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An Historical Review of the
Fish and Wildlife Resources of the San Francisco Bay Area
by John E. Skinner

June, 1962

Striped Bass  Pages 71 - 83

Commercial Fishery

Striped bass (Roccus saxatilis) were introduced into California in 1879 by Livingston Stone at the suggestion of Mr. S. R. Throckmorton of the California State Board of Fish Commissioners. Stone obtained 132 fish from 1 to 3 inches in length and 30 medium sized specimens from the Navesink River in New Jersey. These were brought out by rail and deposited in Carquinez Strait at Martinez in July of 1879. An estimated 25 fish died enroute and several others were discarded, so the number released is not exactly known, but is usually quoted at 132. A second plant of 300 fish obtained from the Shrewsbury River, New Jersey, was undertaken by Mr. J. G. Woodbury of the California Fish Commission and Mr. Emmet L. Marks of New York. These fish were placed in Suisun Bay off Army Point, near Benicia.

Therein lies one of the most remarkably successful attempts ever made to establish a species in new waters. Conditions must have been ideal because those planted made phenomenal growth and the species increased at a prolific rate. A few were reported taken in 1880, and several more appeared in the San Francisco markets between 1880 and 1884. A fish weighing 17 pounds was taken in 1883 and another of I8- pounds was offered for sale in 1884. By 1888 several thousand were displayed in the markets and the commercial fishermen began to direct their efforts toward them. Eleven years later (1899), a mere twenty years after the introduction, the commercial catch as recorded by the U. S. Bureau of Fisheries was 1,234,000 pounds.

As late as 1888, striped bass sold for as much as a dollar per pound in the San Francisco market. However, by 1890 due to increasing abundance the price had dropped to 18 cents per pound and, according to Smith (1895), between 1889 and 1892 the average price received by the fishermen fell from 25 to 11- cents. In 1893 and 1894 the price was further reduced to about 3- cents. Quoting Smith: "On June 21, 1894, the day following the large catch on the Berkeley Flats in San Francisco Bay the wholesale price in San Francisco was 3- cents and the retail price 7- cents a pound." (The report by Smith incidentally is one of the best we have on the early introduction and distribution of striped bass in this state.)

The State Board of Fish Commissioners in 1910 stated: "From the commercial standpoint the striped bass stands next in value to the salmon as a food fish in this state. It is also one of the most highly prized of the game fishes, being eagerly sought after by thousands of anglers throughout the State."

Again quoting Smith: "In referring to their abundance, mention is made of the presence of a numerous body of fish on the Berkeley Flats in San Francisco Bay, in June, 1894, and in the San Joaquin River in December,1893.

"An idea of the abundance of this species may be gained from the following statement by Mr. Babcock, [California Fish Commission]: 'On June 19, 1894, the fishermen struck a school of striped bass on the Berkeley Flats in San Francisco Bay; on June 20 one boat caught 1,500 fish and the other boats made large hauls. 'These fish weighed on an average 6 pounds apiece.'

"It is doubtful if in recent years at any point on the Atlantic Coast so large a catch of striped bass— 9,000 pounds—has been taken by one boat in one day's fishing."

The bass distributed themselves widely, very shortly after being introduced. Within a few years they were found as far upstream as Sacramento and Stockton. Less than a year after being placed in Suisun Bay a specimen was taken in Monterey Bay. They appeared in the Russian River by 1890 and in Tomales Bay at about the same time. By 1893 one was taken at Santa Cruz, and the following year two were seined at Redondo Beach, Los Angeles County.

Small populations of striped bass became established on the Russian and Salinas Rivers as well as Elkhorn Slough near Monterey Bay. In Oregon, stripers are found in Coos Bay and the Umpqua River. However, in spite of a considerable coastwise dispersion, the overwhelming center of abundance of the striped bass has been and remains in San Francisco Bay and the Delta Area.

The principal commercial fishing grounds for striped bass were located on the San Joaquin River in the Delta country and the majority of the catch was taken in gill and trammel nets. River landings reached a peak between October and February, with the maximum catches made in December. In San Francisco Bay itself landings were most abundant during the summer.

Records of commercial landings are available for most, but not all, years between 1889 and 1915. However, between 1899 and 1915 it is evident that the catch regularly exceeded one million pounds (Appendix B-4). After 1915, regulations became progressively more restrictive and the annual commercial catch dropped below a million pounds (Appendix B-2). The species was completely removed from the commercial category in 1935.

Several reports have been written about this species in California. Scofield (1931) described the life history, fishery and commercial catch. Craig (1928 and 1930) analyzed the commercial catch records and discussed the status of the fishery. Clark (1933) continued this work and came to the same general conclusion, namely that the supply was at the time capable of supporting the existing fishing pressure. Both cautioned, however, against neglecting the effects of the rapidly growing sport fishery.

Sport Fishery

Smith (op. cit.) points out that few anglers were fortunate enough to catch striped bass before 1895. Shortly thereafter, however, the anglers began to take them with increasing success. A number of striped bass clubs were formed and the sport fishery expanded from year to year.

Since 1935 the fishery has been reserved exclusively for sportsmen. Calhoun (see references) has done extensive work on this species including migrations, spawning, population dynamics, and their relationship to major water projects. Skinner (1955 unpublished data) analyzed the sport catch records dating from 1936, and other available data and came to the conclusion that a decline had occurred in the fishery between 1944 and 1954.

The striped bass fishery is one of the most valuable in the state, both in terms of the recreation and sport it provides and the economic wealth it generates. Only trout rank higher in the number of days spent by anglers (Skinner 1955). The trout fishery, however, is statewide, whereas the bass fishery is concentrated in San Francisco Bay and the Delta.

The number of anglers participating in the fishery now exceeds 200,000 a year. They expend on the order of 2 million days and 18 million dollars a year on this activity (Pelgen, 1955). The catch is estimated at a million or more fish per year with an aggregate weight close to four million pounds.

