Tidal movements and residency of subyearling Chinook salmon (Oncorhynchus tshawytscha) in an Oregon salt marsh channel

Abstract

A novel application of full-duplex passive integrated transponder (PIT) tag technology was used to investigate movements of individual subyearling Chinook salmon ( Oncorhynchus tshawytscha ; fork length ≥ 60 mm) into and out of tidally flooded salt marsh habitat in the Salmon River estuary, Oregon, USA. PIT interrogation was effective, with mean tag detection ≥ 92%. Salmon movement peaked late during both flood and ebb tide periods, indicating that salmon did not drift passively. Most movements were in the direction of tidal currents, but 20% of individuals entered the channel against the ebbing tide. Individuals occupied the intertidal channel for a median 4.9 h and as long as 8.9 h per tidal cycle, and few were detected moving when water depth was <0.4 m. Some individuals used the channel on multiple successive tidal cycles, and others entered intermittently over periods of up to 109 days. Using an individual-based approach, we characterized diversity of juvenile Chinook salmon behavior within a marsh channel, providing insight into the value of such habitats for conservation and restoration of salmon populations.

Residency and Movement of Juvenile Chinook Salmon at Multiple Spatial Scales in a Tidal Marsh of the Columbia River Estuary

“…Our measures of R MARSH represent minimum values, as some individuals may have been tagged and released near the end of their wetland residency while others may have remained in or near the survey area for longer periods but went undetected by our sampling gear. Nevertheless, our observations of maximum R MARSH were consistent with results from other studies in Pacific Northwest estuaries where subyearling Chinook Salmon residence times were measured on a similar spatial scale (Healey 1980;Levy and Northcote 1982;Hering et al 2010).…”

“…Scale analyses by Reimers (1973) indicated that the majority of returning fall Chinook Salmon in the Sixes River, Oregon, had resided in the estuary as juveniles for approximately 3 months. In a brackish emergent wetland of the Salmon River estuary, Oregon, Hering et al (2010) observed maximum residency periods of 128 d (in 2004) and 48 d (in 2005) for subyearling Chinook Salmon. In contrast, estuarine residency of subyearling Chinook Salmon in the Columbia River has mostly been inferred from the travel time of large subyearlings fitted with acoustic transmitters. Acoustic-tagged subyearlings moved quickly from Bonneville Dam (the upper limit of tidal influence at river kilometer [rkm] 234) to the river mouth, with a mean travel time of 4.1 d (McComas et al 2008).…”

“…In a study focusing on migration pathways through the estuary, Harnish et al (2012) found that the travel times of acoustic-tagged subyearling Chinook Salmon through specific estuary reaches were on the scale of hours rather than days. More recently, Johnson et al (2015) used acoustic tags to measure the residence time of subyearlings in main-stem and off-channel areas near the Sandy River delta (rkm 198 on the Columbia River); those authors reported median residence times of 2.5-3.4 h. However, measures of residency and travel time based on the larger individuals that are used for acoustic tag implantation likely do not apply to the smaller fry or fingerlings that reside in many estuaries for extended periods (Healey 1980(Healey , 1991Levy and Northcote 1982;Hering et al 2010;Volk et al 2010;Harnish et al 2012).…”

“…For example, fish can be detected during the night, on days when no sampling occurs, and after sampling surveys are discontinued. Passive integrated transponder antenna arrays have been deployed successfully in tidal marsh channels to monitor the movements of tagged individuals within a wetland complex (e.g., Hering et al 2010).…”

Survival, Tag Retention, and Growth of Spot and Mummichog following PIT Tag Implantation

“…In recent years, small PIT tags have been used in estuarine and marine environments to determine the rates of movement and survival of both juvenile fish and smallerbodied fish species (Adams et al 2006;Hering et al 2010;Rudershausen et al 2014). Due to their small size, PIT tags now allow researchers to test for the effects of factors such as habitat and density-dependence on the mortality and growth of fish at their early life stages, using data at the individual level (Hering et al 2010; Barbour et al 2012).…”