Chapter Nine

GENERAL DISCUSSION AND CONCLUSIONS 9.1 Summary 9.1.1 The Port Lincoln Silver Gull Population Silver Gull abundance has undoubtedly increased in the Port Lincoln area over the last three decades; a growth which has coincided with the development of the Southern Bluefin Tuna aquaculture industry. The number of nesting pairs on the main breeding colony, Rabbit Island has increased from 100 pairs in 1982 (Farlam, unpublished data) to as high as 19,400 pairs in 2005. Similarly, the maximum number of nesting pairs in the Port Lincoln area has risen from 3,300 in 1999 (Farlam, unpublished data) to as high as 27,800 in 2005. This rapid increase is similar to trends reported for gull species around the world (Furness, 1996; Garthe et al., 1996; Belant, 1997; Walter & Becker, 1997; Oro, 1999; Huppop & Wurm, 2000; Bertellotti et al., 2001; Martinez-Abrain et al., 2002; Yorio & Caille, 2004), and for Silver Gulls in Australia (Smith et al., 1991; Smith, 1992; 1995; Smith & Carlile, 1993; Higgins & Davies, 1996; Temby, 2003; 2004).