Zebras

[Sam]

When we first started hearing about Zebra Mussels spreading from the Great Lakes region, the reports were so bad that I expected fresh water fishing around here would hardly oullast me (I'm over 60).  All the articles talked about these things filtering out all the plankton, starving everything up the food chain including top predators, and lakes and rivers finally ending up with crystal-clear water supporting little life except for the mussels.  Turns out, that's not exactly true.

This thread caused me to do some online reading about the effect of Zebra Mussels on fisheries, and I found that the comments from fishermen in heavily-infested areas are very mixed.  ZM's change fisheries for sure - and they fray braid and cut fishing lines too, but exactly how they change the fishing seems to be different in different places.  If we had our 'druthers', I think we'd rather not have them - but we're going to have to put up with them and they don't mean the end of all fishing like some early reports said.

Worst thing about it in local lakes is that I think we'll miss out on the only real benefit Zebra Mussels have brought to fishing in other places.  Some fishermen up around NY, PA, and OH talk about smallmouth populations and fishing getting a LOT better since the ZM's came.  Trouble is, they say that's because clearer water has allowed sunlight to penetrate deeper into their lakes, causing the weedbeds their smallies use for cover to grow and expand into areas where weeds couldn't grow before.  Won't do us any good - we don't have water weeds!

[Rob P]

Exactly Sam.  The water is already very clear, up to 20ft at times.  Lake Erie and Michigan actually cleared up and the walleye and smallies improved.  But local region we have rock and mixed cobble shore.  I just hope the fry that compete with the zm zooplankton (?) food system will do ok. 

[mojorig]

We currently don't know the impacts, if any, of the zebra mussels in Bull Shoals Lake. The population is still expanding and will likely crash at some point. Then the numbers will stabilize at some level. At that point, their levels will fluctuate over time. We have found zebra mussels all the way to the dam. However, this hasn't stop us from still monitoring the fish populations in the lake. At this point, we are going to have to figure out a way to live with them.

Again, we haven't found a measurable impact of the zebra mussels besides bothering the anglers.

[Ham]

Any chance that youwill stock more Reear Sunfish to combat the ZM. I'd love to catch > 2 lb Redears that got FAT on ZM. Apparently Redears have gotten real big in some AZ lakes in part by eating invasive shellfish.

[mojorig]

Yes, we have been trying to get some stocked in the lake. We will likely grow a crop of Redear Sunfish in the nursery pond in 2016.

[Sam]

I love big Redear Sunfish, but I've read that studies show ZM's aren't a preferred food of Redears.  They'll eat Zebra Mussels, but several articles said Redears aren't a "panacea" against ZM infestation because they prefer lots of other foods instead, when available.

BUT - there are studies showing that Blue Catfish really chow down on Zebra Mussels!  In some infested lakes in Arkansas, ZM's were found to be 57% of the Blue Cats' diet in the warmer months, spring through fall.  One 16" Blue Catfish caught in a survey had 134 Zebra Mussels in its' stomach!   That AR study found that when the water gets warm and oxygen levels drop, Blue Catfish don't have much energy to chase active prey like shad.  Instead they stay fairly inactive and close to beds of mussels, laying on the bottom and taking full advantage of the easy buffet.

The Conservation Department is worried about, and has reduced limits on, Blue Catfish anyway because they're so long-lived, are slow to reproduce, and people like to catch and keep them.  They're a desirable fish and native to Missouri - why not give them a boost by hatching and stocking LOTS of Blue Catfish around the state, especially where Zebra Mussels are present?  Blue Cats are slow-growing, but in time such a program might really help.

[mojorig]

We do and have (for many years) stock blue catfish annually in Bull Shoals Lake.

We agree that Redear Sunfish aren't going to be the cure all for the zebra mussels in the lake. However, we are willing to try give them a shot.

[Ham]

Mean ole Sam throwing a big bucket of cold water on my Hopes for a 3 lb Redear. That's just mean. I do like the sound of Fat Blue cats though.

 

[Fish24/7]

wonder if  we'll see a crawfish population explosion with these zebras, don't they eat zebras too?

[Quillback]

There are some studies out there regarding Crayfish predation on Zebras.  Just do a search on "Zebra mussel crayfish predation".

Crayfish will eat Zebra mussels, but hard to know if it will lead to a population increase of crayfish.   Here's a couple of excerpts:

"Crayfish typically attacked a zebra mussel by using the first and second pairs of walking legs to orient the sharp edge of the shell so that it could be chewed with the mandibles. Smaller zebra mussels (≤5 mm) were commonly ingested whole, but larger shells were cracked open. "

"In general, our field experiment suggests that lakes and streams containing O. rusticus populations may experience slower colonization and lower overall densities of zebra mussels than systems lacking crayfish. Consumption of zebra mussels by O. propinquus and O. virilis in our laboratory experiments suggests that natural populations of those species would also reduce natural zebra mussel populations. If smaller crayfish had been used in the field experiment, they would most likely not have consumed the larger mussels. However, smaller crayfish may be capable of exploiting intercobble spaces inaccessible to adult crayfish. Densities of juvenile crayfish are often higher than those of adults (Lodge and Hill 1994), and this higher density may result in an even larger impact on small zebra mussels than revealed by our field experiment. Certainly, while crayfish may act to reduce populations of zebra mussels and while the presence of large populations of zebra mussels may provide a novel food resource for crayfish, it is unlikely that crayfish can reduce zebra mussel populations below densities that are ecologically im- portant."