A Great Day on the Emory!

Some days seem a lot more like fun than work! On Thursday, TNACI staff got to guide Alexandra Cousteau and her National Geographic Expedition Blue Planet Team on the Emory River. We spent the morning in Watts Bar Reservoir, catching fish and talking about the long-term impacts of the coal ash spill. We caught a few fish with infections while we were there, an indication that there is still environmental stress. TVA has finished Phase I of the clean-up—approximately 85% of the spilled ash was removed from the reservoir. The crew filmed interviews about our research on the spill and helped us catch and release the fish.

In the afternoon, we got to show off one of our most scenic parts of Tennessee. We headed upstream on the Emory River in the National Wild and Scenic River portion. We snorkeled for four hours there, saw over 30 species of fish, and found two darters that hadn't been documented that far upstream before! The only thing we couldn’t find was a hellbender… I guess we had to leave a reason for Alexandra to come back!

You can follow along with her expedition at: http://www.nationalgeographic.com/water. It is a web-based expedition and they post new photos and videos almost daily!

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Lake sturgeon tagging

As anyone who has ever spent time near our lake sturgeon touch tank knows, sturgeon aren’t covered in scales like most fish. Instead, they have five rows of bony scutes on their back and sides which are made of a substance called ganoin. These rigid plates act as a suit of armor for the fish, especially for young sturgeon where the scutes are still sharp- the scutes wear down as the fish ages and become smaller in relation to the body size of the sturgeon.

Scientists and fisheries managers use these scutes to keep track of the age of sturgeon that we raise and reintroduce into the wild. Every fish that leaves our TNACI facility has a specific scute removed to identify the age of the fish. On odd-numbered years (i.e. 2007, 2009) we remove a lateral scute from the right side of the fish; on even years we remove lateral scutes from the left side of the fish. That way, when a scientist captures a fish from the river, he or she can run their fingers down the lateral scutes of the fish, and identify the soft spot where a scute has been removed. By counting how many scutes back from the head of the fish to where the missing scute is, the scientist can identify which year the fish was born and use this data in conjunction with length and weight measurements to judge how fast the fish has grown.

The scute removal process is inexpensive and quick, but it does not allow for identification of individual fish and over many years, it becomes increasingly difficult to tell which scute was removed because the remaining scutes will migrate together and partially fill in the gap. Next week, we will talk about another tagging method we use that allows for identification of individual fish called “PIT” tagging.



-LSF

The hellbender, the largest salamander found in N. America, is found in cool, clear, fast flowing streams from New York to northern Georgia and westward to Arkansas and Missouri. The species is divided into two subspecies, with the Ozark hellbender occupying a very small range in the White River Drainage in Missouri and Arkansas. The Ozark hellbender species (Cryptobranchus alleganiensis bishopi) was listed last week as a candidate species for listing as “endangered” under the Endangered Species Act. This species, which occupies a much smaller range than the closely related Eastern hellbender is in serious decline and has become extremely rare in the wild. Like many aquatic species, causes of decline are believed to include poor land management leading to siltation in the watershed, impoundments, and chemical pollution from industry and agriculture. In an unusual move, the Service also cited legal (for scientific purposes) and illegal harvest (poaching) as a major threat to the viability of this subspecies.

The U.S. Fish and Wildlife Service determined that the species is in enough trouble to consider giving it the highest level of federal protection. Now that the Ozark hellbender is being considered for protected status, the U.S. Fish and Wildlife Service is seeking public comment from concerned parties regarding potential listing. This is a required step in which scientists, stakeholders, and representatives from concerned governmental and non-governmental agencies may present additional data or comments as the Service considers listing status.

-LSF

Pallid Sturgeon Listed as Threatened by USFWS

On Wednesday of this week, an interesting ruling was issued by the U.S. Fish and Wildlife Service regarding two species we have on display at the Tennessee Aquarium. The two species are the shovelnose and the pallid sturgeon (Scaphirhynchus platorynchus and S. albus respectively) and they are exhibited in the Reelfoot Lake tank in the Tennessee River Gallery. These very similar looking fish, both belonging to the same genus, are found in portions of the Mississippi and Missouri Rivers. Both species prefer similar big river habitat and can be found inhabiting the same stretches of river. The larger of the two species, the pallid sturgeon, has been listed as “Endangered” by the USFWS since 1990, receiving the highest level of protection. The smaller shovelnose sturgeon whose population is in much better shape, is not deemed to need protection- in fact, a commercial fishery exists in some states for the harvest of shovelnose sturgeon for their roe (eggs) used to make caviar. According to the recent ruling, however, shovelnose sturgeon will be listed as “Threatened” for the portions of their range that overlaps the range of the pallid sturgeon prohibiting all commercial fishing for this species for large parts of pallid sturgeon range. This ruling goes in to effect as of October of this year under a Similarity of Appearance clause in the Endangered Species Act (50 CFR 17.50).

