����������������������������������������� R. Raines/D-5820/66780

����������������������������������������� Revision of 10/14/92

 

����� FISHERY RESOURCES

 

 

AFFECTED ENVIRONMENT

 

This section primarily focuses on the fishery resources of the San Joaquin Basin within and downstream of the Friant Division of the Central Valley Project.Fisheries of the Sacramento-San Joaquin Delta (Delta) are included because of potential downstream effects of the proposed action, and because many fishes depend on the San Joaquin River and the Sacramento-San Joaquin estuary for successful completion of their life cycles.Tulare Basin fisheries are mentioned.

 

Moore et al. (1990) provides a comprehensive summary of the historic conditions and biotic diversity of this important region of the Central Valley of California.Some of the other more recent and pertinent reviews of conditions in the area include Steinhart (1990), Connelly et al. (1990), Moyle et al. (1989), USFWS (1989, 1984), Jones & Stokes Associates, Inc. (1989), Ogden (1988), Taylor and Davilla (1986), Warner and Hendrix (1985), and Werschkull et al. (1984).The Friant Division is not separated out from discussions about the San Joaquin Valley in these documents and no attempt is made to do so here.It is considered that the trends for the Friant Division are similar to the trends identified for the San Joaquin Valley in these documents.

 

Historically, the San Joaquin Valley floor contained a diverse and productive patchwork of aquatic, wetland, riparian forest, and surrounding terrestrial habitats which supported abundant populations of resident and migratory species of fish and wildlife.European settlement of central California in the mid-1800's initiated the era of water diversion and stream habitat degradation.Draining of the once extensive lakes, diversions, water storage projects and interbasin transfers drastically reduced instream flows.Declining water quality due to contamination by municipal, industrial, and agricultural wastes, and other human activities took a substantial toll on the fisheries, and populations of aquatic and wetland wildlife of the valley.��

 

The riverine, lacustrine, and estuarine habitats of the San Joaquin Valley and Delta form a complex and diverse freshwater-estuarine ecosystem of which the San Joaquin drainage contributes necessary freshwater.Effects of contract renewals are widespread and include downstream areas affected by reductions of San Joaquin River flows.However, a detailed discussion of the fisheries of the whole complex (Central Valley including San Francisco Bay) is beyond the scope of this EIS.

 

 

Preproject Conditions

 

The San Joaquin Valley includes two drainages, the San Joaquin drainage (principal tributaries include Merced, Tuolumne, Stanislaus, Calaveras, and Consumnes Rivers) and the Tulare drainage (Kings River).Hydrology of the area is characterized by periods of high spring flows resulting from snowmelt and lower winter flows from rainfall and early snowmelt.In between were periods of low flows and late summer droughts.Native fishes(some 27 species; Table 1) were adapted to this regime of fluctuating flood and drought events (Brown and Moyle, in press).

The San Joaquin Valley historically contained a complex network of sloughs, creeks, rivers, lakes and ponds.These supported a variety of resident and anadromous fishes (Brown and Moyle, in press).Resident fishes included cold-water stream-dwellers (e.g., rainbow trout, riffle sculpin); large, warm, mid-elevation stream species (Sacramento squawfish, hardhead, Sacramento sucker); small, intermittent, warm-water stream forms (California roach, juvenile hardhead, Sacramento sucker, Sacramento squawfish); fishes of lakes, sloughs, and mainstream San Joaquin (thicktail chub, Sacramento perch, tule perch, Sacramento blackfish, hitch, Sacramento sucker, Sacramento squawfish), and estuarine species (e.g., starry flounder, hitch Sacramento splittail, threespine stickleback, tule perch).

