544 Abstract—Migratory behavior af- fects growth, survival, and fitness Residency, partial migration, and late egress of individual fish, the dynamics and resilience of populations, and the of subadult Chinook salmon (Oncorhynchus ecosystems that fish occupy. Many tshawytscha) and coho salmon (O. kisutch) in salmonids are anadromous but in- dividuals vary in the duration and Puget Sound, Washington spatial extent of marine migrations. We used telemetry to investigate Anna N. Kagley (contact author)1 movements of Chinook salmon (On- 2 corhynchus tshawytscha) that re- Joseph M. Smith mained in Puget Sound (residents) Kurt L. Fresh1 rather than migrated to the Pacific Kinsey E. Frick1 Ocean. Most tagged Chinook salmon 2 (26 of 37=70%) remained in Puget Thomas P. Quinn Sound for a substantial period, stay- ing in the region where captured. Email address for contact author: [email protected] However, 30% of tagged individuals, termed “transients,” subsequently 1 Northwest Fisheries Science Center left Puget Sound. Residents and National Marine Fisheries Service, NOAA transients did not differ in tagging 2725 Montlake Boulevard East date, body size, or origin (hatchery Seattle, Washington 98112 or wild). Compared with sympatric 2 School of Aquatic and Fishery Sciences coho salmon (O. kisutch) where 80% University of Washington remained as residents according to Box 355020 similar data, Chinook salmon tend- Seattle, Washington 98195 ed to be detected closer to shore, in shallower water, and on fewer dif- ferent receivers. For both species, residents showed limited movement within Puget Sound. We conclude that Chinook and coho salmon dis- play resident and transient move- Many of the world’s most abundant and Myers, 2004). These patterns ment patterns across a behavioral fish species are migratory within have been studied extensively ow- continuum rather than within dis- fresh or marine waters or between ing to the importance of salmonids crete migrational categories. These these distinct environments (Lucas in commercial and recreational fish- movement patterns are important and Baras, 2001; Secor, 2015). How- eries, ecosystem function, and bio- because they affect the role of salm- ever, species and populations often diversity (NRC, 1996). Many stud- on in the ecosystem, their vulner- vary greatly in the prevalence, dura- ies have investigated the ecological ability to fisheries, and their accu- mulation of chemical contaminants. tion, and spatial extent of their mi- and evolutionary basis of anadromy grations (Quinn and Brodeur, 1991; and nonanadromy (Wood and Foote, Chapman et al., 2012a; Chapman 1996; Dodson et al., 2013; Kendall et al., 2012b). Such variation (e.g., et al., 2015) but there is also great partial and differential migration) variation in the extent of migra- can affect the population’s stability tion among anadromous individu- through alterations in exposure to als, especially for Chinook salmon predators, fisheries, and contami- (Oncorhynchus tshawytscha). The nants (Kerr et al., 2010; Gahagan tendency to use different marine en- Manuscript submitted 11 January 2017. et al., 2015). Consequently, a full vironments (coastal and open ocean) Manuscript accepted 24 August 2017. understanding of variation in move- varies markedly among populations, Fish. Bull. 115:544–555 (2017). ment patterns is important for man- as does the tendency to migrate Online publication date: 14 September 2017. agement of these populations, such northward or southward along the doi: 10.7755/FB.115.4.10 as conservation planning and the coast of North America (Myers et al., measurement of survival. 1998; Trudel et al., 2009; Weitkamp, The views and opinions expressed or implied in this article are those of the Among fishes, salmonids show a 2010; Sharma and Quinn, 2012). In author (or authors) and do not necessarily particularly wide variety of migra- addition, some individuals do not reflect the position of the National tion patterns (Jonsson and Jonsson, migrate into the North Pacific Ocean Marine Fisheries Service, NOAA. 1993; Klemetsen et al., 2003; Quinn but rather spend all or most of their Kagley et al.: Residency, partial migration, and late egress of Oncorhynchus tshawytscha and O. kisutch 545 marine period within protected waters of southeastern conspecifics that migrate to the coastal ocean (O’Neill Alaska (Orsi and Jaenicke, 1996) and British Columbia and West, 2009). As a prey item these salmon contain (Healey and Groot, 1987). It has also been known for high enough levels of persistent organic pollutants to decades that some Chinook salmon, termed “residents,” have possible health effects on ESA-listed killer whales are found throughout the year within Puget Sound, the (Hickie et al., 2007; Cullon et al., 2009) and to require Strait of Georgia, and associated inlets (Pressey1; Haw human health advisories (WDOH3). et al.2; Buckley, 1969). It has been unclear to what ex- In this study, individual Chinook salmon were im- tent these salmon move within the inland marine wa- planted with