VALENTINE, SOULE. and SAMOLLOW: ASYMMETRY ANALYSIS IN FISHES 



rl. 



Table 3. — CKj values and character means (->;,.+/) by size class of barred sand bass from Baja California. 



T,\BLE 4. — CK^ values and character means (.v 



r-f 



.) by size class of barred sand bass from southern California. 



(Table 5). These three cohorts were pooled to 

 increase sample size. From Table 5 it is 

 evident that both pectoral fin ray and gill raker 

 asymmetry increased as these particular cohorts 

 aged. The specimens do not exist to perform 

 a similar analysis on Mexican barred sand 

 bass, although we might infer from Table 3 

 that significant asymmetry changes cease when 

 fish exceed 100 mm. 



An historical trend of increasing asymmetry 

 is also indicated. In Figure 1 the appropriate 

 specimens are grouped by their probable dates 

 of hatch. There is evidence for plateauing of 

 this trend since fish hatched after 1966 appear 

 to be no more asymmetric than those hatched 



in the late fifties. A sampling problem may exist 

 because the collections differ in the average 

 size of specimens examined. This could partially 

 account for the apparent plateauing. To examine 

 this, fish of similar size and age were analyzed 

 (Table 6). The plateau is still apparent, so it is 

 probably real. 



To summarize the barred sand bass data, 

 there is evidence for two asymmetry trends in 

 southern California — an increase with size 

 (age) and the other with time. An attempt to 

 partition the asymmetry contributions of these 

 two probable sources by using multiple regres- 

 sion produce inconclusive results due, we 

 think, to the inadequate nature of the samples. 



361 



