Wednesday, February 15, 2012

On a mission for the Barrens Topminnow

Matt (TNAQUA) and Ashford (TNACI) pulling a seine net.
As many of you probably know, the Tennessee Aquarium is part of the Barrens Topminnow Working Group (BTMWG), in partnership with U.S. Fish& Wildlife Service, Conservation Fisheries, Inc., TennesseeTechnological University and Tennessee Wildlife Resource Agency. Through the work of the BTMWG and cooperative landowners, the range of Barrens Topminnows has been expanded, and the species has not been listed as federally endangered. Our primary focus at the Aquarium has been to generate babies to be released back into the wild, but each winter we get to be a part of the monitoring as well. Every year the BTMWG surveys as many of the ~30 populations as possible to check on the health of that group. There are three basic types of populations: 1) wild populations that have never received fish from the captive propagation program 2) populations where past reintroduction efforts have been successful, and we now see wild reproduction and 3) sites where reintroduced fish are still struggling. The information we gather during these surveys allows us to make better decisions about what leads to a successful reintroduction and what work to do next.

Kathlina (TNACI), Pat (CFI), Brad, James and John (USFWS)
pulling a seine at Pond Springs.

Every BTM is measured and their lengths recorded as an
indicator of how many year classes are living at each site.
This lets us know if they are successfully reproducing.
On January 25th and February 2nd the BTMWG convened in middle Tennessee and got to work. We sampled six sites over the course of the two days using seines and dip nets. Every topminnow that is collected is measured for total length, and 10 from each site are fin clipped for genetic analysis. We were able to have good conversations with several land owners and found lots of Barrens Topminnows too! This project is only possible through the cooperation of landowners so communicating with them is vital. Most of them enjoy seeing the science in action as well, so it is fun for everyone. Of course, in addition to the topminnows, several sites are overloaded with Western Mosquitofish. This invasive species is one other of the worst threats to Barrens Topminnows so we also quantify their density at each site as an indicator of site health.
Matt (TNAQUA), Pat and Rebeckah (CFI)
sort through the fish and debris collected
while seining.

This site is the type locality site and has no mosquitofish
to pester the Barrens Topminnows. Brood stock are
collected each year from here.
The last thing that we are able to accomplish during these site visits each year is the collection of brood stock for the following breeding season. Both CFI and the Tennessee Aquarium have to make sure that their breeding stock is healthy, not too old and that they have the proper sex ratios to get optimal genetic diversity as well as production numbers. Breeding tanks are usually stocked with 2 males and 3 females and the fish are swapped around every couple of weeks. This process is tedious and rearing the babies is very time consuming but the efforts pay off in the end. Since 2001, well over 16,000 Barrens Topminnow have been released into the wild! 

Brood stock collected for the Tennessee Aquarium.

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