My name is Dan and I’m a culvert assessor.  To be more specific, I along with my partner Amber Masters assess and inventory culverts within the BLM Rawlins, WY Field Office to determine whether they present a barrier to native fish populations.  Before Amber and I arrived in Rawlins the GIS personnel out of the BLM Wyoming state office produced a map highlighting all points on public lands within the Rawlins Field Office where river, stream, and creek met road.  It’s the job of Amber and I to ground truth these points, as they are not all culverts, and to assess the culverts we come across.  I will not detail this procedure as Amber has already done so but I will say that though culvert inventory and assessment may seem dull its importance shouldn’t be trivialized as barriers (culvert, dam, etc.) present a great threat to many of North Americas fish species.

Purple Rain

I will now step away from passage assessment, as though it does make up the majority of what Amber and I do, it’s not all that we do as we dabble in other fishery related projects like population estimates and exotic species removal.  The former was performed using a multiple-pass depletion method which entails pulling a seine the length of representative segments of the stream or creek being surveyed.  This process can be a bit strenuous at times but is quite fun and interesting as you never know what your haul is going to contain; it also allows one to learn the native and exotic fish species quickly.  Removal of exotic fish populations from drainages within the field office is an interesting procedure as well.  The treatment method which Amber and I participated in involved the use of the piscicide rotenone.  Rotenone is a naturally derived chemical used by many fishery managers as a way to effectively remove undesirable fish populations.  Rotenone’s effectiveness comes from its ability to inhibit cellular respiration thereby starving a fish of oxygen.  It sounds cruel but in many cases it’s the only means for wholly removing exotic fish populations from systems and allowing the re-establishment of native fish species.  The Rawlins Field Office works in conjunction with the Wyoming Game and Fish on projects involving the treatment of systems within the field office.

Roads We Drive

Before a stretch of water is treated an effort is made to recover native fish species from this area.  Recovering native fish is done by donning electrofishing packs and trying to temporarily stun native fish so they can be caught.  After the initial recovery process the rotenone is applied in a coordinated process via multiple drips at a concentration, rate, and duration based on flow (CFS) as well other factors.  A second recovery begins at this time for native fish missed during the initial recovery.  Native fish under the influence of rotenone or those fleeing the rotenone will run into block nets placed within the treatment area.  Those fish that are native are pulled off the nets and placed in fresh water which can reverse the effects of the rotenone if the fish isn’t too far gone.

To prevent effects outside the treatment area the rotenone is neutralized through the application potassium permanganate.  This is a strange site as the potassium permanganate turns the entire treatment stretch purple.  Also, within the treatment area and outside the treatment area baskets of native fish (canaries) are placed and monitored to check the treatment progress and to make sure the rotenone is not reaching outside the treatment area.  After the treatment is complete the effected fish are enumerated and identified.  Before restoration can begin the treatment will be performed a number of times to make sure all non-native fish species have been removed.  Semi-permanent barriers within the treatment area prevent non-native fish from repopulating the treatment area.

Dan Rapp-BLM-Rawlins, WY