The mathematics of trophy largemouth bass management


Producing trophy bass takes the right genetics, plenty of food -- and time. On average it takes 10 years to grow a 10-pound bass.

Remember that trophy bass that you caught last year? What a fish! The result of good management, right? A carefully thought-out plan by your state fish and game agency to produce trophy bass – all it took was stocking bass, forage fish management and those special length limits, right?

I only wish it were that easy.

In some states, Florida bass stockings have paid off handsomely in the production of trophy bass. In other states, reservoir construction that left flooded timber and encouraged growth of aquatic vegetation improved habitat. Prey species introductions helped reduce competition for food. A strong catch-and-release ethic among anglers has slowed the harvest of mid-sized bass that might someday grow to double-digit size. All good.

But, despite fishery managers having years of schooling and experience, Mother Nature still has more control over what happens in our lakes than they care to admit. And this is nowhere more evident than in the production of trophy largemouth bass.

To put how rare and special trophy bass really are, let’s spend a few minutes in class – Fishery Population Dynamics 101 – to see the math behind the biology. 

Let’s start with 100,000 fingerling bass that were spawned out in a given year. Yes, there are probably way more than that spawned out each year in a large lake or reservoir, but we need a number to start with to make this example easy to understand. 

If water levels provided plenty of nursery cover and foraging for plankton, insects and tiny fish were all good, the little bass survive to fall. But then the cold water drives them from the protective shallows, and only those that have grown large enough to avoid starvation or being eaten make it through the winter. 

The following spring we estimate the survival of our first year class. Over-winter survival of bass fingerlings typically averages 60% or less – that means 40% die or get eaten the very first year. Survival of stocked Florida bass fingerlings may be as low as 5%. The genetic adaptations that allow them to grow large may let them down when they are stocked outside of regions with favorable climate.