Matt Dicken, An Investigation into the Nearshore and Offshore Distribution Patterns of White Sharks
Channel: African Campus
Date: 13/06/2013

Oral Presentation

Matt L Dicken1, Malcolm J Smale2,3
1Department of Development Studies, School of Economics, Development and Tourism, Nelson Mandela Metropolitan University. PO BOX 77000, Port Elizabeth, 6031. South Africa
2Department of Zoology, Nelson Mandela Metropolitan University. PO BOX 77000, Port Elizabeth, 6031. South Africa
3Port Elizabeth Museum, P.O. Box 13147, Humewood, 6013, South Africa

This study provides information on the nearshore and offshore distribution patterns of white sharks (Carcharodon carcharias) in Algoa Bay, South Africa. Between October 2010 and March 2012 a total of 43 flights were conducted, using a Robinson R22 Helicopter, to survey white sharks close inshore between Cape Recife and St. Croix Island. A total of 50 white sharks were sighted with a maximum sighting rate of 7 sharks per hour in October 2010. The majority (96.0%) of sharks observed were less than 2.5 m in length, immature and sighted in the spring and summer months between October and March (98.0%). Over a similar time period key informant interviews were conducted with selected shore anglers to investigate the number and size of white sharks caught. A total of 58 white shark catches were recorded. Sharks ranged in size from 1.5 to 2.5 m TL with young of the year sharks (&lt; 1.75 m) accounting for 69.0% of the catch. These results suggest the existence of a possible inshore nursery area for white sharks (Carcharodon carcharias) in Algoa Bay.
Between November 2009 and October 2011, twenty two boat trips were made to Bird Island to chum for sharks. A total of 53 sharks were observed over the study period ranging in size from 1.5 to 4. 5 m. In both study years sharks were only present in the winter months between April and November with a maximum of 1.2 sharks sighted per hour. This study identified Bird Island as an important white shark aggregation site along the east coast of South Africa. The results from both studies indicate a seasonal shift in the summer/winter distribution of sharks between inshore and offshore locations, respectively.