Performance of a high-frequency (180 kHz) acoustic array for tracking juvenile Pacific salmon in the coastal ocean

Table 3 Estimated detection efficiency (DE) of the 180-kHz (V4-1H) tags implanted in steelhead (Oncorhynchus mykiss) smolts

Array	Time period	N present	N detected	N corrected	DE (SE)	Corrected DE (SE)
Discovery Islands	< 50% expired	22	14	16.7	0.64 (0.10)	0.76 (0.09)
Discovery Islands	100% off	28	17		0.61 (0.09)
Discovery Is. south	< 50% expired	22	9	10.5	0.41 (0.10)	0.48 (0.11)
Discovery Is. south	100% off	27	11		0.41 (0.09)
Discovery Is. north	< 50% expired	20	7	8.5	0.35 (0.11)	0.42 (0.11)
Discovery Is. north	100% off	28	11		0.39 (0.09)

DE estimates are for two time periods: for detections recorded before day 42 following tag activation when 50% of 180-kHz tags were predicted to have expired; and for all detections until the tags were programmed to turn off (day 54). Numbers detected in both time periods exclude counts of 180-kHz tags only detected > 24 h after their paired 69-kHz tag (N = 3 at Discovery Islands, N = 5 at Discovery Islands south, and N = 3 at Discovery Islands north). N Present is known from the detection of the 69-kHz tag. The corrected DE is up to day 42

ISSN: 2050-3385