FISHERY BULLETIN: VOL. 80, NO. 3 



and their egg production, when compared with 

 the coastal areas. 



The Abrolhos Islands area, therefore, contrib- 

 uted only about 14% of total egg production in 

 1979. No data on the catch rates of spawning fe- 

 males at the Abrolhos Islands are available for 

 years other than 1979, so it has had to be assumed 

 that the Abrolhos Islands area contributed 14% 

 of the total egg production in each year from 

 1966, although year-to-year variation in the geo- 

 graphical distribution of settling puerulus lar- 

 vae will no doubt change this value to some 

 extent. The index of abundance of the spawning 

 stock for all coastal and Abrolhos Islands areas 

 has therefore been estimated by multiplying the 

 coastal index for each year by 1.14. These values 

 are also shown in Table 1. 



Abundance of Puerulus Stage 



The relative densities of settlement of the 

 puerulus stage (expressed as the mean number 

 per collector settling between September and 

 January at Rat Island (Abrolhos Islands), Seven 

 Mile Beach, Jurien Bay, and Garden Island) are 

 given in Table 3. The data for the different sites 

 have been pooled as an unweighted arithmetic 

 mean and expressed as the mean number of 



puerulus settling on the collectors, to provide an 

 annual index of settlement. 



Abundance of Juveniles 



Estimated densities of various year classes at 

 Garden Island and Seven Mile Beach were calcu- 

 lated as described by Chittleborough and Phil- 

 lips (1975) (Table 4). 



Abundance of Recruits to 

 the Fishery 



The catch per pot lift of "white" rock lobsters 

 taken during November and December has var- 

 ied during the years 1964-78 (Table 5) and has re- 

 sulted in similar variations in total catch from 

 the fishery (Table 6). 



The Relationships 



Spawning Stock and Puerulus Settlement 



Since the peak of puerulus settlement each 

 year occurs from September to January (Phillips 

 and Hall 1978) and is the result of spawning in 

 the previous January and February (Chittlebor- 

 ough and Phillips 1975), the settlement of pueru- 



Table 4.- 



'Converted from two collectors to a different set of four collectors to ensure compatability with later samples 



-Estimates of year-class strength (no./ha) for juvenile western rock lobsters on nursery reefs (in January). — 



measured; NA = not yet available. 



not 



480 