 

Anadromous fishes included long-distance migrators (e.g., chinook salmon, rainbow trout (steelhead), white sturgeon) and species that primarily used the lower San Joaquin River and Delta (e.g., longfin smelt, delta smelt).Although pre-Friant Dam fisheries are not well documented, almost continuous fisheries existed for "salmon", "sturgeon", and "smelt" (Moyle and Morford 1991).The Sacramento perch also supported a commercial fishery in the late 1800's and was eaten by the Native Americans (Moore et al. 1990). Some anadromous fishes (white sturgeon, steelhead rainbow trout, chinook salmon) would migrate as far south as Tulare Lake (Mooreet al. 1990) and these and other fishes of Tulare Lake were harvested by early basin residents.

 

 

Post Project Conditions

 

San Joaquin Basin and River

 

The San Joaquin Valley and basin today bears little resemblance to historic times due to the draining of lakes and wetlands, interbasin water transfers, alteration of natural flow, temperature, and sediment regimes following completion and operation of Friant and other mainstream dams, and declining water quality from placer mining operation and municipal, industrial, and agricultural wastes.Many of the native fishes are in decline due to cumulative effects of the above and other human related activities (Brown and Moyle, in press).

 


 

������������������������������������������������������������������������������������������������������ ����������

Table 1.����������� Native and introduced fishes of the San Joaquin River and Sacramento-San Joaquin Delta.

���������������������������������������������������������������������������������������������������������������������������� Common (Scientific) Name����������������������������������� Common (Scientific) Name����������������������������

Migratory-Native����������� ����������������������� ����������������������� ����������� Migratory-Introduced

 

Hardhead(Mylopharodon conocephalus)�������������������� ����������� Striped bass(Morone saxatilis)

Pacific herring(Clupea harengeus pallasii)��������� ����������� American shad(Alosa sapidissima)

Kern brook lamprey(Lampetra hubbsi)

Pacific lamprey(Entosphenus tridentatus)

River lamprey(Lampetra ayresi)

Chinook salmon(Oncorhynchus tshawytscha)

Delta smelt(Hypomesus transpacificus)

Longfin smelt(Spirinchus thaleichthys)

Green sturgeon(Acipenser medirostris)

White sturgeon(Acipenser transmontanus)

Steelhead rainbow trout(Salmo gairdneri gairdneri)

 

Resident-Native����������� ����������������������� ����������������������� ����������� Resident-Introduced

 

Sacramento blackfish(Orthodon microlepidotus)������ ����������� Largemouth bass(Micropterus salmoides)

Thicktail chub(Gila crassicauda) ����������� ����������� Redeye bass(Micropterus coosae)

Speckled dace(Rhinichthys osculus)�������� ����������� ����������� Smallmouth bass(Micropterus dolomieui)

Starry flounder(Platichthys stellatus)������� ����������� ����������� Spotted bass(Micropterus punctulatus)

Hitch(Lavinia exilicauda)���� ����������������������� ����������� Bluegill(Lepomis macrochirus)

Sacramento perch(Archoplites interruptus)��� ����������� Black bullhead(Ictalurus melas)

Tule perch(Hysterocarpus traski)������� ����������� ����������� Brown bullhead(Ictalurus nebulosus)

California roach(Lavinia symmetricus)����������������������� ����������� Yellow bullhead(Ictalurus natalis)

Prickly sculpin(Cottus asper)������������ ����������� ����������� Common carp(Cyprinus carpio)

Riffle sculpin(Cottus gulosus)�������� ����������������������� ����������� Channel catfish(Ictalurus punctatus)

Sacramento splittail(Pogonichthys macrolepidotus)������ White catfish(Ictalurus catus)

Sacramento squawfish(Ptychocheilus grandis)��� ����������� Black crappie(Pomoxis nigromaculatus)

Threespine stickleback(Gasterosteus aculeatus)�� ����������� White crappie(Pomoxis annularis)

Sacramento sucker(Catostomus occidentalis)����������� Chameleon goby(Tridentiger trigonocephalus)

Golden trout(Salmo aguabonita (native))��������� ����������� ����������� Yellowfin goby(Acanthogobius flavimanus)

Resident rainbow trout(Salmo gairdneri (native))��������� ����������� Goldfish(Carassius auratus)

