Monitoring of Sea Turtle & Marine Mammal Mortalities

Although only green and hawksbill turtles are known to nest in Tanzania, leatherback, loggerhead and olive ridley turtles forage in Tanzanian waters. Tanzania is also home to several species of dolphin and east Africa’s most endangered marine mammal, the dugong. Sadly, all of these species are at risk from entanglement in fishing nets and many are deliberately slaughtered for their meat. Their remains are frequently found stranded on Tanzania’s beaches.

Conservation Officers collect data on sea turtle and marine mammal strandings to identify areas of high risk from fisheries interactions and illegal slaughter. Morphometric data is collected from each specimen including width and length, sex and distinguishing marks (eg tags). If possible, a tissue sample is taken for genetic analysis.

Green turtle strandings are the most commonly recorded in Tanzania but hawksbill, olive ridley and loggerhead strandings have also been observed.  Leatherback strandings are less common with only five records in the past seven years.  The majority of green turtle strandings in Tanzania are juveniles with curved carapace lengths (CCL’s) measuring well below those expected at sexual maturity.  This suggests that Tanzanian waters are important foraging grounds for juvenile green turtles but pose a significant threat to their survival.

Direct take of sea turtles is common in many coastal communities. Turtles caught as bycatch are sold to dealers who supply local markets, despite laws prohibiting trade in sea turtle products. The amount of direct take of sea turtles at migrant fisher camps is a major concern. Large quantities of sea turtle bones and carapaces have been found in camps in Mafia, Rufiji, Kilwa and Temeke Districts.

Stranding data are used by Sea Sense to identify areas of high risk to sea turtles from fisheries interactions and deliberate take and to target education and awareness programmes more effectively.

Did you know?

Sea turtles return each nesting season to lay their eggs on the same beach on which they themselves were born.

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