Date of Award

7-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Wildlife and Fisheries Biology

Advisor

Yarrow, Greg K

Abstract

This study was designed to determine whether Double-crested cormorants (Phalacrocorax auritus) were having an impact on the Santee lakes fishery for Striped bass (Morone saxatilis). I surveyed the lakes' population in the summer of 2007 and winter of 2008 to determine population levels and 76 birds were necropsied in order to determine foraging preferences. Summer populations were estimated at 203 birds and winter at 6000. Clupeids (primarily Gizzard, Threadfin, and American shads) made up the bulk of the diet in both seasons with an overall percentage of 86.19%. No bass of any size or species were found in the stomachs of birds collected. Though this most likely indicates there is no direct impact by the Double-crested cormorants on the Striped bass fishery; however indirect effects are more difficult to quantify and more data is required before any conclusions can be drawn about effects from interspecific competition. The Double-crested cormorants do share a prey base with the Striped bass, and further examination of the energetic needs of the Striped bass as well as population estimates for the forage fish are necessary. Bomb calorimetry yielded the energetic densities for primary target fish and I estimated daily fish consumption for Double-crested cormorants on the Santee lakes to be approximately 8 fish/day. Management recommendations consist of continued population monitoring on lakes and roost harassment if local stakeholders continue to take issue with the birds' presence.

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