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Lake Tahoe and Yellowstone Lake have many things in common
Dave Rice, RENO GAZETTE-JOURNAL
9/30/2003
At an elevation of 6,228 feet, Lake Tahoe is the second largest body of water at that or any greater elevation in the world.
I have come across that fact many times in various publications, but never took the time to find out which body of water is the largest. Then on a recent visit to Yellowstone National Park (YNP) I found it quite by accident. Yellowstone Lake, lying at an elevation of 7,732 feet, is about 14-by-20 miles, with more than 110 miles of shoreline. Its average depth is 139 feet, with its greatest depth between 387 and 400 feet depending on the source of information.
Lake Tahoe’s vitals are a bit smaller. It is 12 miles by 22 miles, with about 72 miles of shoreline. Its greatest depth, 1,645 feet, is far greater than Yellowstone. So when full, it appears that Lake Tahoe probably holds far more water than Yellowstone.
There are a number of similarities between the two lakes, including concerns over native and alien fish found in both. In two recent columns, I discussed concerns about potential predation posed by introduced mackinaw trout in Lake Tahoe on Lahontan cutthroat trout should the decision be made to reintroduce them into the lake.
At Yellowstone Lake (YL), there is a similar concern, but the story is a little different. In YL, there is a well-established native population of Yellowstone cutthroat that are tenaciously protected by the National Park Service (NPS). You are allowed to catch these fish, but all must be released unharmed. Things were going well until July 29, 1994, when a young angler on YL reeled in a mackinaw trout, known there as lake trout, according to Marsha Karle, NPS chief of public affairs at YNP.
According to Karle, no one knows how the fish got into YL, but through extensive studies, it appears they were probably transported from nearby, and downstream, Lewis Lake where they were legally introduced more than a century ago, about the same time Lake Tahoe received them. There is no natural way the fish could have migrated into YL from Lewis according to NPS.
Illegal introductions by person or persons unknown is one theory on how they got into the lake; however, the possibility exists that a helicopter may have “...inadvertently scooped the lake trout from Lewis Lake while fighting the 1988 fires and dumped them into Yellowstone,” according to an online report by the Greater Yellowstone Coalition (GYC) (greateryellowstone.org).
According to Karle, NPS’s major concern in learning that the mackinaw now inhabits YL is that this alien would feed heavily upon the native cutthroat. It is estimated that one mackinaw can eat up to 50 to 60 cutthroats each year, and that if no action was taken to eradicate the mackinaw, the cutthroat population could decline 50 to 90 percent in 20 to 50 years.
NPS estimates that 75,000 of the park’s three million annual visitors fish while at the park, and the financial loss caused through the loss of the cutthroat is estimated at $36 million annually. In addition, NPS says the potential ecological losses are equally staggering. The cutthroat is an important food species of 42 species of animals in the park, including those of special concern like the grizzly bear, bald eagle and osprey. Because of its habit of living on the bottom of the lake, NPS says mackinaw will not replace the cutthroat as food for animals nor as an easy catch for anglers.
Realizing that total eradication of the mackinaw was never going to happen once it became established in YL, NPS has taken two major steps to reduce the population. The first was to adopt a regulation that requires anglers who catch mackinaw in YL and its tributaries to immediately kill them, even if they wish to return them to the water. The second is a major gill netting operation, something that was mentioned by a member of the Tahoe Research Group as a way to reduce the mackinaw population at Lake Tahoe should cutthroat be reintroduced.
Gill netting got off to a bad start in 1995, according to the GYC report, with gill netting crews catching 250 cutthroat for every mackinaw in the net. Gill nets are set vertically in the water, with floats on the top and weights on the bottom, hanging like a great big curtain in the water column. Fish that are too large to go through the net’s mesh “holes” go around or turn back. Small fish just swim through the mesh holes, while many others swim into the holes and get snared, at about their gills, as they try to swim through. Many die after struggling for hours to get free. Others bleed to death as they rupture their gills.
Once the gillnetters learned that mackinaw are deep dwellers in the lake (amazingly, they had to study the mackinaw population in the Great Lakes to find this out), and they switched to smaller mesh nets, the ratio dropped to one cutthroat to 50 lake trout. NPS now operates a 32-foot gill netting boat on YL and boasts a take of 15,000 mackinaw last year, the highest on record, for a total of 56,000 since 1994.
According to Karle, NPS gillnetters are not catching as many fish as they did two years ago, which they interpret as making an impact on the population. The GYC report concurs with that conclusion, “The average size of the Lake trout is decreasing, indicating that the population of spawning-size fish is shrinking.”
On this subject, a recent NPS report, Yellowstone Resources and Issues 2003, concludes, “Lake trout cannot be eliminated from YL.” However, the report also includes a more optimistic outlook, “With continued aggressive control efforts, lake trout numbers can be reduced and the impacts to cutthroat trout lessened.”
Dave Rice retired in 2001 after 30 years with the Nevada Division of Wildlife, 25 years as chief conservation officer. He can be reached at thomascreek@worldnet.att.net.