There is a year-round season which provides ample opportunity to fish and assures an open season within all parts of its range.

The fish are taken by a variety of angling methods in an area extending from the beaches outside the Golden Gate up the Sacramento River to Red Bluff and up the San Joaquin River to Mendota. The upstream limits of its range were formerly more important fishing areas than they now are. Most of the fishery recently has been confined to the area below Sacramento on the Sacramento River and below Stockton on the San Joaquin River.

Fishing from an anchored boat has been the most popular method. Bait used includes fresh or frozen sardines, anchovies, clam, squid and live or dead sculpins. Usually these baits are fished on or near the bottom.

Trolling has been practiced on a limited scale in selected areas, the most renowned being Carquinez Strait. This type of fishing is most rewarding in the summer, when in Carquinez Strait upwards of a hundred of boats may be seen plying the water. A number of party boats operate all summer for the purpose of taking anglers trolling.

Since the summer of 1957 fishing in the Bay near Alcatraz and vicinity has been extremely rewarding and appears to involve a new development in the fishery. The boats use heavy tackle and weights up to 3 pounds to fish deep. Salmon party boats were the first to locate and fish the area, and word of the excellent catches of striped bass soon brought the regular striped bass party boats on the scene. In 1957, during the two months of July and August, 8,726 striped bass weighing 98,245 pounds were taken in 5,301 angler days. The party boat records from which these data are derived are not a full measure of the effort or catch, however, since a great many private boats which are not required to report also fished the area.

Scofield (1926) pointed out the favored "old fishing grounds" for striped bass. These included San Antonio Slough near Petaluma, Oakland Estuary, San Leandro Bay and Petaluma Creek at Schultze's Slough. Other noted areas were Cache Slough and its tributaries. Sausalito, Petaluma, Napa, Rodeo, Crockett, and Cuttings Wharf on the Napa River were favorite striped bass resort sites. Baker's Beach, San Francisco, provided excellent surf casting.

Most of these are still good "bass grounds" but virtually the entire South Bay including the aforementioned Oakland Estuary and San Leandro Bay have been abandoned as bass fishing areas. The principal explanation for the absence of bass in the South Bay appears to be the polluted conditions which prevail there.

Similarly, the Napa River has lost much of its once famous reputation because of pollution. Scofield (op.cit.) emphasizes the conditions there by quoting an ardent Napa River angler, Mr. W. P. West, " . . . pollution from garages [oil] and tanneries has ruined fishing of all kinds in the vicinity of Napa except when the rains have purified the river; then it is possible to catch fish in town for a few weeks out of the year, whereas formerly they could be taken nearly the year around.

"During the fall of 1924 fish died in the Napa River within a radius of six miles from the city of Napa. The stench from the thousands of dead fish floating on the water became so bad that it was necessary to chemicalize the carcasses. "Years ago bass were so numerous in the lower reaches of Napa's sloughs that a man rowing a boat would strike a fish every few minutes with his oars. In recent years bass fishing in these sloughs has been largely abandoned because almost every slough that formerly afforded good fishing has been leveed off."

Angling Statistics. The Department of Fish and Game has given particular attention to this species because of the intense interest expressed by sportsmen regarding it, the recreation it provides and its economic importance.

Through periodic postal card surveys it has been possible to observe the trends in the fishery. Catch figures thus obtained are exaggerated but the long term trends are considered fair indices of the status of the fishery. Calhoun (1950) discussed the methods, Validity and reliability of them.

The catch figures obtained from these surveys are shown in Table 18 along with the number of successful anglers and the proportion of the state's total which they represent.

Since 1943 there has been a general reduction in the total catch in spite of a doubling in the number of successful anglers. The mean annual catch per angler is now about one-third its former level.

Party Boat Fishery. Another method of observing angling conditions in this fishery has been by an analysis of daily logs maintained by operators of striped bass party boats. These men are required by law to complete a form, supplied by the Department, consisting of the number of anglers carried, number and aggregate weight of the catch and location and time fished.

These records are subject to some error but they provide the most reliable data available on the trends in the fishery. Calhoun (1949) discussed their usefulness, reliability and the party boat fishery in some detail. The data provided in Appendix C-4 are taken from his report for the years prior to 1949. Data on subsequent years were provided by personnel engaged in the "Study of Sturgeon and Striped Bass", another of the State's Federal Aid to Fish Restoration programs.

For statistical purposes and record keeping the Bay and Delta area is divided into so-called "Block Areas" each with a designated code number. The specific location of each block is shown in Figure 30. Without describing them in detail the blocks are as follows:

 Location Block
301 San Pablo Bay 308 Carquinez Strait
302 Suisun Bay Area 488 North San Francisco Bay
303 The Delta 489 South San Francisco Bay

Block 489 - South San Francisco Bay Block 488 - North San Francisco Bay Block 301 - 308 San Pablo Bay and Carquinez Strait Block 302 - Suisun Bay Block 303 - Delta Region

Block 308, Carquinez Strait: This area normally accounts for from one-quarter to one-half of all party boat trips recorded each year. Angler success has been much better here than any other block. Block 301 (San Pablo Bay) on occasion has supported a greater number of boat trips but Block 308 must be considered the most important party boat area year in and year out. Fishing in Block 308 is negligible from December through April, becomes increasingly good as the summer and fall progresses and peaks during the months of October and November. Fishing effort and success coincides with the upstream migration of adult fish in the fall.

Block 301, San Pablo Bay: Party boat angling in San Pablo Bay has fluctuated widely, at times exceeding Block 308, but at other times only accounting for a small percentage of the boat days reported (only 10 percent in 1947 as compared to 40 percent in 1943.) The seasonal activity here parallels that of Block 308, and in addition supports a fair spring and light summer fishery for the smaller non-migratory bass.