����������������������� ����������������������� ����������������������� ����������� Rainwater killifish(Lucania parva)

����������������������� ����������������������� ����������������������� ����������� Bigscale logperch(Percina macrolepida)

����������������������� ����������������������� ����������������������� ����������� Fathead minnow(Pimephales promelas)

����������������������� ����������������������� ����������������������� ����������� Mosquitofish(Gambusia affinis)

����������������������� ����������������������� ����������������������� ����������� Threadfin shad(Dorosoma petenense)

����������������������� ����������������������� ����������������������� ����������� Golden shiner(Notemigonus crysoleucas)

����������������������� ����������������������� ����������������������� ����������� Red shiner(Notropis lutrensis)

����������������������� ����������������������� ����������������������� ����������� Inland silverside(Menidia beryllina)

����������������������� ����������������������� ����������������������� ����������� Green sunfish(Lepomis cyanellus)

����������������������� ����������������������� ����������������������� ����������� Redear sunfish(Lepomis microlophus)

����������������������� ����������������������� ����������������������� ����������� Brook trout(Salvelinus fontinalis)

����������������������� ����������������������� ����������������������� ����������� Brown trout(Salmo trutta)

����������������������� ����������������������� ����������������������� ����������� Warmouth(Lepomis gulosus)

������������������� ��������������������������������������������������������������������������������������������

 

Although surface and ground water was diverted prior to the placement of Friant Dam, its completion and subsequent operation directly impacted some 61 percent of the native San Joaquin fish fauna by blocking migration routes, eliminating spawning habitat, and altering natural flow conditions (Brown and Moyle, in press).Less than 60 percent of low-elevation stream habitat is now available to anadromous fishes and no mid-elevation habitat remains accessible (Moore et al. 1990).Mendota and Sack Dams, constructed in the late 1800's/early 1900's, acted as migration barriers to salmon, but it is believed that the decline of the salmon in the San Joaquin River was due to a combination of factors including multiple fish barriers and the total reduction of flows in the mainstream river with completion of Friant Dam and Millerton Lake.

 

The fish fauna of the San Joaquin drainage is dominated today by more than 30 introduced fishes (Table 1).Many of these have proliferated in habitats disturbed by water depletion and flow alteration whereas native species generally decline in such conditions (Brown and Moyle, in press).Various species were introduced to California (beginning in the 1800's) to improve sport fisheries (e.g., bass, sunfish, catfish), to provide forage fish for game fish (e.g., threadfin shad), to control mosquitos (e.g., mosquitofish), as baitfish (e.g., red shiner, fathead minnow, golden shiner), and some were accidentally introduced (e.g., logperch)(Moyle 1976).

 

The higher elevation cold-water streams now include brook and brown trouts; the large, mid-elevation stream fauna has generally been replaced by bluegill and largemouth bass; the intermittent stream forms are threatened with continued habitat degradation from grazing and from proliferation of green sunfish and mosquitofish; native fishes of lakes, sloughs, and rivers of the San Joaquin Valley floor have almost entirely been replaced by sunfishes, catfishes and carp (Moyle 1976, Brown and Moyle, in press).The thicktail chub, an inhabitant of sloughs and lakes is believed extinct, and the Sacramento perch is extirpated from its native range and rarely occurs in some farm ponds (Moore et al. 1990).From an economic perspective, protecting native species such as delta and longfin smelts, and chinook salmon, may also serve to protect the fisheries for introduced species such as striped bass because of their similar habitat requirements.

 

Fishes of the San Joaquin River include reservoir species in Millerton Lake, and stream-dwelling forms downstream of Friant Dam.The fisheries of Millerton Lake have fluctuated as the reservoir has aged.Forage fish introduced in the 1950's included golden shiners (1953), fathead minnows (1955), and threadfin shad (1959).Striped bass, kokanee, rainbow trout, largemouth bass, and possibly American shad were introduced in the 1950's and 1960's (Leidy and Myers 1984).The American shad probably was introduced in water diversions originating from the Delta.Spotted bass were introduced in 1975 and 1976.The reservoir is currently dominated by a warm-water centrarchid fishery (Leidy and Myers 1984).

