Date of Award

Spring 2003

Document Type

Legacy Thesis

Degree Name

Bachelor of Science (BS)


Marine Science


College of Science

First Advisor

Robert F. Young


Apex predators occupy a unique and important role in the marine food web. Free ranging transient killer whales feed primarily on other marine mammals, making them extremely unique in their communities and in the ecosystem as a whole. We propose that the marine ecosystem cannot support viable populations of an additional similar species at the same trophic level as killer whales. We estimated the maximum number of killer whales that could be supported by the marine ecosystem, based on estimates of annual global oceanic primary production, trophic transfer rates, and the trophic level of killer whales. The estimated population of killer whales would be 6.3 million if all primary production went toward supporting only this species at trophic level 5. Actual global population estimates for killer whales are between 10 and 15% of this value. We will consider a number of variables in discussing whether there is room for another similar species at the top. These include the distribution of primary production on a global basis relative to the size and range of viable killer whale populations, competition with other apex predators, and variability in feeding habits of killer whale populations.