Salmon and sea trout spawning migration in the River Tweed: telemetry-derived insights for management

Abstract

. (2016) 'Salmon and sea trout spawning migration in the River Tweed : telemetry-derived insights for management. ', Hydrobiologia., Further information on publisher's website:http://dx.doi.org/10.1007/s10750-015-2481-0Publisher's copyright statement:The nal publication is available at Springer via http://dx.doi.org/10.1007/s10750-015-2481-0Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. River Tweed, UK, using acoustic telemetry to complement exploitation rate data and to quantify 17 catchment penetration. Salmon (n=79) and sea trout (n=65) were tagged in the tidal Tweed in 18 summer-autumn. No tagged salmon left the river before spawning, but 3% (2010) and 8% (2011) of 19 pre-spawning sea trout dropped out. Combined tag-regurgitation/fish mortality in salmon was 20 12.5%, while trout mortality was 6% (2010) and 0% (2011). The estimated spawning positions of 21 salmon and sea trout differed; tagged salmon were mostly in the main channel while trout occurred 22 mostly in the upper Tweed and tributaries. Early fish migrated upstream slower than later fish, but 23 sea trout moved through the lower-middle river more quickly than salmon, partly supporting the 24 hypothesis that the lower exploitation rate of trout (1%, vs 3.3% for salmon) there is by differences 25 in migration behaviour. This study illustrates the utility of telemetry in exploring differences in 26 catchment use and exploitation patterns of multiple stocks.

An acoustic sensor transmitter for in situ assessment of water quality and fish behaviour during chemical treatment of a parasite-infected river system: tag design and practical use

“…Acoustic tags have been used in river environments both for Atlantic salmon smolts [20,28,29] and adults [30,31], and provides a well-tested approach for tracking migratory fish in rivers [32]. Davidsen et al [26] used a variation of the presented conductivity tag to track anadromous brown trout (Salmo trutta) during the CFT Legumin treatment of the river Vefsna to eradicate G. salaris.…”

The influence of aquaculture unit proximity on the pattern of Lepeophtheirus salmonis infection of anadromous Salmo trutta populations on the isle of Skye, Scotland

“…There is strong evidence that salmonid populations are in decline in many areas, including the U.K., Europe and Canada (Ford & Myers, ; Middlemas et al, ; Thorstad et al, ). Although this trend is difficult to quantify because of the logistical problems associated with sampling fish populations that travel such large distances (ICES, ), it is apparent in rivers with long term count data, as well as in those with historic rod catch records (Gross et al, ; Gjelland et al, ; Gauld et al, ; ICES, ). As a result of its cultural and economic importance, considerable previous research has focused on the challenges facing S. salar populations (Limburg & Waldman, ).…”

“…It is well established that, during the marine stage of their life cycle, anadromous S. trutta gain benefits from access to increased resources, but they are also exposed to increased costs, such as disease and predation, which can result in high levels of mortality (Drenner et al, 2012;Gjelland et al, 2014). Thus, any change to the relative costs and benefits of marine migration have the potential for significant effects on anadromous populations.…”

“…Thus, any change to the relative costs and benefits of marine migration have the potential for significant effects on anadromous populations. This has led to speculation that changes in marine migration costs might be contributing to the decline in anadromous S. trutta (Gjelland et al, 2014;Jennings et al, 2016).…”

“…One suspected contributing source of mortality that may have increased in recent years is the potential for infestation by Lepeophtheirus salmonis, a naturally occurring sea louse parasite that feeds on the mucus, tissue and blood of their hosts, primarily salmonids (Boxaspen, 2006;Fast et al, 2007;Thorstad et al, 2015). The complex L. salmonis life cycle can be divided into eight developmental stages: two larval napulii phases that are planktonic, one copepodite phase that is also planktonic and free floating but must attach to a host, two chalimus phases (when the lice are able to begin feeding on their host), two pre-adult phases and a final mature or reproductive phase (Fast et al, 2007;Gjelland et al, 2014;Thorstad et al, 2015). Beginning at the pre-adult phases, L. salmonis are able to move on the body surface of their host and can actively swim for short distances .…”