Block 303, Delta: The Delta ranks about third in terms of boat trips recorded. In recent years it has exceeded Block 301. The party boat fleet moves up into this area during the fall and winter to follow the run of adult fish. Fishing is usually excellent in November, moderate from December to April or May, (presumably because of the feeding habits of the fish and not abundance), picks up for a short period in late spring, and then drops off as the fish move back down toward the Bay. Fish taken in this area are generally large, weighing between 5 and 15 pounds with fish up to 40 pounds being not uncommon.

Block 488, North San Francisco Bay: The North Bay has been good on occasion but is highly variable. In 1944 this block accounted for 23 percent of all party boat days, in 1948 a mere one percent. The best fishing location is in the vicinity of Alcatraz and farther north. Fishing is best during the summer months and almost at a standstill from September to April. Success in this block was very poor from World War II until 1957, when the deep water troll fishery previously described began to operate.

Block 302, Suisun Bay: Suisun Bay and the area upstream to approximately Antioch forms Block 302. It is less important than the previous four but on occasion has yielded excellent catches of striped bass. Prior to 1945 about 10 percent of the boat days were spent in this area, since then less than five percent. The best fishing coincides with the fall run. Small fish are characteristic of Suisun Bay, and it is frequently referred to as the "kindergarten" by people familiar with fishing here. Record analysis depends upon a sample of at least 30 reports per month, and for many months and even for a few complete years this block did not provide sufficient party boat records. It is possible, therefore, that angling quality in this block could have been good but because of small fish the operators preferred to take their clientele to other areas.

Block 489, South San Francisco Bay: This area is now relatively unimportant to the party boat fleet. Two locations, Hunters Point and Mission Rock, are responsible for most of the records in this block. Fishing in this block has been fair in only three years since 1938. Between 1943 and 1946 less than one percent of all party boat days were spent here. The area was somewhat restricted during -World War II, which partially explains the lowered use during this period. However, even several years after the war it continued to be devoid of party boats. The fish which are taken are large, giving the area some appeal. The fishery is a summer one when it does exist.

In addition to these areas operators may take their clientele directly to the ocean on the rare occasions striped bass are hitting there. In 1956, for instance, 1,257 anglers caught 442 fish in the ocean from party boats.

The party boat fishery is a small but important component of the overall striped bass fishery. The amount of effort from this source is perhaps on the order of 5 to 10 percent of the total. For the 11 year period, 1938-1949, party boats were responsible for an average of just over 13,500 angler days per year including half day trips.

Table 19 & 20Because of the knowledge, experience and skill of the operators, party boat anglers are somewhat more successful than the general angling public. The operator knows when and where to find the fish and will travel some distance to assure his party of good fishing.

Regardless of this fact there has been a decided reduction in the daily success of party boat anglers since 1944. The reduction is approximately of the same magnitude as that previously discussed for the postal survey. In Block 308 for instance, party boat angler success diminished from 3.8 fish per angler per day in 1938 to 2.0 fish in 1954, a 50 percent decrease.

Harold K. Chadwick of the Department of Fish and Game in the course of the striped bass study made an estimate of the amount of money anglers spent for party boat fares, based on the number of anglers using these facilities and the average fare. His estimate for 1957 was between $97,000 and $110,000 per year.

The number of party boats engaged in the fishery varies from year to year and has been decreasing over the past few years. Not all boats are operated the yeararound. Individual boats may vary from large well equipped vessels down to the smallest inboard cruiser. Calhoun's data on the composition of the fleet for the year 1947 is given in Table 19. Mr. Chadwick has furnished data on the fleet for the years 1946-1956, shown in Table 20.

General Features of the Fishery. The writer while in charge of the striped bass investigation conducted a survey of known striped bass anglers to obtain qualitative data on the striped bass sport fishery. Questionnaires were mailed to all anglers who in the regular postal survey had declared they fished for striped bass in 1955. Approximately 50 percent of the more than 400 contacted responded.

Angler Characteristics: Sixty-eight percent of the respondents claimed residence in the Bay Area counties and another 20 percent resided in Sacramento and San Joaquin counties. Alameda and Contra Costa counties alone accounted for 18.6 and 18.1 percent respectively or 36.7 percent of the total.

These figures indicate that 88 percent or about 176,000 of California's estimated 200,000 anglers who fish for striped bass reside in those counties immediately adjacent to the Bay and Delta. Twenty-four of California's 58 counties were represented by at least one striped bass angler. These data are summarized in Table 21.

Anglers were asked to record the number of years they had fished for striped bass in California. It was interesting to note that 40 percent of the respondents reported having fished 10 years or more, indicating many striped bass anglers have had considerable experience. The mode, however, was one year.

In order to obtain some insight about the number of trips made by striped bass anglers each year, the fishermen were asked to record the number of times they went fishing. The mode was three and the mean ten trips. These data agree well with the postal survey re- Catch Localities: The recipients of questionnaires suits of 1953. Forty-four percent of the respondents were also asked to indicate the locations in which they went fishing 5 days or less, 26 percent 6 to 10 days and caught their fish. In tabulating these returns the Bay 30 percent fished more than 10 days.

Characteristics of the Fishery: Another objective of the survey was to determine the approximate distribution of angler effort by several methods of fishing -- party boats, private boats and from the shore.

In this respect, 110 (40 per cent of respondents) reported fishing 715 days from shore, bank, pier or bridge, accounting for 35.8 percent of the effort and 25.1 percent of the catch. Party boat anglers (10 percent of respondents) reported 7.7 percent of the total effor, and 10.6 percent of the catch. The small boat fishery, private and rented skiffs, accounted for 56.5 percent of all effort in 1955, and 64.3 percent of the catch. These data are summarized in Table 22.
It is interesting to compare the success of anglers engaging in each of the three methods of fishing. Shore fishermen averaged 3.9 fish per year for 65 trips and a mean catch per day of 0.59 fish. Skiff anglers caught 7.8 fish while averaging 8.2 days per year and a mean catch per day of 0.96 fish. Party boat anglers, presumably reflecting the skill of the operator, averaged 1.16 fish per day.
These figures are given in Table 23. Success as reported by these anglers is in the direction and within general magnitude one might expect. As a matter of fact, the success the party boat anglers in 1955, as determined by the actual records, is identical to the results reported in this survey.

