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. ,, ~ _ ..-. ,. ...: ,,__ ~ _ _ a , . .. _ ~~~. .~. ` ~ .. Woos fishes (e.g., grass carp, e or change the composition f fishes already present. bspecies has been a problem :em in California to another. Because it has hybridized in b and the hybrids are almost 2). Results are similar when ;inbow trout. Hybridization as a distinct form. The loss ;nts an irreplacable aesthetic sir of potential future use by 'mg are today major factors ~ishing is highly selective for rimarily at large carnivorous large fishes not reserved for sport fishing removes a large ;population structure of the simple systems, such as farm excessive harvest of the top ,unless fishing imbalances are mouth bass from a pond may ;gill. The bluegill in turn may ieeded to support young bass, tunted bluegill. tt also contain squawfish may quawftsh in rivers, such as the it fishing. In an undisturbed dominate squawfish and keep ~.). Removal of trout allows rout, presumably resulting in squawfish then presents more lion more difficult. Assuming to be answered are: (I) how before the situation becomes c it has been upset? rs and warmwater streams, the well understood than in trout tg populations of gamefishes line, it is usually the result of najor exception to this rule, CHANGE 55 however, was the turn-of-the-century commercial fishery for white sturgeon in the Sacramento-San Joaquin Estuary, which so reduced the populations that only a complete prohibition of fishing for nearly fifty years allowed them to recover. The imbalances created by heavy fishing are not always undesirable. Commercial fishing in lakes and reservoirs for carp, tut chubs, and other nongame fishes may create more favorable situations for gamefishes by making more food available to their young. The effects of the few such fisheries that now exist in the state are not known but it might actually pay to subsidize them to the extent that they would be willing to overfish the commercial species (especially carp) in order to provide better sport fishing. THE FUTURE It is possible to be both pessimistic and optimistic about the future of California's fish fauna, native and introduced. Pessimism comes easily in the face of the all too frequent fish kills, major and minor, that result when one of the products of our industrialized society enters a watercourse. Even more depressing are the rapes of watersheds by careless developers, loggers, dam builders and other groups who have a greater concern for quick profits and growth than they do for proper watershed management which can, in fact, be compatible with their aims. The massive transfer of water from one part of the state to another, mostly via th California Water Project, is another cause for concern, especially as flows through the Sacramento-San Joaquin Delta decrease and as dams are built on the few large, free-flowing streams still remaining. It is difficult for stream-adapted fish to live in the absence of flawing water and impossible for them to exist in the absence of any water at all. In addition to these stresses, the native fauna will have to cope with an inevitable increase in exotic species. In the SacramentoSan Joaquin system alone, three recently introduced species (Mississippi silverside, logperch, and yellowfin goby) -are undergoing population explosions. It seems unlikely that any of the three will be particularly beneficial in the long run. Despite the above trends there are reasons to be optimistic as well. Both public and official attitudes towards water utilitization have changed dramatically in the past few years as part of a general awareness of how rapidly the natural features of California have been disappearing. Hopefully, the changes in attitude mean that the destructive trends of the past are slowing down or even reversing themselves. Some of the more prominent signs of this are listed below. 1. A number of dam projects, specifically those on the Eel and Mad rivers, have been scuttled, or at least delayed, in recent years, due not only to public opposition but also to changes in the method of evaluating the worth of such projects. The possible destruction of natural areas and native faunas now has to be taken into account. 2. The National Environmental Policy Act, requiring reports on the environmental impact of a proposed project, has forced watershed users to at least consider the effects of their projects on water quality and fish populations. Short-term economic benefits still seem to take precedence over long-term environmental degradation but the environmental impact documents are a step in the right direction. ;.~ --:s