FISHERY BULLETIN: VOL. 73, NO. 2 



May 

 1969 



June 



July 



Aug 



Sept 



Oct 



Figure 7.— Relationship of puerulus settlement to lunar, temperature, and seasonal cycles. The 

 habitat trap catches are presented as catch per unit effort, and represent the total combined catch 

 of two seaweed traps (primarily the single and double frame designs, Figure 2) maintained in the 

 lighted pier positions (a and b). The date of original settlement for each puerulus was estimated 

 within 1 to 2 days by its degree of pigmentation. Temperature data are from Scripps Institution 

 pier records. 



prevailing influx of pueruli corresponds with the 

 seasonal period of highest temperatures, as shown 

 in Figure 7. The peaks of puerulus settlement oc- 

 curring during the first weeks of July and August 

 also appear to correspond with periods of rising 

 water temperatures. However, another possible 

 interpretation of the settlement patterns shown in 

 Figure 7 is that the low abundance of pueruli ob- 

 served during the period of 10-25 July may have 

 been caused by an influx of cold water originating 

 from local submarine canyon upwelling, which oc- 

 curs periodically. Such a cold upwelling water mass 

 would not be expected to contain any pueruli if the 

 surface-swimming habits attributed to this stage 

 are correct, and could effectively prevent pueruli 

 in warmer water masses from entering the pier 

 area we sampled. 



Lunar Perdicity 



Studies by Witham et al. (1968) and Sweat (1968) 

 of P. argus pueruli in Florida and by Phillips (1972) 

 of P. longipes cygnus pueruli in Australia deter- 

 mined that puerulus settlement was highest dur- 

 ing the new moon phase and did not occur at all 

 during full moon periods. The abundance of P. in- 

 terruptus pueruli, on the other hand, did not show 

 any evident relationship to lunar phases. On two 

 occasions during the first parts of July and 

 August, there were apparent peaks in puerulus 

 abundance during the full moon phase, as shown 



by the habitat trap results in Figure 7. Night-light 

 and habitat trap collections and their relationship 

 to lunar phases are summarized in Table 5. These 

 data indicate that there were no lunar periods 

 when pueruli of P. interruptus were not present 

 and did not settle, and thus that they apparently 

 do not respond to lunar cues, or at least not in the 

 same manner as do species studied elsewhere. 



Witham et al. (1968), Sweat (1968), and Phiflips 

 (1972) were unable to determine whether the ab- 

 sence of pueruli from their habitat traps during 

 full moon periods was due to their absence from 

 the area or their avoidance of the traps. The fact 

 that pueruli of P. interruptus were present and 

 settled in our habitat traps directly under the 

 bright lights of the Scripps Institution pier in- 



Table 5.— The relationship between lunar phases and puerulus 

 abundance, as determined by habitat trap and night-light 

 results. Total catches, given in detailed form in Tables 1 and 2, 

 are presented below as catch per unit effort. 



'Based on catches of the single and double frame traps only. 

 ^Periods of poor conditions (i.e., unsuitable for observing 

 pueruli) were excluded from calculation of the mean. 



370 



