Phillip S. Levin

Regime, phase and paradigm shifts: making community ecology the basic science for fisheries.

Modern fishery science, which began in 1957 with Beverton and Holt, is ca. 50 years old. At its inception, fishery science was limited by a nineteenth century mechanistic worldview and by computational technology; thus, the relatively simple equations of population ecology became the fundamental ecological science underlying fisheries. The time has come for this to change and for community ecology to become the fundamental ecological science underlying fisheries. This point will be illustrated with two examples. First, when viewed from a community perspective, excess production must be considered in the context of biomass left for predators. We argue that this is a better measure of the effects of fisheries than spawning biomass per recruit. Second, we shall analyse a simple, but still multi–species, model for fishery management that considers the alternatives of harvest regulations, inshore marine protected areas and offshore marine protected areas. Population or community perspectives lead to very different predictions about the efficacy of reserves.

Estimating relative abundance of seagrass fishes: a quantitative comparison of three methods

Precise descriptions of ecological patterns are fundamental to generating hypotheses about both the patterns and the mechanisms generating them. Fishes in seagrass meadows are difficult to sample because dense vegetation and turbid water make it necessary to rely on traps, nets or enclosure devices. We compared the relative abundance of species and community structure in a North Carolina estuary caught by otter trawls, throw traps and minnow traps and determined how habitat structure affected estimates of abundance from the different sampling methods. We collected more fishes with otter trawls than with throw traps or minnow traps, and our estimates of species richness were highest with trawls. The rank order of pinfish, Lagodon rhomboides, abundance and species richness were concordant among all three sampling methods, but varied for pigfish, Orthopristis chrysoptera. Our results suggest that minnow traps and throw traps were not affected by variability in seagrass biomass. Our results also indicate that selection of a particular sampling method may have important consequences for conclusions drawn from studies using different methodologies.