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W.D. Hubbard

Publications and source records attributed to W.D. Hubbard.

2 recordsLinked to original sources

Segmentation of Mississippi’s natural and artificial lakes

Segmentations divide a diverse resource into groups, or segments, based on distinctive attributes that may respond similarly to management actions. A 4-way segmentation based on lake origin (natural or artificial) and size (small or large) was constructed for Mississippi lakes using a 30 yr data set. We aimed to document elements distinguishing these segments to understand relationships among them and to seek insight into lake management that may be apparent at the segment scale but not at the lake scale. Analyses pinpointed differences among the 4 segments relative to nutrient levels, fish assemblage composition, fishery characteristics, angler catch, and fishery management objectives. In general, most artificial lakes were eutrophic, varied widely relative to species composition depending on whether they impounded small or large rivers, their fish assemblages could be heavily influenced by stocking, provided principally centrarchid fisheries, and the management focus was on angler harvest. Most natural lakes were hypereutrophic, included higher species richness, provided a greater diversity of fisheries, and the management focus was on fish populations and habitat. Fishing success was similar across segments. The group-wise differences substantiate the segmentation and bring into focus a new level of concepts not typically relevant when considering lakes in isolation, such as issues about lake quantities, similarities, and geographical distributions. The segmentation represents the framework needed for considering lakes as parts of a larger and interactive management system.

Mississippi

Centrarchid assemblages in Mississippi state-operated fishing lakes

We evaluated electrofishing catch per effort in 27 state-operated fishing lakes in Mississippi to identify patterns of centrarchid community composition and to determine whether those patterns were related to selected environmental characteristics and to artificial nutrient enrichment. Ordination with detrended correspondence analysis recognized two major axes accounting for 77% of the variability in species ordination. Axis 1 showed a distinct separation between the body sizes of various species. A notable exception was the density of small (<30 cm) largemouth bass Micropterus salmoides, which aligned with the large individuals of other centrarchid species. This pattern suggested that through predation, high densities of small largemouth bass exerted significant control over the size structure of fish communities. Axis 2 separated species of crappies Pomoxis spp., suggesting that conditions other than strong species interactions also moderated the composition of crappies in the assemblages. However, neither lake morphometry nor watershed composition exhibited a major influence over axes 1 or 2. In small, intensively managed lakes with low habitat complexity, the regulatory importance of biotic interactions may overwhelm that of abiotic factors. Nutrient enrichment influenced community structure by changing the densities of bluegill Lepomis macrochirus and largemouth bass substantially but had a minor or no effect on other species. The management techniques used in these state-operated lakes are usually targeted toward a particular species without adequately considering the other species within the community. Our results show that attention to community-level interactions could provide valuable insight into factors that affect the quality of the fishery, insight that is not available through traditional population-level assessments. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management