1
Date
Mortalities
Tank M32
Total abalone at risk
Daily incidence
% Mortalities
Tank M33
Total abalone at risk
Daily incidence %
11 / 6 0 156 0 0 97 0 12 / 6 3 156 1.9 0 97 0 13 / 6 9 153 5.9 0 97 0 14 / 6 18 144 12.5 5 97 5.2 15 / 6 27 126 21.4 12 92 13.0 16 / 6 32 99 32.3 11 80 13.8 Totals 89 28
Table 1 . Mortality data for two tanks at “ Happy Abs ”
We can state with certainty that this is an outbreak . At this stage we have not developed a case definition , but we can say the number of dead abalone is well beyond what is expected .
The attack rate for dead abalone in these two tanks between 11 / 6 and 16 / 6 is :
2
3
4
5
6
7
Tank M32 Tank M33
8
89 28 = 57.1 per cent = 28.9 per cent
156 97 9
Attack rates are useful when we are looking at exposure factors and will be further explored in Step 7 ( see “ Step 7 Analyse the data ” on page 46 ).
10
13