Aquaculture for all

Atlantic Bluefin are Highly Vulnerable


GLOBE - Atlantic bluefin tuna spend long periods in highly predictablelocations, which makes them easy targets for fishermen and leavesthem highly vulnerable to overfishing, reports a recent study inthe journal PLoS One.

According to Seaweb's OceanUpdate, AndreasWalli of Stanford University and colleagues used electronic tags to examine the seasonal movements, distribution and aggregation of Atlantic bluefin tuna to shine greater light on their migration patterns, ecology and habitat preferences. Between 1996 and 2005, a total of 561 electronic tags were implanted in bluefin tuna captured and released in North Carolina waters.

After analysing the tags’ data, the researchers found that the fish could be divided into two groups: western resident and trans-Atlantic.

Walli and colleagues concluded that, not surprisingly, the tunas’ presence in the various areas corresponds primarily to availability of prey, particularly Atlantic menhaden, sardines, mackerel and blue whiting.

Therefore, these high-use areas “may represent a network of critical foraging habitats that are essential to the persistence of bluefin tuna populations in the North Atlantic” and their apparent dependence on seasonal movements and distribution of their prey suggests they are likely highly sensitive to environmental changes as a result of, for example, climate change.

Additionally, the predictability of their movements and their presence in high aggregations in just a few areas renders them potentially highly vulnerable to concentrated fishing.

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