Science NOAA Fisheries conducts research on harbor porpoise biology, behavior, and ecology. This research informs management decisions and enhances conservation efforts. Stock Assessments Determining the number of harbor porpoises in each population—and whether a population is increasing or decreasing over time—helps resource managers assess the success of conservation measures. Our scientists collect and present these data in annual stock assessment reports. Aerial Surveys Scientists use small aircraft to observe and record harbor porpoise numbers and distribution. Under the MMPA, NOAA’s Southwest Fisheries Science Center conducts population estimates every 2 to 5 years to monitor the health, status, and trends of the population in its region. By comparing numbers collected over multiple years, scientists can spot trends, for instance, whether the population is increasing, decreasing, or remaining stable. Learn more about aerial surveys of harbor porpoises Harbor porpoises seen in aerial survey. Photo: NOAA Fisheries/Peter Duley. Genetic Research We have used DNA markers to study population structure among harbor porpoises living off the coasts of Alaska, California, Oregon, and Washington. NOAA scientists are studying this DNA evidence to determine whether different groups of harbor porpoises are functionally independent of one another or reproductively isolated from one another. Results of the study indicated that there is limited dispersal among groups. These results, along with data on harbor porpoise their distribution and abundance, were used to redefine the management units used for assessing status. There are now six management units of harbor porpoise recognized off the coasts of California, Oregon, and Washington. In Alaska, DNA markers are currently being assessed to investigate the genetic relatedness of populations. Additional research is being conducted in various regions to help us better understand the population structure and movement patterns of harbor porpoise.