MORGAN ET AL.: STOCK AND RECRUITMENT RELATIONSHIPS IN PANULIRUS CYGNUS 



TABLE 1.— Catch (numbers) per pot lift of spawning female Panulirus cygnua taken in 20-30 

 fathoms in January and February each year (c/g), the mean size of the spawning females (S) (in 

 millimeters carapace length), and the resultant fecundity at this size (F), for two coastal areas. 

 The method of calculation of the index of abundance of the breeding stock (I. A. S.) is explained in 

 the text. NA = Not yet available. 



Table 2.— Comparison of egg production estimates for coastal areas north and south of lat. 

 30°S and the Abrolhos Islands area for 1979. 



hos Islands (Morgan 1974) but it has not been 

 considered necessary to introduce additional 

 assumptions by converting relative to absolute 

 numbers. From Table 1, it is apparent that for 

 each area the average size of spawning female P. 

 cygnus has remained approximately constant for 

 the years for which data are available, although 

 significant differences are apparent between the 

 two coastal areas. Consequently, the mean value 

 of the yearly average sizes for each area has been 

 taken and used to calculate average fecundity for 

 the years 1966-80 using the relationship given by 

 Morgan (1972). These values are north of lat. 

 30°S, CL 92mm (fecundity 319,750) and south of 

 lat. 30°S, CL 105 mm (fecundity 447,150). Calcu- 

 lation of an index of abundance of the spawning 

 stock for each coastal area each year can now be 

 made while summation for each year gives the 

 index for all coastal areas. These are as follows: 



North of lat. 30°S: Catch rate X 6,690 X 319,750. 

 South of lat. 30°S: Catch rate X 3,500 X 447,150. 

 All coastal areas: Catch rate (north of lat. 30°S) 



X 6,690 X 319,750 + catch rate (south of lat. 



30°S) X 3,500 X 447,150. 



Annual indices of abundance of the spawning 

 stock for all coastal areas are shown in Table 1. It 

 should be noted that this is a more refined index 

 than that used by Morgan (1980a). 



During the research vessel cruises in the 

 Abrolhos Islands area in January and February 

 1979, the average catch per pot lift of spawning 

 females was 1.16 or about six times that of coastal 

 areas. However, as shown in Table 2, the small 

 geographical area and the smaller average size 

 of spawning female P. cygnus reduces the appar- 

 ent importance of the Abrolhos Islands area, 

 both in terms of the number of spawning females 



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