Publication Date

Summer 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

Lynne Trulio; Salvador Jorgensen; Rachel Lazzeri-Aerts

Abstract

As human activities increasingly impact marine ecosystems, understanding the effects of anthropogenic activity on white sharks is important for their continued conservation. Human-induced injuries are observed in many shark species. Such injuries have been found to have physiological and ecological impacts. Four sites in Central California off the coasts of Aptos, Año Nuevo Island, Southeast Farallon Island, and Point Reyes are all known areas of white shark aggregation with varying levels of human use and protection. Utilizing a vast video database, this study evaluated the effects of natural and non-natural anthropogenic shark injury types across all locations, age classes, and body conditions. I found that 11.5% of all Aptos sharks displayed severe wounds resulting from anthropogenic interaction, while 92.3% of sharks retained mild and severe injuries indicative of prey handling. Juvenile sharks exhibited the highest proportion of observed anthropogenic injuries when considering all severe injury types. Boat propeller wounds occurred with similar frequency and severity as natural conspecific bites, both contributing to poor body condition in affected individuals. Effective conservation of white sharks warrants consideration of these findings to minimize the harmful impacts of human activities in areas of high use, particularly considering regions that may comprise essential habitat for juvenile white sharks.

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