The College of Aquatic Sciences and Applied Technology traces its roots to the Pias-Gaang Community High School which became the Currimao School of Fisheries in 1966 by virtue of Republic Act No. 4765. In 1972, a two-and-a-half-year course, Associate in Fishery Education, was offered in addition to the secondary curriculum. On June 16, 1976, the late President Ferdinand E. Marcos issued Presidential Decree 945 integrating the School of Fisheries, together with the Dingras National Agricultural School (DNAS) in Dingras, Ilocos Norte, and the Ilocos Norte School of Craftsmen (INSC) in Paoay, Ilocos Norte to the Mariano Marcos Memorial College of Science and Technology (MMMCST) in order to attain a unification of programs and policies for regional development.

          The school began to offer the four-year Bachelor of Science in Fisheries (BSF), with Inland Fisheries, Marine Fisheries, and Fish Processing as major fields of specialization. A year-and-a-half later, on January 6, 1978, the MMMCST and the Northern Luzon State College (NLSC) of Laoag City were merged as the Mariano Marcos State University (MMSU) by virtue of Presidential Decree 1279. From 1978 onwards, the school has metamorphosed into a lead institution in fisheries, particularly in Northern Luzon. In June 1998, with the growing concern for suitable development and rational utilization, management, and conservation of the fisheries and aquatic resources, the College also offered the Bachelor of Science in Marine Biology (BSMB) program. In 2001, by virtue of Board Resolution No. 461, s. 2001, the Board of Regents approved the consolidation of the three majors of the course into one general BS in Fisheries course. This is in preparation for the then-upcoming licensure examination for Fisheries Technologists which requires a fisheries graduate to have the knowledge and skills in all the fields of specialization of the BS Fisheries course. The Fisheries Technologists Licensure Examination was first conducted in 2003.

           The paradigm shift from having majors to non-majors is a call to provide competent fisheries professionals who can contribute better to sustainable and responsible fisheries and total approach to freshwater and marine coastal management, and would be flexible in tackling job opportunities in both private and government sectors. The curriculum is expected to provide students with a strong scientific background on aquatic resources and ecology, aquaculture, marine fisheries, and post-harvest fisheries, among others.

          Under MMSU, the College is initially named as College of Fisheries; then in 2004, the College was renamed College of Aquatic Sciences and Applied Technology (CASAT) to encompass all aspects of aquatic sciences and marine biology, as well as the emerging new technologies related to these fields of specialization.