Droughts & Floods: What They Mean to Our Bass

October 04, 2010

Over the past few years, North Carolina's largemouth waters have seen severe drought followed by major flooding. We asked the experts how these events have affected the bass populations.

By Tony Garitta

For the past several years, Mother Nature has tested the resiliency of largemouth bass populations in North Carolina's lakes and rivers from Murphy to Manteo.

First, there was central North Carolina's four years of below-average rainfall that culminated in the "exceptional drought" of 2002, the worst since 1927. Heavy rains that persisted throughout the Labor Day weekend of 2002 broke the dry period. Thereafter, a pattern of rainfall developed that would yield record-breaking amounts of rain through the Labor Day weekend of 2003.

Greensboro recorded its wettest August since 1901 with 9.22 inches of rainfall and by Labor Day weekend, it had a total rainfall of 48 inches, a mark that threatened the record rainfall of 57.95 inches set 102 years ago.

The fishing community hailed the downpours as they filled dwindling municipal water-supply lakes and nearly bone-dry reservoirs, some of which had dropped to such low water levels that access areas were closed and fishing either had to be halted or restricted.

The transition from dry to wet counties resulted in an ironic turnabout for fishermen.

Two years ago, some of their fishing waters became inaccessible because of the drought; one year later, some became inaccessible because of high lake levels that covered ramps and roads.

On Feb. 22, 2003, not a single bass was brought to the scales at the Two-Man Team Bass Challenge on Jordan Lake. On March 8, 2003, a 2.06-pound bass was the only fish caught during the American Bass Anglers tournament on High Rock Lake. A weight of 3.97 pounds topped at the March 23 Piedmont Team Tournament on Tuckertown Lake.

Although lake waters were slow to warm, once they did, the fishing exploded.

From late March through May, bass fishermen needed five-fish tournament limits of 20 pounds or more to win team events at High Rock, Falls of the Neuse and Jordan lakes.

In many reservoirs, the spawn itself got a boost from swollen lake levels, which prevented bass eggs from being left high and dry and created more shoreline cover where bass fry could hide from predators.

Despite favorable spawning conditions, fisheries biologists cautioned that only time would tell if high lake levels would result in significant changes in bass populations.

"We won't know the effect for a couple of years," said Wayne Jones, fisheries biologist for District 3.

Scott Van Horn, aquatic non-game supervisor for the North Carolina Wildlife Resources Commission, said that high water can impact the spawn differently depending upon the size of the body of water.

"High water in a reservoir in the spring is probably an advantage to bass spawning," he said. "It may be neutral in terms of eggs produced and hatched, but flooded brush probably raises young-of-the-year bass survival by putting them in an environment that is cover rich and potentially food rich.

"High water in a much smaller reservoir might flush zooplankton from the system making it difficult for small fish. Young-of-the-year game fish rely on zooplankton before they get big enough to feed on insects and fish."

Van Horn put to rest the fear that largemouth bass could be washed downstream - he does not expect that many bass were washed downstream with high flows. Besides, in most reservoirs, flooding does not translate into high flows within the reservoir.

Van Horn said if flood conditions have a negative impact, it's usually upon rivers and streams rather than large impoundments.

From the Piedmont to Raleigh, the soggy conditions were preferred over the multi-year drought.

"It's better to have too much water than no water at all," said Brian McRae, assistant fisheries biologist for District 5. "It's easier to cope with high water levels than it is with low water levels."

However, the favorable outlook upon high water waned in the west. While mountain reservoirs benefited from the heavy rainfall, the rushing waters could have adversely affected the smallmouth bass spawn in streams and rivers.

In the east, the heavy rainfall compounded existing problems in coastal rivers where bass populations were still struggling to recover from high salinity and low oxygen levels caused by hurricanes in the '90s, especially Hurricane Floyd in 1999.

Then a new hurricane hit, again seriously stressing may freshwater fish species living in rivers near the coast.

Let's journey from west to east across the state to examine the impact of last year's rainy season.

WESTERN NORTH CAROLINA

While high water limited boating access on lakes in central North Carolina, the high water improved boating access on western lakes.