 

The lotic environment downstream of Friant Dam has been greatly modified by the lack of regular flooding (flushing flows), dewatering, and agricultural runoff.The river channel is aggrading and vegetation encroachment is widespread; fish habitat is intermittent in most years.The reach immediately below the dam supports a catchable rainbow trout fishery (stocked throughout the year at Lost Lake County Park) but no longer sustains anadromous fish.The last recorded chinook salmon spawning event was in 1982 (Blum 1984, USFWS 1991).Streamflows generally range from 20 cubic-feet-second (cfs) in the winter to 250 cfs during the irrigation season.

 

The river becomes shallow, warm and slow-moving downstream to Gravelly Ford (about 41 miles) and warmwater fishes dominate the system.Except in wet years, the San Joaquin River is generally dry from the Gravelly Ford gaging station to the upper reaches of Mendota Pool (about 17 miles).Mendota Pool, a re-regulating reservoir (some 500 surface acres and a capacity of about 3,000 acre-feet) for Delta water delivered by the Delta-Mendota Canal, supports a small warmwater fishery.Some fishes common to the Delta (e.g., striped bass) are introduced into the San Joaquin River by Mendota Pool releases.From Mendota Pool to Sack Dam (about 23 miles), the river contains a perennial flow.Downstream of Sack Dam to the Bear Creek and Salt Slough confluences (about 46 and 54 miles, respectively) the San Joaquin River is generally dry.From the Salt Slough confluence the river contains a perennial flow downstream to the Merced River confluence (about 10 miles), and warmwater fishes are maintained by seepage and agricultural runoff.The San Joaquin River downstream of the Merced River confluence contains adequate passage for chinook salmon smolts and adults and supports resident and other anadromous fishes.

 

Chinook salmon are one of the more important sport (ocean and stream sportfishing) and commercially harvested (ocean) fish species in the San Joaquin Basin.The following narrative describes its decline in the basin and indicates the deteriorating health of the mainstream San Joaquin River.

 

 

���� Chinook Salmon

 

Chinook salmon are anadromous meaning that they migrate from the ocean to their natal rivers to spawn.After a few months in freshwater, the young disperse downstream as smolts and eventually migrate to the ocean where they generally mature in 2-3 years.

 

The San Joaquin River historically supported both spring and fall-runs of chinook salmon.These fish migrated upstream to the area now inundated by Millerton Lake.The spring-run was once the most abundant salmon run in the San Joaquin drainage (runs exceeded 100,000 fish annually; Moore et al. 1990).However, due to curtailment of spring flows by Friant Dam operations and lack of adequate water temperatures for passage and spawning, this fish is believed to have been extirpated from the mainstem San Joaquin (Moore et al. 1990, Reynolds et al. 1990).Estimates of spring-run adults entering the upper San Joaquin River near Mendota Dam (Table 2) illustrates their decline following completion of Friant Dam.Only fall-run chinook salmon (and a small amount of winter-run fish in the Calaveras River) persist today and their production in the San Joaquin Basin has declined by over 85 percent since the 1940's (Loudermilk et al. 1989).

 

 

�����������������������������������������������������������������

Table 2.����������� Estimated counts of spring-run chinook salmon near Mendota Dam (after Cone 1973, Reynolds et al. 1990).

