Movements and associated observations of bait-attracted White Sharks, Carcharodon carcharias: A preliminary report

Abstract

Basic population parameters and behaviours of great white sharks, Carcharodon carcharias, were studied during four expeditions to Spencer Gulf, South Australia. In all, 58 white sharks were observed, ranging in length from about 2.2 to 5.5 m TL (X= 3.7 m TL � 0.7 s.d.); of these sharks, 32 were subsequently tagged. Many sharks were observed repeatedly, the most frequently resighted individual being seen on 22 days over a 197-day period spanning two expeditions. Sharks in the study area were segregated by sex but not by size. Females were most abundant at 'inshore' islands, whereas males occurred mainly at 'offshore' islands. Further, there were no marked differences in abundance between summer and winter. Nine ultrasonic trackings, lasting a maximum of 27.5 h, revealed three general horizontal movement patterns: downstream circling, island patrolling, and inter-island cruising. Average rate of movement was 3.2 km h-1 (n = 145 time intervals of 15 min each). Sharks generally remained near the surface or along the bottom (about 20 m), spending relatively little time in midwater. Daytime swimming depths were significantly shallower than those at night.

Large-scale tropical movements and diving behavior of white sharks Carcharodon carcharias tagged off New Zealand

“…This is consistent with studies conducted elsewhere describing white shark behaviors ranging from site fidelity to trans-oceanic migrations (Strong et al 1992, Goldman & Anderson 1999, Boustany et al 2002, Bonfil et al 2005, Bruce et al 2006, Weng et al 2007a,b, Domeier & Nasby-Lucas 2008. While our data do not provide unequivocal evidence for residency because light-based geolocation estimates are subject to error particularly for latitude (Musyl et al 2001, Itoh et al 2003, the most-probable position estimates for the 3 sharks have relatively small confidence regions and are tightly grouped around the islands (Fig.…”

“…They rarely dove deeper than 75 m, although depths exceeding 100 m exist within 9 km of the Star Keys tagging site. Preferences for depths shallower than 50 m have also been displayed by white sharks near pinniped colonies elsewhere (Strong et al 1992, Goldman & Anderson 1999, Boustany et al 2002, Bruce et al 2006, Hammerschlag et al 2006, Weng et al 2007b). …”

“…Previous estimates of white shark swimming speeds maintained for several hours or longer are mainly within the range of 2.9 to 4.5 km h -1 (Carey et al 1982, Strong et al 1992, Boustany et al 2002 over a 24 h period for a white shark in the northeast Pacific. Thus, white sharks can make extended migrations at sustained speeds of about 5 km h -1 , or 120 km d -1 .…”

Movements of the white shark Carcharodon carcharias in the North Atlantic Ocean

“…The speed setting in GPE3 is used to build daily diffusion kernels that govern allowable distance moved per day. Thus, while most published white shark speed estimates are 0.3 to 1.3 m s −1 (Strong et al 1992, Klimley et al 2001, Bruce et al 2006, Johnson et al 2009), we determined 2 m s −1 to be a suitable diffusion parameter in the model to avoid spatial constraint of model likelihoods should sharks in this study move a larger distance for any period of the track. Known locations (e.g.…”

Fish Resources of the Gulf of Mexico

“…Great white sharks carry 7-10 embryos and are thought to reach maturity at 9-10 years (Cailliet et al 1985;Francis 1996;Uchida et al 1996). Small localized populations, susceptibility to longlines, and limited reproductive potential contribute to making the great white shark vulnerable to overfishing (Strong et al 1992).…”