"Because our boat ramps on western lakes are affected more by low water, access was probably better overall this spring than in recent years," said David Yow, warmwater research/survey coordinator for the NCWRC.

For reservoirs, the influx of high water was largely positive; for streams, just the opposite.

The heavy rains raised spring water levels on Fontana and Hiwassee lakes, which usually don't fill until midsummer. Last year, they remained high through July.

The high spring levels of mountain lakes probably enhanced the spawn, assuming good numbers of young fish survived their first winter. The extent to which the spawn was successful, however, won't be known for three to five years. Conversely, the flooding in large western streams combined with increased land development might have harmed the smallmouth spawn.

"Increased rainfall also means high levels of sediment washing into the streams," Yow said. "We don't have any information on what effect last year's rainfall had on our smallmouth fisheries, but . . . smallmouth populations are resilient enough to withstand such natural events, at least in areas where human activities haven't severely damaged watersheds and tributary streams," he added.

The heavy rains washed more nutrients and prey into streams for larger fish and brought about changes in water clarity and water temperature that affected fishing, Yow said.

"Overall, the cooler, wetter weather made for a longer spring fishing season in many places, whereas in previous hot, dry springs, spawning and other fish behavior seemed to occur earlier than normal," he said.

CENTRAL PIEDMONT/ RALEIGH AREA

Randy Waterman, a guide on Kerr Lake, and Jeffrey Thomas, a guide on Jordan Lake, said the early spring bass fishing was poor last year on their respective lakes because of muddy water conditions and cooler water temperatures caused by the heavy rains.

High Rock Lake guide Maynard Edwards said last year was one of his toughest as a bass-fishing guide. After an excellent late-spring bite, the fish became unpredictable.

"The high water made fish stay shallow in the spring like they're supposed to," Edwards said. "The lake didn't drop and expose shoreline cover and bass beds as it usually does in the spring. After the spawn, I could see a tremendous number of fry in the pockets of coves. That should be great for the lake in years to come."

Though the fishing was excellent at High Rock throughout the late spring, the high water altered summer fishing patterns, baffling many anglers.

"High Rock fishermen have never seen the lake this high in the summer," Edwards said. "It was a new experience for everyone. The high water repositioned the fish, and there was no consistency to the bite."

An April 2003 electrofishing sampling of High Rock conducted by District 6 fisheries biologist Lawrence Dorsey and assistant fisheries biologist Bob Barwick indicated High Rock had recovered from the drought of 2002.

"The catch rate for bass is a little down from what it was in 2001, but it's consistent with what we saw in 1999," Dorsey said. "The catch rate at High Rock is still one of the highest in the state for bass."

Except for the unique situation at High Rock, fisheries biologists did not observe any major changes wrought by the heavy rains on Piedmont or Raleigh lakes.

McRae said the wet weather had little impact on Jordan Lake or water supply reservoirs in his district.

"There were no major effects at Jordan on fish or fish habitat, and there were no dissolved oxygen problems like elsewhere," he said. "The spawn should have been successful.

At Falls of the Neuse, Jones said he didn't expect any long-term damage from the heavy rains or any significant changes in fish habitat or lake structure. The bass should have had a productive spawn.

"We anticipate that largemouth fishing will again be excellent in Falls next year," Jones said.

EASTERN NORTH CAROLINA

While the heavy rains replenished water-starved reservoirs in most parts of the state, they thwarted the NCWRC enhancement program for largemouth bass in coastal rivers.

"Heavy rains and receding flood waters have lowered oxygen levels and have made many areas of our coastal rivers unsuitable for fish," said District 1 fisheries biologist Chad Thomas."

Droughts didn't help, either.

"What we have been dealing with the last two years are environmental conditions that fall on both ends of the spectrum: drought and flood," Thomas said. "Under both scenarios the effects on the bass population are negative."

One objective of the enhancement program was to increase largemouth bass populations by stocking 2- to 3-inch micro-tagged fingerlings within designated sites in selected coastal rivers.

The electrofishing samples of these stockings proved disappointing.

