happens when the entire water column is now the same temperature. This allows the wind to create current that mixes the water at the bottom and top alike. This turnover is what allows the fish to return into the more nutrient rich shallow water as they attempt to gain more fat before winter.

Largemouth Bass Movements: Winter

The term winter is the same across the country, but the temperatures it brings vary depending on what part of the country you are in. The one thing that is consistent however, is that largemouth bass become much more lethargic in those colder temperatures. The colder water slows their metabolisms to where they do not need to feed as often or as frequently because they are not as active. This is why anglers find winter to be a much more difficult time of year to fish.

So, where do these fish go in the winter?

Most of the bass slide out into deeper water, very similar to where they were positioned during the summer periods. This deeper water was cooler in the summer but is now much warmer than the shallower water in the winter. This provides these fish with a more stable temperature zone in which to live. Most fish will spend their time either following schools of shad species or chasing different species of bluegills in flat basins.

Areas with extreme drop offs, whether it be bluff walls or steep points, also are highly utilized throughout these colder months. They provide these fish with the easy ability to slide up into shallower water to feed for short periods of time during the day. These deeper and warmer temperature zones will ultimately act as buffers from the cold elements until the warmer temperatures of spring begin to warm the shallower waters. Once again triggering the annual spawning activity to start this entire movement over again.

Largemouth Bass: Biology

Chapters

Chapter 1: Basic Description

Chapter 2: Basic Biology

Chapter 3: Seasonal Movements

Chapter 4: Life Cycle

Meet the Author

Chapter 1 - Largemouth Bass: Basic Description

Largemouth Bass: Basic Description

Chapter 2 - Largemouth Bass: Basic Biology