Harvest regulations for bass vary throughout Mississippi, and they change with time. The largemouth bass slot limit was removed at Grenada, and 14-inch minimum-length limits were implemented at Columbus and Aberdeen lakes.

This not a plan to confuse anglers. Rather, it is forward-thinking biologists and managers trying to provide the best fishing possible.

 

Guiding principles

As recently as 50 years ago, season closures were the most common type of regulation for black bass. The mentality at the time was to protect the spawn. If you had a lot of little fish, the fishing, in time, would be good. Ironically, this outmoded reasoning probably had a lot to do with anglers' present infatuation with stocking.

Times have changed, and season restrictions have, with only a couple exceptions, been abandoned. Creel and length limits are now implemented in all states where black bass are popular sport fish.

Creel limits, or the daily limit, regulate the number of bass an angler can harvest on any given day. Theoretically, the creel limit ensures that individual anglers do not take too many fish, thereby distributing the resource among the users. Because so few bass anglers catch limits on most trips, creel limits generally have little impact.

Length limits determine the segment of the bass population that is available to harvest. Minimum-length limits allow harvest of bass above a certain size, protected slot limits allow harvest of bass below and above some specified size range, and maximum length limits limit the removal of large fish. Length limits tend to have a greater effect on bass populations because they apply to all anglers, whether they catch a lot or a few bass and whether they are fishing for black bass or other species.

Minimum-length limits are used when the population of sexually mature, spawning bass is small and recruitment - the addition of young bass to the catchable and spawning population - is low. A minimum-length limit protects bass to ensure that they have spawned one or more times before they are vulnerable to harvest and also increases the size of bass available to anglers.

A protected slot limit is used to increase the size of the bass in a population when recruitment is high and growth rate of the bass is slow. With high recruitment, protecting spawners and young bass is not necessary. The slot limit is designed to decrease the numbers of small fish and increase the growth rate of large fish. With fewer small bass, more food is available to fuel faster growth of the remaining bass, and the bass in the protected slot quickly grow to memorable and trophy size.

Maximum-length limits are usually "one-over limits," whereby anglers can harvest only one bass per day larger than a specified size. Maximum-length limits are used specifically to build and maintain trophy fisheries.

 

Fine-tuning

Every lake is different, and so is every bass population - different habitat, different forage, different bass growth rates, different spawning success, different amounts of fishing pressure and different amounts of harvest by the anglers.

It makes sense that regulations that work on one lake would not necessarily work as well on others.

Indeed, that is the case, and Mississippi Department of Wildlife, Fisheries & Parks demonstrates its commitment to anglers by providing lake-specific regulations where needed.

The guiding principles described above form the basis for lake-specific regulations, but they are fine-tuned with computer-based population simulation models. Biologists measure the bass's growth rate and the total mortality rate (the percentage of fish that die in a year) for the population. Ideally, fishing mortality (the amount of mortality that is caused by fishing) is also known. The biologist then specifies various length limits, and the computer simulates what the population will be in the future if the length limit were put in place.

A year ago, District I biologist Jason Olive, himself an avid bass angler, was not satisfied with the bass population structure at Aberdeen and Columbus lakes, where biological assessments revealed that less than 15 percent of the largemouth bass larger than 8 inches were larger than 15 inches. Mortality was high, recruitment was variable, and growth rates were above average.

Compared to no minimum-length limit (the 2009 condition), the models predicted that bass over 16 inches would more than double with a 14-inch minimum-length limit; a 15-inch minimum-length limit would provide only modest increases above that.

A 14-inch minimum-length limit was implemented this year. Give the bass in Aberdeen and Columbus a couple years to grow, and we'll see if Mr. Olive and his computer are right.

Of course, the managers can only fairly evaluate the regulation if anglers comply.