The Spotted Handfish 1999-2001 Recovery Plan
BD Bruce and MA Green
Spotted Handfish Recovery Team, March 1998
ISBN 0 643 061657
Appendix B
Logistic and cost assessments of population surveys
The effort and corresponding cost required to reliably detect different levels of change between population surveys is listed in the table below. For example, in Option 1 the density of handfish would have to decrease by 80% or increase by 400% before a change could be reliably detected. Similarly for Option 7, the density would have to decrease by 29% or increase by 40% to be reliably detected.
|
OPTION |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|
Min decrease detectable |
80% |
75% |
66% |
50% |
45% |
37% |
29% |
|
Min increase detectable |
400% |
300% |
200% |
100% |
80% |
60% |
40% |
|
Survey effort required* |
22 |
46 |
68 |
108 |
138 |
216 |
340 |
|
Implementation cost |
$4,900 |
$10,500 |
$15,500 |
$24,600 |
$31,600 |
$49,200 |
$77,300 |
* Survey effort is the total number of diver days required to conduct each option at the three sites, twice each year.
Option 1 is clearly the cheapest, however its ability to resolve changes in density is inadequate. We decided that a minimum resolution of detecting a 50% decrease (Option 4) was the most appropriate given costs and number of diver days required. Being able to detect smaller changes in density is desirable, however implementing the greater survey effort required is not cost effective and would be logistically difficult.
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