Parasites Remain in Smith Mountain Lake Striped Bass Dec 13, 2019 18:20:40 GMT
Post by Ghost Comanche©® on Dec 13, 2019 18:20:40 GMT
Parasites Remain in Smith Mountain Lake Striped Bass
by the Roanoke Times
The striped bass fishery at Smith Mountain Lake is on a rebound, but it isn’t likely to fully shake a parasite problem, according to Dan Wilson, a biologist of the Department of Game and Inland Fisheries.
Wilson told members of the Smith Mountain Striper Club that the infestation of parasites is expected to vary, but stay near current levels, which are much reduced from when the copepods first showed up in the early 2000s. There is no known way to eradicate them in a large lake environment, he said.
“The parasites have not disappeared in any waters they have become established, so there is no evidence that they will ever go away,” Wilson said in written remarks to the club.
The parasites are thought to have played a role in a major die-off of adult stripers about a decade ago when they were at their highest concentrations.
The concern now is that they might slow the growth of striped bass, Wilson said.
They can cause increased respiration which boosts metabolism, meaning the stripers need more forage to survive.
“More food going to metabolic needs may be less resources going to growth,” he said. That could be a problem when it comes to producing the trophy stripers that once put Smith Mountain on the map.
“We have to wait a few more years to observe fish stocked after the fish kill to get a better idea of what to expect,” Wilson said.
Answering a question often asked, Wilson said there is no evidence that eating fish infected with the copepods can cause harm to humans.
Where did the parasite come from?
Evidence gathered from kills in Virginia and North Carolina suggest that the parasite in fairly new to these areas. Previous research on the parasite in Europe showed that a heavily infested fish would have 7-8 copepods inside the mouth. It was also shown that approximately 30% of the population was infested with the parasite. A few striped bass collected in Smith Mountain Lake had over 400 parasites attached inside the mouth and every fish that biologists have captured in the past two years has had some level of infestation (incidence rate of 100%). This evidence suggests that the striped bass in Smith Mountain Lake may be naïve to the parasite and are heavily infested.
Dan Wilson (VA) has shown that the striped bass parasite showed up in the headwaters of the Roanoke River and has eventually moved down the river system into bordering waters of North Carolina. This suggests that the parasite is spreading throughout the system and may have been introduced.
Others believe the parasite has been around for a long time and conditions are right for it to cause fish kills. These fish kills have put the parasite on the map.
Other species can carry the Copepod parasite.
The parasite has been found on a variety of fish, but fish kills have only occurred in striped bass populations. Biologists from Tennessee have found the copepod in small numbers on largemouth and smallmouth bass.
Identification and life cycle of the parasite
The copepod is easily identified in its adult life stage and can be found inside the mouth of adult striped, largemouth and smallmouth bass. The parasite will attach to the gill cartilage, mouth and tongue. Two large egg sacks are indicative of adult females attached in the mouth.
The life cycle of this copepod is similar to other species of parasites, where sub-adult life stages can be found on the gill filaments. These life stages mature and migrate to the inside of the mouth to release eggs and infest other striped bass.
Anecdotal evidence has shown that high concentrations of salt can effectively control the parasite. Employees for a large aquarium in Virginia have eliminated the copepod from striped bass by switching from freshwater (salinity 1-5 ppt) to saltwater (20-25 ppt salinity).
Thankfully, the parasite does not cause fish kills in every lake where fish have been found to harbor the pathogen. The copepod has been found in the following lakes in Tennessee, but no striped bass kills have occurred:
Watts Bar, Tims Ford, Old Hickory, Tellico, Melton Hill, and Cherokee. All kills took place when striped bass were exposed to stressful conditions (high water temperature and limited forage).
Parasite did not seem to affect smaller fish (up to 1 ½ years of age—20-24”).
Kills have subsided and there have been no repeat kills.
Where has the copepod been found?
The parasite has been found in the following reservoirs and watersheds in Virginia, North Carolina, Tennessee, Virginia, North Carolina and Arkansas.
1981 - Tellico Reservoir, TN - largemouth bass
2000 - Watts Barr Reservoir, TN - striped bass
2000 -Tim’s Ford Reservoir, TN - striped bass
2001 - Melton Hill Reservoir, TN - striped bass
2001 - Watauga Reservoir, TN - 1 smallmouth bass
2002 - Old Hickory Reservoir, TN - striped bass
2002 - Norris Reservoir, TN - striped bass
2002 - Smith Mountain Lake, VA - striped bass
2003 - Kerr Reservoir, VA - striped bass
2003 - Leesville Resrvoir, VA - striped bass
2004 - Lake Norman, NC - striped bass
2004 - Gaston Reservoir, NC - striped bass
2004 -Tellico Reservoir, TN - 1 striped bass
2004 - Smith Mountain Lake, VA - largemouth
2004 - Cherokee Reservoir, TN - black bass
2005 - Cherokee Reservoir, TN - white bass (angler report)
2006 - Ouachita Lake, AR - striped bass
2006 - Fort Patrick Henry Reservoir, TN - striped bass (angler report)
2006 - Hiwassee River, TN - striped bass (angler report)
2007 - Cherokee Reservoir, TN - striped and hybrid striped bass