Dr. Jaramillo obtained his first experience with marine mammals through undergraduate studies in marine biology, where he participated in a survey to study sea lions (1986). Since then, his activities have been focused on the research of marine mammals, primarily cetaceans. He obtained his degree with thesis work on population relationships of humpback whales in the Mexican Pacific. In 1996, he was hired by National Fisheries Institute to collaborate in vaquita population research. In 1997, he participated in the first survey to estimate vaquita abundance and was later responsible to do the analytical work, which helped him obtain a Master's in Science.

In the same year, he participated in the first survey to test passive acoustic techniques to study the vaquita population. Since then, he is responsible for this research, working for National Institute of Ecology. In 2007, he prepared a report to inform the Mexican Government of vaquita population decline, which described the development of the Action Program to Recover Vaquita. He authored a paper calling for the urgency to implement recovery actions. In 2008, he obtained a doctoral degree with a Vaquita Bayesian population model, which incorporated acoustic information. In the same year, he participated in the second survey to estimate vaquita abundance, as part of the group of experts in charge of developing an acoustic monitoring scheme. Since then, he has been charged to coordinate this effort, using the so-named acoustic detector C-POD. In 2016, he led the preparation of a report about vaquita population trends in the period 2011–2015, based on acoustic data. He is a member of an expert panel group to review the models, which are presented to CIRVA, to which he has served as a member since its inception in 1997. In 2015, he participated in the Expedición Vaquita 2015, as chief scientist of passive acoustic research. He has published several papers in peer-reviewed journals and book chapters; he is part of the delegation for Mexico in the Scientific Committee of the International Whaling Commission; he is a member of the council group for biodiversity of the Mexican Commission for Biodiversity; and he is the former President of the Mexican Society of Marine Mammalogy (SOMEMMA, A.C.).