DeMartmi: Annual variations in reproductive traits of Senphus politus 



15 



In another detailed study, Parrish et al. (1986) 

 detected allometric weight-specific fecundities in a size- 

 (age-) structured stock of the northern anchovy. Em- 

 pirical data for additional species of "weedy" (fast- 

 growing, high-fecundity) fishes suggest that allometric 

 fecundity-weight relations may be a general phenom- 

 enon (Blaxter and Hunter 1982, Clarke 1987). Reiss 

 (1987), in a review and interpretation of relevant data, 

 calculated that larger (older) fish in general have 

 disproportionately large reproductive investments. 

 Williams (1966), Wootton (1979), and Reiss (1987) have 

 argued that disproportionate investments by older in- 

 dividuals should be adaptive for many iteroparous 

 fishes with indeterminate growth. The queenfish data 

 further suggest that allometry in gonadal allocation 

 may be more common than is generally appreciated. 

 Adjustments for allometry are required when calcu- 

 lating egg-based stock size estimates for species like 

 queenfish and northern anchovy (Parrish et al. 1986). 



Covariates of egg size 



Egg size was positively related to queenfish body 

 length, but declined for females of all sizes as water 

 temperatures increased between the beginning 

 (March- April) and end (July- August) of the spawning 

 season. Egg size has been observed to increase with 

 female body size, and decreases in egg size have been 

 related to increases in water temperature during 

 spring-summer production cycles, for diverse marine 

 fishes (Williams 1967, Ware 1977, Blaxter and Hunter 

 1982 and references, Kashiwagi et al. 1985, Knutsen 

 and Tilseth 1985, Daoulas and Economou 1986 and 

 references, Imai and Tanaka 1987, Tanasichuk and 

 Ware 1987). A positive female size-egg size relation 

 and a seasonal decline in egg size with increasing water 

 temperatures, the latter either ecophenotypic or 

 genetic responses to the changing prey or predator 

 (Clarke 1989) spectra confronting larvae, are now 

 recognized as general phenomena in marine pelagic- 

 spawners (Ware 1975; Markle and Frost 1985). It is 

 obvious that estimates of mean egg size (and fecundity) 

 must account for the effects of female body size and 

 subseasonal variation. 



Annual variations in fecundity and egg size 



Batch fecundities of queenfish (adjusted for annual 

 variations in female size) varied less than 6% during 

 four out of the five years of this study. A marked 

 change in batch fecundity, after adjustments for varia- 

 tions in female size, occurred only in 1984. Weight- 

 specific fecundities paralleled batch fecundities. 



Queenfish egg size varied little among the five years 

 studied. Apparent egg volume averaged about 24% 



smaller in 1979 than during the other four years. 



Few data exist on annual variations in the egg pro- 

 duction of marine fishes (Bagenal 1957 and references, 

 Antony Raja 1971, Pinhorn 1984, Hunter et al. 1985, 

 Bailey and Almatar 1989). As one might expect, the 

 size-specific fecundity of individuals varies among 

 years, but sometimes fecundities are remarkably 

 similar within a short series of years (Antony Raja 

 1971, Pinhorn 1984, Hunter et al. 1985). Observational 

 and experimental studies (e.g., Tyler and Dunn 1976, 

 Wootton 1979, Hunter and Leong 1981, Hay and Brett 

 1988) demonstrate that fluctuations in fecundity can 

 and do result from naturally occurring food limitation. 

 Food rations can also affect egg size (Hislop et al. 1978, 

 Le Clus 1979). The trivial inference is that food can 

 sometimes, although not invariably, limit egg produc- 

 tion. Of greater interest is that, for queenfish, the max- 

 imum observed deviation from long-term average 

 fecundity was only a 20% decline in a single year of 

 unique oceanographic conditions, as described in the 

 following section. 



El IMirio effects 



The anomalously low fecundities and somatic condition 

 of queenfish in 1984 occurred at a time when the 

 1982-84 El Nino was still evident in the Southern 

 California Bight (McGowan 1985). During 1983-84, 

 zooplankton production was at unusually low levels in 

 inner-shelf waters (Petersen et al. 1986), mirroring the 

 nadir in phyto- and zooplankton production in the 

 California Current, farther offshore (McGowan 1985). 

 This decline in planktonic production off southern 

 California lagged the more extreme declines in produc- 

 tion that resulted from the parent El Nino that oc- 

 curred off the western coast of South America during 

 1982-83 (Barber et al. 1985). 



During the 1982-84 California El Nino, tropical 

 pelagic fishes migrated northward; many species 

 became abundant off southern California, with some 

 noted as far north as Washington-British Columbia 

 (Smith 1985, Mysak 1986). El Nino effects on sub- 

 tropical and cold-temperate fishes are poorly under- 

 stood. Bailey and Incze (1985) and Mysak (1986) 

 summarized the fragmentary data then available on 

 distributional shifts and fluctuations in stock sizes of 

 temperate fishes. Bailey and Incze (1985) speculated 

 that El Nino effects on water temperature, nutrients, 

 and planktonic production could effect egg and larval 

 physiologies, disrupt the transport of early-life-history 

 stages, and impact the somatic condition and egg pro- 

 duction of adults. For vagile species, major impacts 

 such as these should prompt movements to regions 

 more favorable for growth and reproduction (Bailey 

 and Incze 1985). 



