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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

Page 4 of 6

Striped Bass  Pages 71 - 83

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.

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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.
1957 Striped Bass Fishing Map (Revised by John E. Skinner). California Department of Fish and Game.

Calhoun, A. J., and John E. Skinner
1954 Field Tests of Stainless Steel and Tentalum Wire with Disk Tags on Striped Bass. California Fish and Game, Vol. 40, No. 3, pp. 323-328.

Calhoun, A. J., and C. A. Woodhull
1948 Progress Report on Studies of Striped Bass Reproduction in Relation to the Central Valley Project. California Fish and Game, Vol. 34, No. 4, pp. 171-187.
1950 Striped Bass Reproduction in the Sacramento River System in 1948. California Fish and Game, Vol. 36, No. 2, pp. 135-145.

Clark, G. H.
1929 Sacramento-San Joaquin Salmon (Oncorhynchus tshawytscha) Fishery of California. California Fish and Game, Fish Bulletin No. 17.
1932 The Striped Bass Supply of California, Past and Present California Fish and Game, Vol. 18, No. 4, pp. 297-298.
1933 Fluctuations in the Abundance of Striped Bass (Roccus lineatus) in California. California Department of Fish and Game, Fish Bulletin No. 39.
1934 Tagging of Striped Bass. California Fish and Game, Vol. 20, No. 1, pp. 14-19.
1936 A Second Report on Striped Bass Tagging. California Fish and Game, Vol. 22, No. 4, pp. 272-283.
1938 Weight and Age Determination of Striped Bass. California Fish and Game, Vol. 24, No. 2, pp. 176-177.

Cole, Charles E.
1930 Angling for Striped Bass. California Fish and Game, Vol. 16, No. 4, pp. 286-290.

Craig, J. A.
1928 The Striped Bass Supply of California. California Fish and Game, Vol. 14, No. 4, pp. 265-272. 1930 An Analysis of the Catch Statistics of the Striped Bass (Roccus lineatus) Fishery of California. California Department of Fish and Game, Fish Bulletin No. 24.

Hatton, S. Ross
1940. Progress Report on the Central Valley Fisheries Investigations, 1939. California Fish and Game, Vol. 26, No. 4, pp. 334-373.

Jackson, H. W. and R. E. Tiller
1952 Preliminary observations on spawning potential in striped bass (Roccus saxatilis). Maryland Dept. Res. and Ed., Pub. 93, pp. 1-6.

Johnson, W. C, and A. J. Calhoun
1952 Food Habits of California Striped Bass. California Fish and Game, Vol. 38, No. 4, pp. 531-533.

Morgan, Alfred R. and Arthur R. Gerlach
1950 Striped Bass Studies on Coos Bay, Oregon in 1949 and 1950. Oregon Fish Commission, Contribution No. 14.

Pearson, John C.
1938 The Life History of the Striped Bass or Rockfish, (Roccus saxatilis) (Walbaum). U. S. Department of Commerce Bureau of Fisheries, Vol. XLIX, Bulletin No. 28.

Raney, Edward C, Ernest F. Tresselt, Edgar H. Hollis, V. D. Vladykov and D. H. Wallace
1952 The Striped Bass (Roccus saxatilis). Bulletin of the Bingham Oceanographic Collection, Vol. 14, Article 1.

Scofield, N. B.
1910 Notes on striped bass in California. Biennial Report, Calif. Board of Fish and Game Commissioners for 1909-1910, pp. 104-109.

Shapovalov, Leo
1936 Food of the Striped Bass. California Fish and Game, Vol. 22, No. 4, pp. 261-270.

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.
1957b. Status of the Striped Bass—Sturgeon Study and Suggestions for its Future. California Department of Fish Fish and Game, Inland Fisheries Branch, Administrative Report No. 57-11.

Smith, Hugh M.
1895 The Striped Bass History and Results of Introduction. U. S. Fish Commission Bulletin, Vol. 15, pp. 449-458.

Woodhull, Chester
1947 Spawning Habits of the Striped Bass (Roccus saxatilis) in California Waters. California Fish and Game, Vol. 33, No. 2, pp. 97-101

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