DeMARTINI ET AL: DISTRIBUTION PATTERNS OF QUEENFISH 



Table 5. — Results of Spearman's 

 rank correlations (Siegel 1956) be- 

 tween index of state of digestion of 

 stomach contents and time of collec- 

 tion for immature, adult male, and 

 adult female queenfish. All samples 

 collected prior to midnight. Sample 

 fish collected during day, night, and at 

 shallow (5-10 m) and middepths 

 (1 1-16 m) are pooled over both onshore 

 periods of distribution (see text). 

 Digestion versus time 



rho 



N 



Immatures 

 Adult males 

 Adult females 



-0.35 

 -0.20 

 -0.22 



57 

 228 

 236 



0.007 



0.003 



;0.001 



and Fountain 1981). During the February-July/ 

 August spawning season, ripe females with 

 ovaries in hydrated (ready-to-spawn) condition 

 can be collected throughout the daylight period 

 beginning 1 h after sunrise, while females col- 

 lected as soon as 1 h after sunset are either ripen- 

 ing (but nonhydrated) or are recently spent (De- 

 Martini and Fountain 1981). 



The diel distributional (CPUE) data of this 

 study (Fig. 1) clearly illustrate the differences in 

 diel migration made by immature, adult male, and 

 adult female queenfish. Size-composition data 

 (Figs. 2-4) further characterize the diel migrations 

 as related to size of fish, regardless of maturity 

 state or whether adults in the populations were 

 reproductively active. 



Certain aspects of the diel CPUE data suggest a 

 breeding function for offshore dispersal at night, 

 since only the distribution of immatures remained 

 centered onshore at night. Also, a dispropor- 

 tionately greater number of adult males versus 

 females emigrated offshore at night (Fig. IB, C). 

 This is consistent with an offshore migration by 

 females for spawning that occurs on a less fre- 

 quent than daily basis, since individual female 

 queenfish ripen and spawn batches of eggs on av- 

 erage only once a week (DeMartini and Fountain 

 1981). The male-biased, daytime aggregations of 

 ready-to-spawn queenfish (DeMartini and Foun- 

 tain 1981) suggest that individual males spawn at 

 more frequent than weekly intervals. Also, pre- 

 flexion stages of queenfish larvae are most abun- 

 dant in midwaters over 12-45 m bottom depths 

 from 1.9 to 5.4 km offshore in the region of San 

 Onofre-Oceanside (Barnett et al.^), which strongly 



suggests that most spawning occurs in outer near- 

 shore regions. 



Other distributional data, however, indicate a 

 primarily feeding function for offshore dispersal 

 at night. The nighttime, offshore shift in the dis- 

 tribution of adults of both sexes, for example, oc- 

 curred during both the nonbreeding and breeding 

 seasons. In addition, relatively more of the larger 

 individuals among the immatures (as well as more 

 of the larger adults of both sexes) moved offshore 

 at night (Fig. 3) from the shallow region wherein 

 queenfish of all sizes co-occurred during the day 

 (Figs. 1, 4). The latter pattern persisted during 

 both breeding and nonbreeding periods of year 

 when distributions were generally inshore of 30 m 

 bottom depth. On balance, the size composition of 

 immature and adult female queenfish censused at 

 5-27 m depths at night resembled the composition 

 of those censused at 5-10 m depths during the day 

 (Fig. 4A, C), indicating that few very large imma- 

 tures or females move offshore of 27 m at night. 

 This moreover confirms that the queenfish seined 

 offshore at night had resided at 5-10 m depths 

 during the day and not in a region (e.g., shallower 

 or deeper) that we did not census. Analogous data 

 for adult males (Figs. 1, 4B) indicate that this may 

 not be true for the largest males. However, the 

 pattern of larger individuals farther offshore per- 

 sisted for males as well as immatures and females 

 during the nonbreeding period. 



The diel food habit data also are largely consis- 

 tent with the hypothesis that queenfish disperse 

 offshore at night to feed, despite several dis- 

 crepancies. Certain prey are known to be much 

 more abundant at either extreme of the queenfish 

 depth distribution. The presence of shallow-living 

 "marker" species such as Diastylopsis tenuis (Ta- 

 ble 6) in the stomachs of queenfish collected 

 offshore of the respective prey distribution likely 

 reflects some feeding activity just prior to or dur- 

 ing the dusk offshore emigration. The presence of 

 some night-active meroplankton in stomachs of 

 fish collected during the day probably represents 

 the partial confounding of nighttime foraging by 

 circumdiel gut residence times. We consider it un- 

 likely that queenfish feed on prey such as D. tenuis 

 during the day, as the nocturnal activity patterns 

 of this and other species of demersal meroplankton 



"Barnett, A. M., A. E. Jahn, P. D. Sertic, and W. Watson. Long 

 term average spatial patterns of ichthyoplankton off San Onofre 



and their relationship to the position of the SONGS cooling 

 system. A study submitted to the Marine Review Committee of 

 the California Coastal Commission, July 22, 1980. Unpubl. 

 rep., 32 p. Marine Ecological Consultants of Southern Califor- 

 nia, 531 Encinitas Boulevard, Encinitas, CA 92024. 



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