Catch Localities: The recipients of questionnaires were also asked to indicate the locations in which they caught their fish. In tabulating these returns the Bay and Delta were divided into 19 sub-areas and the catches were assigned to those areas in which the fish were reported caught by respondents. San Pablo Bay accounted for almost twice (20 percent of the total) the catch of any other location. The combined catch catch of all Bay Area locations was 43 percent of the total as compared to 57 percent in the Delta. Next to San Pablo Bay, Suisun Bay and Napa River were most important in the Bay catch. Considering its size and location, the South Bay was negligible as compared to other locations, yielding less than one percent of the total catch. The catches in each area and their respective percentages of the total are given in Table 24. Table 24

The San Joaquin portion of the Delta contributed almost twice as many fish as the Sacramento, 36.7 percent as opposed to 20.3 percent. Surf fishing along the beaches of outside the Golden Gate has been good at times in the past, but this fishery is very sporadic. A few fish are taken by this method every year, but the number is usually only a small portion of the total. The data in Table 24, for instance, indicate only one percent of the fish were taken in the ocean in 1955.

Due to the vagaries of sampling the results of the survey cannot be considered conclusive; however, in the light of our present knowledge about the fishery, they appear reasonable enough to place a fair degree of confidence in them. Other factors including regulations, migrations, weather conditions, etc. would also affect the results to some extent from year to year.

Striped Bass Life History Notes

Striped bass is a relatively long lived species and the population therefore is made up of fish of many ages, as compared to salmon, for instance, which generally have a 3 to 5 year life cycle. Stripers may live as long as 20 years or more.

Time of Run. The adults begin to enter Carquinez Strait from the Bay and ocean about August; the run usually peaks in October, and tapers off rather abruptly. They spread out over the entire Delta for the winter season. Angling is excellent during October and November throughout the Delta and as far north as the Feather River. With decreasing water temperatures, angling drops off to a very low point in January and February.

Spawning Conditions. About March or April the fish become active again to provide a short period of good angling. Potential spawners move up into the fresh water of the sloughs and rivers of the Delta system and begin to spawn in March or April. Spawning usually reaches a peak in May depending on water temperatures, and continues through most of June.

Temperature: Water temperature appears to exert an important influence on the time at which striped bass spawn. Raney (1952) summarizing the data of several investigators lists temperatures from 54 F. to 71 F. as being the known range at which they have been observed spawning. Scofield, working with this species here in California, found sperm viable at a temperature ranging from freezing to 90 F. He found the sperm most active at 68 F., sluggish below 42 F. and died at 100-110 F. Spermatazoa were found to remain active after 24 hours between 54 and 68 degrees in a 0.05 percent salt solution. He found that the sperm were active for about 3 minutes in water, after which time their swimming motion ceased.

In the Delta, spawning generally does not begin until temperatures reach 59 or 60 F. The optimum temperature appears to be 64 to 68 degrees.

Salinity: Spawning occurs in essentially fresh water. Larval bass and eggs are found in brackish water, but evidence has not yet been uncovered to show that spawning actually takes place in brackish water. Woodhull (1947) states that in the area which he observed them spawning (San Joaquin River), the salinity (in terms of chlorides) varied from 1 to 7 parts of chlorine per 100,000 of water.

Spawning Activities. Several authors have described the activities involved in the spawning process. Woodhull (op. cit.) observed them on the San Joaquin River in the vicinity of Venice Island. According to his description innumerable groups of fish gathered at the surface of the water for a distance of 3 miles along the river on a flood tide. The fish began to roll over on their sides at a 45 degree angle near the surface and splashed about with their caudal fins. This activity continued for several hours. During the process he used a plankton net to collect eggs not yet water hardened to corroborate the fact that the fish were spawning. Morgan and Gerlach (1950) observed a similar situation in the Coos River, Oregon.

Fecundity. Several investigators have estimated the egg production of female striped bass. The number is correlated with the size of the fish and in general, it may be said that this species is extremely prolific. This phase of their life history has not been specifically explored for California striped bass, therefore, the data presented are from observations elsewhere. Merriman (1941) found that the number of eggs ranged from 11,000 to 1,215,000 with the majority of fish yielding 180,000 to 700,000 each. Jackson and Tiller (1952) found the number to vary from 68,000 in a 4 year old fish weighing 4.4 pounds to 4,536,000 in a 14 year old fish weighing 35 pounds. Morgan and Gerlach (op. cit.) found that Coos Bay striped bass produced about 1 million eggs when they reached 10 pounds and that this figure reached almost 5 million for fish weighing between 30 and 50 pounds.

Spawning Locations. In California a few striped bass spawn in the larger coastal rivers, the Russian River particularly, and formerly the Salinas River. A few apparently persist in Elkhorn Slough, which enters Monterey Bay, and spawn there also. The major tributaries to San Francisco Bay are the principal spawning grounds, however, particularly those above Antioch and Collinsville.

Strong currents appear to be absolutely necessary for the development of striped bass eggs. They have not been found in stagnant water, nor have the adults been observed spawning under lacustrine conditions. The tidal action in the Delta seems to be particularly favored.

Since 1946, a considerable amount of effort has been expended to determine spawning locations. Sampling with plankton nets for eggs has indicated the San Joaquin River below Stockton and many of the sloughs in that portion of the Delta to be the major spawning area.

Eggs were found in greatest abundance in an area extending upstream from the Antioch Bridge to Venice Island and Salmon Slough. The Old River and Middle River systems are perhaps the next most important followed by the Sacramento River system, the San Joaquin River above Salmon Slough and the Mokelumne River. These can be considered the most important year after year, but conditions from year to year may change the sequence. In wet years, for example, spawning may occur below Pittsburg.

