Calibration of Assessment Methods for Fraser Sockeye Enumeration

Since 2007, with support from the Southern Boundary Restoration and Enhancement Fund, calibration work has been conducted on twenty-three Sockeye populations of various stream types in the Fraser and has led to the development of indices for aerially surveyed Sockeye populations on the following three stream types: i) medium sized, clear streams, ii) medium sized, partially turbid/tannic streams and iii) large sized, clear streams. Although this represents substantial progress, significant gaps still exist on the remaining stream types and lake spawning populations. Calibration work involves the comparison between estimates generated using high precision enumeration techniques (enumeration fences, sonar, and/or mark-recapture programs) and those generated using standard low precision visual techniques. As annual calibration opportunities on target populations are limited, calibration work over the long term will be required to satisfy the data requirements for all stream types. For example, based on the 2012 brood year escapements, several potential calibration opportunities exist in 2016 (i.e. Nadina River, Upper Chilliwack River, Harrison River, Tachie River, Chilliwack Lake and Birkenhead River). The actual populations to be calibrated will be determined based on in-season estimates of abundance.