FISHERY BULLETIN: VOL. 79, NO. 3 



seem that queenfish reproduction is timed to 

 coincide with peak zooplankton densities later 

 in the production cycle. 



Further evidence for the controlling influence of 

 planktonic production on the timing of reproduc- 

 tion by many fishes, including queenfish, comes 

 from subseasonal variations in egg size. Blaxter 

 and Hempel (1963) demonstrated that larval sur- 

 vival is related to hatchling size, which in turn is 

 proportional to egg volume. The egg (hence larval) 

 size of temperate spring-summer spawning spe- 

 cies in general declines over the spawning season, 

 whereas size of eggs of autumn-winter spawning 

 species increases over the season (Ware 1975). 

 These changes in egg size coincide with the 

 planktonic production cycle as it affects the kinds, 

 sizes, and quantities of zooplankton prey available 

 for fish larvae. Larval growth and mortality rates 

 (influenced by seasonally changing predator den- 

 sities and water temperatures as well as den- 

 sities of planktonic prey) may also elicit adaptive 

 changes in egg size (Ware 1975). A scenario for 

 spring-summer spawners like queenfish might be 

 as follows: At low water temperatures in early 

 spring, growth offish larvae is slow, relatively few 

 large (adult) zooplankton are available as food for 

 larval fish, and larger hatchlings are better able to 

 temporarily withstand starvation and to capture 

 and ingest large zooplankton. Also, since survival 

 is related to size of larvae (Ware 1975), larger fish 

 larvae have a lower probability of being eaten. As 

 spring becomes summer, water temperatures rise, 

 larvae can grow faster as more zooplankton of 

 a greater array of sizes become available, and 

 it is then adaptive to spawn greater numbers of 

 smaller eggs that subsequently hatch as smaller 

 larvae (Ware 1975). A large number of spring- 

 summer spawners in the temperate zone track the 

 production cycle in this manner (Bagenal 1971). 

 Serial spawning in regions of upwelling appears to 

 be a tropical adaptation to a temperate production 

 cycle of high amplitude that is highly variable 

 in timing (Gushing 1975). Fishes like queenfish 

 spawn on numerous occasions, perhaps so as 

 to "hedge their bet" against unpredictable, and 

 often poor, subseasonal conditions for planktonic 

 propagules. Of course, serial spawning may also 

 be influenced by the fecundity demands necessi- 

 tated by small adult body size and high adult 

 mortality rates. 



We estimate that the spawned eggs of S. politus 

 declined from about 685 to 580 /^m in diameter 

 over the interval from March to August 1979. This 



15% decrease in diameter corresponds to a 39% 

 decrease in volume, or 65% of the difference 

 expressed as a percentage of the smaller volume. 

 This is a reasonable value; for marine fishes with 

 planktonic eggs, the median percentage difference 

 in intraspecific egg volume is just over 100%, 

 with a range from 4.5 to 403% (Bagenal 1971). 

 Assuming that the chemical composition of yolk 

 in queenfish eggs remains constant during the 

 spawning season, the calorific value of individual 

 eggs declined by about 39%. Since the relation 

 between batch fecundity and female body size is 

 constant throughout the spawning season (Figure 

 6), queenfish appear to allocate less energy to 

 egg production later in the season by producing 

 smaller eggs. Engraulis mordax likewise pro- 

 duces smaller (Smith and Lasker 1978) and per- 

 haps fewer (Hunter") eggs later in its spawning 

 season. The availability of food for adults as well 

 as larvae appears to determine the timing and 

 intensity of spawning by northern anchovy (Hunt- 

 er and Goldberg 1980) as well as queenfish and 

 perhaps also influences egg size in these fishes. 



SUMMARY 



The queenfish is a serial spawner with a pro- 

 tracted spawning season. Spawning frequency, 

 although generally asynchronous among females, 

 can be estimated from the incidence of fish with 

 hydrated eggs and averages about once per week 

 for females of all adult sizes. Duration of the 

 spawning season, however, is proportional to fe- 

 male body size, ranging from 3 mo (April- June) in 

 recruit spawners ( 10.0-10.5 cm SL) to 6 mo (March- 

 August) in repeat spawners 013.5 cm). Larger 

 females begin spawning earlier in the year and 

 continue spawning after the smallest fish have 

 ceased. Recruit spawners and the largest repeat 

 spawners thus produce about 12 to 24 batches of 

 eggs during their respective spawning seasons. 



Batch fecundity is proportional to female body 

 size and is better correlated with weight than with 

 length of female. Batch fecundity ranges from 

 about 5,000 eggs in 10.5 cm SL recruit spawners to 

 about 90,000 eggs in the largest (25 cm) repeat 

 spawners. The average (14 cm) fish produces about 

 12,000-13,000 eggs per batch. Almost all hydrated 

 eggs are liberated at the time of spawning, which 



"J. Roe Hunter, Southwest Fisheries Center, NMFS, NOAA, 

 PO. Box 271, La Jolla, CA 92038, pers. commun. August 1980. 



558 