Dave Rice, RENO GAZETTE-JOURNAL
9/30/2003
At an elevation of 6,228 feet, Lake Tahoe is the second largest body of water at that or any greater elevation in the world.
I have come across that fact many times in various publications, but never took the time to find out which body of water is the largest. Then on a recent visit to Yellowstone National Park (YNP) I found it quite by accident. Yellowstone Lake, lying at an elevation of 7,732 feet, is about 14-by-20 miles, with more than 110 miles of shoreline. Its average depth is 139 feet, with its greatest depth between 387 and 400 feet depending on the source of information.
Lake Tahoe’s vitals are a bit smaller. It is 12 miles by 22 miles, with about 72 miles of shoreline. Its greatest depth, 1,645 feet, is far greater than Yellowstone. So when full, it appears that Lake Tahoe probably holds far more water than Yellowstone.
There are a number of similarities between the two lakes, including concerns over native and alien fish found in both. In two recent columns, I discussed concerns about potential predation posed by introduced mackinaw trout in Lake Tahoe on Lahontan cutthroat trout should the decision be made to reintroduce them into the lake.
At Yellowstone Lake (YL), there is a similar concern, but the story is a little different. In YL, there is a well-established native population of Yellowstone cutthroat that are tenaciously protected by the National Park Service (NPS). You are allowed to catch these fish, but all must be released unharmed. Things were going well until July 29, 1994, when a young angler on YL reeled in a mackinaw trout, known there as lake trout, according to Marsha Karle, NPS chief of public affairs at YNP.
According to Karle, no one knows how the fish got into YL, but through extensive studies, it appears they were probably transported from nearby, and downstream, Lewis Lake where they were legally introduced more than a century ago, about the same time Lake Tahoe received them. There is no natural way the fish could have migrated into YL from Lewis according to NPS.
Illegal introductions by person or persons unknown is one theory on how they got into the lake; however, the possibility exists that a helicopter may have “...inadvertently scooped the lake trout from Lewis Lake while fighting the 1988 fires and dumped them into Yellowstone,” according to an online report by the Greater Yellowstone Coalition (GYC) (greateryellowstone.org).
According to Karle, NPS’s major concern in learning that the mackinaw now inhabits YL is that this alien would feed heavily upon the native cutthroat. It is estimated that one mackinaw can eat up to 50 to 60 cutthroats each year, and that if no action was taken to eradicate the mackinaw, the cutthroat population could decline 50 to 90 percent in 20 to 50 years.
NPS estimates that 75,000 of the park’s three million annual visitors fish while at the park, and the financial loss caused through the loss of the cutthroat is estimated at $36 million annually. In addition, NPS says the potential ecological losses are equally staggering. The cutthroat is an important food species of 42 species of animals in the park, including those of special concern like the grizzly bear, bald eagle and osprey. Because of its habit of living on the bottom of the lake, NPS says mackinaw will not replace the cutthroat as food for animals nor as an easy catch for anglers.
Realizing that total eradication of the mackinaw was never going to happen once it became established in YL, NPS has taken two major steps to reduce the population. The first was to adopt a regulation that requires anglers who catch mackinaw in YL and its tributaries to immediately kill them, even if they wish to return them to the water. The second is a major gill netting operation, something that was mentioned by a member of the Tahoe Research Group as a way to reduce the mackinaw population at Lake Tahoe should cutthroat be reintroduced.
Gill netting got off to a bad start in 1995, according to the GYC report, with gill netting crews catching 250 cutthroat for every mackinaw in the net. Gill nets are set vertically in the water, with floats on the top and weights on the bottom, hanging like a great big curtain in the water column. Fish that are too large to go through the net’s mesh “holes” go around or turn back. Small fish just swim through the mesh holes, while many others swim into the holes and get snared, at about their gills, as they try to swim through. Many die after struggling for hours to get free. Others bleed to death as they rupture their gills.
Once the gillnetters learned that mackinaw are deep dwellers in the lake (amazingly, they had to study the mackinaw population in the Great Lakes to find this out), and they switched to smaller mesh nets, the ratio dropped to one cutthroat to 50 lake trout. NPS now operates a 32-foot gill netting boat on YL and boasts a take of 15,000 mackinaw last year, the highest on record, for a total of 56,000 since 1994.
According to Karle, NPS gillnetters are not catching as many fish as they did two years ago, which they interpret as making an impact on the population. The GYC report concurs with that conclusion, “The average size of the Lake trout is decreasing, indicating that the population of spawning-size fish is shrinking.”
On this subject, a recent NPS report, Yellowstone Resources and Issues 2003, concludes, “Lake trout cannot be eliminated from YL.” However, the report also includes a more optimistic outlook, “With continued aggressive control efforts, lake trout numbers can be reduced and the impacts to cutthroat trout lessened.”
Dave Rice retired in 2001 after 30 years with the Nevada Division of Wildlife, 25 years as chief conservation officer. He can be reached at thomascreek@worldnet.att.net.
