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John Veil's recent post about hooking a snakeheard got me to thinkning...
It has been 20 years since a snakehead was found in a Crofton, MD pond creating hysteria about "Frankenfish." Undoubtedly, they were in our waters before the discovery of that Crofton fish. Since then, we've seen them spread throughout the mid to upper Chesapeake watershed. Perhaps they were helped along by bucket brigades of unscrupulous anglers. But I suspect, snakeheads have largely expanded their presence on their own via migration.
In July 2011, when snakeheads were thought to be confined to the Potomac River, The Chesapeake Bay Program published an article with the following sentence.:
"Snakeheads are freshwater fish, so the Bay’s brackish waters usually prevent them from leaving the Potomac River."
Here's the article: https://www.chesapeakebay.net/news/b...elaware_rivers
I suspect the author of that article would like to retract that sentence.
"Eyes on the Bay" is an information resource provided by the MD DNR.
If I've copied the link correctly, this map shows average salinty levels at various stations in the Cheseapeake Bay and its tributaries for June 2022:
Eyes on the Bay: Current Water Quality Conditions, Historical Results & Aquatic Habitat Models (maryland.gov)
It's interesting to look at the areas where we know snakeheads reside. For example Indianhead (near Mattawoman on the Potomac) had a salinity level of .1 PPT (Parts per Thousand -- grams of disolved salt per thousand grams of water) in June. The Severn and Magothy, both rivers with snakehead populations had readings of 7.1 and 5.9 PPT respectively for the same month. Those are large variances from Indianhead. An even larger variance in salinity is at the Bay Bridge. Last month it was 9.4. Interestingly, crabbers setting their pots near the bridge have been known to catch snakeheads in them.
Heading north, the tidal Gunpowder River has snakeheads. Its salinty in June was .4 PPT, four times higher than Indianhead but much lower than the Severn, Magothy and Bay Bridge.
Our mid Bay salinities certainly qualify as brackish water. But in contrast, salinity at the mouth of the Bay can exceed 30 PPT.
Questions that arise in my mind are:
1. Just how wide a range of salinity can snakeheads tolerate?
2. Did those snakeheads currently in mid-Chesapeake tributataries migrate from the north or south? (Either direction, they had to swim through waters with much higher salinity waters than they were uccustomed to.)
3. Will salinity levels near the mouth of the Bay limit the spread of snakeheads in the Chesapeake or will the fish adjust to them and eventually reside throughout the entire Bay?
After 20 years of living with them, I think we still have much to learn about Snakeheads.
It has been 20 years since a snakehead was found in a Crofton, MD pond creating hysteria about "Frankenfish." Undoubtedly, they were in our waters before the discovery of that Crofton fish. Since then, we've seen them spread throughout the mid to upper Chesapeake watershed. Perhaps they were helped along by bucket brigades of unscrupulous anglers. But I suspect, snakeheads have largely expanded their presence on their own via migration.
In July 2011, when snakeheads were thought to be confined to the Potomac River, The Chesapeake Bay Program published an article with the following sentence.:
"Snakeheads are freshwater fish, so the Bay’s brackish waters usually prevent them from leaving the Potomac River."
Here's the article: https://www.chesapeakebay.net/news/b...elaware_rivers
I suspect the author of that article would like to retract that sentence.
"Eyes on the Bay" is an information resource provided by the MD DNR.
If I've copied the link correctly, this map shows average salinty levels at various stations in the Cheseapeake Bay and its tributaries for June 2022:
Eyes on the Bay: Current Water Quality Conditions, Historical Results & Aquatic Habitat Models (maryland.gov)
It's interesting to look at the areas where we know snakeheads reside. For example Indianhead (near Mattawoman on the Potomac) had a salinity level of .1 PPT (Parts per Thousand -- grams of disolved salt per thousand grams of water) in June. The Severn and Magothy, both rivers with snakehead populations had readings of 7.1 and 5.9 PPT respectively for the same month. Those are large variances from Indianhead. An even larger variance in salinity is at the Bay Bridge. Last month it was 9.4. Interestingly, crabbers setting their pots near the bridge have been known to catch snakeheads in them.
Heading north, the tidal Gunpowder River has snakeheads. Its salinty in June was .4 PPT, four times higher than Indianhead but much lower than the Severn, Magothy and Bay Bridge.
Our mid Bay salinities certainly qualify as brackish water. But in contrast, salinity at the mouth of the Bay can exceed 30 PPT.
Questions that arise in my mind are:
1. Just how wide a range of salinity can snakeheads tolerate?
2. Did those snakeheads currently in mid-Chesapeake tributataries migrate from the north or south? (Either direction, they had to swim through waters with much higher salinity waters than they were uccustomed to.)
3. Will salinity levels near the mouth of the Bay limit the spread of snakeheads in the Chesapeake or will the fish adjust to them and eventually reside throughout the entire Bay?
After 20 years of living with them, I think we still have much to learn about Snakeheads.
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