FISHERY BULLETIN: VOL. 71, NO. 2 



to the population explosion of barred sand 

 bass and, on the other, to increased angler 

 success. No such trends are to be found in our 

 data. As previously mentioned, catch data for 

 grunion and barred surfperch are lacking so 

 that it is impossible to examine these species 

 for the possible effects of fishing pressure. 



The effects of a population explosion on 

 asymmetry variance should be temporary and 

 will cease when the population stabilizes. The 

 highest asymmetry values should reflect periods 

 of exceptionally high juvenile recioiitment. 



Our data on probable year of hatch and 

 cohorts analyses show that asymmetry values 

 of barred sand bass are lower in 1957-59 than 

 in later periods. Recall that this is the time 

 when a population explosion of barred sand 

 bass is supposed to have begun. If the asym- 

 metry is genetic and/or congenital, then the 

 low asymmetry of these fish is inconsistent 

 with the above prediction. For our data to 

 support such an hypothesis it would have to be 

 shown that the population of barred sand bass 

 and, for that matter, grunion and barred surf- 

 perch, have been continually increasing. Our 

 data do not support this premise. No data 

 exist for either barred surfperch or gi-union 

 which can be used as a basis on which to test 

 this premise. 



The question of shifting predator-prey ratios 

 is most difficult to analyze. There undoubtedly 

 exist changes in such ratios not only from 

 year to year, but also seasonally. Whether such 

 changes can result in significant shifts in 

 asymmetry variances is unknown. The fact 

 that all three species occupy different habitats, 

 all appear to be undergoing similar asymmetry 

 changes, and all are probably preyed upon by 

 different predators would seem to argue 

 against such a simple cause and effect 

 explanation. 



Fish density around outfalls may be high, 

 but this has never been shown to be an effect 

 of the local productivity gradient. A logical 

 alternative is that outfalls, being constructed 

 over sand or muddy bottoms, provide an 

 artificial habitat. Studies by the California 

 Department of Fish and Game (Turner et al., 

 1969) have shown that artificial reefs in pre- 

 dominantly sandy areas of low relief rapidly 



attract large assemblages of fish. Barred sand 

 bass were the most frequently observed species 

 and were reported inhabiting artificial reefs 

 within hours after construction terminated. 



That larger populations of some species (e.g., 

 barred sand bass) are apparently residing in 

 southern California now than in the past may 

 be ascribed to fluctuations in normal environ- 

 mental conditions. Furthermore, of the three 

 species studied, only barred sand bass and 

 possibly grunion are likely to be found around 

 sewer outfalls. Barred surfperch are pre- 

 dominantly inshore and seldom venture past 

 the surfzone. They are, therefore, unlikely to be 

 affected as much as are the other two species, 

 unless an increase in primary productivity is 

 widespread. Yet data on asymmetry for all 

 three species are similar. 



Arguments for 

 Category B Hypotheses 



Naturally occurring, clinally varying abiotic 

 factors would also seem to be a logical source 

 of induced meristic variation since asymmetry 

 increases from Mexico northward. Experi- 

 mentally, Schmidt (1919, 1920) with brown 

 trout, Salmo trnttta, and the blenny, Zoarces 

 viviparus; Lindsey (1954, 1958) with the 

 paradise fish, Macropodiis opercularis; Blaxter 

 (1957) with the herring, Clxpea hareiigus; 

 Taning (1952) with the sea trout, Salnio tnitfa 

 frutta; and others have clearly demonstrated 

 that temperature plays a very important role 

 in determining the ultimate meristic counts in 

 a wide range of fishes. Barlow (1961) stated 

 that a good correlation exists between cooler 

 environmental temperatures and higher meristic 

 scores. Other environmental factors such as 

 light intensity (McHugh, 1954, with the grun- 

 ion), light duration (Lindsey, 1958, with the 

 kokanee, OiicorJiynclnts iierka), oxygen and 

 carbon dioxide tensions (Taning, 1944, 1952. 

 with the sea trout), and salinity (Heuts, 1947, 

 with the stickleback, Gasterosteus aculeatus) 

 have been examined with similar results. About 

 the only factors studied that have not been 

 shown to significantly alter meristic counts 

 are pH and phosphate and nitrate concentrations 

 (Taning, 1952). 



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