hydroacoustic tags at a time after the ters, collectively known as the Salish Sea, and whether majority of salmon had typically left Puget Sound for they leave for the coast at some point. Brannon and ocean feeding grounds (Healey, 1991). The detections of Setter (1989) inferred from coded wire tagging data these presumably resident Chinook salmon were used that both maturing and immature Chinook salmon to determine: 1) whether these individuals remained may make annual “loop” migrations from Puget Sound within Puget Sound, and 2) whether origin (wild or north into the Strait of Georgia in spring and sum- hatchery), body size, or season of tagging influenced mer and then back south into Puget Sound. However, their tendency to remain in Puget Sound. For the fish there is no direct evidence of individual fish making that stayed as residents within Puget Sound, we also such migrations. determined 3) whether resident salmon remained in Resident salmon seem to constitute a persistent and the same region where they were tagged or moved substantial fraction of the entire Puget Sound popula- throughout Puget Sound and parts of the Salish Sea, tion of Chinook salmon. Analysis of coded-wire tag data and 4) whether detections depended on the receiver lo- indicated that an estimated 29% of hatchery Chinook cation’s water depth and proximity to shore. salmon subyearlings and 45% of yearlings entering Finally, we compared the location features of receiv- Puget Sound remained as residents (O’Neill and West, ers that recorded Chinook salmon with those features 2009). Subsequent analyses based on similar data but that were recorded with receivers that detected coho reflecting a different analytical approach also revealed salmon collected and tagged at the same locations and that many Puget Sound Chinook salmon adopt a resi- times (Rohde et al., 2013). Coho and Chinook salmon dent marine distribution pattern (Chamberlin et al., in Puget Sound are ecologically similar and both ex- 2011). This pattern occurs but is less common with hibit partial migration (i.e., residency). The factors coho salmon (O. kisutch; Rohde et al., 2014). However, affecting residency, inferred from coded wire tagging because coded wire tags document only the location data, were similar for the 2 species (Chamberlin et al., where fish are captured, and not movement patterns, 2011; Rohde et al., 2014), and both species tended to movements of individual fish cannot be determined be caught as residents in the natal basin where they with these tags. Research using hydroacoustic trans- entered Puget Sound. We therefore combined data from mitters revealed differences between coho and Chinook this study and that by Rohde et al. (2013) to compare salmon depth distributions and diel vertical migrations directly the movement patterns of individual residents but did not provide information on movement through- of these species in Puget Sound. out the basins in Puget Sound and the Salish Sea (Smith et al., 2015). Four Chinook salmon distribution patterns were observed in the Salish Sea (Arostegui et Materials and methods al., 2017), but information on resident Chinook salmon movements in the main basins of Puget Sound is still Tagging very limited. The Chinook salmon evolutionarily significant unit On 9 dates in June (2006 and 2007), November (2006), in Puget Sound is listed as threatened under the U.S. and December (2006, 2007, and 2008), 87 Chinook Endangered Species Act (Federal Register, 2005). A salmon were caught with a commercial purse seine in better understanding of the movements of these fish central Puget Sound (tagging area, Fig. 1). On the ba- between Puget Sound and the coastal ocean, and sis of the dates, locations, and sizes (range: 208–370 within Puget Sound, will help to identify patterns in mm in fork length) of these salmon, all were assumed habitat use, to evaluate fishery management objec- to be residents at the time of capture. To determine tives across jurisdictional boundaries, and even help residency we presumed that fish of this size would to determine pathways to contaminant exposure. Resi- have entered salt water as smolts the previous spring dent Chinook salmon, for example, have higher accu- or summer and were still in Puget Sound about a year mulations of polychlorinated biphenyls (PCBs) than later at a time when migratory individuals would be moving along the coast or in offshore waters of the North Pacific Ocean (Trudel et al., 2009). 1 Pressey, R. T. 1953. The sport fishery for salmon on Puget Sound. Wash. Dep. Fish., Fish. Res. Pap. 1:33–48. 2 Haw, F., H. O. Wendler, and G. Deschamps. 1967. Devel- 3 WDOH (Washington State Department of Health). 2006. opment of Washington State salmon sport fishery through Human health evaluation of contaminants in Puget Sound 1964. Wash. Dep. Fish., Res. Bull. 7, 192 p. [Available from fish, 136 p. Div. Environ. Health, Wash. State Dep. Health, website.] Olympia, WA. [Available from webiste.] 546 Fishery Bulletin 115(4) fed by gravity through a tube and deliv- ered to the gills.