| Summary | Eastern Atlantic Bluefin Tuna are a subpopulation of Atlantic Bluefin Tuna that spawn in the Mediterranean |
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| Project | SESMAD |
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| Subtype | Natural Resource Unit |
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| Sector | Fisheries (Stock-specific) |
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| Biotic | Yes |
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| Explanation | |
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| Commons Aggregation | Population |
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| Explanation | Eastern Atlantic Bluefin Tuna are a meta population or stock of Atlantic Bluefin Tuna that spawn in the East Atlantic and Mediterranean. It is generally accepted that they do not interbreed with the Western stock. |
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| Commons Boundaries | Very unclear boundaries (1) |
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| Explanation | Although the Eastern Atlantic Bluefin Tuna is most commonly found on the Eastern side of the Atlantic Ocean and Mediterranean Sea, they also migrate across the 45th parallel which marks the official boundary between Eastern and Western stocks. The extent of this migration is generally unknown. |
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| Commons Unit Size | Medium (3) |
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| Explanation | Eastern Atlantic Bluefin can weigh up to 900 kg, although mature adults typically weigh 250kg with a length of approximately 2.5m. |
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| Environmental Medium | Oceanic |
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| Explanation | Located throughout much of the Atlantic Ocean and Mediterranean Sea. |
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| Inter Annual Predictability | Moderate (2) |
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| Explanation | Stocks of Eastern Atlantic Bluefin Tuna are moderately predictable, but scientific assessments are highly contested and it is generally acknowledged that there are important uncertainties regarding the size of stocks, and the methodologies used to estimate spawning stock biomass. However, given the use of consistent methodologies the relative magnitude of stocks can be ascertained. |
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| Intra Annual Predictability | High (3) |
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| Explanation | Very little variation in resource numbers within a given year. |
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| Commons Renewability | Renewable (1) |
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| Explanation | |
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| Productivity | Moderately Productive (2) |
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| Explanation | Eastern Atlantic Bluefin Tuna support a fairly large-scale fishery. However, the rate of regeneration is insufficient to cope with modern extraction technologies that have started to lead to declines in resource stocks. |
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| Commons Accessibility | Very accessible (3) |
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| Explanation | Although Eastern ABFT are located throughout much of the Atlantic Ocean, they are easily accessible to the ocean-going fleets that target them. |
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| Commons Heterogeneity | High (3) |
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| Explanation | During the spawning season, sexually mature adults congregate in the Mediterranean Sea. There is some debate whether individual adults spawn annually over every 2-3 years. During the rest of the year, however, tuna are distributed widely over feeding grounds. |
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| Commons Mobility | High (3) |
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| Explanation | Eastern Atlantic Bluefin Tuna migrate extensively throughout the Eastern-Mid Atlantic and Mediterranean Sea and can travel at speed up to 60 km/h. |
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| Commons Spatial Extent | 108000000 |
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| Explanation | Approximate size of Atlantic Ocean and Mediterranean Sea. Although the Eastern Stock is more concentrated in the Mediterranean and Eastern Atlantic Ocean, Trans-Atlantic migration is known to occur at least in small numbers |
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| Technical Substitute | No |
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| Explanation | |
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