Critical habitat is lost to forces the fisheries manager has very little influence on. In 1986 the CA Department of Fish and Game used rotenone to treat a stretch of Big Chico Creek with the intent to remove competitors and predators and improve the survival of juvenile spring chinook. No improvement in the fishery ensued because passage and entrainment problems for migration were more critical to the population than were limits to juvenile rearing. Environmental filters such as tolerance ranges. It is assumed that each species occupies it's own niche, to the exclusion of other species.
Deterministic communities are persistent and resilient.
Populations will remain about the same from year to year unless some outside force depresses one or more of them. A deterministic community would be characterized by species showing little overlap in the use of resources and a high degree of morphological divergence from one another. Competing species coexist because the conditions favoring one do not persist long enough for others to be excluded. There is no particular coherence to a community. Environments typically consist of a mosaic of habitats with various histories of disturbance.