The efficacy of air, sound and acoustic bubble screens in deflecting Atlantic salmon, <i>Salmo salar</i> L., smolts in the River Frome, UK

Welton, J. S.; Beaumont, W. R. C.; Clarke, R. T.

doi:10.1046/j.1365-2400.2002.00252.x

Cited by 65 publications

(70 citation statements)

References 13 publications

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“…Recent studies have demonstrated behavioural avoidance in smolts related to hydraulic conditions (Haro et al 1998;Enders et al 2009), in-stream structures (Kemp and Williams 2008), overhead cover and absence of visual clues (Kemp et al 2005;Kemp and Williams 2009). Moreover, fish guidance may be accomplished using strobe lights (Johnson et al 2005), bubble curtains and sounds (Welton et al 2002;Sonny et al 2006) and deep, mid-channel furrows (Svendsen et al 2007). These findings indicate that smolts can be guided rapidly past the water withdrawal zone and over the weir crest to ensure passage.…”

Section: Resultsmentioning

confidence: 99%

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

Svendsen

Aarestrup

Malte

et al. 2011

Aquat. Living Resour.

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-Seaward migration of immature salmonids (smolts) may be associated with severe mortality in anthropogenically altered channels. Few studies however, have identified distinct behaviours that lead to exposure to adverse habitats or even unsuccessful migration. This study used high resolution telemetry to map migration routes of Atlantic salmon (Salmo salar) smolts approaching a water withdrawal zone associated with an aquaculture facility in a lowland river. Individual smolts were tagged with an acoustic transmitter and released upstream of the water withdrawal zone. A trap was installed downstream of the water withdrawal zone. The trap captured all smolts that passed the water withdrawal zone. The tracking results confirmed previous studies on Pacific salmon showing that Atlantic salmon smolts may perform milling behaviours (i.e. upstream excursions and circular swimming behaviour) in anthropogenically altered channels. Non-milling and milling smolts were compared. Smolts performing milling behaviours covered a larger area (m 2 ) and experienced an increased probability of entering the water withdrawal zone, considered an adverse habitat. Finally, smolts were identified as either passing (67%) or non-passing (33%) the water withdrawal zone based on the recapture data from the trap. In total, 20% of the non-passing smolts entered the aquaculture facility. Several behavioural traits differed between the remaining (80%) non-passing smolts and the passing smolts. In particular, time spent near the water withdrawal zone correlated negatively with the probability of passage. These links between individual behaviours and exposure to adverse habitats and passage probability may be applied to improve management of salmonid populations.

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Section: Resultsmentioning

confidence: 99%

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

Svendsen

Aarestrup

Malte

et al. 2011

Aquat. Living Resour.

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“…The detailed operation of the counter has been described (Welton et al 2002), but essentially the smolts are diverted from the main River Frome with the aid of an acoustic bubble screen into the East Stoke millstream that flows through a fluvarium. Fish are then counted without handling as they pass through resistivity counting tubes.…”

Section: Methodsmentioning

confidence: 99%

A size-dependent migration strategy in Atlantic salmon smolts: Small smolts favour nocturnal migration

Ibbotson

Beaumont

Pinder³

2011

Environ Biol Fish

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Migration theory states that migration behavioural strategies should be optimised to maximise fitness. Many studies have shown that in downstream migrating Atlantic salmon Salmo salar L. smolts, mortality from predation is high and negatively size dependent. The most common predators are birds and piscivorous fish that are mainly daylight feeders. Given the high mortality during this stage we should expect to observe smolts to follow predator avoidance strategies that may be affected by body size. We tested the hypothesis that small smolts have a higher tendency to exhibit predator avoidance strategies (i.e. nocturnal versus diurnal migration) than larger smolts. The number and size of out-migrating/downstreammigrating wild Atlantic salmon smolts was recorded as they passed through a glass-sided channel during April-May, 1996-1999. In all years, the mean size of nocturnal migrating smolts was significantly lower than the mean size of diurnal migrating smolts. Analysis of the size of smolts, during early and late stages of the migration period showed size-dependent nocturnal migration behaviour up to the end of April. After this, no such size dependent migration pattern was observed. However, small smolts (<100 mm) were absent during this period. We suggest that nocturnal migration is an adaptive behaviour that small Atlantic salmon smolts have to avoid predation by large daylight feeding visual piscivorous predators (e.g. pike Esox Lucius L. and fish eating birds).

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“…Salmonids have been observed to avoid areas with continuous overhead cover (e.g. Welton et al 2002 for Atlantic salmon smolts) such as at culverts. In an experimental study, actively migrating Chinook salmon smolts encountered a divergence of downstream route through two channels (Kemp et al 2005).…”

Section: Physical Structure and Habitat Fragmentation: Culvert Restormentioning

confidence: 99%

In‐Channel Placement of Structure to Enhance Habitat Complexity and Connectivity for Stream‐Dwelling Salmonids

Kemp

2010

Salmonid Fisheries

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Mechanisms responsible for observed responses of fish populations to manipulations of physical habitat are poorly understood. This chapter provides an overview of research conducted to investigate the response of salmonids to the placement of physical structure in streams and rivers and associated infrastructure (e.g. culverts) to restore degraded habitat complexity and connectivity. Although benefits of placement of physical structure are recognised, the response may be superficial, reflecting local increases in density rather than enhanced productivity and recruitment for the system as a whole. Inconclusive results and failures may be inconsistently reported, limiting the ability of managers to assess the effectiveness of alternative techniques. Biological response to physical habitat is complex and efficiency of techniques varies over a range of biotic and abiotic conditions raising concerns about their transferability to other regions or species. There is a need to develop robust audit protocols for all restoration projects undertaken against original objectives set, rather than report only perceived positive outcomes to the community of end-users. To address the lack of understanding of mechanisms that underpin the biological response to physical habitat, it is necessary to integrate the results of fine-resolution experimental studies with field observations of large-scale manipulation of structure.

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The efficacy of air, sound and acoustic bubble screens in deflecting Atlantic salmon, Salmo salar L., smolts in the River Frome, UK

Cited by 65 publications

References 13 publications

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

A size-dependent migration strategy in Atlantic salmon smolts: Small smolts favour nocturnal migration

In‐Channel Placement of Structure to Enhance Habitat Complexity and Connectivity for Stream‐Dwelling Salmonids

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