���������������������������������������������������������������� ��

����������� Year���� Count������������ ����������� ����������� Year���� Count

 

����������� 1943�� 35,000����������� ����������������������� ����������� 1947�� ��� 6,000

����������� 1944��� 5,000������������ ����������������������� ����������� 1948�� ��� 2,000

����������� 1945�� 56,000����������� ����������������������� ����������� 1949��� no count

����������� 1946�� 30,000����������� ����������������������� ����������� 1950��� no fish

����������������������������������������������������������������

 

 

Chinook salmon no longer occur in the San Joaquin River between Friant Dam and the confluence with the Merced River, and no longer spawn in the mainstream San Joaquin River (Brown 1991).Fall-run fish continue to persist in several East-side tributaries (Merced, Tuolumne, Stanislaus, Mokelumne, and Cosumnes Rivers) partly because adequate flows are maintained, and hatchery propagation efforts have been successful.Fall-run chinook salmon generally migrate upstream in the San Joaquin River during September, October, and November and spawning occurs from October to January in tributary streams.Successful egg incubation requires river temperatures not more than 57 degrees Fahrenheit (F).Eggs hatch in 50-60 days and downstream migration of young ranges from March through May in the mainstream San Joaquin River.Use of the San Joaquin River by fall-run chinook salmon is presented in Table 3 (CDFG 1987).

 

The primary migration route for San Joaquin drainage fish is themainstream river, however, some fish do use the Old River channel or other routes throughout the South Delta.During low flow years, some adult chinook salmon become trapped in Mud and Salt Sloughs on their way to historic upstream spawning grounds.These fish are collected by the California Department of Fish and Game, artificially spawned, and the young are transferred to more suitable rearing locations in tributary streams (e.g., Merced River).Approximately 85 percent of the fall-run fish in the San Joaquin Basin are associated with Merced River Fish Facility operations.Fall-run chinook salmon can only gain access to the upper mainstem San Joaquin River (i.e., below Friant Dam) in wet years (Blum 1984, USFWS 1991, Brown and Moyle, in press).Total production (adult harvest, plus spawning runs) for the San Joaquin River declined by more than 70 percent of the 1940's levels, even with the Merced River Fish Facility enhancement program (USFWS 1990).During the last 3 years of the 1980's, San Joaquin Basin runs were extremely low, averaging less than 25,000 fish (USFWS 1990).

 

 

����������������������������������������������������������������

 

Table 3.����������� Use of the San Joaquin River by life stages of fall-run chinook salmon (CDFG 1987).

����������������������������������������������������������������

����������������������� �����������

Fall-run���������� ����������� Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun���������

����������������������������������������������������������������

 

Adult

Migration������� ����������� xx xxx xxx xxx

 

Spawning������ ����������� ��������� x xxx xxx xx

 

Incubation�������������� x xxx xxx xxx xxx xxx x���

 

Rearing and

Outmigration�������������������� x xxx xxx xxx xxx xxx xxx x

�����������������������������������������������������������������

 

There is little available information on instream flow needs of chinook salmon in the San Joaquin Basin.Several studies are underway in the Mokelumne, Stanislaus, and Tuolumne Rivers. Suitable flows and water quality are required to sustain the migration events (fall - adults and hatchery stocked fish; spring - juvenile outmigration) and fry rearing.Gravels suitable for spawning still exist below Friant Dam, however, water releases remain generally inadequate to sustain adult and juvenile passage above the confluence of the Merced River.Re-establishment of the run in this reach would minimally require changes in the operation of Friant Dam.

 

The major factors that are limiting the abundance and distribution of San Joaquin River chinook salmon also include mainstream barriers to historic spawning areas, insufficient instream flows for passage, declining water quality, elevated river water temperatures, and losses associated with export pumping and reverse flows in the southern Delta.Reverse flows affect salmon in several ways: young and adults are vulnerable to entrainment and predation, and capture and handling stresses at the export facilities.Migrating fish may become disoriented and never reach their intended destinations.Proposed barriers (e.g., at the Old River) would force smolts to take a more circuitous route and so enhance survival.

 

 

Merced, Tuolumne, and Stanislaus Rivers

 

The Merced, Tuolumne, and Stanislaus Rivers support the fall-run chinook salmon.Average escapement during the 1980's was 13,000, 14,000, and 5,500, respectively.These runs were greater during the higher flow years 1983, 1984, and 1985 (33,500, 60,000, and 70,000 adult spawners, respectively) indicating the fishery potential under favorable fall flow conditions (Reynolds et al. 1990).

