Cesar2000-Economics of Coral Reefs.pdf

Table 3.
Tied P-Values for Differences in Perceived Trends between Resource, Habitats, Threats and Compliance Categories.
Non-Parametric Test Statistic
Indicators _________________________________________________________
CpUE Habitats Threats Compliance
Test for Variation Between Indicator
Categories (Kruskal-Wallis) 1 0.09 0.0001 0.0001 0.0001
1
Siegel & Castellan (1988).
Indicator categories reflect broad groupings of resources, habitats, threats or management rules (e.g., ‘finfish’ and ‘shellfish’ resources for the CpUE
indicator).
P-values show the significance of the test statistic. A p-value of 0.0001 indicates a probability of less than one in 10,000 that the differences in
perceptions for the various categories occurs by chance (SAS 1998).
The Kruskal-Wallis test is a non-parametric version of a one-way analysis of variance by ranks that tests the null hypothesis that the categories
come from the same distribution.
No. of responses
180
160
140
120
100
80
60
40
20
0
Declining
a lot
Catch per unit of effort perceptions
Declining
a little
Stable
N: 399 reponses (3 resources per focus group)
Improving
a little
Improving
a lot
Figure 2. Distribution of perceptions on trends in the
catch per unit of effort of key resources.
3. RESULTS
3.1 Perceived Trends in
Catch-per-unit-of-effort (CpUE)
Community groups were generally pessimistic about resource
trends. Out of 399 responses, only 39 (10 percent)
perceived an improving CpUE over the last decade
(figure 2). Moreover, only 11 responses at 6 sites (3
percent) indicated a positive trend that was related to
coastal resource management. Where this occurred,
communities identified prevention of destructive fishing,
creation of sanctuaries, controls in harvesting of
particular species, and a ban on external fishermen as
causing the improvement in CpUE. Declining CpUE,
by contrast, was thought to be caused by overfishing
(the most frequent answer) destructive fishing practices,
cyclones, increased population, the use of nets and night
diving, siltation, water pollution, coral destruction, the
construction of causeways 4 , and habitat degradation.
Differences in CpUE perceptions between resource
categories were only significant at the 10 percent level
(table 3). Pairwise comparisons indicated that the CpUE
for bêche-de-mer (Holothuriae) was perceived as having
declined faster than for shellfish, clams, reef finfish and
octopus, but this result was only significant at the 10
percent level 5 .
3.2 Perceived Trends in Coastal Habitats
Only a minority of 396 responses (22 percent) shared
the perception that the quality of coastal habitats had
improved. Most (52 percent) mentioned a decline (figure
3). The reasons offered for mangrove and seagrass
improvements were generally unrelated to coastal management.
By contrast, the majority of the reasons given
4
Causeways are raised roads built over bodies of water which link, for
example, the surface of atoll islets.
5
This was tested using a Mann-Whitney rank test (Siegel & Castellan
1988).
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JEFF MULLER, SOFIA BETTENCOURT & ROBERT GILLETT: