Brown Trout on the Move – Migration Ecology and Methodology

Aarestrup, Kim; Jepsen, Niels; Thorstad, Eva B.

doi:10.1002/9781119268352.ch17

Cited by 8 publications

(11 citation statements)

References 155 publications

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“…Passive integrated transponder (PIT) telemetry is now one of the most effective ways used to study fish migration and survival in streams (Cooke, Hinch, Lucas, & Lutcavage, ), due to the small tag size, theoretically indefinite lifetime and low costs. However, for studies of predation and migration patterns in less physically constrained habitats, it is less suited, because PIT tags are limited in detection range (typically less than 1.3 m) and manual traceability (Aarestrup, Jepsen, & Thorstad, ; Cooke et al ). Radio tags, on the contrary, can be tracked over long distances and pinpointed with submetre precision (Kuechle & Kuechle, ; Lucas & Baras, ).…”

Section: Introductionmentioning

confidence: 99%

Telemetry observations of predation and migration behaviour of brown trout (Salmo trutta) smolts negotiating an artificial lake

Schwinn

Baktoft

Aarestrup

et al. 2018

River Research & Apps

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Eutrophication of coastal areas as a consequence of the agricultural use of fertilizers is a widespread problem. The development of artificial lakes and constructed wetlands in nutrient‐rich rivers is a widely used management tool in the fight to decrease eutrophication. Juvenile salmonids that have to negotiate these lakes during their downstream migration to the sea are commonly subjected to high mortality due to increased predation pressure and delayed passage. In this study, we double tagged 39 brown trout smolts with passive integrated transponder and radio tags to gain further insight into predation rates and migration patterns during their passage of an artificial lake in a Danish lowland stream in the spring of 2016. Thirty‐four of the tagged smolts, caught and released upstream, entered the lake, of which 22 (65%) successfully exited the lake. Four smolts (12%) returned upstream to the river. Three smolts were predated in the lake by two northern pike (Esox lucius). Three tags were recovered from the lake bottom, and two disappeared out of the study area after a last detection in the lake. Tracking the smolts manually and by automatic listening stations showed highly erratic movement patterns during lake passage. Further, we observed long delays of up to 27 days after the smolts reached the river mouth and before they entered the sea, potentially due to low sea water temperature or due to the stocking of a large amount of hatchery‐reared brown trout smolts. The results are discussed in the context of abiotic and biotic factors, which differed considerably in the year 2016 compared with previous years.

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Section: Introductionmentioning

confidence: 99%

Telemetry observations of predation and migration behaviour of brown trout (Salmo trutta) smolts negotiating an artificial lake

Schwinn

Baktoft

Aarestrup

et al. 2018

River Research & Apps

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“…This could be related to the increase in photoperiod and solar radiation during summer months, and the consequent increase in water temperature. Other studies have also shown that the influence of temperature on the river entrance of sea trout seems to be conflicting and inconclusive (Aarestrup et al., 2018). On the other hand, river discharge is considered a stimulus (Clapp et al., 1990) and a facilitator for overcoming obstacles (Ovidio & Philippart, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…River discharge during peak migrations was very important in both RF models but with a greater importance for the sea trout. The increase in discharge has been demonstrated as an important stimulating factor for the river entrance of salmonids, especially in smaller rivers (Aarestrup et al., 2018). Considering this, it was concluded that alterations in discharge and thermal regimes can produce delays in the migrations due to a loss of the migration signal, a difficult obstacle ascent and/or a reduction of habitat connectivity (Aarestrup & Koed, 2003; García‐Vega et al., 2018; Gauld et al., 2013; Oliveira et al., 2018).…”

Section: Discussionmentioning

confidence: 99%

Effect of restoration measures in Atlantic rivers: A 25‐year overview of sea and riverine brown trout populations in the River Bidasoa

García‐Vega

Leunda

Ganuza

et al. 2020

Fisheries Management Eco

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Effective protection of migratory fish requires long‐term conservation encompassing active restoration and management measures with follow‐up studies. The main findings of long‐term (1995–2019) monitoring of anadromous and potamodromous brown trout Salmo trutta in the River Bidasoa are presented. The main aims were evaluating trout number and median migration date changes, and assessing the effects of management (closures, size limits and quotas, fish stoking) and connectivity measures (fishways and weir removals). Results showed an increasing trend in upstream migrants and decrease in migration dates (earlier migrations). Effects of overlapping measures were difficult to differentiate and were affected by environmental conditions. Statistical analysis demonstrated that fishing closures (2008–2011) and fishway construction (2008) were of great importance, whereas the effect of fish stocking (2003–2012) was variable and unclear. The unexpectedly short‐term effect of three weir removals (2014–2016) may have been due to unusually high discharges in March, affecting the recruitment during previous years.

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“…ranging from fjord residents to individuals migrating out of the fjord) 54 . Indeed, recent evidence suggests that sea trout from the same population can display high variation in habitat utilization and migration behaviour in fjord systems 15,57,60 . The PIT-telemetry methods used in this study did not allow us to assess the extent of migration out of the fjord system.…”

Section: Discussionmentioning

confidence: 99%

“…Juvenile trout typically migrate to the sea in the spring and early summer (e.g. 13–15 ). In Denmark, this migration to sea usually takes place from early March to the beginning of June with a peak in number of migrants in the last half of April and early May 16–18 .…”

Section: Introductionmentioning

confidence: 99%

The influence of initial developmental status on the life-history of sea trout (Salmo trutta)

Villar-Guerra

Larsen²,

Baktoft

et al. 2019

Sci Rep

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Spring migrating sea trout juveniles can be classified as parr, pre-smolt or smolt based on body morphology and osmoregulatory capacity. In this respect, parr are assumed to be less prepared for a marine life and to have lower survival at sea than pre-smolts and smolts. However, the behaviour and survival of these trout phenotypes upon entering the sea is not well known. Using passive integrated transponder telemetry, this study found that the return rate from the sea to the natal river was higher for parr compared to pre-smolts and smolts. Additionally, trout classified as parr generally migrated earlier to the sea and a larger proportion returned to the river after less than one year at sea. The daily mortality rate at sea was comparable among the different phenotypes of trout, suggesting that the higher proportion of returning parr to the river was linked to their shorter duration at sea. These results provide evidence of different life-history strategies for seaward-migrating juvenile sea trout, ultimately affecting their return rate to the natal river. Investigations failing to consider downstream migrating parr and pre-smolts risks neglecting a large part of the anadromous population and may result in inaccurate assessments of sea trout stocks in rivers.

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Brown Trout on the Move – Migration Ecology and Methodology

Cited by 8 publications

References 155 publications

Telemetry observations of predation and migration behaviour of brown trout (Salmo trutta) smolts negotiating an artificial lake

Telemetry observations of predation and migration behaviour of brown trout (Salmo trutta) smolts negotiating an artificial lake

Effect of restoration measures in Atlantic rivers: A 25‐year overview of sea and riverine brown trout populations in the River Bidasoa

The influence of initial developmental status on the life-history of sea trout (Salmo trutta)

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