Life-history information is extremely important in fisheries management, especially details regarding age, fecundity, growth, food habits, and so on. Such knowledge has been lacking for the principal species comprising commercial rockfish catches from California waters. Recent studies have furnished details on annual growth, size and age at maturity, weight-length relationship, season of spawning, fecundity, and feeding habits for 10 species of rockfish (genus Sebastodes) that are commonly taken off California. These are bocaccio, S. paucispinis, chilipepper, S. goodei, yellowtail rockfish, S. flavidus, canary rockfish, S. pinniger, vermilion rockfish, S. miniatus, widow rockfish, S. entomelas, dark-blotched rockfish, S. crameri, splitnose rockfish (rosefish), S. diploproa, stripetail rockfish, S. saxicola, and shortbelly rockfish, S. jordani. Although 57 varieties of scorpaenids (family Scorpaenidae) exist off the coast of western North America, only two had been studied in any detail prior to this time. Wales (1952) published a partial life history of the blue rockfish, Sebastodes mystinus, and Westrheim (1958), and Alverson and Westrheim (1961) published data on the biology of the Pacific ocean perch, S. alutus. The blue rockfish is a shallow water form, caught mainly by sportfishermen in California. Although poorly represented off California, Pacific ocean perch are abundant in offshore waters of the Pacific Northwest, where they are the primary rockfish sought by otter trawl fishermen. In California waters, the rockfish family is now represented by 50 species of Sebastodes (rockfish or "rock cod"), 2 species of Sebastolobus (channel rockfish), and 1 of Scorpaena (sculpin). This fish family is one of the most important and colorful in our waters. Most of the species are highly desirable for food and are subjected to both commercial and sportfishing pressure. Only a few are too small to be of direct value for human consumption. Even these are utilized as food by other fishes, often by larger forms of rockfish. Nine of the species in the present study are of considerable commercial value; the tenth, the shortbelly rockfish, is a small form whose greatest value probably is as food for salmon (Merkel, 1957) and similar predators. As time permits and based upon future catch composition evaluations, other prominent species will be studied in similar detail. The most important of these at present seem to be the shortspine channel rockfish, Sebastolobus alascanus, and flag rockfish, Sebastodes rubrivinctus, in northern California; the speckled rockfish, S. ovalis, in central California; and the bronzespotted rockfish, S. gilli and cow rockfish, S. levis, in southern California.

The rockfishes and scorpionfishes (family Scorpaenidae) form one of the most important fish families in the ocean waters of California. At present, in California waters, this family is represented by 49 species in the genus Sebastodes, two in the genus Sebastolobus, and one in the genus Scorpaena.

Not only does this family contain more species than any other marine or freshwater fish family known to inhabit our waters, but most of the species are highly desirable for food. Only a few are too small to be of direct value for human consumption. Even these, however, are utilized as food by other fishes, often by larger species of rockfishes. The pygmy rockfish for example, which barely reaches a size of eight inches, has been taken only from the stomachs of other rockfish.

Various rockfishes were of commercial importance in California as early as 1875 and, as a group, the rockfish have continually increased in importance not only in California but along the Pacific Coast, as well. The California catch, which in 1900 totaled between one and two million pounds, has in recent years risen to an average of between 12 and 13 million pounds annually. The importance of rockfish for human consumption during World War II is reflected in the peak Pacific Coast catch of 60 million pounds in 1945.

For many years the majority of the catch was marketed fresh in the form of fillets. At present, only a small amount of the rockfish catch is marketed in a fresh dressed form, particularly in Southern California, but a sizable proportion is processed as frozen fillets. Preliminary tests on the frozen storage life of the fillets of a few important species indicate definite differences in keeping qualities. In this regard, it is hoped that this publication will be of particular value to both the fisherman and the processor in the proper identification of the numerous rockfish species.

In the filleting process of rockfish, there is a loss of about two-thirds from the round weight. The carcasses that remain after filleting are either reduced to meal for livestock feeds or are mixed with scrap fish some of which consists of small unmarketable species of rockfish. This mixture is ground and frozen for use as mink food or as a supplement in the diet of hatchery-raised trout.

During the past decade, sport fishing in the ocean waters of California has become increasingly important as a source of recreation for our growing population, and rockfish are now one of the most important components of the sport catch. Party boat records for all of California reveal that rockfish comprised 9 percent of the two and one-half million fish caught by anglers in 1947. By 1955, 55 percent of the three million fish caught by sport anglers consisted of rockfish.

