Stimulating investment in pearl farming in ... - World Fish Center

Seasonal temperature variation is slight in Solomon Islands. An incomplete annualrecord for 2007 shows a maximum of close to 31 o C in May, falling with the onset ofwinter winds, lower insolation and air temperatures to 29 o C in July (Figure 7). Theonset of the spawning peak in September is likely to coincide with the annualtemperature minimum. Very little vertical temperature structure is evident in figure 7,with occasional period of weak temperature stratification that last for a few days toone week.4.4 Inter-annual differencesOengpepa et al., (2006) examined inter-annual differences in spat collection at sites inNoro and Gizo using an eight year dataset from 1997 to 2005. These data were atemporal extension of the dataset described in section 2.2, based on 10, 0.4 m 2 shadecloth bundles attached to a longline as in figure 4.These data are plotted as figure 8and show the annual summer peak described above – though it is clear that in any oneyear the peak can be more pronounced than in the long term average of figure 6.Figure 8 indicates how the exact size and timing of the peak varies from year to yearbut show no obvious trend or periodicity. The range of peak spatfalls varied overmore than an order of magnitude, with median values of 3.8-4.8 spat per collector.The latest a peak occurred was in collectors harvested in March, the earliest inDecember.Table 3. Mean, maximum and minimum sizes of annual spat peaks (as spat percollector) on collectors deployed at Gizo and Noro from 1997-2005.Measure Noro GizoMean 5.8 5.5Median 3.8 4.8Maximum 19.6 11.1Minimum 0.4 1.410