| Summary | The green turtle acts as a proxy for migratory species in the GBR. There are numerous nesting beaches throughout the GBR, including a few beaches with such high numbers of nesting green turtles that these areas are considered globally important. |
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| Project | SESMAD |
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| Subtype | Natural Resource Unit |
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| Sector | Marine protected areas, Tourism, Scientific Research and Conservation |
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| Biotic | Yes |
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| Explanation | |
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| Commons Aggregation | |
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| Explanation | There are two genetically distinct stocks (Northern and Southern) of Green Turtle in the GBR (GBRMPA 2014). |
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| Commons Boundaries | Somewhat unclear boundaries (2) |
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| Explanation | Green turtles are known to migrate to foraging areas and to nesting beaches, but where exactly various populations of turtles spend their time is not well known. One telemetry study has shown that most turtles have their own ‘home-range’ (Gredzens et al 2014), and turtles show strong site fidelity to their nesting beaches (Limpus et al 2003). |
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| Commons Indicator | ["Status of highly migratory species"] |
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| Explanation | Green turtles may travel over hundreds or thousands of kilometers. Turtles in the GBR have been known to travel as far away as Vanuatu, New Caledonia, Papua New Guinea, and Indonesia (GBRMPA [online]). |
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| Commons Unit Size | Medium (3) |
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| Explanation | On average, adult Green Turtles are generally in the range of 105cm long, and often weigh around 130 kg. |
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| Environmental Medium | |
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| Explanation | Green turtles spend the vast majority of their lives at sea, but use beaches for nesting. |
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| Inter Annual Predictability | Moderate (2) |
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| Explanation | Since turtles are a long-lived species with slow reproduction, we might expect the population to have similar numbers of turtles each year. Nesting data indicates that there are considerable fluctuations in the number of nesting turtles each year, and these fluctuations show correlation with the Southern Oscillation Index (i.e. El Nino) (Limpus et al 2003, Chaloupka et al 2008). However, since females do not nest every year, it is difficult to suggest overall population numbers from the number of turtles which prepared to nest in a given year. |
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| Intra Annual Predictability | Moderate (2) |
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| Explanation | Turtles typically arrive at nesting grounds around the same time each year, and show strong site fidelity by returning to the same beach to nest (Limpus et al 2003). Predictability of turtle locations during the rest of the year is less predictable. |
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| Commons Renewability | Renewable (1) |
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| Explanation | |
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| Productivity | Poorly productive (1) |
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| Explanation | Green Turtles are long-lived, slow-growing, and late-maturing. Few offspring survive to adulthood. Therefore, the annual growth rate is slow (3.8-11% per year), and recovery following disturbance may take several decades (Chaloupka et al 2008). |
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| Commons Accessibility | Very accessible (3) |
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| Explanation | Nesting areas and foraging sites within the GBR can easily be accessed by common boats. |
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| Commons Heterogeneity | Moderate (2) |
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| Explanation | In a summary report, Dobbs (2007) suggests that all of the GBR is potential foraging habitat for Green Turtles. However, some foraging areas are more important than others, and nesting sites show strong patchiness towards multiple key areas (Limpus et al 2003). |
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| Commons Mobility | High (3) |
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| Explanation |
Green turtles may travel over hundreds or thousands of kilometers. Turtles in the GBR have been known to travel as far away as Vanuatu, New Caledonia, Papua New Guinea, and Indonesia (GBRMPA [online]).
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| Commons Spatial Extent | |
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| Explanation | Green Turtles are found throughout tropical oceans around the world.
Exact migration routes are unknown, but turtles found in the GBR may travel long distances to Vanuatu, New Caledonia, Papua New Guinea , and Indonesia (GBRMPA [online]).
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| Technical Substitute | No |
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| Explanation | |
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