Feature Stories 2019: Chang Liu '19: PhD in marine science

Chang Liu conducting research
Feature Stories 2019: Chang Liu '19: PhD in marine science
Chang Liu '19: PhD in marine science

Developing geolocation methods to benefit fisheries stock assessment and management.

Chang Liu’s interest in marine science began when he was pursuing his undergraduate degree in marine science at Nanjing University of Information Science and Technology in China. While at Nanjing, Chang simulated the Yangtze River estuary and Hangzhou Bay currents using FVCOM, a numerical model originated by UMass Dartmouth Professor of Fisheries Oceanography Changsheng Chen and developed at SMAST in collaboration with researchers from Woods Hole Oceanographic Institution. 

“Wanting to further my studies, I learned about the UMass Intercampus Marine Science Graduate Program during my senior year,” he says. “I thought the location and program would offer a very unique opportunity along with a chance to broaden my experience in the field of marine science, pursue my studies in the states, and participate the state-of-the-art research activities at SMAST.”

Chang contacted SMAST about graduate school opportunities. Dr. Chen's colleague Dr. Geoffrey Cowles, an oceanographer who specializes in computational methods was seeking a student with modeling experience, ideally working with the FVCOM. Chang was accepted into the UMass Intercampus Marine Science MS program and went onto to matriculate into the PhD program.

Chang Liu's track
Example of the most probable track and associated uncertainty distribution estimated for an Atlantic cod tagged with a data storage tag, released and recaptured in coastal Massachusetts waters.

Developing & applying geolocation methods

The research, which comprised Chang’s PhD in Marine Science and Technology program, focused on the development and application of geolocation methods for groundfish species, including cod, halibut, monkfish, and yellowtail flounder.

“Using data such as pressure and temperature recorded and stored on tags attached to the fish, the geolocation process can determine the most likely track of the animal while it is at large,” Chang says. “The data is retrieved either through recapture of the animal or in the case of popup satellite tags (PSATs) through the Argos communication system. Geolocation results can provide insights into fish migration patterns, habitat usage, and stock structure. All of these are important information that can benefit fisheries stock assessment and management.”

While tag technology has continued to advance and unit costs decrease, the methods and software needed to make use of the retrieved data have been deficient. “A primary goal of my research is to alleviate this deficiency by developing tools, which break some of the technological barriers and enable fisheries biologists to derive reliable movement and behavioral information from the data,” he says.

Studying at SMAST

“Earning my PhD at SMAST has been a very pleasant experience for me,” Chang says. “Most of SMAST faculty and my peers have been collaborative and have provided the support I needed while working toward completing my PhD, which I very much appreciate.”

Chang’s research work also involved collaborating with colleagues at government agencies and NGOs. “The applied learning experience coupled with the courses and research I have done at SMAST provided me with solid knowledge about marine science and important skills on scientific computing and data analysis, especially in the context of marine science research.”

Next steps

Now that Chang is days away from grasping his PhD as he walks across the stage during UMass Dartmouth Commencement on May 13, what’s next to come? “I’ve landed a position as a Postdoctoral Research Associate at the University of Connecticut,” he says. “I look forward to expounding upon my marine science research by applying the computational modeling methods to help with the Connecticut coastal resilience planning to better prepare for future climate change and sea level rise.”


Liu, C., Cowles, G.W., Zemeckis, D.R., Fay, G., Le Bris, A., Cadrin, S.X. (2019), A hardware-accelerated particle filter for the geolocation of demersal fish. Fisheries Research, 213C(2019):160-171. doi:10.1016/j.fishres.2019.01.019.

Liu, C., Cowles, G., Zemeckis, D.R., Cadrin, S.X, and Dean, M.J. (2017), Validation of a hidden Markov model for the geolocation of Atlantic cod. Canadian Journal of Fisheries and Aquatic Sciences, 74(11): 1862-1877. doi:10.1139/cjfas-2016-0376.

Zemeckis, D.R., Liu, C., Cowles, G.W., Dean, M.J., Hoffman, W.S., Martins, D., and Cadrin, S.X. (2017), Seasonal movements and connectivity of an Atlantic cod (Gadus morhua) spawning component in the western Gulf of Maine. ICES Journal of Marine Science, 74(6):1780–1796. doi:10.1093/icesjms/fsw190.

Liu, C., Cowles, G., Churchill, J. and Stokesbury, K. (2015), Connectivity of the bay scallop (Argopecten irradians) in Buzzards Bay, Massachusetts, U.S.A. Fisheries Oceanography, 24(4):364–382. doi:10.1111/fog.12114.

DeCelles, G., Cowles, G., Liu, C., and Cadrin, S. (2015), Modeled transport of winter flounder larvae spawned in coastal waters of the Gulf of Maine. Fisheries Oceanography, 24(5):430–444. doi:10.1111/fog.12120.

Hall, V.A., Liu, C., and Cadrin, S.X. (2015), The impact of the second seasonal spawn on the Nantucket population of the northern bay scallop. Marine and Coastal Fisheries, 7(1):419–433. doi:10.1080/19425120.2015.1065301.