Striped bass were formerly reported to spawn in the Napa River. A special trip to collect eggs there during 1957 was unsuccessful, although large, ripe fish were known to be present in the river just previous to the sampling period.

Embryology. The eggs of this species are small (16 to the inch) and transparent at the time of expulsion, but they enlarge to about twice this size upon water hardening. They are very similar to shad eggs, and because both species spawn in the same places and at the same time, the two are easily confused. Striped bass eggs, however, can usually be differentiated by a relatively large oil globule which is not so apparent in shad eggs. Once the eggs are spawned, they are left to drift freely with the currents: Because of the oil globule, they are only slightly heavier than water and are kept suspended by the slightest current. The eggs develop while thus suspended. On the San Joaquin side of the Delta, they are flushed back and forth by the currents and their movement downstream is somewhat restricted. The opposite situation exists in the Sacramento River. Eggs spawned as far up as the Feather River or beyond are moved down into the Delta rather rapidly until they reach the Rio Vista area where they come under the oscillating influence of the tides.

The incubation period is influenced by temperature, higher temperatures being conducive to faster hatching. The known range has varied from 74 hours at 58 F. to 30 hours at 72 F. Hatching occurs in about 48 hours at 67 F. In our waters the temperature is usually in the vicinity of 62 to 68 degrees and the normal incubation period from 48 to 60 hours.

The larvae at hatching are about 0.1-0.2 inch (3-5mm.) in length. They subsist on the yolk material for the first 200 hours while being carried by currents. If they encounter still water, the larvae may settle to the bottom and die. According to Pearson (1938), if food is not available by the time they reach 6mm. (about 0.25 inches), they soon begin to die. This is perhaps the most critical stage in the life history of this species. At this small size they are almost completely at the mercy of the tides and predators.

Postlarval Stage. A great deal of work has been done in the Bay and Delta in sampling the abundance and distribution of small fry. Calhoun and Woodhull (1948), Calhoun, Woodhull and Johnson (1950), Calhoun (1953), Skinner (1955), Hatton (1940), Hatton and Clark (1942), and Erkkila et al. (1950), have all investigated the subject, chiefly because of the presence of millions of these small fish in the vicinity of large industrial and irrigation diversions and sewage and industrial waste discharges; Skinner and later Chadwick (unpublished data) have continued the work.

Surveys have been conducted almost annually since 1946 to obtain a measure of the distribution and abundance of bass fry over the Bay and Delta Area where they are widely distributed. Calhoun (1953) in conjunction with personnel from the U. S. Fish and Wildlife Service divided the entire area into 67 different sections, sampled each to obtain the density of fry per thousand cubic feet of water strained, and projected the result to the approximate volume of water within each section. They derived an estimate of 35 million fry during 'mid-July of 1951 and a second estimate of 20 million for late July.

Fry were found in greatest abundance in Honker, Grizzly and Suisun bays and in the main channels of the Sacramento and San Joaquin rivers in the Delta, particularly heavy concentrations were found in Honker Bay and in the San Joaquin River between Pittsburg and Antioch.

The surveys since 1951 have not been as extensive as in that year, but they indicate that a similar distributional pattern has prevailed each year since. Between 1953 and 1956 the surveys were conducted under identical conditions to obtain continuity for year-to-year comparisons of fry abundance. Five stations were selected and sampled on minus tides, when the fry reached a mean length of one inch in the vicinity of Antioch.

It appears that reproduction was exceptionally good in 1953 and 1954 with progressively poorer years in 1955 and 1956. Unfortunately, statistical procedures have revealed certain discrepancies in the sampling methods which limit the usefulness of past surveys as indices of abundance. A new approach is being employed which it is hoped will yield more useful data.

Experimental data indicate the fry are usually located nearer the surface than the bottom, although a recent series of tests designed to determine their vertical distribution, showed the reverse to be true on at least one occasion. Chadwick (unpublished data) conducted tests in the summer of 1957 which showed that the smaller fish are found in greater numbers near the shoreline than in mid-channel. As they approach two inches in length, they are found more evenly dispersed throughout the channel. Evidently, even fry less than an inch in length have some control over their movements despite rapid tidal currents. His findings agree with observations made by the writer in 1954 and 1955 while engaged in this work.

Juveniles. By early summer young fish are scattered throughout all parts of the Delta and at least as far downstream as San Pablo Bay. Apparently, all fry are not carried into the Delta because they can be found far up the Sacramento and San Joaquin Rivers in the late summer and fall. It seems rather improbable that they return upstream after having once gone down. Juvenile fish have been seined all along the Sacramento and San Joaquin rivers and at least as far down as Point Wilson in San Pablo Bay.

During seining operations during the fall (October) of 1956 and 1957, throughout the Bay and Delta, fish with mean lengths ranging from 2.9 to 4.0 inches were taken. The overall average is probably about 3.5 inches. There does not appear to be any perceptible difference of growth pattern in any particular part of the area covered. Growth ceases, or at least is greatly diminished from October until the following March. Juvenile fish apparently remain principally in the Delta for two to three years before moving into San Francisco Bay or the ocean. During this period they tend to be gregarious, moving about in scattered schools.

Fish up to 16 inches may be found anywhere throughout most of the year, but certain areas seem to be more favorable than others. Such juveniles are almost always present in San Pablo Bay in the vicinity of Mare Island, the Napa River, Suisun Bay, and in a number of localities in the Delta.

Raney (1952) states: "During the first and second years they remain in small schools or feeding groups, but it has been observed that they exist in large schools by the end of the second summer."

The age at which they first begin their annual migrations between fresh and salt water has not been positively established on the West Coast. Most fish, it is thought, undertake them in the third year though many unquestionably begin in the second and others probably wait until their fourth year or later. Inherent differences between fishes, and sexual differences, are likely factors influencing the age at which they move into salt water. The proportion of adults making these annual excursions is not known; however, since large fish are very scarce in the Delta during the summer, it may be concluded that the great majority are involved.

