Research on the Basking Shark Forming an argument to list the Basking Paper

On the Basking Shark Forming an argument to list the Basking Shark as an Endangered species (with consideration to ES - Research Paper Example The color of basking shark is typically blackish to grey-brown, grey or blue-grey above and below the body and fins, often with irregular white blotches on the underside of the head and abdomen (Compagno, 2001 from COSEWIC, 2007). Basking sharks prefer cool and temperate coastal shelf waters and are distributed worldwide. In the North Atlantic (Compagno, 2001), basking sharks are sighted in waters off countries as far south and east as Senegal, through Europe, Norway, Sweden, Russia, Canada, along the eastern seaboard of the United States and into the Gulf of Mexico. In the North Pacific, they are observed as far south and west as Japan, through to China, Alaska, British Columbia, along the western seaboard of the United States and Mexico (Compagno, 2001, from COSEWIC, 2007). Habitat requirements The habitat requirements for basking shark (Sim et al, 1997) are associated with the oceanographic events on zooplankton concentration. Fronts off headlands, around islands and in bays with strong fluctuation of water masses from tidal flow were also frequented. In a study conducted by Compagno (2001), it recorded basking shark in the epipelagic zone by aerial surveys, in pelagic driftnet fisheries and is caught in bottom trawls off the St. Lawrence River, Scotian Shelf and Scotland. Te Newfoundland Observer Program (NOP) also noted that basking sharks have been caught in trawl nets fishing in depths up to 1370m. Fifteen percent of the records from waters deeper than 1000m were also observed. Skomal (2005) suggested that basking sharks migrate to different wintering habitats. They are seen to be influenced by patterns of prey distribution, varying by depths, location, and season (COSEWIC, 2007). Observed on the habitat trends of the basking sharks is the consistency of target areas and preference for high concentration of zooplankton. This has been linked to both large and small scale oceanographic conditions that change quickly (Sims and Quayle, 1998, from COSEWIC, 20 07). Reproduction and Mortality The pairing of the basking shark (Sims et al, 2000) is perceived to occur in early summer. This is based on the observed courtship behavior which is nose to tail circling, and scarring. The gestation period of basking shark with a litter of six young is at 2.6 years (Pauly, 2002). The assumed length at birth is 1.5m. The time between successive litters may be two to three years (Compagno, 2001) and like other lamnoid sharks, the basking sharks develop embryonic ovophagy which supplies nutrients to the developing embryos (Compagno, 2001, from COSEWIC, 2007). The longevity of the basking shark is approximated at 50 years. The age of maturity is about 12 to 16 years in males and 16 to 20 years in females (UK CITES, 2002). Generally, females are presumed to mature at larger sizes than males with an estimated size at 4.6 to 6.1m in length at the stage of maturity. Yearly productivity ranges from 0.013 to 0.023 based on the methodology of Smith et al (1998) . They used age at maturity, maximum age and average fecundity. Smith et al (1998) suggested that the potential for recovery or rebound rate may be lower for basking shark when compared to other species of Pacific sharks. Pauly (2002) determined the natural mortality to be 0.068 based on the age of maturity at 18 years for female which midrange is 16 –