Spring bass closures have gained even greater significance in recent years following the efforts of bass researcher Dr. Mark Ridgway of the Ontario Ministry of Natural Resources. For the past 16 years, Ridgway has headed a team of biologists working out of the Harkness Laboratory of Fisheries Research in Algonquin Provincial Park. His work on the smallmouth bass of Lake Opeongo has contributed to the longest continuous census of any animal population on earth, nearly 70 years worth of data. Ridgway’s findings have shed light on factors that determine the reproductive success and year class production of smallmouth bass in Ontario waters.

One of Ridgway’s most significant discoveries was that smallmouth of this region don’t spawn for the first time until they’re between five and nine years old and between 10 and 16 inches long. Also, the timing of an individual’s spawning is based on its size. As a rule, large males and females spawn earlier in spring than smaller fish. This difference is hugely important for reasons we’ll see in a minute.

Perhaps Ridgway’s most astonishing finding, though, is the revelation that only about one-third of all adult smallmouths actually attempt to spawn in a given year. Moreover, the factors that determine which bass comprise the limited spawning cadre are established during the previous summer.

“What this means,” Ridgway says, “is that if you pull a bass off a nest, no rush of new fish are waiting to move in. Once the spawning decision is made, it’s final. Pull a male off his nest, and no one else will replace him.

“Furthermore,” Ridgway says, “if the population of larger smallmouth is fished down, smaller bass must be rushed into the spawning stock—ahead of their time—to assume the spawning chores in subsequent years. But smaller bass spawn later than larger fish, even when small bass are the only nesters left in a lake.”

The offspring that small bass produce are at a distinct disadvantage in reaching the critical size necessary to survive the winter starvation period. For all intents and purposes, bass don’t eat once a lake freezes. As a result, young-of-the-year bass must eat and grow fast enough in the first year of life—typically to the size of your little finger—to survive to the following spring. Thus every day’s delay in the egg-laying stage is another potential threat to survival. But the scenario gets worse still.

“Once the big bass population has been ratcheted down through harvest, small bass are forced to start spawning ahead of their time, thereby reducing their reproductive life span to just one or two years,” Ridgway explains. “Like the young-of-the-year, they starve to death during winter. Smaller nesting bass, 12 inches or so, suffer a high mortality rate—the cost of reproduction.

“Few of these fish survive to spawn twice. But, as the size of nesters increases, up to seven, eight, nine or more years of age, the return rate is much higher. Older bass don’t seem to pay a survival price in terms of reproduction as smaller fish do.”

These severe conditions scarcely affect southern bass or southern bass anglers, as frozen lakes are rare south of Kansas. In warmer regions, largemouth and smallmouth bass can feed year-round. They essentially avoid the crucial winter starvation period, yielding fitter bass and greater numbers of spawners. The annual production of strong year classes of bass increases the farther south you travel.

Catch and Release

What about catch and release of spawning bass? Several northeastern states recently have imposed such a regulation, banning harvest yet allowing anglers to target bass. In the south, the often long spring spawning period is considered by most anglers to be the best time to fish. In the north, however, the practice can be harmful, and according to Dr. Ridgway, can seriously decrease reproductive success.