Frontier-Tanzania Environmental Research REPORT 103 Misali Island

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Misali Island: A detailed description of the subtidal regionsNo sphyraenids (barracudas) or carcharhinids (requiem sharks) were observed at any ofthe survey sites during the commercial fish census surveys. There have been sightingsof sphyraenids during observations outside of the commercial fish surveys, but none ofcarcharhinids. The total number of dasyatids, myliobatids and mobulids (sting, eagleand manta rays respectively) recorded during the commercial fish surveys was 4, allwithin the deep surveys (14 – 18m): 3 at site 5; 1 at site 7. There were 2 muraenids(moray eels) recorded from all the surveys, both observed during the deep surveys atsite 3. Given the absence, or infrequent presence, of the above taxa these have not beenincluded in the graphs that follow.The mean lengths of the observed rays were 0.14m and 0.35m at sites 5 and 7respectively. The mean length of the observed eels was 0.20m. A total of four rayswere observed at site 5 and 7, all during the deeper surveys.Carangids (jacks and trevallys) were found to have the largest mean length(approximately 0.45m) amongst all the fish families observed at sites 1, 2, 4, 6 and 8.Overall their size showed a relatively large variation (0.14m – 0.80m), indicated by thelong standard error bars (refer to Figure 24, sites 5 and 6).Labrids were observed with smaller mean lengths at sites 2 and 3 ( ≤ 10cm ) incomparison to the remaining sites ( ≥ 15cm ). However, these lengths were not foundto be significantly different (e.g. sites 3 and 6, Kruskal-Wallis, χ 2 = 2.665, p 0.103).However, the other fish families were observed with similar mean lengths at all sites.The observed frequency of fish seen can be derived using both the figures for meanabundance and mean length at each site. For example, at site 6 the mean number ofCaesionidae observed was about 80 within 19 surveys (N=19, refer to Figure 25, site6). Figure 26, site 6, shows that N=14, where N is the number of surveys out of thetotal conducted in which that fish family was present. In summary, for the 19 surveysconducted, Caesionidae were not observed in 5 of these. The mean abundance from allthe surveys conducted (i.e. 19) was approximately 80 and the mean lengthapproximately 0.17m.Frontier-Tanzania Environmental Research Report 103 38
Misali Island: A detailed description of the subtidal regionsSITE: 1SITE: 2Mean +- 2 SE140.0120.0100.0Mean +- 2 SE140.0120.0100.080.080.060.060.040.040.020.020.00.00.0-20.0-20.0N =1919191919191919191919191919N =2020202020202020202020202020Mean +- 2 SE140.0120.0100.0AcanthurinaeBalistidaeCaesionidaeSITE: 3CarangidaeHaemulidaeHolocentridaeLabridaeLethrinidaeLutjanidaeMullidaeNasinaeScaridaeSerranidaeSiganidaeMean +- 2 SE140.0120.0100.0AcanthurinaeBalistidaeCaesionidaeSITE: 4CarangidaeHaemulidaeHolocentridaeLabridaeLethrinidaeLutjanidaeMullidaeNasinaeScaridaeSerranidaeSiganidae80.080.060.060.040.040.020.020.00.00.0-20.0N = 21 21 21 21 21 21 21 21 21 21 21 21 21 21-20.0AcanthurinaeBalistidaeCaesionidaeCarangidaeHaemulidaeHolocentridaeLabridaeLethrinidaeLutjanidaeMullidaeNasinaeScaridaeSerranidaeSiganidaeN = 18 18 18 18 18 18 18 18 18 18 18 18 18 18AcanthurinaeBalistidaeCaesionidaeCarangidaeHaemulidaeHolocentridaeLabridaeLethrinidaeLutjanidaeMullidaeNasinaeScaridaeSerranidaeSiganidaeFigure23: COMMERCIAL FISH ABUNDANCE: Mean and standard error values, survey sites 1, 2, 3 & 4. N = total number of surveys conducted at each siteFrontier-Tanzania Environmental Research Report 103 39
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Frontier-Tanzania Environmental Research REPORT 103 Misali Island

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