The adult forms of some rockfish are found only in relatively shallow water, often close to shore, but others are found only in deeper water and the adults of a few may occur in offshore water as deep as 3,000 feet. Surveys being conducted by the California Cooperative Oceanic Fisheries Investigation show that the larvae of various species of rockfish occur in great abundance and are widely distributed along the coast, in some cases appearing as far as 300 miles offshore. They are abundant during most of the months of the year. Thus, during their pelagic existence and later as young and immature forms seeking an ultimate bottom habitat, these species are of considerable importance as food for pelagic, mid-water, and bottom living fishes. The young of various rockfish sometimes form a large and important part of the diet of such highly prized species as king salmon, albacore, and petrale sole.

Most of the Pacific Coast scorpaenids were described prior to 1900 by a number of different workers. These men often based their descriptions on a single specimen, and occasionally a freak or variant would be described as new. Others of these early descriptions are inadequate for satisfactory identification of the fish at hand. As a result, the identity of a number of species of rockfish has been in doubt for many years. A number of recent workers have unraveled some of the nomenclatorial problems and reduced several species to synonymy, however, until now no major attempt has been made to redescribe the different species in the light of current knowledge. The present work presents uniform, concise descriptions of all the species comprising the family Scorpaenidae in California waters. Keys and photographs of all these species are presented to facilitate identification.

Proper identification of the 52 kinds of rockfish, inhabiting our waters, will not only aid the industry by providing means of maintaining a uniformity in its products, but is logically the first step in helping to speed future research studies on this increasingly important group of fishes.

Starting with the 1941–42 sardine season, a comprehensive age-reading program on the Pacific sardine or pilchard, Sardinops caerulea, was undertaken along the Pacific Coast of North America. These readings were based on scales from fish in the commercial catch with collections made by the Fisheries Research Board of Canada, the Washington State Department of Fisheries, the Fish Commission of Oregon, the California Division of Fish and Game and the U. S. Fish and Wildlife Service. The actual age interpretations were made jointly by the members of the latter two agencies and were published by Felin and Phillips (1948). Tables 1 – 6, reproduced from Felin and Phillips, list the number of fish, mean length and standard error of the mean for each year-class for each season, 1941–42 through 1946–47, by region of catch. In addition, Table 7 lists the number of fish and mean length for each age during the period 1941–42 through 1946–47, combined. In the presentation of figures that follow, no averages have been plotted for any year wherein fewer than 10 fish are represented. The left-hand vertical scale of each figure shows the body length2 in millimeters, while the righthand vertical scale shows the corresponding total length in inches. The horizontal scale at the bottom of each figure lists the actual number of observed rings and also the corresponding approximate age that each ring represents. As age is estimated from the number of annual rings present on the scale, 0-ring fish are those that are in their first year of life before the first winter ring is formed and 1-ring fish are those that have formed one winter ring between late fall and early spring, etc. Thus, a fish which is caught in the winter fishery and shows one annulus well inside the margin of the scale is in its second year of life. Since the commercial sardine fishery along the Pacific Coast is conducted almost entirely during the late summer, fall and winter months, the actual ages of the fish are approximately one year more than that indicated by the number of rings. Even though a second annulus has formed recently during a current winter, for example in a scale that already has one annulus formed during the previous winter, that fish is still referred to as a 1-ring fish, and the second annulus is indicated as "forming" or "new" until the end of that season. The following general observations concerning the life-history of the sardine are reviewed as an aid in interpreting the results of this study: This species ranges from southern Alaska to Cape San Lucas and into the Gulf of California. However, there is strong evidence that sardines found in southern Lower California and the Gulf of California constitute a separate population which rarely intermingles with the northern population but that a considerable, and perhaps variable, amount of interchange takes place throughout the range of the northern population from Alaska to Pt. San Eugenio in central Lower California. Exploratory work indicates that spawning may occur throughout the range of the sardine population, usually 50 to 200 miles offshore, but that the heaviest concentration is off Southern California. In this region, the spawning season extends from about January through June with a peak in April. Important nursery grounds are known off Southern California and Lower California and nursery areas of lesser importance may extend as far north as British Columbia. The young that result from the spring spawning in Southern California waters may remain on the nursery grounds in Southern California and Lower California for six months or a year. In their second year, if not earlier, they exhibit some northward movement and the extent of this northward movement increases year by year, with the largest and oldest fish eventually reaching the waters of the Pacific Northwest. A study of the size composition of samples and of tagging results indicates extensive migrations for a large portion of the stock, the largest and oldest fish undertaking the greatest movements. An influx of large fish into the Pacific Northwest fishery in the summer is followed by the appearance of these large fish in the California fishery in the winter preceding the spring spawning season. (Clark, 1935, 1940, 1947; Clark and Janssen, 1945; Hart, 1934, 1943; Scofield, 1934.)

