Migratory patterns of exotic brown troutSalmo truttain south‐western Hokkaido, Japan, on the basis of otolith Sr:Ca ratios and acoustic telemetry

Abstract

Acoustic telemetry and microchemical analysis of otolith strontium-calcium ratios were used to evaluate how exotic brown trout Salmo trutta have responded to Japanese riverine environments of south-western Hokkaido by observing their migratory patterns. The existence of anadromous S. trutta was also verified. Most S. trutta caught in rivers for otolith analysis were freshwater residents (95·6%), whereas those caught in the sea were mainly smolts (91·3%), which had just migrated from rivers during spring. Anadromous S. trutta (n = 6) were captured in rivers and in the sea, confirming the existence of mature pre- and post-spawning fish. According to telemetry results, both mature and immature S. trutta used the river in winter, and their estimated sea-run timings showed individual differences. Through the combination of these two methods, migratory patterns on various spatio-temporal scales were observed. This first documentation of the presence of both male and female anadromous S. trutta in the same region within Japan indicated the risk of further colonization of exotic S. trutta via oceanic migration.

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

“…Surprisingly, only three other studies have combined otolith analysis with telemetry, such as passive telemetry (i.e., PIT tagging; Downs et al 2006), radiotelemetry (Brenkman et al 2007), or acoustic telemetry (Honda et al 2012), to obtain a more complete understanding of migratory salmonids. Perhaps the lack of studies using both methods is because a fish must be sacrificed to obtain the otoliths, which could be undesirable for endangered or threatened species.…”

“…Moreover, chemical signatures in otoliths require that isotopes differ among water bodies in which the fish reside. Regardless of the limitations of each approach individually, combined they provide complementary tools to understand life history patterns of fish populations, but have been rarely used together (but see Brenkman et al 2007;Honda et al 2012).…”

Acoustic telemetry and fisheries management

“…Incorporating genetic or genomic approaches to telemetry studies will provide managers with the sorts of data that can bolster the delineation of management boundaries and preserve genetic diversity (Christiansen et al 2015, Stewart et al 2016, while chemical tracers like stable isotopes and trace elements can provide a means for determining site fidelities to areas critical to different life-history stages (juvenile rearing, reproduction, etc. ; Bergstad et al 2008, Honda et al 2012, Matich and Heithaus 2014, Papastamatiou et al 2015. Linking traditional tag recapture data sets with telemetry will improve our understanding of species movements relative to management areas , Raabe et al 2014, while also allowing estimation of population demographics such as survivorship and population size (Dudgeon et al 2015).…”

Assigning origins in a potentially mixed‐stock recreational sea trout (Salmo trutta) fishery

“…Curiously, it appears that anadromy in brown trout is more common in the Southern Hemisphere (McDowall 2006), which may reflect closer proximity to the ocean by many populations or greater feeding opportunities in higher southern latitudes (Hendry et al 2004a). Whatever the reasons, the anadromous life history form of brown trout in Newfoundland, and recently detected in Honda et al (2012), are apparently rare exceptions to the general life history patterns and are not well known. As an applied issue, it is currently unclear whether, and to what extent, populations of anadromous brown trout mix while in the marine environment and therefore are susceptible to angler harvest.…”

“…freshwater resident) life histories, with the frequency of the migratory life history varying among populations and among individuals within populations (Jonsson & Jonsson 1993). Whatever the reasons, the anadromous life history form of brown trout in Newfoundland, and recently detected in Honda et al (2012), are apparently rare exceptions to the general life history patterns and are not well known. Berg & Berg 1987, 1989Olsen et al 2006).…”