Regional movements of the tiger shark, Galeocerdo cuvier, off northeastern Brazil: inferences regarding shark attack hazard

Abstract

An abnormally high shark attack rate verified off Recife could be related to migratory behavior of tiger sharks. This situation started after the construction of the Suape port to the south of Recife. A previous study suggested that attacking sharks could be following northward currents and that they were being attracted shoreward by approaching vessels. In this scenario, such northward movement pattern could imply a higher probability of sharks accessing the littoral area of Recife after leaving Suape. Pop-up satellite archival tags were deployed on five tiger sharks caught off Recife to assess their movement patterns off northeastern Brazil. All tags transmitted from northward latitudes after 7-74 days of freedom. The shorter, soak distance between deployment and pop-up locations ranged between 33-209 km and implied minimum average speeds of 0.02-0.98 km.h -1. Both pop-up locations and depth data suggest that tiger shark movements were conducted mostly over the continental shelf. The smaller sharks moved to deeper waters within 24 hours after releasing, but they assumed a shallower (< 50 m) vertical distribution for most of the monitoring period. While presenting the first data on tiger shark movements in the South Atlantic, this study also adds new information for the reasoning of the high shark attack rate verified in this region.

Tiger shark (Galeocerdo cuvier) movement patterns and habitat use determined by satellite tagging in eastern Australian waters

“…This was evident during the migration of TS#2, which after leaving the Australian EEZ travelled along the Lord Howe Rise, a deep-sea marginal plateau surmounted by small volcanic islands and seamounts that is influenced by eddies shed from the EAC (Harris et al 2012). Ocean currents may also influence tiger shark movements (Hazin et al 2013), and the seasonal fluctuations in the strength of the southward-flowing EAC likely contribute to the time spent in offshore waters in this region. Indeed, the unique oceanography parallel to the Australian coast between 32° and 39°S is known as 'Eddy Avenue', an area commonly containing large anticyclonic eddies causing sea surface temperature anomalies in the region.…”

Structure and Dynamics of the Shark Assemblage off Recife, Northeastern Brazil

“…This species could thus be using deeper waters as they grow larger, although they will probably still move regularly to shallow, inshore waters to forage [7]. On the other hand, satellite tagging has shown that tiger sharks in this region use both the neritic and oceanic provinces [41], [87]–[88], thus these juveniles could also be moving to oceanic waters after attaining an adequate size, as suggested by low numbers of sharks ≥200 cm TL.…”

Is the tiger shark Galeocerdo cuvier a coastal species? Expanding its distribution range in the Atlantic Ocean using at‐sea observer data

“…Galeocerdo cuvier is regularly described as a coastal pelagic predator with circumglobal distribution in warm and temperate waters of all oceans (Ebert et al , ). Although commonly associated with coastal areas and continental and insular shelves (Holland et al , ; Hazin et al , ; Afonso & Hazin, ), G . cuvier is also capable of travelling long distances, even across oceanic waters (Kohler et al , ; Heithaus et al , ; Hammerschlag et al , ).…”