Migrations. Clark (1934 and 1936) and Calhoun (1952) are responsible for most of our present knowledge on striped bass migrations in California. Both have conducted tagging experiments showing the migratory patterns. A third study, by Chadwick, was underway at the writing of this report.

Clark reported the results of tagging 1,544 bass, mostly small ones (mean length 11 inches), and found that they did not move in a well defined migration but more or less diffused out of the tagging area.

Calhoun's work was with legal sized fish (then 12 inches and over), of which he tagged more than 4,000. He found that unlike the smaller fish, the adults did undertake well defined seasonal migrations. Recoveries of tagged fish by sportsmen and gill net fishermen showed that the adults move upstream into San Pablo Bay and Carquinez Strait in the fall, then into the Delta in the winter, spread out and ascend the tributary rivers in the spring, and move down to the Bay again by early summer.

Their movement to and in the ocean is not yet understood, although a fair number appear to enter the ocean each year. Occasionally, good catches are made by surf casters off San Francisco beaches. Although stripers are seldom taken off shore, the party boat fleet made good catches of striped bass in the ocean during 1956. On the Atlantic Coast extensive north-south ocean migrations are made, presumably for feeding purposes. This phenomenon has not been observed to occur here.

Food Habits. Scofield (1911) found that fish up to four inches, in Napa Creek, relied on marine worms (50 percent) crustaceans (48 percent) and small fish (2 percent). The items are listed in Table 25.

Hatton (1940), in a collection of 76 fish ranging from one to six inches in length taken at Martinez, found that 69.4 percent of all stomachs contained crustaceans. The percentage of stomachs containing each item found is shown in Table 26.

Hatton points out that the items were found during September and November while the water at Martinez was brackish.

Under freshwater conditions in this area, during the spring, the amphipods and isopods disappear, and the small fish were found to be feeding almost exclusively on a species of Mysidacea (Neomysis mercedis).

The writer has on several occasions while checking the stomachs of young-of-the-year bass (2 to 4 inches) from the San Joaquin River and Suisun Bay during the summer also found that mysid shrimp {Neomysis mercedis) was by far the major item in the diet. Some of the stomachs examined were simply packed with them. Each spring and summer the River and Delta abound with these small crustaceans.

Messrs. Fisk and McCammon of the Department, who have studied the food habits of the white catfish in the Delta, observed that amphipods (Corophium spinicorne) were the most important organism utilized by catfish. Hatton's work seems to confirm the importance of it in the diet of small bass. Unfortunately, data are meager on feeding habits of small bass from the time they begin to feed until they are through the first year.

On the East Coast, freshwater shrimp (Gammarus), and Dipterid (chironomid) larvae were found to be major food items.

Striped bass become piscivorous [ Habitually feeding on fish; fish-eating.] at least by thetime they reach 6 inches and perhaps earlier. Their diet from this size on is extremely varied, and appears to depend upon the forage available. The larger fish appear to have a proportionately larger percentage of fish in the diet but even the largest specimens were found to contain crustaceans.

Bay shrimp (Crago sp.) appears to be one of the most common items, along with Neomysis mercedis and the small forage fishes found in the Bay, such as smelt, herring and anchovy. Hatton (op cit) examined 224 stomachs of adult bass taken near Pittsburg between March 13 and May 4, 1939 and found 56.6 percent to be empty (during the spawning season). His findings are summarized in Table 27.


Johnson and Calhoun (1952) examined 387 stomachs of adult bass collected during a period of a year. All fish were over 12 inches in length. One group of 229 was collected between San Rafael and Martinez during the summer and fall, while the other lot of 158 was taken from the Delta portion of the San Joaquin River between Antioch and the mouth of Middle River between November 1947 and June 1948.

Shrimp (Crago sp.) were the most numerous item and comprised the largest volume of all organisms found in the summer group. It occurred in 35 percent of all stomachs examined and formed 53 percent of the volume of all foods. Anchovies, the next most important item, occurred in 11 percent of the stomachs and comprised 39 percent of the food volume Isopods, crabs, mysid shrimp, and other fish were also found but none occurred more than six times or formed more than 2 percent of the total volume. Of this group of fish 28 percent of the stomachs examined were empty.

Their winter sample, the one from the Delta, contained 66 individual fish (42 percent of the sample) with empty stomachs. Neomysid shrimp occurred in more stomachs than any other item and formed, surprisingly enough for large fish, 20 percent of the total volume. Small fish, however, were the most frequent item and accounted for the greatest volume (64 peicent). Bay shrimp (Crago sp.) accounted for 13 percent of the volume.

Shapovalov (1936) examined the stomachs of 47 striped bass taken from the mouth of Waddell Creek, Santa Cruz County. He found a large variety of items, with crustaceans predominating in the small bass, and other fish being the principal food of the larger bass.

Bass are obviously omnivorous feeders; quoting Scofield (1931): "Practically every marine form common to the San Francisco Bay region has been found in their stomachs. Their food includes fishes, such as small Pacific herring, smelt, anchovies, split-tails, striped bass, shad, gobies, carp and perch; crustaceans and mollusks—crabs, shrimps, periwinkles, clams; and various other forms such as worms, copepods and vellella."

From the available data, it may be concluded that the very young fish at first depend on the microcrustacea, diatoms and other minute invertebrates. From one to four inches they depend heavily on larger crustaceans, Neomysis mercedis, Crago sp., aquatic isopods, amphipods, and marine worms. During succeeding years their diet becomes largely piscivorous, although crustaceans continue to be important.

