December 9, 2022

Dear Members of Our Campus Community,

I am deeply saddened to share with you the news that Professor Emeritus Allan Stewart-Oaten of our Department of Ecology, Evolution, and Marine Biology passed away on October 15.

Professor Stewart-Oaten devoted nearly four decades to UC Santa Barbara, joining our campus in 1970 and retiring in 2008. He was a pioneer in the use of applied statistics in field biology to assess environmental impacts on ecological communities. In addition to his outstanding research, he was known as a deeply devoted teacher and mentor. He contributed to our academic community in numerous ways, including serving as Associate Dean of Undergraduate Education in the College of Letters and Science and as Director of the UC Study Center in Australia.

Our hearts go out to his wife, Linda, and their family, as well as to Allan’s many friends, colleagues, and former students around the world. Our campus flag will be lowered in his honor on December 15th.

I am honored to share the following remembrance from Professors Bill Murdoch, Roger Nisbet, and Cherie Briggs in our Department of Ecology, Evolution, and Marine Biology.

Allan Stewart-Oaten (1939-2022)

In 1970 Allan came to UCSB as the statistician to the then-Biology department, and spent his career teaching statistics to undergraduates and graduates in what became the Dept. of Ecology, Evolution and Marine Biology (EEMB). His door was always open to the wide range of graduate students and faculty in the department, and he spent much of his time helping those who needed statistical advice in the design of experiments and the analysis of data. He was equally welcoming to undergraduates with “office hours” meaning any time his door was open. This commitment to undergraduate education was reflected in two years’ service as Director of the University of California Study Center in Australia and service as an Associate Dean of Undergraduate Education in the College of Letters and Science in the years preceding his retirement in 2008.

Allan’s major contribution in applied statistics arose from the need for a sampling design to detect the effects of a single point-source of environmental damage – in his particular case the effects on marine ecological communities (such as a nearby kelp bed and populations of fish larvae killed by the cooling system) of the effluent from a nuclear power plant in Southern California. In 1986, to provide an answer to this problem, he published a widely-cited and enormously influential paper (Stewart-Oaten et al. 1986, Ecology). Briefly, the paper proposed repeatedly measuring conditions Before the plant began operation, and After it was operating, at the Impact site and at a Control site. The latter should be chosen to be as similar as possible to the Impact site, while being outside of the power plant’s influence. The key observation was the change in a measure of the difference between Impact and Control in the After period compared with the Before period. Hence Allan gave the approach the title of BACI (or preferably BACIP, since the sites should be paired to be a similar as possible). Field biologists have long been used to detecting effects by comparing the difference between replicated experimental sites with randomly-selected control sites, and Allan published several important papers explaining why, especially randomly-selected, control sites were not appropriate for estimating single-point impacts. 

A measure of the influence of this paper is that the approach has become standard in the field, not only in the analysis of environmental impacts, but in the design of experiments in the field where the effects of a single experimental disturbance need to be measured. It is now essentially conventional wisdom, and one encounters its widespread application among field scientists who have never read the original papers. 

Allan’s other main contributions were in collaborations with population ecologists, and were, again, widely cited. Early in his academic career (1970s, at a time when many ecologists doubted the value of dynamic models), he provided underlying mathematical theory in models of population dynamics, especially those trying to explain interactions between populations of predators and their prey. Important papers in this area ranged from relatively simple situations focusing on the effects of likely behaviors of individual predators in response to changes in abundance of their prey to more complex analyses of the dynamical effects of uneven spatial distributions, and individual prey and predator movements among such heterogeneous patches.

Allan will be remembered by the many students and colleagues he helped, not only for his understanding and unlimited willingness to help, but for his kindness and his wonderful sense of humor.

Allan is survived by his wife Linda and his three sons, Albert, Nick, and Josh.



Henry T. Yang