Spatio-temporal variability in movement, age, and growth of mountain whitefish (Prosopium williamsoni) in a river network based upon PIT tagging and otolith chemistry

Abstract

Connectivity of river networks and the movements among habitats can be critical for the life history of many fish species, and understanding of the patterns of movement is central to managing populations, communities, and the landscapes they use. We combined passive integrated transponder tagging over 4 years and strontium isotopes in otoliths to demonstrate that 25% of the mountain whitefish (Prosopium williamsoni) sampled moved between the Methow and Columbia rivers, Washington, USA. Seasonal migrations downstream from the Methow River to the Columbia River to overwinter occurred in autumn and upstream movements in the spring. We observed migration was common during the first year of life, with migrants being larger than nonmigrants. However, growth between migrants and nonmigrants was similar. Water temperature was positively related to the proportion of migrants and negatively related to the timing of migration, but neither was related to discharge. The broad spatio-temporal movements we observed suggest mountain whitefish, and likely other nonanadromous fish, require distant habitats and also suggests that management and conservation strategies to keep connectivity of large river networks are imperative.Résumé : La connectivité des réseaux hydrographiques et les déplacements entre habitats peuvent revêtir une importance capitale pour le cycle biologique de nombreuses espèces de poissons, la compréhension des motifs de déplacement constituant donc un aspect central de la gestion des populations et des communautés, ainsi que des paysages utilisés par ces dernières. L'intégration de données de radio-étiquettes passives intégrées recueillies sur 4 ans et de données d'isotopes de strontium d'otolites permet de démontrer que 25 % des ménominis de montagnes (Prosopium williamsoni) échantillonnés se déplaçaient entre la rivière Methow et le fleuve Columbia (État de Washington, États-Unis). Des avalaisons saisonnières de la rivière Methow vers le fleuve Columbia pour y passer l'hiver se produisaient en automne, et des montaisons, au printemps. Nous avons observé que la migration était répandue durant la première année de vie, les individus migrateurs étant plus grands que les autres. Ces deux groupes présentaient toutefois des taux de croissance semblables. La température de l'eau était positivement corrélée à la proportion d'individus migrateurs et négativement corrélée au moment de la migration, aucune de ces variables n'étant toutefois corrélée au débit. Les grands déplacements spatiotemporels observés portent à croire que le ménomini de montagnes et, vraisemblablement, d'autres poissons non anadromes ont besoin d'habitats éloignés les uns des autres et qu'il est donc impératif d'adopter des stratégies de gestion et de conservation visant à préserver la connectivité des grands réseaux hydrographiques. [Traduit par la Rédaction]

Spatiotemporal patterns of mountain whitefish (Prosopium williamsoni) in response to a restoration of longitudinal connectivity

“…We speculate that upriver movement was largely a pursuit of improved foraging opportunities, because 60% of all movement occurred in spring/early summer and consisted primarily of subadult to adult-sized individuals (>200 mm total length); these attributes are consistent with observations from other studies (Baxter, 2002;Benjamin et al, 2014;Davies & Thompson, 1976). Baxter (2002) hypothesised that the spring upriver migration of adult-sized mountain whitefish in tributaries to the Grand Ronde River, OR, USA, was to access foraging conditions energetically superior to those available in downstream portions of the study system.…”

“…We also expected that annual rates of upstream movement through the ladder would co-vary with water temperature (Benjamin et al, 2014) and discharge (Bret et al, 2016); therefore, these predictors were used in our statistical analysis with data measured at the dam during the spring-summer period between 2008 and 2014 (WSDOE 2016) (see Appendix A, Table A4 for list of predictor variables). The reach-scale spring-summer period was used in our analyses as this period coincided with peaks in upstream movement through the ladder and abundance estimates from snorkel surveys.…”

“…Furthermore, while some individuals within a population are relatively stationary (Davies & Thompson, 1976;Northcote & Ennis, 1994), others can be migratory. Available evidence indicates these migratory individuals require access to different portions of the river network for foraging, reproduction and overwintering (Baxter, 2002;Benjamin, Wetzel, Martens, Larsen, & Connolly, 2014;Davies & Thompson, 1976;Pettit & Wallace, 1975).…”

Assessment of PIT tag retention and post-tagging survival in metamorphosing juvenile sea lamprey

“…PIT tags have been used to track in-stream movement and migration patterns of many fish species [8][9][10]. PIT tags are small, individually coded capsules that range from 8 to 32 mm in length.…”

When Do Mountain Whitefish (Prosopium williamsoni) Spawn? A Comparison of Estimates Based on Gonadosomatic Indices and Spawner and Egg Counts

“…Historically, Mountain Whitefish have not been as extensively studied as other native western salmonids, perhaps due to their lack of popularity as a sport fish and their perceived robust abundance [4]. However, more recent investigations on Mountain Whitefish have illustrated their sensitivity to changes in lotic environments from impoundment [5] and highlighted significant declines in at least some parts of their range [6,7].…”