By: Jack May

I am a graduate student currently in my second year of working in Dr. Chris Lowe’s Shark Lab at California State University Long Beach. I am conducting my research on the influence of environmental and social factors on the behavior of leopard sharks aggregating along the coast of Southern California.

It is common in the warmest months for leopard sharks to group together in shallow warm water in relatively large numbers. The sharks occupying these aggregations are typically mature females. They are thought to be using the relatively warmer water in the shallows to increase their body temperatures. This increased body temperature can result in pregnant mature female sharks shortening the time that they are pregnant by increasing the development rate of their embryos. I am using an unmanned aerial vehicle or drone along with temperature loggers spaced throughout the aggregation area on the seafloor to collect data on sharks from a bird’s eye view and determine what specific temperatures they are occupying. I am also investigating what social interactions may be taking place between individuals in an aggregation.

I am just beginning my second field season on Santa Catalina Island and I am fortunate enough to have sharks already aggregating at Catalina Harbor. Having Catalina Harbor within a short drive from the USC Wrigley Institute certainly will simplify the logistics of conducting research there. The only potential downside is that water visibility at Catalina Harbor is not as good or clear as in other locations I have surveyed. Ideally, I will study this site for about two weeks before other aggregations start consistently occurring at different spots around the island. I plan to sample from at least two different aggregation sites this season.

The most challenging part of moving to a new location is retrieving and then emplacing the 50 temperature loggers and their associated weights. It is very important to acquire precise GPS locations for each of the temperature loggers to allow for creating an accurate map of the temperature distribution of the seafloor. I can then layer locations of sharks on top of the temperature map to determine what temperatures the sharks are occupying.

Conducting research on the island and living on the Wrigley Institute campus is an amazing opportunity that I am fortunate to have for a second summer. If sharks continue to aggregate, I hope to have a successful field season and to spend the fall analyzing my data.