Relationships of Female Age and Size to Embryo Number and Size in the Shiner Perch, Cymatogaster aggregata

Abstract

Ages, lengths, and weights were determined for 124 female shiner perch, Cymatogaster aggregata Gibbons, collected in Yaquina Bay, Oregon, from May 17 through June 29, 1968. Embryos (1005) were obtained from 111 gravid females either by dissection (737) or at parturition in the laboratory (268). Embryo lengths, weights, and numbers per female parent were determined.As females increased in age from 1 to 6 years, their mean fork length increased from 9.32 to 13.65 cm, their weight from 13.65 to 47.78 g, and the mean number of embryos per parent female increased from 5.83 to 20.00. The equations and their correlation coefficients (R) computed for the relationships of embryo number (Y) to parent female fork length, weight, and age are, respectively: log Y = −1.892 + 2.735 log X (R = 0.89); Y = 1.131 + 0.313 X (R = 0.70); and Y = 4.23 + 1.73 X (R = 0.51). Embryo size at birth was also directly related to female parent size. The equations computed for the relationships of total length of embryo at birth (Y) to parent female fork length and parent female weight are, respectively: Y = 24.211 + 1.620 X (R = 0.79); and Y = 0.384 + 0.015 X (R = 0.72). The equation computed for the relationship of embryo weight (Y) to embryo length at birth is Y = −2.266 + 0.712 X (R = 0.95).

Reproductive Strategies in the Surfperches. I. Multiple Insemination in Natural Populations of the Shiner Perch, Cymatogaster aggregata

“…The larger size of multiply-inseminated females is not due solely to the greater chance of detection of multiple insemination in larger broods; when females with less than eight embryos (the maximum number examined) are excluded from calculations of average size, the difference still exists (Table 4). The known multiply-inseminated females also appear to have more embryos, undoubtedly due to a close correlation between female length and number of embryos (Wilson and Millemann, 1969;Odenweller, 1975;Noble et al, unpubl.). Multiply-inseminated females have the same number of young as other females of the same size.…”

“…This species occurs from southern Alaska to Baja California. The life history of the shiner perch has been investigated by sev-MATERIALS AND METHODS eral researchers (Gordon, 1965;Wilson Female shiner perch (N = 501) were and Millemann, 1969; Anderson and collected from three localities in central Bryan, 1970;Bane and Robinson, 1970; California during the spring of 1978. San Odenweller, 1975).…”

Life history variation among female surfperches (Perciformes: Embiotocidae)

“…Presumably the size of young at birth increases with female size in all embiotocids ; however, the length of young at parturition has been documented for only two species, the shiner surfperch (Wilson & Millemann 1969) and the redtail surfperch (Bennett & Wydoski 1977) . Positive correlations exist between female size and the size of embryos in nearterm females of barred surfperch, spotfin surfperch, tule perch and walleye surfperch .…”

Habitat‐dependent geographical variation in ontogenetic allometry of the shiner perch Cymatogaster aggregata Gibbons (Teleostei: Embiotocidae)

“…Parturition occurs after seasonal migrations into estuaries in spring and summer, during which this species can become one of the most abundant fishes in shallower waters. Mothers usually bear no more than 20–24 offspring per year (Wilson & Millemann, 1969) and mate soon thereafter. Adult males and females, including young‐of‐year with noticeable secondary sexual characteristics, move into open waters during fall and winter as evidenced by their disappearance from estuaries, but no more is known about migratory behaviour.…”