 

 

East-side Delta Tributaries

 

The East-side Delta tributaries, Consumes, Mokelumne, and Calaveras Rivers, drain the central Sierra Nevada foothills and are considered part of the lower San Joaquin Basin.The Mokelumne and Cosumnes Rivers support fall-run chinook salmon; annual escapements averaging 6,600 and 200 spawners respectively, during the past decade (Reynolds et al. 1990).The Calaveras River supports a small population of winter-run chinook salmon but its status is unknown.

 

Steelhead trout are occasionally captured in the Mokelumne and Calaveras Rivers, but few are ever taken in the Consumnes River (Reynolds et al. 1990).A catchable trout fishery is maintained on the Mokelumne River by frequent plantings of yearling steelhead.Flows that may improve salmon and trout fisheries in these tributaries are currently being investigated but are problematic because of the complexity of Delta water issues.��

 

 

Lower San Joaquin River and Delta �����������

 

The San Joaquin River enters the Delta near Vernalis and flows northward towards Stockton.The San Joaquin drainage contributes about 20 percent of Delta inflows (5 percent of this from East-side tributaries); the majority (about 80 percent) coming from the Sacramento River (Moore et al. 1990, Reynolds et al. 1990).

 

The Delta is part of a complex estuarine system that depends on a mixing of river (freshwater) and oceanic (saltwater) flows.This zone of mixing, i.e., the entrapment zone, is critical to survival of Delta species because it acts as a primary food source for younger fish.However, its water quality is influenced by agricultural, municipal, and industrial diversions and runoff, and river inflows.The Delta is also important as a corridor for fish migrating to and from the Pacific Ocean and for fishes whose entire life history is dependent on Delta flow dynamics.

 

North of Vernalis, a portion of the San Joaquin River flows westward and enters the Old River.The amount of flow diverted at this point is dependent on export pumping in the South Delta.When pumping operations are low (typically in the winter), about half of the San Joaquin River flows into the Old River.When export pumping is high (exceeding 3,500 cfs), there is a net upstream flow in the lower San Joaquin River during all but wet years, and in the summer and fall of all years (Moore et al. 1990, Reynolds et al. 1990).The hydrology of the Delta is altered such that when freshwater inflow is low and export pumping in the South Delta is high, saltwater intrusion progresses landward and the entrapment zone is located in deeper and less productive areas.

 

Reverse flows may impact fish species by disorienting migratory fish (upstream, downstream and across Delta movements; striped bass, salmon, steelhead) from their natural migration course and by reducing primary and secondary productivity in the Delta.In addition, large numbers of fish eggs and larvae are drawn toward the pumping facilities where they are susceptible to predation, screening mortality, and to stresses from being transported through canals into agricultural diversions or captured and transported to other locations.����������

 

Fish are not commercially harvested from any area in the Delta, however, a small crayfish fishery exists.The most important sport fisheries include striped bass, American shad, sturgeon, steelhead trout, white catfish and various sunfish.The Delta also supports several native fishes including the Delta smelt which are showing signs of population decline.Survival of all fishes using the lower San Joaquin River and Delta is dependent on a robust plankton community because this forms the foundation of the entire estuarine food chain.The health of the planktonic community is directly impacted by low river inflows, export pumping, poor water quality, and ultimately, the location of the entrapment zone.

 

 

���� Striped Bass

 

Striped bass were introduced to California in 1879 from the East Coast of the United States.Their numbers increased so quickly that from 1916 to 1934, 0.5 to 1.0 million pounds of fish were commercially harvested annually (USFWS 1990).Commercial fishing was halted in 1935 primarily to protect the sport fishery.However, the striped bass fishery has declined significantly from 3,000,000 fish in the 1960's to about 1,000,000 in the 1980's to about 500,000 in 1990 (EIP Associates 1992).The decline has been attributed to poor recruitment resulting from direct and indirect effects of export pumping, reduced San Joaquin River inflows, and reverse flows in the southern Delta.Other factors include water pollution, reduced egg production because of fewer spawning females, and predation.

