Tuesday, February 12, 2013

Virile Crayfish

The Ozarks, Home of the Long-Pincered Crayfish


There has been some pressure recently to loosen the restriction on selling live crayfish for fishing bait. Given the recent history of bad effects from releasing non-native species, this subject is worthwhile discussing. In this case it is more complicated as it is the virile crayfish, a species that is native in most prairie streams in Missouri.

The Missouri Conservation Commission passed a regulation amendment to the Wildlife Code of Missouri in August 2011 that prohibits selling, buying and importing live crayfish for fishing bait. This action was a culmination multi-year research efforts (see 2009 MDC study) by state and university biologists in Missouri and other states on invasive crayfish to determine their actual and potential effects on biodiversity and fish species.

The intent of the regulation was supported by numerous national and international experts on crayfish biology, ecology and fisheries as a common sense, practical proposal to limit the damage that invasive crayfish species might do to our native fauna and fisheries. Further research by MDC showed economic and social consequences would be minor.

Virile Crayfish- MDC
Now some parties with an economic interest are proposing to the Department of Conservation that the regulation be amended to allow the sale of one crayfish species – the virile crayfish (Orconectes virilis) – as fishing bait.  It is now found in some rivers where it isn't native, likely due to accidental release or dumping bait at the end of the day.

The long term impact of this crayfish on native populations in streams where it is foreign is unknown. Examples such as zebra mussels and Asian carp have shown us that populations take time to build up and the decline or loss of native species is only discovered with time.

The probable effect, again supported by numerous distinguished crayfish ecologists and fisheries scientists, is that this new regulation would be unenforceable, easily evaded, and, most importantly, ineffective in protecting our valuable aquatic resources. In this time of overextended resources, what agency has the manpower to inspect bait shops and which bait shop has the expertise to identify species of crayfish to see if they are legal?

The Orconectes virilis occurs in most northern parts of the state. The name virilis should be a clue as this is the predominate trait of most invasive species. This MDC Discover Nature page describes it this way:  "The virile (also called “northern”) crayfish (Orconectes virilis) occurs in just about any prairie stream capable of supporting crayfish. The virile crayfish is probably Missouri’s most widespread species."

The map on the right shows Missouri prairie areas where O. virilis is native. Notice that it doesn't include the Ozarks. Unfortunately, they are now found in the White River system and on the Current River.  O. virilis is even now found in George Washington Parkway waters in Washington D.C.!   Here is the Current River description as described by MDC biologists.
“In February of 2012, U.S. National Park Service (NPS) biologists contacted MDC to report they had discovered an invasion of virile crayfish in the upper Current River watershed. They had discovered the species at 13 locations along the Current River watershed, totaling about 42 stream miles. Invasions were later confirmed by MDC staff, working with NPS staff.

Nobody has yet studied this invasion to determine effects. However, NPS biologists noted several sites where virile crayfish outnumbered native crayfish and numbers of native spothanded crayfish (Orconectes punctimanus) were notably lower than expected (relative to observations from around the watershed).”
Long-pincered crayfish MDC

This is a little more personal to me. We live on Bull Creek one of several streams that is the home to the large and beautiful long-pincered crayfish. It is unlikely that the White River population of O. virilis will make it upstream 10-20 miles on Bull or Swan Creek to offer a threat to our native crayfish. It is likely that with regulation changes and time it will make it up here in a bait bucket.

If this isn't enough of a threat for you, how do reports of catching piranha in Lake of the Ozarks since 2007 "grab you"?   You can read more by Shelly Cox including the quotes below from her MOBugs site.
"Bait fishermen also are unknowingly spreading invasive crawfish species. About half of U.S. states and Canadian provinces have restricted use, sale, and transport of crawfish, or are considering doing so because the threat that these invaders pose to native crawfish and the fisheries that they inhabit.

In considering regulations to prohibit the import and sale of crawfish, the Missouri Department of Conservation discovered 25 invasions in its streams. It also learned that 40 percent of anglers surveyed release live bait that they don’t use, more than 50 percent of bait shops sell species not native to regions where they are sold, and 97 percent of bait shop owners admitted or showed that they didn’t know what species they were selling.

“It is important for anglers to understand that any crawfish species moved from its natural range to new water bodies has the potential to become invasive in those new waters and to adversely affect fisheries,” said Missouri biologist Bob DiStefano.

Not surprisingly, the aquaculture industry and Farm Bureau oppose Missouri’s proposed regulations, citing economic hardship for those who import, grow, and/or sell crawfish. In the Mid-South years ago, fish farmers made the same argument in convincing resource managers to allow them to import and sell bighead and silver carp."
Whether you support the change or not, consider sending your opinion in a letter to the Missouri Conservation Commission (c/o Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102.)

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