Growth. The growth rate and relationship between age, length and weight was first worked out by Scofield (1931) for California striped bass. Robinson (1960) recently completed another study of the subject to determine if any appreciable change had occurred over the intervening 30 years. Both studies show a rapid gain in length for the first 4 years of life after which the rate becomes progressively less. Robinson, however, found that growth both in length and weight was more rapid than shown by Scofield, the difference being about 10 percent greater length and 25 percent greater weight by the end of the 7th or 8th years of life. Difficulty in aging specimens after their 7th year of life precluded accurate interpretations beyond this age without a great deal of careful study. Stripers reach a length of about 32 inches and a weight of 14 pounds by their 9th year of life. The maximum length attained in California may exceed 50 inches while the maximum weight may exceed 60 pounds (a 63 pound striped bass has been recorded). Fish attaining the above dimensions are most likely 20 years of age or over. Stripers gain weight at a relatively constant rate after their fifth year of life; the gain may be in excess of 2 pounds per year.

Age to Maturity. Scofield (op. cit.) made a careful study of maturing bass and came to the conclusion that 35 percent of the females mature by their fourth year, 87 percent by the fifth year, 98 percent spawn in their sixth year and 100 percent thereafter. Males mature earlier, many spawning while only 2 years old and most by the time they are three. Morgan and Gerlach (1950) reported mature male fish at one year of age. Males may be scarcely more than 10 inches in length by the time they mature. Females, on the other hand, are generally more than 18 inches long.

Artificial Propagation. In California, between 1907 and 1910, a brief attempt was made to propagate this species artificially. A small hatchery was built on Bouldin Island and operations were carried on for several seasons but the difficulties encountered, particularly the inability to collect ripe spawn, resulted in the abandonment of operations.

On the Atlantic Coast there still exists a hatchery at Weldon, North Carolina for this purpose.

Striped bass are extremely prolific and attempts to propagate them artificially are unwarranted. So many fry are produced through natural propagation that almost any contribution from artificial sources would be superfluous. Once established in an area any decline in the population is most likely the result of environmental factors rather than insufficient natural propagation.

Sources of Mortality. This phase of the life history of striped bass requires more investigation. Information simply is not available concerning the ages at which various types of mortality occur. Several earlier attempts to obtain data on angler haryest were attempted, but these met with difficulties.

An unknown proportion of the eggs deposited by the female are not fertilized. Losses occur while the eggs and larvae develop in their hazardous position of drifting in the river or tidal currents. Predation, sudden changes in temperature, pollution, and a number of other factors must also take a tremendous toll of eggs and larvae. As the yolk material is used up the larval fish must begin to fend for themselves, and it is at this stage that perhaps the greatest losses occur. Those which survive are continually subjected to predation, diversions and pollution, each of which could account for significant losses. Predation is everywhere apparent, but losses to pollution and water diversions occur at specific locations.

Losses at diversions are similar to those previously described for king salmon and need not be repeated here, except to say that the magnitude of striped bass losses at diversions far exceeds those of any other species in the Bay and Delta area. Some idea of the numbers involved can be obtained from recent tests at two major water diversions in the Delta.

The Contra Costa Steam Plant of the Pacific Gas and Electric Company located near Antioch requires 868 cubic feet of water per second for cooling purposes at peak capacity. Screening small fish from this amount of water presented a formidable problem but one which was eventually overcome by research and cooperation between the Pacific Gas and Electric Company and the Department of Fish and Game. This plant alone, it was estimated, could conceivably affect 10 percent of the annual striped bass fry population which, it will be recalled, was estimated at 35 million fish in 1951. Fortunately, salvage operations have greatly reduced the numbers of small fish destroyed at the installation.

Similarly, but on a more gigantic scale, the Tracy Pumping Plant of the Central Valley Project draws water from Old River and pumps it into the Delta- Mendota Canal for irrigation purposes in the San Joaquin Valley. A very conservative estimate of fry under the influence of this large diversion (designed to draw 4,600 cfs at peak periods) would be 10 to 15 percent of the population each year. Research by the Bureau of Reclamation and the Fish and Wildlife Service in cooperation with the Department, resulted in a revolutionary new type of salvage facility termed the "louver facility". Up to 98 percent of fish one inch or more in length have been successfully deflected from the diversion by it. From March through August of 1957, the completed structure bypassed over 1,750,- 000 striped bass, 217,800 salmon and steelhead, 1,187,- 000 catfish, and 261,800 miscellaneous fish.

Pollution affects fish in several ways: the most obvious, of course, is the direct lethal action of toxic substances which results in mass kills but which is seldom detected. Small fish under the influence of tidal currents are carried in the vicinity of toxic discharges which they might otherwise avoid. Even the adults are sometimes caught in particularly toxic discharges as in the case of the Stauffer Chemical Company fish kill in San Francisco Bay in May of 1957 and the Napa River die-off of several years ago.

Usually, however, polluting substances destroy the bottom fauna or food organisms upon which fish depend, or set up a barrier in the form of odors, acidity, temperature or some other condition which is detected by the fish and which they avoid. The latter two are not sources of mortality but they restrict the habitat and result in loss to the fishery.

Predation undoubtedly causes large losses among striped bass under 12 inches in length. After this, however, they themselves are predators and are pretty well removed from the forage class.

Old age, diseases, and parasites also take their toll of fish. Little work has been done concerning the former two. The author has observed striped bass completely riddled with the larval form of a cestode of the order Trypanorhynca. It is thought to be of the genus Gymnorhynchus. Striped bass are the intermediate host of this parasite which has as its definitive host certain sharks, skates and rays. Another common parasite observed was the nematode Contracaecum, of undetermined species.

Scofield (1929) reported injuries to striped bass from lampreys, presumably the Pacific lamprey (Entosphenus tridentatus). The author has observed a large number of striped bass with lamprey scars, and in a few instances with fairly fresh wounds. The effects of predation by lampreys cannot be assessed at this time without considerable conjecture; nevertheless, it is thought that lampreys are not a particularly important source of mortality.

