Partitioning survival during early marine migration of wild and hatchery-reared Atlantic salmon (Salmo salar L.) smolts using acoustic telemetry

Table 4 Watson’s U² values measuring for circular uniformity around a tidal cycle

	Fish type	Time from first low (h)			Test statistic	P-value	n
		Mean	CI	Median	U²
Lake	Hatchery	9.57	9.03–10.20	09.15	1.16	< 0.01	75
Lake	Wild	10.85	09.63–10.48	10.85	0.27	< 0.01	43
Estuary	Hatchery	10.50	09.17–11.77	10.63	0.35	< 0.01	63
Estuary	Wild	07.90	06.67–09.40	07.67	0.31	< 0.05	38
Marine arrays	Hatchery	09.85	08.88–10.82	10.02	0.44	< 0.01	39
Marine arrays	Wild	10.77	08.97–12.00	10.73	0.19	< 0.05	22

Data in bold indicate departure from circular uniformity, i.e. Atlantic salmon (Salmo salar) smolt movements were more likely to occur at a specific tidal time. n is the total number of fish detected passing the receivers at each section. Mean and median times are hours since low tide at which smolts left the lake, left the estuary and arrived at the final marine array. Confidence intervals (CI) for the population mean time were calculated using a bootstrapping approach assuming an underlying von Mises distribution. Watson’s critical value is 0.19 for all sample sizes

ISSN: 2050-3385