LOVE ET AL.: LIFE HISTORY AND FISHERY OF WHITE CROAKER 



stricted in northern waters (Westrheim 1975). 

 However, on examination, the water temperatures in 

 Monterey Bay more closely approximate optimal 

 white croaker spawning conditions than those off 

 southern California. The peak spawning periods, 

 based on gonosomatic indices and ichthyoplankton 

 surveys, in southern California occur between 

 January and March, when mean surface tem- 

 peratures decrease to 13°-14°C (U.S. Department of 

 Commerce 1956). Off Monterey, the mean tem- 

 peratures of the warmest months are 13°-14°C 

 (June-October), whereas the other months are 1°- 

 3°C cooler. Thus white croaker encounter tem- 

 peratures conducive to spawning for more months off 

 Monterey than off southern California. 



White croaker reproductive behavior is in some re- 

 spects the opposite of the cooccuring queenfish. White 

 croaker spawn almost entirely during late winter and 

 early spring (peak February-March), but our 

 ichthyoplankton survey gives a March-April peak, 

 whereas queenfish are spring and summer spawners 

 (peak April-May, DeMartini and Fountain 1981). 

 Most egg hydration in white croaker takes place dur- 

 ing the night, with spawning occurring from just 

 before dawn to midmorning. Queenfish spawn be- 

 tween late afternoon and evening. We have not ascer- 

 tained the extent that habitat partitioning has played 

 in this separation. Off Monterey, where queenfish are 

 rare, white croaker spawn virtually year round. As 

 discussed before, this is perhaps a reflection of a 

 more favorable temperature regime. It would be 

 instructive to know if in the absence of queenfish, egg 

 hydration and spawning time are simlar to those off 

 southern California. 



Larvae 



Data from both gonosomatic indices and 

 ichthyoplankton surveys show white croaker spawn 

 year-round in southern California waters. However, 

 peak spawning clearly is in the winter and spring. Our 

 data, combined with Watson's (1982), indicate that 

 peak densities of white croaker larvae were in either 

 January, February, or March from 1974 through 

 1980. This is out of phase with other southern 

 California sciaenids, all of which spawn primarily in 

 the spring and summer (Lavenberg and McGowen 

 footnote 7). 



White croaker larvae are an important component 

 of the southern California neritic ichthyoplankton 

 fauna. Along the three sections of the Southern 

 California Bight, defined and studied during this 

 investigation, white croaker larvae contributed 11.7, 

 43.6, and 17.9% of the total larvae from south to 



north. Highest densities were found at stations 

 located in 15-22 m depths (Fig. 15). The decreasing 

 densities, as one moves shoreward of the 15 m 

 isobath, apparently continues into the enclosed bays 

 and estuaries of southern California. McGowen 

 (1981) did not collect any white croaker larvae in 

 south San Diego Bay during a 13-mo study. Larval 

 white croaker ranked sixth, contributing 0.6% of the 

 larvae collected in Newport Bay during an 18-mo 

 study by White (1977). The percentage reported by 

 White may have a bias toward lower values because 

 the period of peak spawning was sampled only once 

 during the 18 mo. However, even a doubling of 

 White's percentages does not make white croaker 

 larvae dominant members of the Newport Bay ich- 

 thyoplankton assemblage. Leithiser (1981) reported 

 white croaker to contribute 1.9% of the total catch of 

 larval fishes in Anaheim Bay during a 12-mo 

 study. 



King Harbor is typical of the estuarine-enclosed bay 

 habitat rather than that of the open coast and is 

 dominated by blennies, clinids, gobies, and 

 engraulids (McGowen footnote 8). White croaker lar- 

 vae ranked either fourth or fifth in the King Harbor 

 study, depending on the year and the stations 

 sampled. 



Densities of white croaker larvae also decreased 

 between the 22 and 36 m isobaths (Fig. 15). This 

 indication that white croaker larvae are not common 

 in offshore waters is supported by CalCOFI data. 

 The highest any sciaenid ranked in these collections 

 between 1955 and 1958 was 18th, contributing 

 0.30% of the total larval catch (Ahlstrom 1965). 



This pattern of white croaker larvae being dis- 

 tributed in a narrow band along the coast, between 

 the 15 and 22 m isobaths, is similar to the pattern 

 reported by Watson (1982) and Barnett et al. 13 off 

 San Onofre. They designated white croaker larvae as 

 having an inner nearshore epibenthic pattern. Bar- 

 nett et al. (footnote 13) indicated highest densities on 

 the bottom, shoreward of the 22 m isobath, and the 

 second highest densities in the water column be- 

 tween the 12 and 22 m isobaths and on the bottom 

 between the 22 and 45 m isobaths. The major dis- 

 crepancy between their data and ours is the higher 

 epibenthic densities that they report shoreward of 

 the 12 m isobath and seaward of the 22 m isobath. 

 This discrepancy may be partially explained by dif- 



"Barnett, A. M., A. E. Jahn, P. E. Sertic, and W. Wat- 

 son. 1980. Long term 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 California, 533 

 Stevens Ave., Suite D-57, Solana Beach, CA 92075. 



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