The SM/LM Ratio
If your lake contains bass, chances are you have some combination of smallmouths and largemouths. That’s the case here on Birch Lake, although the ratio has varied over the years. When we started vacationing here more than three decades ago, largemouths dominated. In fact, I never caught a smallie until after the rusty crayfish decimated the weedbeds and exposed the rocky bottom habitat they prefer.
Then, for years, we had trophy smallies, but I never saw a largemouth. Now they big-mouths are blending in – a few weeks ago I caught one that likely topped 20 inches. They’re returning because the aquatic vegetation is regrowing with the collapse of crayfish population.
Smallmouths still dominate, though, and I must say I prefer them as a sport fish. I caught one for the first time when I was eight or nine years old, fishing with my parents from a rowboat on a lake in Michigan’s Upper Peninsula.
It fought like mad and boiled the surface a few times; I thought I had a lunker on the line. But it measured half an inch below what was then the legal size limit of 10 inches. Back then, the lake where I caught that smallie actually held more largemouths. Now, six decades later, the proportion seems to be about 50-50 if my unscientific sampling is to be trusted.
The same is true on another of my favorite UP lakes. The interesting part is how they’re distributed. The smallies hang out mostly in the deep, hard-bottom stretches of open water, especially on and around a mid-lake rock hump that rises from about 18 feet into seven feet of water.
The largemouths patrol a weedy sandbar not far out from the boat landing, and a shallower, warmer, weedier area on the lake’s farthest end. If you get a strike on a swim bait or a leech on a slip bobber, you can pretty well guess which bass species you’ll bring in, based on the habitat where you’re fishing.
As a kid I struggled to tell the two species apart. I made the mistake of focusing on the size of the mouth instead of the largemouths’ signature black stripe down the side, and the smallmouths’ greenish-bronze coloring and bright-red eyes.
The most compelling way to distinguish a smallmouth, though, is to get one on the line. No disrespect to largemouths, but as fighters, smallies simply punch far above their weight class. Their resistance is tenacious; when hooked they’ll leap two feet clear of the water.
Smallmouth are also, to me, slightly more elegant, more sophisticated creatures. If largemouths are beer and bluejeans, smallmouths are brandy and khakis. If largemouths are tavern brawlers, smallies are fine-tuned, highly trained fighters. If all that seems elitist, so be it.
It’s also true that smallmouths relatively more intolerant of pollution; their presence in a lake is an indication that water quality is pretty good. That’s one more reason I’m glad to have them in Birch Lake, and you may appreciate their presence in your favorite body of water.