FISHERY BULLETIN: VOL. 87, NO. 1 



Transect 1 

 Transect 2 

 Transect 3 



OCT NOV DEC JAN FEB MAR APRIL MAY JUNE JULY AUG SEPT 

 MONTH 



Figure 2.— Temporal fluctuation in the abundance of cabezon embryo masses at 

 Transects 1, 2, and 3. 



turbance) between dives; thus the totals may have 

 been underestimated. 



It was assumed that incubation time of eggs till 

 hatching was the time between when an embryo 

 mass was first observed and when hatching was first 

 noted. For 13 nests that were monitored from 21 

 January to 26 May 1985, incubation time ranged 

 between 25 and 49 days and averaged 34 days with 

 a standard deviation of 6.8 days. Water temperature 

 varied between 8° and 10°C during this period. 



Embryo masses were found in the intertidal to 

 depths of 17 m and were deposited on hard sub- 

 strates including wood pilings and logs, rocks, and 

 steel. Embryo masses were always observed on ex- 

 posed surfaces rather than underneath structures 

 or inside crevices. 



Spawning Frequency 



Ova diameter frequency plots were used, in part, 

 to determine the frequency of spawning. Eight 

 stages of ovarian development, designated I to VIII, 

 were delineated based on the modal configurations 

 of ova diameter frequency plots (Fig. 3). Seven 

 ovaries were in Stage I, characterized by relatively 

 small resting oogonia with diameters <0.40 mm 

 (Fig. 31). The bulk of the eggs from Stage I were 

 translucent, devoid of yolk, and had diameters <0.20 

 mm. Eggs of this size and with these characteris- 

 tics were present in all eight stages. 



Stage II ovaries were found in six cabezon (Fig. 

 311). In addition to the large reserve of resting 

 oogonia, there was another mode of opaque eggs 



which averaged 0.46 mm and ranged from 0.35 to 

 0.65 mm. 



Stages III to VII represented two basic types of 

 female spawners: those which were going to spawn 

 for the first time (Stages III to V) and those which 

 had already spawned once and had the potential for 

 spawning again (Stages VI and VII). For both 

 groups (spawned and unspawned), there were two 

 groups of yolked oocytes. 



There were seven female cabezon with F ^e III 

 ovaries (Fig. 3III). Besides the resting oogonia, 

 there was an intermediate mode (average 0.47 mm, 

 range 0.35 to 0.65 mm) which represented a reserve 

 group of immature oocytes for future spawoiing, and 

 a larger mode (average 0.84 mm, range 0.70 to 1.10 

 mm) which consisted of maturing ova destined to 

 be spawned within the current spawning season. In 

 Stage IV, egg hydration was beginning and the 

 largest mode was more distinct than in Stage III 

 ovaries (Fig. 3IV). The largest mode of yolked 

 oocytes averaged 1.23 mm and ova diameters 

 ranged from 1.00 to 1.45 mm in Stage IV ovaries. 



For females with Stage V ovaries, spawning was 

 imminent and there was no evidence of prior spawm- 

 ing (Fig. 3V). The modal configuration of an ova 

 diameter frequency plot of a female captured while 

 actually spawning was Stage V. For all Stage V 

 ovaries combined, the average diameter of the 

 largest mode (hydrated eggs) was 1.48 mm and the 

 range was from 1.35 to 1.65 mm. Eggs from the in- 

 termediate mode had an average diameter of 0.55 

 mm and ranged from 0.35 to 1.0 mm. 



Stage VI ovaries were characteristic of recently 



148 



