NOTE O'Neill et a\. Accuracy of at-sea commercial size grading of Penaeus spp. 



399 



0.6 

 0.5 

 0.4 -I 

 0.3 

 0.2 

 0.1 

 



Period 1 : July - December 1993 



U/6 6/8 9/12 13/15 16/20 



0.6 



Period 2: January - June 1994 



u/6 6/8 9/12 13/15 16/20 



U/6 6/8 9/12 13/15 16/20 



0.6 

 0.5 

 0.4 

 0.3 

 0.2 

 0.1 

 



Size grade 



9/12 13/15 16/20 



u/6 6/8 9/12 13/15 16/20 



U/6 6/8 9/12 13/15 16/20 



Figure 1 



The proportion ( +SE ) of misgraded tiger prawns from each size grade, for (A) the small packs and 

 (B) the large packs. The proportion misgraded was split between prawns that were misgraded too 

 large (white) and those that were misgraded too small (gray). 



changes in the proportion misgraded with period of 

 catch and size grade, with significant differences in 

 the proportion misgraded with period of catch, and 

 generally higher proportions of the smaller size 

 grades misgraded (Table 2; Fig. IB). 



There was a tendency for smaller-prawn grade 

 packs to contain larger prawns (Fig. IB). The pro- 



portion of misgraded prawns that should have been 

 in a larger-size grade, however, was 



1 not constant over all size grades, within any one 

 period of catch (Table 3; Fig. IB); 



2 not the same for each size grade, over the three 

 periods examined (Table 4; Fig. IB). 



