Fifty years of dart tag recoveries for tropical tuna: A global comparison of results for the western Pacific, eastern Pacific, Atlantic,and Indian Oceans

The assumption of single Indian-wide stocks is based on results from the Indian Ocean Regional Tuna Tagging Program (RTTP-IO) that suggest rapid and large-scale movements of the three tropical species in the Indian Ocean.

“This assumption is based on the results obtained from the Indian Ocean Regional Tuna Tagging Program (RTTP-IO) that suggest rapid and large-scale movements of the three tropical species in the Indian Ocean (Fonteneau and Hallier, 2015).”

Skipjack tagged in Tanzania showed the larger and fastest migrations (average distances of 1129 miles after one month at liberty), followed by skipjack tagged in Mozambique Channel (an average of 894 miles travelled).

“Skipjack tagged in Tanzania showed the larger and fastest migrations (e.g. average distances of 1129 miles after one month at liberty), followed by skipjack tagged in Mozambique Channel (an average of 894 miles travelled).”

Fonteneau and Hallier (2015) advised that current tagging programs targeting tropical tuna may still not be adequate to estimate the potential stock mixing rates.

“Fonteneau and Hallier (2015) advised that current tagging programs 616 targeting tropical tuna, may still not be adequate to estimate the potential stock mixing rates.”

Short-term recoveries of yellowfin tuna were associated with relatively long distances (249 miles on average), about 5 times longer than the distances of short-term recoveries in other oceans.

“For instance, short-term recoveries were associated with relatively long distances (249 miles on average), about 5 times longer than the distances of short-term recoveries in other oceans (Fonteneau and Hallier, 2015).”

Results from tagging programs describe fast and large-scale skipjack movements, with an average monthly distance of 1066 miles between tagging and recovery positions in the first year.

“Results obtained from these programs describe fast and large-scale skipjack movements, with an average monthly distance of 1066 miles between tagging and recovery positions in the first year (Fonteneau and Hallier, 2015).”

Results obtained from the RTTP-IO describe fast and large-scale bigeye movements, with an average monthly distance between tagging and recovery positions of 918 miles in the first year, with distances increasing slowly in subsequent years.

“Results obtained from the RTTP-IO also describe fast and large-scale bigeye movements. The average monthly distance between tagging and recovery positions is 918 miles in the first year, with distances increasing slowly in subsequent years (Fonteneau and Hallier, 2015).”

Despite rapid movements described for skipjack tuna tagged in the Mozambique Channel, most tagged tuna returned to this area within one year, coinciding with the March-May fishing season, a pattern recurrent over the studied years.

“Despite the rapid movements described for skipjack tuna tagged in the Mozambique Channel, most tagged tuna returned to this area within one year, coinciding with the March-May fishing season, a pattern that was recurrent over the studied years (Fonteneau and Hallier, 2015).”