Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks

Abstract

The large-scale spatial dynamics and population structure of marine top predators are poorly known. We present electronic tag and photographic identification data showing a complex suite of behavioral patterns in white sharks. These include coastal return migrations and the fastest known transoceanic return migration among swimming fauna, which provide direct evidence of a link between widely separated populations in South Africa and Australia. Transoceanic return migration involved a return to the original capture location, dives to depths of 980 meters, and the tolerance of water temperatures as low as 3.4 degrees C. These findings contradict previous ideas that female white sharks do not make transoceanic migrations, and they suggest natal homing behavior.

Movements and habitat use of reef manta rays off eastern Australia: offshore excursions, deep diving and eddy affinity revealed by satellite telemetry

“…'CE' marks the presence of the Capricorn Eddy feature in the satellite signal, and white arrows denote intrusions of upwelled oceanic wa ters onto the shelf. EAC = East Australian Current migrations are typically attributed to the need to reproduce and exchange genetic material between members of separate populations (Bonfil et al 2005, Skomal et al 2009) or the search for abundant food resources (Zerbini et al 2006, Anderson et al 2011. The question of sex-biased dispersal in M. alfredi could not be assessed here because of our limited data, despite tagged females noticeably dispersing farther than the 2 males.…”

“…Such studies have shed new light on the ecology of marine predators, unravelling a variety of behaviours ranging from localised movements made in relation to foraging opportunities (Sims et al 2006, Papastamatiou et al 2012) to larger-scale migrations (Bonfil et al 2005, Block et al 2011. In most cases, movements are driven by the availability of food resources (Zerbini et al 2006, Anderson et al 2011, species-specific physiologies (Pillans 2006) or the need to reproduce (Bonfil et al 2005, Skomal et al 2009). …”

Inferring vertical and horizontal movements of juvenile marine turtles from time-depth recorders

“…While the horizontal and vertical movements of large marine vertebrates are being increasingly described (Priede 1984, Duron-Dufrenne 1987, Polovina et al 2000, Block et al 2005, Bonfil et al 2005, remote recording of accurate spatial movements made by smaller species or early life stages has been slower, due to the challenges of miniaturising power sources, development of attachment techniques and hydrodynamic packaging of equipment (Watson & Granger 1998, Wilson & McMahon 2006, Pavlov et al 2007, Godley et al 2008). …”

Movements of the reef manta ray (Manta alfredi) in the Red Sea using satellite and acoustic telemetry

“…However, only a handful of publications have reported the use of PSAT (Graham et al 2012;Braun et al 2014) or acoustic tags (Dewar et al 2008) to understand manta ecology. Moreover, while a few published studies have combined satellite and acoustic telemetry techniques to quantify behavior of marine organisms (Bonfil et al 2005;Kneebone et al 2014), no studies have combined the different tag types to quantify manta ray movements at multiple scales. This lack of knowledge is particularly acute in the Red Sea where historically very little elasmobranch research has been conducted (Spaet et al 2012;Berumen et al 2013).…”