Less anxious salmon smolt become easy prey during downstream migration

Fish need to move upstream and downstream through rivers to complete their life cycles. Despite the fact that fishways are the most commonly applied solution to recover longitudinal connectivity, they are not considered viable for downstream migration. Therefore, alternative facilities are recommended to facilitate downstream migration. However, a few recent studies have disagreed with this general assumption, showing the potential for bidirectional movements. This study advances our understanding of the potential of fishways for downstream migration by studying their efficiency in a run-of-the-river hydropower plant in the Duero River (Spain). To achieve this, downstream movements of the Iberian barbel (n = 299) were monitored in a stepped fishway for two years with passive integrated transponder (PIT)-tag technology, considering the effect of fish origin and release zone. The results showed that 24.9% of barbels descended through the fishway, with the origin and release zone affecting the fishway location. In addition, downstream movements were observed throughout the whole year, except in winter. The study concludes that, under specific scenarios, fishways could act as safe alternative routes for downstream migration.

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Downstream migration and feeding of young coho salmon Oncorhynchus kisutch in the northern part of the range in Kamchatka

Biology Bulletin ◽

10.1134/s1062359006030071 ◽

2006 ◽

Vol 33 (3) ◽

pp. 248-259 ◽

Cited By ~ 2

Author(s):

D. S. Pavlov ◽

E. A. Maslova

Keyword(s):

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Downstream Migration

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Mark-recapture models

Advances in Applied Probability ◽

10.1017/s0001867800022217 ◽

1984 ◽

Vol 16 (1) ◽

pp. 24-24

Author(s):

P. D. M. Macdonald

Keyword(s):

British Columbia ◽

Biological System ◽

Probabilistic Model ◽

General Model ◽

Mark Recapture ◽

Salmon Smolt

The interpretation of mark-recapture data depends on a probabilistic model for the biological system. The assumptions of the general model must be verified against what is known about the particular system. This talk considers the application of markrecapture methods to the estimation of salmon smolt migrations from Babine Lake, British Columbia.

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Maturation and Oviposition in the Japanese Mitten Crab Eriocheir japonicus (De Haan) in Relation the Their Downstream Migration

Fisheries Science ◽

10.2331/fishsci.61.766 ◽

1995 ◽

Vol 61 (5) ◽

pp. 766-775 ◽

Cited By ~ 17

Author(s):

Satoshi Kobayashi ◽

Shuhei Matsuura

Keyword(s):

Downstream Migration ◽

Mitten Crab ◽

Japanese Mitten Crab ◽

Eriocheir Japonicus

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Temporary turbine and reservoir level management to improve downstream migration of juvenile salmon through a hydropower complex

Knowledge and Management of Aquatic Ecosystems ◽

10.1051/kmae/2021004 ◽

2021 ◽

pp. 4

Author(s):

Stéphane Tétard ◽

Romain Roy ◽

Nils Teichert ◽

Jocelyn Rancon ◽

Dominique Courret

Keyword(s):

Residence Time ◽

Downstream Migration ◽

Substantial Proportion ◽

Juvenile Salmon ◽

Reservoir Level ◽

Flexible Approach ◽

Hydropower Plants ◽

Good Potential ◽

And Migration ◽

Level Lowering

Developing management rules to improve downstream migration of salmon smolts in large hydropower plants is essential to limit mortality and migration delay. A 2-year telemetry study was conducted to assess the efficiency of temporary measures to enhance the safety and speed of juvenile salmon passage through the Poutès dam (Allier River, France). 124 smolts were tracked through the reservoir and downstream of the dam, during implementation of turbine modulation and/or shutdown during night and reservoir level lowering. Level lowering significantly reduced median residence time from 3.4 days to 4.4 hours. However, even with high spill during turbine modulation, the risk of smolt being drawn toward the turbines was increased at low reservoir level due to the site's configuration, greater proximity to the surface and weak repulsive effect of the rack. Moreover, results revealed that a substantial proportion of smolts can migrate during daytime and twilight during floods, even at the beginning of the migration period. Thus targeted turbine shutdown has a good potential to protect smolts, but implementation requires studies taking account of site specificities and a flexible approach.

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Field evaluation of a visual barrier to discourage gull nesting

Pacific Conservation Biology ◽

10.1071/pc010143 ◽

2001 ◽

Vol 7 (2) ◽

pp. 143 ◽

Cited By ~ 1

Author(s):

P. A. Pochop ◽

J. L. Cummings ◽

R. M. Engeman

Keyword(s):

Columbia River ◽

Field Evaluation ◽

Management Technique ◽

Nesting Habitat ◽

Control Zone ◽

Larus Delawarensis ◽

Polypropylene Fabric ◽

Benton County ◽

Bird Management ◽

Salmon Smolt

Expanding gull populations along the Columbia River have been implicated in depredations to threatened and endangered migrating salmon smolt. We tested a visual barrier made of woven black polypropylene fabric to discourage gull nesting. The barrier was installed on Upper Nelson Island, Benton County, Washington, in parallel rows spaced 5 m apart. Gulls used 87% of the 7.9 ha island as nesting habitat and we estimated >21 000 gull nests, 80% Ring-billed Gull Larus delawarensis and 20% California Gull L. califomicus nests. The zone with fencing had 84% fewer nests than the control zone. Silt fencing showed potential as a nonlethal bird management technique.

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Eel (Anguilla spp.) fishing activity in Poso Area Central Sulawesi, Indonesia

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/869/1/012022 ◽

2021 ◽

Vol 869 (1) ◽

pp. 012022

Author(s):

L Lukman ◽

T Triyanto ◽

G S Haryani ◽

O Samir ◽

L Gogali ◽

...

Keyword(s):

Secondary Data ◽

Downstream Migration ◽

Primary Data ◽

Shallow Waters ◽

Fishing Gear ◽

Fishing Activity ◽

Central Sulawesi

Abstract Poso in Sulawesi, primarily the Lake Poso and Poso River, is known as eel (Anguilla spp.) fishing areas. Therefore, research of eel fishing is required as base information for evaluating and determining policies for its activities. The eel fishing research in the Poso area was conducted through primary data observations, secondary data traces, and interviews from April to June 2021. The fishing activities take place in the Lake Poso and Poso River shore and the rivers of the lake inlets. The fishing gear that contributed greatly to the catch was fence traps and spears. The local community’s fence trap called waya is a unique gear only found in this area, and it is installed in Poso River around the lake outlets. The gears block the rivers to catch downstream migration eels. The spear is fishing gear (including for eels) operated at night in shallow waters, especially in the outlets of Lake Poso. The eel production recorded from the Poso areas for the last four years has been 6.7–15.5 tons per year, and the highest production was in Pamona Puselemba.

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