About katie

Katie McElroy is a scientist who studies salmon at California Department of Fish and Wildlife in Northern California. Growing up in San Diego, Katie spent most of her time at the beach or the aquarium. If she wasn’t in an aquarium, you would have found her surfing, tide-pooling, swimming, snorkeling, reading Harry Potter, or dancing. Her grandfather worked in the shark tank at Sea World, so she spent many summers exploring Sea World and helping her grandpa teach people about sharks. Her summers at the beach and SeaWorld led her to science, specifically marine biology. In college, she worked with a variety of marine species from elephant seals to coralline algae. She saw her first salmon when she was 20 years old and decided that they were her new favorite fish species. When she is not doing science, she enjoys hiking, spearfishing, scuba diving, dancing, reading, snowboarding, and hanging out with her husband and dog Domino.

How did she know she wanted to become a scientist?

"My first grade teacher’s husband was a marine biologist at Scripps Institute of Oceanography. He brought baleen to our class and told us stories about being on boats studying whales all over the world. I didn’t know until then that you could have a whole job dedicated to exploring the ocean, so I decided I too would be a marine biologist." 

What does she love about her job?

"I get to think deeply about ecosystems, human and animal connections, and why animals do the crazy things they do. I am constantly learning and exploring. I also am lucky enough to work in one of the most beautiful places in the world and with people who are incredibly passionate about what they do."

Understanding juvenile salmon behavior and the factors that contribute to (or detract from) their survival is critical to maintaining healthy adult salmon populations. Recently, Katie collaborated with two other scientists to learn how juvenile Chinook salmon (Onchorhynchus tshawytscha) behave in the San Joaquin River, California. 

Specifically, they were interested in which factors influence the aggregating behavior of the juvenile salmon. Aggregating behavior is when organisms stick together in large groups, rather than spending time alone, and can be useful for finding food, for protection from the elements, or for evading predators—especially in smaller juveniles. Katie and her colleagues manipulated the locations of structural cover (like rocks or woody debris) throughout different locations in the river where juvenile salmon size, juvenile salmon density (how many salmon in a certain area), and turbidity (the “clearness” of the water) changed naturally.

Katie and her team predicted that the juvenile salmon would aggregate more as they got farther from structural cover, and as the water became clearer. Clearer water and less structural cover both make fish more susceptible to predation, so it makes sense that those factors would cause the salmon to band together for protection. Contrary to their hypothesis that smaller juvenile salmon would spend more time together than larger ones, aggregating behavior increased as the salmon grew in size. 

Katie and her colleagues think this is because, as salmon increase in size, they are preparing for their transition to the marine environment, where aggregation is the primary means of protection and foraging. Even though they were still in the river, Katie thinks the salmon were getting ready for the behavioral change that the marine environment would bring. Understanding how the habitat needs of salmon change throughout their life will help inform conservation science and policy, and hopefully help preserve important salmon habitat.