VALENTINE. SOULE, and SAMOLLOW: ASYMMETRY ANALYSIS IN FISHES 



of abnormal or extreme juveniles. The geo- 

 graphical concordance of asymmetry in these 

 fish and human population density in the area 

 studied is certainly suggestive. Furthermore, 

 asymmetry has apparently been increasing in 

 southern California over the past two decades, 

 as has the number of anglers. 



There is evidence that a population explosion 

 of southern California barred sand bass occurred 

 some time during the time period 1957-59. 

 Before this time barred sand bass constituted a 

 minor fraction of the "bass" catch in southern 

 California marine waters ("bass" refers to 

 barred sand bass, kelp bass, and spotted sand bass, 

 P. maculatofasciatus), whereas in 1964 they 

 constituted over 50% of the bass catch from 

 private sport fishing vessels (Pinkas et al., 

 1968). The rapid proliferation of one or two 

 year classes of fish has been known to produce, 

 at least temporarily, phenotypically aberrant 

 cohorts (Whitney, 1961). Similar patterns may 

 be postulated for asymmetry. 



A decrease in the predator-prey ratio should 

 have similar effects. One factor maintaining low 

 variability and possibly low asymmetry variances 

 is the elimination of phenotypically and, pre- 

 sumably, genetically deviant individuals via 

 centripetal or stabilizing selection. With less 

 predation there might be higher survival of 

 deviants. Elimination of piscivorous predators 

 may have resulted from increased fishing pres- 

 sure and reduction in marine piscivorous birds 

 and mammals. 



Domestic sewage outfalls in closed bodies of 

 water are known to stimulate productivity 

 (MacKenthun, 1965, for a review). Similar 

 stimulatory effects on marine phytoplankton 

 are to be expected. Increasing primary produc- 

 tivity should lead to higher overall productivity 

 and an increase in the carrying capacity of the 

 environment, particularly near outfalls. An 

 increasing carrying capacity should result in 

 continual growth in the size of the populations 

 of marine organisms associated with outfalls. 

 Increases in asymmetry can easily be correlated 

 with the increasing volume of sewage effluents 

 in southern California. The apparent increase 

 in size of barred sand bass populations can also 

 be so correlated. The higher concentrations of 

 fish near outfalls (reported by fishermen) as 



opposed to adjacent areas would also be cited. 

 These larger populations of fish may be a direct 

 result of the increased availability of food in 

 areas near outfalls. 



Evidence Against 

 Category A Hypotheses 



Increased cropping of adult fishes through 

 angler success leading to an increase in asym- 

 metry is a difficult hypothesis to test with the 

 species we have chosen to study. Virtually no 

 data exist on the numbers of grunion and 

 barred surfperch taken yearly. Fisheries sta- 

 tistics for the three basses are pooled by the 

 California Department of Fish and Game, 

 making separation by species most difficult. 

 Most of the bass catch is, however, composed 

 of kelp and barred sand bass. Separating the 

 bass catch into kelp and barred sand bass is 

 difficult. 



Prior to 1957 barred sand bass composed a 

 very minor portion of the bass catch (Frey, 

 1971). From 1947 to 1959 the bass fishery 

 experienced a general decline, reaching a 23- 

 year low of 428,656 bass caught in 1959. 

 Beginning somewhere around the early 1960's 

 barred sand bass began constituting an increas- 

 ing portion of the bass catch and by 1964, 

 barred sand bass made up roughly half of the 

 bass catch from private fishing vessels (Pinkas 

 et al., 1968). It would, therefore, seem logical 

 that the increase in the bass catch resulted as 

 much from an increase in barred sand bass 

 as from kelp bass. We have seen no informa- 

 tion that the proportion of barred sand bass 

 in the bass catch is declining. The total bass 

 catch has been above 1 million for the past 7 

 years, averaging 1.2 ± 0.109 million individuals 

 from 1963 to 1969. It would, therefore, appear 

 that the barred sand bass population has 

 stabilized. 



Recall from Figure 1 that CV^ values in 

 barred sand bass have been increasing from 

 at least 1954 through 1964. -During this same 

 pei'iod the bass catch passed through a declining 

 phase and then a rapid increase in catch. If 

 fishing pressure were to account partially for 

 these data, we would expect to see relatively 

 stable levels until sometime around 1960, when 

 levels should begin to climb due, on one hand, 



365 



