Development of a multi-scale management perspective for wadeable stream fisheries in Mississippi
Alford, John Brian
AdvisorJackson, C. Donald
CommitteeDibble, D. Eric
Kaminski, M. Richard
I used multivariate, hierarchical analyses to examine the relative influence of watershed-, riparian- and channel-scale environmental characteristics on catch per unit effort (CPUE: fish/angler-hour) and species composition of sport fisheries in Mississippi wadeable streams. Partial canonical correspondence analyses indicated that riparian-scale variables (31.1%) explained more variation in sport fish relative abundances compared to watershed-scale (24.4%) and channel-scale variables (18.9%). Largemouth bass M. salmoides and longear sunfish Lepomis megalotis were more abundant in smaller-watershed streams with dense forest cover and greater woody debris, alkalinity and diverse substrates. Spotted bass M. punctulatus and bluegill L. macrochirus were more abundant in larger-watershed streams with moderate to dense forest cover yet more open riparian canopies. Regional-scale characteristics also influenced relative abundances of these fisheries. Total CPUE, total bass CPUE and largemouth bass CPUE were greatest in watersheds draining the Blackland Prairie-Flatwoods compared to other level III ecoregions. This ecoregion contains fertile soils that influence stream productivity, because alkalinity tends to be large in forested streams draining this ecoregion. I developed and validated watershed-scale models and found that percentage forest cover, stream density, total road density and primary highway density predicted mean total CPUE, mean total sunfish CPUE and mean total bass CPUE accurately (Sign tests comparing observed versus predicted mean CPUE, P > 0.05). The models were precise (R2 > 0.71), explaining 83%, 71% and 80%, respectively, of variation in mean total CPUE, mean total sunfish CPUE and mean total bass CPUE from independent data. Species-specific models performed poorly, suggesting biotic relationships may hinder development of meaningful habitat models for species. My study supports forest conservation to sustain sport fisheries in Mississippi’s wadeable streams. Forests mediate sediment and nutrient loading to stream channels, influence hydrology and channel morphology and provide woody habitat for sport fish and their forage base (benthic macroinvertebrates). My small sample size was small; (N = 13 reaches), thus caution is advised before engaging in comprehensive management of wadeable streams based on my results. Nevertheless, my watershed models can be applied at very low cost using a GIS or topographic maps to identify reaches state-wide that support wadeable stream sport fisheries.