Pallid and shovelnose sturgeon sometimes appear so similar that even trained scientists have difficulty distinguishing some members of each species from the other. There have been documented cases where commercial fishermen unknowingly harvested endangered pallid sturgeon. A small pallid sturgeon could easily be mistaken for a shovelnose, and a large shovelnose sturgeon could easily be mistaken for a pallid. Because of the difficulty in visually distinguishing the two species in the wild, federal regulators felt that it is necessary to prohibit take of both species in order to protect the critically endangered pallid sturgeon.

-LSF

TNACI Husbandry Systems

At the TNACI facility, in Cohutta, Georgia, we have a very different system to supply the animals in our care with clean water than what is used at the Tennessee Aquarium or the ACF. Unlike the water recirculating systems at the Aquarium that reuse the same water with the help of complex filtration systems, our systems are known as flow-thru systems. That means that water is only passes through our tanks one time before it leaves our tanks and flows down a drain. We are able to do this because the facility at Cohutta that we share with the University of Georgia was built next to a spring that provides the whole facility with a constant supply of clean, cool, clear water ideal for keeping sturgeon healthy and happy. We “borrow” the water passing through the facility only briefly before it leaves our tanks and flows into a creek adjoining the property which eventually flows into the Conasauga River. Water is supplied to our tanks from the spring by gravity, and we only minimally filter the water to remove large objects (like sticks, twigs, snails, crayfish) before it enters into our tanks. This system has a few advantages, like being inexpensive, low-maintenance, and easy to maintain. We don’t rely on electricity to power any pumps, so if the power goes out, our fish still receive clean, flowing water without relying on backup power generators. One drawback to this system is the lack of control of temperature. In the winter time, water temperatures in our tanks can drop into the low 40s. The fish do fine, but they barely grow at all when the temperatures drop.

-LSF

Summer Field Work

TNACI scientists have been busy the past two weeks taking advantage of summer’s long days, warm weather, and clear skies. Last week, Lee Friedlander joined two graduate students from Tennessee Tech to survey the French Broad River for lake sturgeon. We used an electro-fishing boat to use electric current to temporarily stun any fish in the vicinity of the boat as it motors downstream next to the bank. When the fish are stunned, they float to the surface where they can be identified and recorded. Any lake sturgeon would have been netted on to the boat and measured before being released back into the water. The team was able to survey two of the three planned sites before bad weather ended the day early. Some of the species we identified in our survey included three species of redhorse, spotted suckers, smallmouth buffalo, yellow perch, smallmouth bass, four species of sunfish, and common carp- but no lake sturgeon! Is this a bad sign? Should we assume that because we did not find any lake sturgeon that there are not many lake sturgeon in the river despite our ongoing stocking efforts? Probably not- the Tennessee River is a big river system with miles and miles of available habitat. The only way for us to observe a lake sturgeon is to be sampling at the right place, at the right time. That’s a pretty tall order in a river system covering so much area.


Though we may have been “skunked” in our recent lake sturgeon sampling efforts, our work with a very different species the following week, the Conasauga logperch, had a lot more success. Conasauga logperch are a federally protected species known to only inhabit a 27 mile section of the Conasauga River in southeastern Tennessee and extreme northern Georgia. Conasauga logperch are habitat specialists, only inhabiting deeper pools with sandy bottoms with small stones usually just downstream of a faster moving riffles. These extremely rare fish feed by using their snouts to flip over small stones on the river bottom to look for tiny invertebrates to feed on. TNACI staff were joined in our search by biologists from the U.S. Forest Service and from Conservation Fisheries, Inc. We searched for these fish by snorkeling in the Conasauga River targeting areas with habitat where we knew we would likely find our target species. Because the water in this area is relatively clear, our team of snorkelers could locate fish relatively quickly…if they were there, we were pretty likely to find them. The first site we sampled turned up no Conasauga logperch, but at the second site, slightly downstream we were able to collect 11 individuals. As far as we know, this may have been the highest number of Conasauga logperch ever observed in a single day! Eight of these fish were sent off to our partner, Conservation Fisheries’ facility near Knoxville, TN for a propagation project. A small genetic sample was taken from the remaining three captured fish for genetic analysis and those fish were then returned to the river.

Compared to our efforts to find lake sturgeon, we had a lot more success finding Conasauga logperch. Does this mean that there are a lot more Conasauga logperch in the Conasauga River than there are lake sturgeon in the Tennessee River? Almost certainly not! It just means that with the right planning, Conasauga logperch may be easier to detect than lake sturgeon given their different habitats and behavior.


-LSF