One thing I have learned over years of doing this - expect the unexpected.

Usually PS do not directly compete with BG. PS fill a different niche than BG much like the RES/BG combo. More likely that with lower reproduction and the same predator base (FH eating both and everything else) that #s of PS surviving to adulthood declined. In addition PS because they are smaller and live near the bottom stay both size and location wise in the FH bulls-eye more.

FYI

North American Journal of Fisheries Management
Article: pp. 198–202

Gape:Body Size Relationship of Flathead Catfish
Joe E. Slaughter IVa,,1 and Brad Jacobsonb
a) Georgia Department of Natural Resources, Wildlife Resources Division, 2065 U.S. Highway 278 SE, Social Circle, Georgia 30025, USA
b) Arizona Game and Fish Department, Region IV, 9140 East 28th Street, Yuma, Arizona 85365, USA

Abstract.

The flathead catfish Pylodictis olivaris is a highly piscivorous ictalurid native to central North America whose range has been extended throughout much of the United States. With this range expansion, many populations of native fishes have experienced declines in the number of individuals due to direct predation by flathead catfish. Previous evidence suggests that flathead catfish are opportunistic feeders and may be the least gape limited of North American freshwater piscivores. To better understand the size of prey vulnerable to flathead catfish, we measured gape dimensions for individuals of various sizes to determine the maximum size prey a flathead catfish can kill based on its gape limitations. Our results show the relationship of total length to horizontal and vertical gape and the relationship of flathead catfish total length to the total lengths of ingestible-sized prey of different body shapes. Furthermore, comparisons of the body depth of three common fish species to the gape dimensions showed that no size of largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, or gizzard shad Dorosoma cepedianum would preclude predation by flathead catfish. Our results support the assumption that the flathead catfish is one of the least gape-limited piscivores.

Received: January 31, 2006; Accepted: May 4, 2007; Published Online: February 11, 2008

DOI: 10.1577/M06-033.1
North American Journal of Fisheries Management 2008;28:198–202

Last edited by ewest; 08/21/19 12:26 PM.