World Status, Exploitation and Trade - WIDECAST

TANZANIAPOPULATION:Chelonla mydaaNesting sites Nesting is Icnown on the mainland, but it is sparselydistributed and of little significance (Frazier, 1974 and 1976a). Mostnesting in Tanzania occurs on the smaller and more remote offshore islands.Maziwi has been cited as the most important C. mydas breeding ground, notonly in Tanzania but in East Africa as a whole (Frazier, 1976b); otherimportant sites include North Fonjove, Shungu-Mbili , Niororo and Barialcuni,all in the vicinity of Mafia Island.Maziwi Island, apparently the major Tanzanian nest site for both C. mydasand E. imbricata , is reported to have effectively disappeared, due toerosion (or perhaps tectonic movements) (Anon [Reuter] 26.3.82, UNEPRegional Seas No. 11). These reports do not seem to have been confirmeddefinitively, and the present condition of the nesting populations isunknownNesting numbers Although C. mydas is relatively common in Tanzanianwaters (Frazier, 1982), the majority of these are foraging migrant animalsand relatively few nest in the country. According to Frazier (1982), fewerthan 200 are estimated to nest annually on Maziwi, with perhaps 100 at allother sites combined, giving an estimated annual total for all of Tanzaniaof only 300. Frazier (1976b) had earlier estimated an overall total offewer than 200. At peak, times on Maziwi, the major nest site, up to threefemales a night nested, and nearly ten a week. (Frazier, 1976b); this islow-level nesting in world terms (see previous paragraph).Trends In nesting numbers No long-term survey data are available, butFrazier 1976b) believes that numbers have been reduced since prehistorictimes; the inferred decline is attributed to exploitation (more intense inthe past), habitat loss and disturbance (more intense in recent years).Nesting season Most nesting appears to occur June-October (Frazier,1982), although it may vary between different sites (Frazier, 1976a), and inMaziwi is at a height in July-August, during the south-east trade winds(Frazier, 1976b).Foraging sites Extensive marine shallows and seagrass pastures occur inTanzanian territory, notably around Zanzibar and Mafia Islands, in Tanga andKilwa bays, and elsewhere (Frazier, 1974), but no information is availableon preferred sites.Migration Most C. mydas occurring in Tanzania are suspected to bemigrants from breeding grounds in the western Indian Ocean, or Somalia andthe Arabian Peninsula (Frazier, 1974), but there may be a small residentpopulation (Frazier, 1982). The only recoveries reported from a brieftagging programme on Maziwi Island were of three C. mydas from the ZanzibarChannel, off Zanzibar Island and the north of Pemba Island, none more than150 km distant (Frazier, 1981).POPULATION : Sretmochelys imbricataNesting sites The species is suspected to nest widely but diffusely;Maziwi is the main site used, but no other site-specific information isavailable (Frazier, 1974 and 1982).511