optimal sustainable yield (OSY) can be approximated by the 

 method of Gulland (1968). In the present case where a portion of 

 this information is lacking, the cost of digging, the OSY can only 

 be very roughly approximated (by inspection of Fig. 16A, B, C) at 

 somewhere between 900-1.100 licensed marine worm diggers. 

 Based upon the proportions presented in Table 2 1 , this would be 

 equivalent to approximately 564-689 bloodworm diggers, 

 267-327 sandworm diggers, and 69-84 diggers who dig both spe- 

 cies. 



Assuming that OSY is very roughly approximated at 900-1,100 

 licensed marine worm diggers, very rough quotas of 28-33 million 

 bloodworms and 26-30 million sandworms can be estimated from 

 the data presented in Figure 16 (A and B). 



Miscellaneous Information Obtained from 

 Sampling Interview 



Digging Frequency .—One interview question dealt with the fre- 

 quency of bloodworm and sandworm digging expressed as the 

 number of low tide periods occurring since the last low tide dug. 

 The mean and standard error of the responses of all diggers inter- 

 viewed during each month of each year (1973-76) are presented in 

 Table 22. 



Table 22.— The frequency of bloodworm and sandworm digging 

 expressed as the mean ( + 1 SE) number of low tide periods occur- 

 ring since the last low tide period dug. 





Bloodworm diggers 



Sandworm di 



ggers 





No. diggers 







No. diggers 









interviewed 



X 



±1 SE 



interviewed 



X 



±1 SE 



1973 















A 



37 



6.5 



±0.8 



11 



6.5 



±2.0 



M 



31 



5.6 



±2.0 



24 



5.3 



±1.0 



J 



26 



3.3 



±0.8 



23 



2.5 



±0.6 



J 



36 



2.1 



±0.2 



13 



2.5 



±0.5 



A 



32 



4.0 



±1.6 



23 



2.2 



±0.3 



S 



20 



10.1 



±5.2 



9 



5.2 



±1.3 





average 



5.3 





average 



4.0 





1974 















A 



34 



3.0 



±0.7 



14 



2.4 



±0.2 



M 



14 



4.4 



±1.8 



6 



5.0 



±1.4 



J 



44 



11.2 



±4.4 



24 



3.1 



±0.6 



J 



20 



3.2 



±0.5 



11 



4.0 



±0.5 



A 



21 



3.0 



±0.3 



28 



2.8 



±0.4 



s 



33 



1.9 



±0.2 



13 



2.9 



±0.9 





average 



4.5 





average 



3.4 





1975 















A 



2 



8.0 



±8.0 



11 



5.8 



±1.5 



M 



14 



2.1 



±0.2 



22 



2.6 



±0.7 



J 



29 



4.1 



±1.1 



12 



1.3 



±0.3 



J 



19 



2.0 



±0.2 



24 



5.5 



±1.7 



A 



24 



3.8 



±1.0 



18 



6.0 



±2.9 



s 



19 



3.3 



±1.3 



10 



1.3 



±0.2 





average 



3.9 





average 



3.8 





1976 















A 



19 



2.2 



±0.2 



6 



2.5 



±1.3 



M 



9 



5.3 



±0.9 



28 



4.0 



±0.4 



J 



30 



13.1 



±4.1 



9 



1.8 



±0.2 



J 



39 



5.7 



±1.4 



32 



2.9 



±0.3 



A 



18 



2.3 



±0.2 



14 



2.0 



±0.0 



S 



36 



16.9 



±7.4 



20 



2.3 



±0.3 





average 



7.6 





average 



2.6 







Overall 







Overall 









average 



5.3 





average 



3.4 





Digging Experience.— The number of years of digging experi- 

 ence was recorded for those bloodworm and sandworm diggers 

 who were interviewed during sampling. These data are expressed 

 as a percent of the total number of diggers categorized in each incre- 

 ment of digging experience by year in Table 23. It is evident from 

 these data that digging for worms is frequently a short-lived work 

 experience; usually, the largest percentage of bloodworm and sand- 

 worm diggers interviewed had participated in marine worm dig- 

 ging activity for 4 yr or less. 



Table 23.— The percent of the total number of bloodworm 

 and sandworm diggers categorized in each increment of 

 digging experience, 1973-76. 



Number of years 











digging experience 



1973 



1974 



1975 



1976 







Bloodworm diggers 





1-4 



50.51 



37.58 



37.73 



35.25 



5-8 



15.82 



16.76 



23.59 



23.02 



9-12 



15.31 



13.87 



13.21 



9.35 



13-16 



6.12 



17.34 



12.26 



11.51 



17-20 



6.63 



6.36 



7.54 



13.67 



21-24 



2.04 



1.73 



1.89 



1.44 



25-28 



2.55 



5.20 



1.89 



2.88 



29 + 



1.02 



1.16 

 Sandworm 



1.89 



diggers 



2.88 



1-4 



34.23 



22.12 



23.71 



27.52 



5-8 



16.22 



11.54 



17.53 



13.76 



9-12 



24.33 



13.46 



17.53 



22.02 



13-16 



9.01 



20.19 



11.34 



6.43 



17-20 



11.71 



14.42 



12.37 



16.51 



21-24 



— 



2.S8 



8.24 



3.67 



25-28 



1.80 



10.58 



2.06 



2.75 



29 + 



2.70 



4.81 



7.22 



7.34 



Age of Marine Worm Diggers.— Age-frequency distributions 

 for bloodworm and sandworm diggers interviewed are expressed 

 as a percent of the total number of bloodworm and sandworm dig- 

 gers interviewed in each age category in Table 24. It is evident from 

 these data that the numbers of diggers in age categories beyond age 

 40 decline rapidly. The results also show that there are few diggers 

 under age 9 and over age 60. The mean age + 1 SE for all blood- 

 worm and sandworm diggers interviewed during each sampling 

 year is shown in Table 25. 



Table 24. — The percent of the total number of blood- 

 worm and sandworm diggers interviewed in each age 

 category (1973-76). 



Digger age 



1973 



1974 



1975 



1976 







Bloodworm diggers 





<9 



1.09% 



0.00% 



0.00% 



0.00% 



10-19 



31.87 



20.23 



24.30 



16.77 



20-29 



26.37 



39.88 



34.58 



34.16 



30-39 



24.73 



23.81 



22.43 



29.19 



40-49 



10.44 



10.12 



14.02 



8.70 



50-59 



3.30 



2.98 



3.74 



7.45 



>60 



2.20 



2.98 



0.93 



3.73 







Sandworm diggers 





£9 



0.00% 



0.00% 



0.00% 



0.00% 



10-19 



21.15 



12.38 



17.53 



21.11 



20-29 



34.62 



35.24 



31.96 



31.11 



30-39 



25.00 



24.76 



22.68 



25.56 



40-49 



9.62 



19.05 



16.49 



17.78 



50-59 



7.69 



8.57 



11.34 



3.33 



^60 



1.92 



0.00 



0.00 



1.11 



51 



