Pacific Biodiversity Institute (PBI) initiated a study of the harbor porpoise in the Puget Sound in 2007. One of the early outcomes of this study was to identify an area, Burrows Pass, south of Anacortes, WA, as part of an apparent stronghold for the harbor porpoise. Subsequently, a series of regular observations of harbor porpoise in Burrows Pass were made from the bluffs of Washington Park from December 2009 through December 2010. The observations are continuing, but the results from the first year are summarized in this report and an initial analysis of the data is presented.
These observations were the first phase of a project to explore and implement various methods of assessing the distribution, population status, and population trend of this species of conservation concern. Consequently, observations were opportunistic and exploratory in nature. The results of this effort were encouraging and are being expanded in 2011 by a second phase of more regular and structured observations.
Two interns and more than 14 volunteers assisted with land-based observations, which were recorded opportunistically for 11 months of the last 12.5 month period. There were 105 hours of observations over 32 days. Porpoise were present for 42 of those 105 hours. Harbor porpoise generally appeared in groups of two to four. Mother and calf pairs were observed and active feeding events were common.
This report presents bar charts of these observations to date showing the number of hours porpoise were observed per unit effort. This report demonstrates that we are able to record data of the porpoise presence and activity. There is some indication of seasonal use of Burrows Pass from this data. The report also includes Appendix A, in which the hours the porpoise were present are plotted on tide charts for each day of observation to look for correlations with tide or current. In these figures, the hours when someone was observing are enclosed in a black box. Porpoise sightings are represented as black dots inside the box. If there were no porpoise observed, there are no black dots. Data for habitat correlation and analysis is being collected and will be used to assess possible locations for reserves and protected areas for the harbor porpoise. WDFW identified locations for forage fish are presented in Appendix B.
After reviewing the data collected, it appears that there is enough information and structure in the observational data that we have taken to date to justify continuing this study. This initial study demonstrates that observational data can be collected at Burrows Pass and points the way toward future research.