Commercial exploitation was prohibited by law in 1935 largely eliminating this source of mortality. However, studies by the writer (Skinner, 1957) from 1954 to 1957 showed that a considerable number of striped bass were destroyed incidental to commercial shad and salmon netting operations. At a minimal estimate, 22,000 fish weighing about 250,000 pounds were destroyed in netting operations during the fall of 1955 and the spring of 1956. The total poundage destroyed each year by this method could easily have amounted to 500,000 pounds. By law, fish taken by the netters had to be returned to the water upon removal from the nets whether dead or alive. Legislation in 1957 prohibited all gill and trammel netting within the Golden Gate, thus eliminating such losses in the future.

Prior to 1935 striped bass were taken commercially. The amount taken each year is described in an earlier section of this report.

The next and probably the greatest single source of mortality among legal size fish is incurred from angling. Tagging studies aimed at measuring the exploitation from this source have not been wholly successful. Clark's tagging study (1934 and 1936) was not intended for this purpose primarily and certain deficiencies in it do not permit application of the results to the fishery in general. He recovered about 10 percent of the fish he tagged within one year of the date of release.

A very intensive tagging program conducted by Alex Calhoun of the Department of Fish and Game was specifically designed to measure the proportion of the population caught by anglers. It soon became apparent, however, that the commercial gill net fishery in the Delta and Suisun Bay region was seriously interfering with the study. The gill netters removed the tagged fish before the anglers had the opportunity to catch them and furthermore, the placement of tags on the fish was found to increase the chances of a fish being captured by the gill nets. Other adverse factors included the reluctance of sport and commercial fishermen to return tags from captured fish. Because of these conditions only the roughest sort of estimate was possible regarding the proportion taken by anglers. The writer made a brief study of tag returns from the above program and concluded that the proportion exploited by both sources, anglers and gill nets, was in excess of 25 percent of the legal population annually. Chadwick, (unpublished data) in a later review estimated a minimal annual rate of exploitation of 10 percent. Anglers, of course, were presumed to catch the greater share by quite a large margin.

Chadwick (unpublished data) initiated another tagging program in the spring of 1958 after removal of the gill net fishery. Preliminary analysis of the first three years of tag returns indicate angling mortality on the order of 20 to 30 percent annually on the population over 16 inches in length.

In spite of all the factors acting against it, the natural survival of this species is obviously high. The frequency with which individuals in excess of 30 or 40 pounds (over 15 years of age) are encountered lead to the conclusion that natural mortality is low.


Striped Bass - Page 169

Generally speaking, this fishery has remained relatively stable. The species was completely removed from the commercial category in 1935 and since then has been subjected to hook-and-line fishing only, except for fish which were taken incidentally with shad and salmon by the gill net fishery. The sport fishery is so intense it is believed that up to 25 percent of all legal-sized fish are removed from the fishery each year.

A review of the catch records and other pertinent data revealed a decline in the fishery from 1944 through 1955. As a consequence, further restrictions in size and bag limits were put into effect to bring the fishery into balance. This appears to have been accomplished.

Under present conditions, it appears that the sport fishery is now exerting sufficient pressure to have a definite influence on striped bass stocks. The governing factor, however, lies in the change in environmental conditions. These have been modified so greatly over the past fifty years that there has been an appreciable loss in the total habitat available to striped bass.

At least three adverse factors, excluding angling, are affecting the striped bass population: reclamation, water development projects, and pollution. It would be next to impossible to evaluate the relative importance of each. Reclamation, many years ago, resulted in extensive habitat changes which removed rich nursery grounds. Water development projects have modified temperature, flow, and salinity patterns in the Delta and in spawning areas, and numerous diversions take a heavy toll of fish. Pollution has resulted in an extensive loss of habitat, destruction of forage organisms, and, frequently, in the outright killing of the fish themselves.

The absence of striped bass in many areas of the Bay may be taken as rather clear evidence of pollution. South San Francisco Bay in particular can be cited, and there are other once-favorable localities which are now similarly devoid of striped bass. End


Calhoun, A. J.
1949 California Striped Bass Catch Records From the Party Boat Fishery; 1938-1948. California Fish and Game, Vol. 35, No. 4, pp. 211-253.
1950 California Angling Catch Records from Postal Card Surveys: 1936-1948 With an Evaluation of Postal Card Non-response. California Fish and Game, Vol. 36, No. 3, pp. 177-233.
1951 California State-Wide Angling Catch Estimates for 1949. California Fish and Game, Vol. 37, No. 1, pp. 69-75.
1952 Annual Migrations of California Striped Bass. California Fish and Game, Vol. 38, No. 3, pp. 391-403.
1953a. State-Wide California Angling Estimates for 1951. California Fish and Game, Vol. 39, No. 1, pp. 103-113.
1953b. Distribution of Striped Bass Fry in Relation to Major Water Diversions. California Fish and Game, Vol. 39, No. 3, pp. 279-299.
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Calhoun, A. J., and John E. Skinner
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Calhoun, A. J., and C. A. Woodhull
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Clark, G. H.
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Cole, Charles E.
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Craig, J. A.
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Hatton, S. Ross
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Jackson, H. W. and R. E. Tiller
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Johnson, W. C, and A. J. Calhoun
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Morgan, Alfred R. and Arthur R. Gerlach
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Scofield, N. B.
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Skinner, John E.
1955a. California State-Wide Angling Estimates for 1953. California Fish and Game, Vol. 41, No. 1, pp. 19-32.
1955b. Observations on the Shad Gill Net Fishery in 1954. California Department of Fish and Game, Inland Fisheries Branch, Administrative Report 55-3.
1957a. Incidental losses of Striped Bass in the Sacramento River Gill Net Fisheries for Shad and Salmon. California Department of Fish and Game, Inland Fisheries Branch, Administrative Report 57-2.
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Smith, Hugh M.
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Woodhull, Chester
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The entire document is available in Adobe PDF format.
John E. Skinner. 1962. An Historical Review of the Fish and Wildlife Resources of the San Francisco Bay Area.
San Francisco Estuary and Watershed Archive

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