Members of the freshwater catfishes (order Siluriformes) are capable of transintestinal expulsion of foreign bodies, including internally implanted tags, which can bias movement and survival estimates. We evaluated long‐term (120‐week) retention rates of passive integrated transponder (PIT) tags in a laboratory setting to assess potential tag loss in Stonecat Noturus flavus. The PIT tags were surgically implanted into the peritoneal cavity of fish (n = 157) ranging from 71 to 213 mm TL. We demonstrated that Stonecats can successfully be tagged with 12‐ and 23‐mm PIT tags with low levels of mortality (5.0%) and tag loss (9.6%). Based on individual encounter histories and covariates, we further evaluated our data set in a multistate framework using program MARK. Based on our findings, tag age has a negative effect on tag loss; if Stonecats lose tags, it is relatively soon after tagging. Additionally, Stonecat TL has a negative effect on tag loss, with tag loss decreasing with increasing fish TL.

Fisheries biologists have been hesitant to use passive integrated transponder (PIT) tags in small‐bodied fishes (40–200 mm TL) such as darters (Percidae: Etheostomatinae) because of the fishes' size and potential effect on swimming performance. The authors used constant acceleration trials to evaluate the swimming performance of Arkansas darters Etheostoma cragini in control (no incision or tag), sham (incision and suture) or PIT tagged (surgically implanted 8 × 1.4 mm intra‐peritoneal PIT tag) treatments. Tag retention and fish survival were monitored for up to 199 days post‐tagging. Maximum swimming velocity did not differ between control, sham and PIT tag treatments, nor was maximum swimming velocity affected by the tagging procedure. Tag retention was 100%, and the overall survival of tagged fish was 88% in the swimming study, and 100% in the long‐term study, suggesting that small PIT tags are suitable for use in darters. The authors include a brief meta‐analysis on the results reported by 20 studies that PIT tagged small‐bodied fishes, representing 38 species and nine families of freshwater fish.

ObjectiveNew fish passage structures are frequently designed using information gained from existing structures, particularly those that have been shown to allow passage of the target species. However, this process rarely involves a preinstallation design and testing phase. Developing an apparatus that allows rapid and relatively low‐cost testing of potential fish passage structure designs prior to field installations could reduce the reliance on a “build it, monitor it, does it work?” approach.MethodsTo meet this need, we developed an indoor research flume at Colorado State University’s Foothills Fisheries Laboratory that housed a full‐scale experimental rock ramp fishway.ResultThe slope of the flume can be adjusted (0–10%) and integrates a set of four PIT tag antennas to allow fine‐resolution tracking of fish movements in the fishway. The flume can deliver variable flows (up to 0.082 m3/s) of 9–25°C water. Lessons learned during the design, construction, and initial operation of the flume are presented here.ConclusionThe basic system could be adapted for similar studies in other regions and provides a robust and flexible infrastructure that could be modified for other evaluations of instream structures in lotic systems.