If you insist on catching that trophy bass in the Magnolia State, I suggest January and February are your best chances. But have you ever wondered about the odds of catching a true trophy bass? Let me tell you a fish story.

Dec. 30, 2006. Ben Davis and I were fishing Bay Springs Lake, a 6,700-acre reservoir in Northeast Mississippi. We’d caught a few chunky largemouth and spotted bass off shallow wood.

About 9 a.m. we stopped on a brushy point. On the third cast, Davis’ rod bowed under the strain of a large fish. Three precarious minutes later, I slid the net under Ben’s 12-pound, 10-ounce largemouth. This was a special day.

Bay Springs, the upstream reservoir in the Tennessee-Tombigbee Waterway, produces a good number of 7s, 8s and a few 9s, but it’s not on the list of places to go to catch the bass of a lifetime.

As we fished out the day, I kept thinking about the odds of catching a bass of that magnitude. The first question to answer was how many 12-pound bass are in Bay Springs. When I returned home, I dug out some research papers and did a few calculations.

First off, 12 years old is a reasonable estimate for a 12-pound largemouth in Mississippi. To grow to 12 pounds, the fish has to survive both fishing and natural mortality for 12 years.

I assumed a very low exploitation rate — the portion of the population harvested every year — of only 10 percent, an appropriate number for a fishery where anglers have a strong catch-and-release ethic. Based on a compilation of bass population studies from across the country, a 10-percent exploitation rate corresponds to a 50-percent annual mortality rate.

A reasonable estimate of the number of yearling bass in mesotrophic Bay Springs Lake is about 50 per acre, or 335,000 bass in the 6,700-acre lake. At 50-percent annual mortality rate, 654 of these fish would still be alive at age 10, 164 alive at age 12, and 20 alive at age 15. If Ben’s bass grew to 12-10 in 12 years, it would be one of 164 12-year-old bass in the lake, and the density of 12-year-old bass would be one fish per 40 acres.

Of course, the number and density of big fish declines as exploitation rate increases or growth rate slows.

Knowing that the lake has trophy fish is one thing — catching them is another matter. The FLW Tour and Stren Series maintain records of big bass, so I looked at the big-bass awards in FLW tournaments during the five-year period from 2002 to 2006. I excluded events in northern waters like Champlain, Erie and the upper Mississippi River — fisheries that are primarily smallmouth and aren’t going to produce a double-digit largemouth.

FLW Tour Pros and co-anglers logged 20,500 angler days. The biggest bass was 10-4. FLW Stren Series anglers did better. They caught 13 10-pound bass, five 11s, three 12s and two 14s in 44,044 angler days. Two of the 12s and both 14s were caught in the California Delta or Clear Lake, Calif.

So how hard is it to catch a bass over 12 pounds? The best anglers fishing the best bass waters at the best times caught five bass over 12 pounds in 64,544 angler days. That’s an average of almost 13,000 days for a fish over 12. Relating that to an avid angler who fishes 50 days a year, it will take about four lifetimes to catch a 12-plus.

And you should probably plan a couple trips to the California Delta, Clear Lake and other noted trophy-bass fisheries.