The sardine population along the Pacific Coast of North America is subject to large fluctuations in the survival of sardines from each season's spawning. This results in some very abundant year classes, some very sparse and some of intermediate strengths. The relative abundance of each year class can be measured in its second or third year when it is first taken in the commercial fishery but it is of material help to the industry and to the biologist to know the abundance of each year class as early as possible. The California Department of Fish and Game has attempted to measure such abundance by surveys along the coast in the late summer and fall months when a new year class of sardines is about six months old.

The first exploratory surveys were conducted in California and Mexican waters during the fall months of 1938, 1939 and 1940. These were discontinued because the correlation between the observed abundance of young fish on the nursery grounds and the subsequent abundance of these fish in the commercial catch was not in good agreement. This was due in part to lack of certain equipment, such as recording echo-sounders, which were not in general use at that time, and in part to an exceptional spawning in 1939 north of the area covered by the survey. This resulted in a serious underestimate of the abundance of the 1939 year class.

Since the earlier survey, the need for a knowledge of the strength of incoming age groups has become even greater. The older sardines, which acted as a buffer against wide fluctuations in the strength of individual year classes, are no longer on the fishing grounds. As a result the industry is dependent upon younger fish, and a weakened fishery now exists which yields a widely fluctuating harvest, varying as varies the abundance and distribution of young sardines one to three years old.

There have been many new developments since the earlier surveys that aid in collecting and compiling the data. The evaluation of the strength of year classes is now possible through the development of a method of age determination. The relative abundance of a year class can now be traced from its first appearance in the commercial catch until it is no longer taken in the fishery. During the surveys sardines of all age groups can be collected and their estimated abundance checked against similar estimates from the commercial catch.

The California Cooperative Sardine Research Program under the auspices of the Marine Research Committee is collecting data regarding concentrations of sardine eggs and larvae throughout the distribution of the sardine. This information about the location of sardine spawn is collected each season prior to the beginning of the young fish survey and the range of the survey can be established thereby. This should prevent omission from the survey of the nursery grounds to the north or south of the usual spawning area as occurred for a major part of the 1939 year class.

New tools are also most useful. The development of radar has been of great help in allowing the vessel to work closer inshore at night. It also makes it possible to define more accurately the locations where fish are found. The echo-sounder aids in finding schools which cannot be located visually.

Although the earlier surveys are not directly comparable with the later, some marked differences in the two time periods are evident. The most striking is the greater abundance of young sardines in all areas in 1938–40 than in 1950–51. Although this is most apparent in Central and Southern California it is also true for the Baja California region. There is no indication that lack of sardines in California waters in the later years has been compensated by an increase in abundance off Baja California.

The maximum surface temperatures where sardine schools were found are similar for both time intervals. The 1938, 1939 and 1940 surveys were extended farther south than the 1950 and 1951 cruises but sardines were not found at temperatures greater than 26.1° C. In the later surveys the highest temperature at which sardines were found was 25.7° C. The maximum surface temperature encountered on all cruises was 28.3° C. The later cruises recorded minimum temperatures as low as 10.4° C. but no sardines were located at temperatures below 11.4° C. The lowest temperature on the earlier cruises was 11.7° C.

Since November, 1919, the California Division of Fish and Game has been gathering data to contribute to the understanding of causes underlying changes in abundance of the sardine,Sardinops caerulea. A knowledge of the relative proportions of the various age groups of fish in the population is an important element in such studies.

Prior to 1924, an attempt was made by Thompson and assistants to read the age marks on the scales and otoliths of this species, but results did not prove satisfactory. However, an indirect method of assessing age by tracing dominant size groups through the fishery was continued. During the period 1928–1933, a study of otoliths of sardines taken in the California fishery was made by H. C. Godsil, but this also proved unsatisfactory. In March, 1938, Walford and Mosher of the U. S. Fish and Wildlife Service started examination of the scales and otoliths of sardines, commencing with the young and later including older fish. This study established the validity of the method of reading scales to determine age in the sardine. The scale method was recommended as more advantageous in some respects than the otolith method, particularly after a rather simple method of mounting scales dry and projecting their enlarged images was developed.

Starting with the 1941–42 season in California a comprehensive program for scale collecting and age reading was undertaken jointly by the U. S. Fish and Wildlife Service and the California Division of Fish and Game. The Fisheries Research Board of Canada, the Washington State Department of Fisheries, and the Fish Commission of Oregon participated in the work by adding the collection of scales from sardines in northern waters. Their collections were included in the age-reading project. This report deals with the first six seasons of age determinations and presents the age composition of the catch without interpretation of the data.