A new research from the University of Hawaii and the University of Florida attempted to explain why a number of mature female tiger sharks was seen swimming in the waters around the remote coral reef of the Northwestern Hawaiian Islands heading to the Main Hawaiian Islands in the late summer and early fall, going to as far as 1,500 miles.
Yannis Papastamatiou of the University of Florida told Science Daily, "When we think of animal migrations, we tend to think of all individuals in a populations getting up and leaving at the same time, but it's not as simple as that. Some are resident and some are transient."
Tiger sharks are natural habitants throughout the islands the whole year. The female tiger sharks’ migration from the Northwestern Hawaiian Islands is somehow connected with the tiger shark’s birth season in September to November and also with the months where shark bite risks are highly noted.
Carl Meyer of the University of Hawaii told Science Daily, "Both the timing of this migration and tiger shark pupping season coincide with Hawaiian oral traditions suggesting that late summer and fall, when the wiliwili tree blooms, are a period of increased risk of shark bites."
Papastamatiou and Meyer, however, advise people not to conclude that this migration is directly related to the latest shark bites incidents in Oahu, Maui and the Big Island. Several factors might be the reason behind shark behavior in ways that would lead to repeated encounters with humans. Scientists don’t have much information on the attributes or particular behavior tiger sharks that bit humans because encounter with humans, although dramatic, are unusual.
Papastamatiou also considers that there is a more possible connection to pupping, with female sharks swimming down to their nursery sites in the Main Hawaiian Islands. Another possible reason is that the Main Hawaiian Islands may offer a variety of foods, security from ocean waves, or some other, unknown contributing factors.
Hawaii's Land and Natural Resources Department commissioned an $186,000-worth of two-year study last year about tiger shark movements in the islands, headed by study co-author Carl Meyer. The commissioned study will commence this month.
Their report is set for publication in the November 2013 issue of Ecological Society of America's journal Ecology
