September 30, 2010
From the Potomac River on Virginia's border with Maryland to the Holston at our border with Tennessee, here's what's happening with smallmouth bass in Virginia's top waters. (February 2007)
VDGIF biologist Scott Smith holds a smallmouth taken on the upper James River. Smith, an avid angler himself, is the VDGIF's point man on smallmouth bass fisheries.
Photo by Bruce Ingram.
Arguably, the smallmouth bass is the second most popular freshwater game fish in Virginia, behind only the largemouth. And traditionally, the Old Dominion has provided some of the highest quality river and lake brown bass action in the country. Let's take a look at the main river systems in Virginia and how they are doing biologically with respect to smallmouth production and health.
THE BASICS: SPAWNING AND MORTALITY
"It looks like most of the spawning takes place from about April 15 through June 30," said Scott Smith, a fisheries biologist for the Virginia Department of Game and Inland Fisheries (VDGIF), who provides an overview of our fisheries. "These dates change somewhat each year based on flows and water temps, but that's a pretty good general rule."
The exact dates vary according to a number of factors, including things as simple as the size of the river the fish live in; the spawn in smaller rivers can be earlier if those rivers warm up faster in the spring, while rivers below dams, for example, the New below Claytor, seem to be a little later due to the colder water.
The survival rates of smallmouths also vary significantly by river.
"Our best estimates put total yearly survival in the 40 to 80 percent range, depending on the river and year for adult fish," Smith said. "This means in some rivers we see as high as 80 percent annual survival, while in others, it's down to 40 percent. This plays a big role in how many bigger fish are out there. The statewide average runs in the 60 to 65 percent annual survival range."
Smith cautioned that these numbers are not exact, as survival is a very hard thing to estimate in these populations, but he does believe that the numbers are pretty close.
One thing that does not normally appear to significantly hurt the success of the spawn is fishing over spawning fish.
"Fishing on spawning beds probably doesn't have a huge impact unless fishing pressure is really heavy," Smith said. "A couple of studies have found that most spawning beds don't produce any fish to adulthood. Something like 90 percent of the fish in any given year come from about 10 percent of the beds. Most of the beds end up failing from various causes, such as being washed out, predation by fish or invertebrates, fungus on the eggs, or predation on the fry as soon as they swim up. I don't have a number as to what percentage of fry survive to their first year, but my best guess is that it's in the 1 to 2 percent range. I do know that the number is very, very low."
Smith added that sometimes Virginia river smallies spawn as early as March and as late as July, but those are "freak" occurrences. To spawn, brown bass need at least a water temperature of 58 to 60 degrees, he said, and the photoperiod (length of day) is a contributing factor to begin the process. That's why, even if, say, the water temperature warms into the low 60s in February, the smallmouths would not spawn because the day length is not long enough. Also, the fish know instinctively not to spawn in very negative conditions, such as floods. The peak reproductive period is usually the last two weeks in May.
When eggs and fry are in an area, many factors come into effect that are often more important than fishing pressure.
That certainly was the case for the 2006 spawn on state rivers. During the reproductive period, the water was very low because of dry weather conditions. And that situation is generally a recipe for the loss of a year-class, Smith explained. When water levels are below normal, the nests and fry are concentrated in smaller areas. More competition for food exists, and predators can more easily find -- and consume -- the eggs and fry. Also, less food enters the overall spawning area because of the reduced flow. What state river smallmouths need, said Smith, are moderate flows and "normal" weather.
In late June, flooding conditions prevailed on our western Virginia rivers. However, the biologist continued, by then, the 2006 year-class was already a failure.
"When the high water came in late June, adult bass moved laterally from the main channel to the banks and, in some cases, into the flood plain beyond the banks," Smith said. "When the water began to recede, the adults followed.
"The 2006 year-class likely did the same. A fish's swimming speed is based on how long it is. The 2006 class was probably 1/2 to 3/4 inch by then, long enough so that they could successfully deal with the high water. Smallmouths less than 1/2 inch usually can't deal with flooding and are swept away."
Statewide in our smallmouth rivers overall, the biologist offered these general classifications for recent year-classes: 2005 (pretty good), 2004 (great), 2003 (awful), and 1998 to 2003 (bad). He emphasized that a "pile" of fish fin in our rivers from the 2004 and 2005 year-classes and that in 2007, members of the 2004 year-class should be 11 to 12 inches and members of the 2005 class should be 8 to 10 inches. Generally, Virginia river smallmouths take three to four years to attain a foot in length.
Smith then offers these last words on the spawn.
"I can see how fishing pressure during the spawn could have an effect on small creeks," he said. "Those fish are much more visible. But in a flowing river with current, it is very hard for many anglers to even spot a bed."
As Smith commented earlier, the mortality rate of any given river smallmouth year-class is quite high. Winter die-off is an especially major factor. Here are the latest figures on survival rates for a given year-class on our major rivers.
€¢ 40 percent survival rate on the Rappahannock system -- the worst in the state.
€¢ 50 to 60 percent survival rate on the James.
€¢ 70 to 80 percent survival rate on the upper New and the Holston -- the best in the state.
Also, Smith listed how much time expires on various rivers before a given bronzeback reaches 18 inches -- a universally recognized "nice" one.
€¢ Lynchburg to Richmond section of James: 7 1/2 years.
€¢ Upper James: 9 1/4 years.
€¢ Staunton: 8.2 years.
€¢ Upper New and Main Stem of Shenandoah: 9 1/2 years.