Anadromous fish in california support a multimillion-dollar sport and commercial fishing industry though somecentral valley (sacramento-SAN joaquin delta and its tributaries) salmon (oncorhynchus…

Anadromous fish in california support a multimillion-dollar sport and commercial fishing industry though somecentral valley (sacramento-SAN joaquin delta and its tributaries) salmon (oncorhynchus tshawytscha), steelhead(oncorhynchus mykiss), and sturgeon (acipenser SPP.) populations have declined to precipitously low levels.population declines have been linked to various factors such as construction of dams, water diversions, andhabitat degradation. Significant alterations to stream channels began with the california gold rush starting IN1849. Today urban expansion, agricultural and industrial development, and water operations continue to negativelyaffect these populations. The california department of fish and wildlife (cdfw), as trustee agency for the states fish and wildliferesources, not only manages catchable stocks and harvest opportunity but also has been steadily working toreverse population declines in anadromous stocks. Since the late 1980S several state and federal legislativeactions recognized these declines and were targeted at reversing them. These include the state salmon, steelheadtrout, and anadromous fisheries program act of 1988, federal central valley project improvement act of 1991, andthe water resources and delta restoration act of 1996.prior to the 1940S, IT is generally understood that spring-run chinook salmon were the dominant salmon run inthe SAN joaquin river basin (sjrb). From the 1940S thru the 1980S, major changes in water use and deliveryoccurred. The cumulative result of these actions have been the extirpation of self-sustaining stocks of springrunchinook salmon, the near extirpation of steelhead (a species listed as threatened by the federal endangeredspecies act), and the substantial curtailment of fall-run chinook salmon production since 2000 (i.e., currently acandidate species for listing review under the federal endangered species act).today fall-run chinook salmon are the dominate run of anadromous salmonids remaining in the sjrb, and that run ISA shadow of its former self. Concurrent with recent declines in both the salmon and steelhead runs has been thereduction of angling opportunity and success, as resource managers have had to curtail seasons, eventuallyreducing bag limits to zero in order to protect the remaining salmon and steelhead stocks still present in sanjoaquin river basin tributaries (e.g., stanislaus, tuolumne, and merced rivers). In recent times, the sacramentofall-run has also had severe declines and ocean fishing was curtailed almost completely. The sjrb, in recent history, is capable of producing tens of thousands of adult salmon. IT is believed thatgreater, and more frequent production of large numbers of adult salmon and steelhead is possible (i.e.,production defined as adult salmon and steelhead escaping into the tributaries to spawn). As salmon and steelheadproduction increases, angling seasons could be reinstated and at least some fish could be legally harvested fromthese rivers.water storage project changes occurring in the SAN joaquin, stanislaus, tuolumne, and merced rivers since THE1940S have significantly altered hydrologic patterns and reduced the amplitude of spring snow-melt and channelforming (maintenance) stream flows. The cumulative effect of these storage projects, in combination with otherprivate, state, and federal water diversions along the rivers and in the sacramento-SAN joaquin estuary, is anincrease in mortality rates for various salmonid life stages, resulting in lowered adult salmon and steelheadproduction.