 

Striped bass spend most of their life in the ocean or estuary, but migrate into freshwater to spawn in April and May.The lower San Joaquin River and neighboring sloughs below Stockton are the major spawning areas for the species.Striped bass require freshwater for successful spawning and the salinity of the lower San Joaquin River influences this event.Eggs drift with the currents and hatch in a few days.Hatching generally occurs in the lower river because low flows and even reverse flows do not flush the eggs into the Delta.Larval survival is largely dependent on transport into the highly productive entrapment zone because the larvae feed on zooplankton.During this period they are vulnerable to a variety of decimating factors including reduced food availability because the entrapment zone is located in less productive areas, entrainment losses, and predation by larger striped bass at the pumping facilities.Another potential factor affecting striped bass is the native plankton populations.The native plankton are being replaced by non-native species which have less food value for young fish.

 

The striped bass population is currently at its lowest level since stock assessments were first made.Entrainment in export pumps in the South Delta is believed to be responsible for substantially reducing the numbers of larval striped bass (USFWS 1990).Loss of striped bass in diversions is directly related to export volume and inversely related to net seaward flows in the lower San Joaquin River.If net flows in the lower San Joaquin River are minimally seaward or reversed, then eggs and larvae are not transported into the productive planktonic zone.Such water export occurs concurrent with striped bass spawning.

 

 

���� American Shad

 

American shad were introduced into the Central Valley in the late 1800's (1871 to 1881) from the East Coast of the United States.The fish is now well established on the West Coast where it provides a popular sportfishery.While American shad are more numerous in the Sacramento River, there is limited spawning in the San Joaquin River, particularly the East-side tributaries, Mokelumne and Stanislaus Rivers (Moyle 1976), during years of high spring flows.

 

American shad are anadromous and spend most of their life in the ocean.Adults move into freshwater to spawn in spring and summer and the young are transported into the Delta with river flows.Thus, their survival is dependent on adequate freshwater flows to support fish ascending rivers, and flows to support outmigration of young.

 

 

���� Sturgeon

 

White sturgeon are native to the San Joaquin/Sacramento estuary.White sturgeon are anadromous and ascend the San Joaquin River at least to the confluence of the Merced River.Spawning occurs from March through June although it is believed unsuccessful in the mainstream San Joaquin River due to poor water quality and low flows (Moyle 1976).White sturgeon were commercially harvested in the late 1800's in the Central Valley, almost to their extirpation.

 

Green sturgeon are also native to the San Joaquin/Sacramento estuary but are less abundant than the white sturgeon.They spawn in the lower reaches of some rivers, but little is known of their life history needs because of their rarity and use of habitats difficult to sample.��

 

 

���� Steelhead Rainbow Trout

 

The steelhead trout is an anadromous form of rainbow trout native to the West Coast.Steelhead are popular in inland sport fisheries in California, but significant viable populations no longer exist in the San Joaquin drainage (Reynolds et al. 1990).Steelhead fisheries in the San Joaquin drainage are dependent on hatchery stocking programs in the East-side tributaries.

 

 

���� White Catfish

 

White catfish were introduced to the Delta in the late 1800's.They currently provide the largest catch of resident sport fish, and much effort is expended in salvaging them at the export pumping fish screening facilities (annual average of 330,000 fish; USFWS 1990).They prefer areas with little or no current and their distribution in the Delta appears to be stabilized over the last three decades (USFWS 1990).

 

 

���� Delta Smelt

 

The delta smelt is a nongame species and occurs only in the estuarine system of the Delta and Suisun Bay.This fish was recently proposed for Federal listing as a threatened species.The delta smelt is extremely sensitive to environmental changes because it has a one year life cycle and thus, could be decimated in a year of poor recruitment.Delta smelt populations began to collapse in 1985 (Moyle and Morford 1991) and have remained low ever since.Although causes of the decline are not well established, it is believed that the cumulative effects of water diversions from the San Joaquin and Sacramento Rivers, exacerbated by California's five-year drought, has directly impacted recruitment (SFI Bulletin, No. 428, September 1991).

