The lower segments of tributary streams provide the only remaining backwater habitat for much of the lower Missouri River. We describe the movements of adult channel catfish Ictalurus punctatus between a 13‐km segment of the Missouri River and a tributary, Perche Creek, that enters the river in this segment to determine the extent to which river‐dwelling fish use the tributary habitats. We used mark‐recapture techniques to describe movements offish larger than 250 mm in total length between these habitats during a 22‐month period. Most fish (59%) initially caught, recaptured, or both in the Missouri River moved into or out of Perche Creek, and most of these transient fish (72%) used the lower 8 km of the tributary. The tributary population was made up predominantly of resident fish (79%), which were initially caught and recaptured in Perche Creek. Channel catfish moved greater distances in the spring than in the fall and were more likely to move upstream in the spring and downstream in the fall. Fish shorter than 250 mm were more abundant in the river than in the creek and made up 45 and 35% of the catches in each area, respectively. Furthermore, of the fish longer than 280 mm, a greater proportion of the fish resident in the river (44%) than in the creek (33%) were longer than 380 mm. More fish longer than 380 mm moved from the creek to the river (44%) than from the river to the creek (26%). Thus, the tributary habitat was used most frequently by fish 280–380 mm long. Flathead catfish Pylodictis olivaris were much less abundant in the creek than in the river and did not provide sufficient sample sizes to evaluate movement patterns. However, based on abundances in our catches, the proportion of river flathead catfish using the creek was much lower than for channel catfish. Most of the few flathead catfish found in the creek were longer than 280 mm.

Blue Catfish Ictalurus furcatus provide a popular sport fishery in Mark Twain Lake, Missouri, but little is known about their population demographics or exploitation by anglers. Our objectives were to (1) determine population demographics of Blue Catfish, (2) determine exploitation of Blue Catfish, and (3) determine whether new harvest regulations would improve the quality (e.g., size structure and abundance) of the fishery in Mark Twain Lake. We sampled Blue Catfish by using jug lines baited with pieces of Gizzard Shad Dorosoma cepedianum, the gear used by the majority of anglers in this reservoir. Blue Catfish grew slowly, reaching a preferred size (762 mm TL) in about 12 years. Annual mortality was estimated at 24.8% using a weighted catch curve. Using reward tags, we estimated exploitation to be between 8% and 12%, and we modeled the effects of 508‐, 610‐, and 660‐mm minimum TL limits on yield and size structure of the Blue Catfish population relative to a baseline of 381 mm TL, the smallest fish usually harvested by anglers. All three length limits increased the proportion of larger fish (≥762 mm TL) in the population without reducing yield, except for slight decreases (6% and 10%) under the 610‐ and 660‐mm limits at the highest modeled natural mortality rate. We recommend the 610‐mm limit instead of the 660‐mm limit because it allows more harvest and higher yields with increases in natural mortality and still doubles the proportion of larger fish relative to the 508‐mm limit.