Post by johnr on Jul 27, 2015 6:45:07 GMT -5
It's apparent that some of us feel there should be some submerged aquatic vegetation (SAV) in the lake. I'll provide some facts and observations to start the conversation.
The last year I observed any large amounts of SAV was 2012. There were large beds in nearly every Blackwater creek, and a few large beds between Beaverdam and the bridge on the Roanoke Side. There were smaller stands trying to establish above Beaverdam, and in a lot of the creeks below the bridge. Most of the SAV at that time, visible from a boat, was Hydrilla. Hydrilla is non-native, and extremely aggressive. This plant is the focus of the SAV control implemented at SML. Hydrilla is/was also present and controlled in Claytor, Buggs, Gaston and Roanoke Rapids (to a lesser extent). The primary means of control had been spraying in the fall with an aquatic herbicide. In the spring of 2013, 6000 grass carp were stocked in Bull Run.
In the fall of 2013, there was NO noticeable SAV in Bull Run. This is a huge change from the previous year, when any depths under 12' were matted with Hydrilla. In the fall of 2013, other parts of the lake still had some SAV, but the beds were noticeably smaller. By mid summer 2014, there was no grass ANYWHERE in the lake, that I had noticed. Not only did the carp control the non-native grasses such as Hydrilla, curlyleaf pondweed and brittle naiad, but they ate the few stands of acceptable grasses such as coontail and sago pondweed.
Some observed effects since the removal of SAV:
- Muddier water. The water in the back of Bull Run is noticeably dingier since the grass is gone. Other creeks tended to always be muddier, but Bull Run was typically very clear water, even in the back.
- Less YOY fish. This is noticeable in cast net by catch.
- Less YOY baitfish in certain areas by fall. Previously smaller gizzards would utilize the dense vegetation as summer refuge while they grew.
- Less panfish of keeping size. No grass = lower recruitment. Specifically Yellow Perch and larger sunfish.
- Less fishing opportunity. Those grass beds provided a lot of opportunity. Bass, sunfish, perch, and catfish could all be caught near or in the cover of those beds. Now those areas are generally poor for catching.
- More geese spread through yards. Typically the geese would congregate on these grass beds in late summer and early fall, gorging on the available food. This would remove them from peoples yards, and keep them out of sight for the most part. Now the geese are in yards, since there is no SAV to eat. There are no fewer geese, they are just spread out more. They will be the next "invasive" species to be eradicated.
- Far fewer migratory waterfowl in the winter staying on the lake. No food is to blame.
So what can be done??
I'm personally not sure that much CAN be done here. The lake group$ want to see the grasses gone so it doesn't tangle in their toes, ski boat props, and jetski pumps. I imagine they'd like to see a pristine lake, where you can see the barren bottom through 20' of crystal clear water. With the addition of the grass carp, any healthy and acceptable SAV would be wiped out rapidly. SAV such as Coontail, Sago pondweed, and Canadian Elodea, while acceptable, will still "top out" and mat just like Hydrilla, if not worse. SML does not have many/any 'offshore' areas that are shallow enough and the right bottom composition to allow SAV growth. This leaves only the narrow margins of 1-15' water depths in the creeks and channel for SAV beds. Unfortunately these areas are the same areas used by the lake residents that don't want the grass.
At Philpott, there are several deep and dense SAV beds. These beds originate in the 20' range and typically stand 6-10' tall. They do not mat, unless the lake is extremely low. If we could find out what type of plant this is, maybe we could push for this to be introduced at SML. These are likely more beneficial than the shallower and densely matted beds that we previously had. It may have trouble rooting at SML though, just due to the poor water clarity at that depth.
The last year I observed any large amounts of SAV was 2012. There were large beds in nearly every Blackwater creek, and a few large beds between Beaverdam and the bridge on the Roanoke Side. There were smaller stands trying to establish above Beaverdam, and in a lot of the creeks below the bridge. Most of the SAV at that time, visible from a boat, was Hydrilla. Hydrilla is non-native, and extremely aggressive. This plant is the focus of the SAV control implemented at SML. Hydrilla is/was also present and controlled in Claytor, Buggs, Gaston and Roanoke Rapids (to a lesser extent). The primary means of control had been spraying in the fall with an aquatic herbicide. In the spring of 2013, 6000 grass carp were stocked in Bull Run.
In the fall of 2013, there was NO noticeable SAV in Bull Run. This is a huge change from the previous year, when any depths under 12' were matted with Hydrilla. In the fall of 2013, other parts of the lake still had some SAV, but the beds were noticeably smaller. By mid summer 2014, there was no grass ANYWHERE in the lake, that I had noticed. Not only did the carp control the non-native grasses such as Hydrilla, curlyleaf pondweed and brittle naiad, but they ate the few stands of acceptable grasses such as coontail and sago pondweed.
Some observed effects since the removal of SAV:
- Muddier water. The water in the back of Bull Run is noticeably dingier since the grass is gone. Other creeks tended to always be muddier, but Bull Run was typically very clear water, even in the back.
- Less YOY fish. This is noticeable in cast net by catch.
- Less YOY baitfish in certain areas by fall. Previously smaller gizzards would utilize the dense vegetation as summer refuge while they grew.
- Less panfish of keeping size. No grass = lower recruitment. Specifically Yellow Perch and larger sunfish.
- Less fishing opportunity. Those grass beds provided a lot of opportunity. Bass, sunfish, perch, and catfish could all be caught near or in the cover of those beds. Now those areas are generally poor for catching.
- More geese spread through yards. Typically the geese would congregate on these grass beds in late summer and early fall, gorging on the available food. This would remove them from peoples yards, and keep them out of sight for the most part. Now the geese are in yards, since there is no SAV to eat. There are no fewer geese, they are just spread out more. They will be the next "invasive" species to be eradicated.
- Far fewer migratory waterfowl in the winter staying on the lake. No food is to blame.
So what can be done??
I'm personally not sure that much CAN be done here. The lake group$ want to see the grasses gone so it doesn't tangle in their toes, ski boat props, and jetski pumps. I imagine they'd like to see a pristine lake, where you can see the barren bottom through 20' of crystal clear water. With the addition of the grass carp, any healthy and acceptable SAV would be wiped out rapidly. SAV such as Coontail, Sago pondweed, and Canadian Elodea, while acceptable, will still "top out" and mat just like Hydrilla, if not worse. SML does not have many/any 'offshore' areas that are shallow enough and the right bottom composition to allow SAV growth. This leaves only the narrow margins of 1-15' water depths in the creeks and channel for SAV beds. Unfortunately these areas are the same areas used by the lake residents that don't want the grass.
At Philpott, there are several deep and dense SAV beds. These beds originate in the 20' range and typically stand 6-10' tall. They do not mat, unless the lake is extremely low. If we could find out what type of plant this is, maybe we could push for this to be introduced at SML. These are likely more beneficial than the shallower and densely matted beds that we previously had. It may have trouble rooting at SML though, just due to the poor water clarity at that depth.