 

Delta smelt inhabit open surface waters of the Delta and move into freshwater dead-end sloughs and shallow shorelines of the lower San Joaquin and Sacramento Rivers from February through June to spawn.Larvae are flushed downstream into the productive entrapment zone with spring flows.When this occurs, growth is rapid and the fish reach 55-70 mm standard length in 7-9 months (Moyle et al. 1989).These fish spawn the following spring (populations are dominated by juveniles in the summer and adults in the spring) and presumably die shortly thereafter.

 

Successful recruitment of delta smelt is partly dependent on the establishment of the entrapment zone in the shallow Suisun Bay.The abundance of food organisms (primarily copepods) used by delta smelt is greater under these conditions than when the entrapment zone forms in the deeper channels of the Delta.Present river outflows usually place the entrapment zone in the dredged Delta channels where larval smelt probably starve to death (Moyle et al. 1989).Newly hatched smelt are also susceptible to other consequences of reduced spring flows in the lower San Joaquin River, including entrainment at the pumping facilities (Arthur et al. 1991).Long-term survival of this species is dependent on provision of spring flows that would establish the entrapment zone in the productive Suisun Bay and flush larvae from the freshwater spawning areas to this area (Moyle et al. 1989).

 

 

Tulare Basin

 

The Tulare Basin once included the largest freshwater lake and wetland complex in California and during particularly wet springs, the Tulare Basin and San Joaquin Basin would become connected.Agricultural diversions of major tributaries in the late 1800's cumulatively increased the salinity of Tulare Lake and other nearby lakes, and by 1900, few fish persisted (Preston 1981).Today, flood waters of major tributaries in the Tulare Basin are all contained by dams and the lakes and wetlands have been drained for agriculture. Tulare Basin flows may be diverted into the San Joaquin River by Fresno Slough Bypass and Kings River North.

 

Fishes native to the Tulare Basin include rainbow trout, Sacramento perch, tule perch, Sacramento sucker, sculpin, and several minnows.Today the basin supports many introduced fishes, including white bass.Because this fish can adversely impact other fisheries such as striped bass, measures are continuing to protect the Delta from invasion of white bass through the Tulare Basin.Trout fisheries are viable in the Tulare Basin due to stocking efforts.

 

The post project status of aquatic resources today in the Tulare Basin is similar to that described for the San Joaquin River and basin in the preceding section (i.e., post-Friant).Trends in degradation of aquatic habitats and species declines continues.

 

 

 

 

Present Project Conditions

 

Chinook salmon no longer spawn in the mainstream San Joaquin River but the river serves as a migration corridor for spawning in the Merced, Tuolumne, Stanislaus, and other tributaries.The lower river also supports spawning habitat for striped bass and delta smelt.The absence of adequate streamflows from Friant Dam, in combination with downstream water diversions to the exchange contractors, directly impacts the survival of anadromous fish populations in the San Joaquin drainage and Delta.Anadromous fish (chinook salmon, American shad, white sturgeon) ascend to Friant Dam only in wet years.

 

Fisheries of the Delta are dominated by striped bass, salmon, white sturgeon, American shad, various sunfishes (bluegill, black crappie, largemouth bass), catfishes (white catfish), and minnows (common carp, goldfish, golden shiner).Little is known about the native Delta species, but delta smelt, Sacramento splittail, Sacramento blackfish, and longfin smelt appear to be declining (Moyle and Morford 1991).Reduction of freshwater inflows and flow reversals in the lower San Joaquin River and Delta adversely affects larval delta smelt by eliminating suitable rearing habitat, and increasing entrainment at water export pumping facilities.��

 

 

Trends

 

If the current trends in fish habitat degradation continues, then more species will no doubt become endangered with extinction during the next 40 years.