Hampton: Estimates of tag-reporting and tag-shedding rates for tuna in the tropical Pacific Ocean 
75 
Total 
0 00 0 20 0 40 0 60 0 80 
Reporting rate 
Figure 2 
Frequency distributions of reporting rates p' sampled from the probability distributions 
specified in Table 6. The arrows indicate values of the sample mean reporting rates p 
obtained from tag-seeding data. The number of observations in each distribution is 1,000. 
A similar quantity of the Korean purse-seine catch 
in the western Pacific was delivered to canneries in 
Thailand. Assuming a similar occurrence of tagged 
tuna in these components of the Korean catch, the 
number of tagged tuna in catches delivered to Korea 
can be approximated by the tag returns from Korean 
purse seiners unloading in Thailand (658) divided 
by the estimated reporting rate for Thailand (0.355). 
On this basis, 1,798 (95% confidence interval of 
1,412-2,386) tagged tuna are estimated to have been 
landed in Korea, of which only four were returned to 
SPC under the special circumstances described 
above. Similarly, the disposition of the Taiwanese 
purse-seine catch (approximately 20,000 t to Taiwan 
and 155,000 t to Thailand annually ) and tag returns 
from Taiwanese purse seiners unloading in Thailand 
(928) implies that 327 (257-434) tagged tuna were 
present in catches delivered to Taiwan. 
Summing across locations, it is estimated that 
31,166 (27,208-37,264) RTTP tags were recovered 
from all fisheries in the western Pacific, resulting in 
an overall reporting rate of 0.586 (0.490-0.671). 
Discussion 
The objective of this study was to quantify two 
sources of tag loss, tag shedding and failure to re- 