In May 2002, 15,000 fingerlings were stocked in 10 shoreline sites within the Chowan, Pasquotank, Perquimans and Scuppernong rivers. Biologists allotted the tagged fish a five-month period before revisiting the sites in October. During that time, the fingerlings could either be eaten by predators or stray from their selected sites or grow into subadults, the last possibility being, obviously, the most desirable.

The October electrofishing sample revealed low returns of stocked fish.

"What we noticed was that at most sites, summer water quality was poor as indicated by low oxygen levels or high salinities or both," Thomas said.

"When oxygen levels at our sites drop below 2 parts per million, which has been the case at several sites, it doesn't matter how many fish we stock: They can't breathe. When this occurs, they can either stay and be stressed or possibly die or move in search of more suitable habitat."

Another sampling occurred April 2003 to determine how many tagged fish survived the winter. The returns of tagged fish, now age 1, were low with only 53 age 1 bass recovered from the 10 selected sites. Of the 53 fish, only three were tagged fish from the original stocking of 15,000 fingerlings.

"Not a stretch to say our stockings were unsuccessful," Thomas said. "For stockings to be successful, not only do the fish have to survive, they also have to stay in the areas where they are needed."

The stocking study was repeated in June 2003, only this time the 15,000 tagged fingerlings were scatter-stocked in four selected rivers and immediate efforts were made to determine the

effect of predator fish upon the stocked fish.

Samplings indicated predation was high on stocked fish and, in one instance, took on a bizarre twist.

"In one of the Perquimans River sites, we found that two 9-inch bass had eaten three of our 2-inch tagged bass. So our attempts to increase the number of bass in this area were foiled by the very species we are trying to enhance."

In October 2003, biologists were to have checked the tagged fish again to assess the survival rate.

Monthly water quality checks at the stocking sites showed disturbing results.

"As was the case in 2002, dissolved oxygen is very low," Thomas said. "Heavy rains and receding flood waters have lowered oxygen levels and made many areas of our coastal rivers unsuitable for fish."

Assessments of coastal rivers indicate that the Chowan and Roanoke rivers offer the most promise for largemouth bass fishermen. The spring 2003 catch rate on the Chowan was 24 adult bass per hour; on the Roanoke, 25 adult bass per hour, both increases from previous samples.

Data indicates the Chowan has rebounded from the effects of Hurricane Floyd and it doesn't have the salinity and dissolved oxygen problems found in other coastal systems.

Studies also show that recruitment of young-of-the-year bass on the Roanoke has surpassed that of any other river system, though oxygen levels in the summer of 2003 were poor in the lower Roanoke.

"The Roanoke River at times is the hottest largemouth bass spot on the coast," Thomas said.

Catch rates on the Perquimans improved from 13 fish per hour in 2002 to 23 fish per hour in 2003, yet the waters above Hertford had low oxygen levels during the summer.

"If these adult bass are able to move into more suitable habitat until conditions improve, the Perquimans River may be a good bet in 2004," Thomas said.

Although the number of adult bass increased in the Scuppernong River in 2003, the river suffers from high salinity and low oxygen levels that might hurt recruitment of the 2002 year-class of fish.

The Pasquotank River faces encroaching salinities in its lower reaches and low oxygen in its upstream areas resulting in low survival rates for young bass.

"This situation has crippled the largemouth bass population in the Pasquotank," Thomas said.

The North River also has had saltwater intrusions into its upper reaches, but an August 2003 sampling showed increased catch rates, offering hope for the fishery.

The Alligator River and Currituck Sound had increased salinity levels because of drought conditions in 2002 that hindered bass reproduction. At Currituck, high salinity levels forced bass into small creeks and manmade canals for survival.

"Although heavy rains in the drainage in 2003 have freshened Currituck Sound, the pattern over the last 15 years continues to be one of elevated salinities and loss of aquatic vegetation in the main body of the sound," Thomas said.

"Tullis Creek and the Northwest River are protected from saltwater intrusion and continue to support the best largemouth bass populations in the Currituck Sound area."

In September its resiliency would be tested again. Hurricane Isabel struck the Carolina coast, and pushed large amounts of saltwater into the river systems. Only time will tell how the bass population responds to this, but Isabel may well dampen the fishing in parts of the coast for some time.

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