Here are the facts the VGIF and other state biologists are getting from population surveys from electroshocking and netting. "Although the VDGIF staff has done less
electro-shock sampling this year than
previously, their catch has gone up
exponentially, more than doubling the
number captured in 2004-2005 combined.
“There has been a big increase in the
Occoquan River system,” Odenkirk said,
and they have been found far upstream.
Larger numbers of fish have been found at
Belle Haven and in Pohick Bay. Substantial
increases have been observed in Oxon
Creek on the Maryland side, as well as in
Other studies show that the Snakeheads biomass is indeed increasing in the Potomac and that theyre favorite food is Sunfish and topminnows.
Don't misuse catch per unit effort (CPUE) data. Yearly changes in CPUE usually mean absolutely nothing. If anything, CPUE can read changes over many years or decades using trendlines, but by saying "we caught a bunch more at our sites this year..." you are really just saying that there were more fish caught in that one place at one point in time. I've looked at lots of CPUE charts, and they usually just go up and down at random intervals. Again, over long periods of time they can show something, but when a state biologist says "catches are up/down this year," it should be taken with a grain of salt.
For instance, I just did some standardized electrofishing on a dam the other night. The catches were abysmal. The past couple of years have been great. What will I tell you about the bass populations? Well, they weren't at the dam the other night, most likely. On the flipside, we had a site that was extremely productive compared to other recent years. I'd tell you the same type of thing about that site; there were a lot of fish there that night. On the management side of things, we're going towards looking at age, growth, and mortality of fishes in systems to get better ideas of what populations are doing. It gives you a better idea than "there were a bunch/few fishes in that one place at that one moment."