Piscine predation on juvenile salmon in sub‐arctic Alaskan rivers: Associations with season, habitat, predator size and streamflow

2021 ◽  
Author(s):  
Erik R. Schoen ◽  
Kristen W. Sellmer ◽  
Mark S. Wipfli ◽  
Juan A. López ◽  
Renae Ivanoff ◽  
...  
Keyword(s):  
Juvenile Salmon ◽  
Predator Size

A Sigmoid Model to Predict Gastric Evacuation Rates of Smallmouth Bass (Micropterus dolomieui) Fed Juvenile Salmon

1991 ◽  
Vol 48 (5) ◽  
pp. 933-937 ◽  
Author(s):  
Jean Beyer Rogers ◽  
Craig C. Burley
Keyword(s):  
Water Temperature ◽  
Laboratory Experiments ◽  
Prey Size ◽  
Stomach Contents ◽  
Smallmouth Bass ◽  
Juvenile Salmon ◽  
Gastric Evacuation ◽  
Predator Size ◽  
Micropterus Dolomieui ◽  
Increasing Temperature

Laboratory experiments were conducted to examine the effects of water temperature, predator size, prey size, and prey number on gastric evacuation of smallmouth bass (Micropterus dolomieui) fed juvenile salmon. The smallmouth bass were allowed to feed voluntarily after 24–48 h of starvation and stomachs were pumped at intervals of 1–4 h until 90% of the stomach contents were evacuated (E90). Evacuation approximated an S-shaped curve over time, and a sigmoid model was developed to predict evacuation at varying water temperatures, total meal weights, predator sizes, and prey number. The rate of evacuation increased with increasing water temperature, meal weight, or predator size. The E90 increased with larger meal weights but decreased with increasing temperature or predator size. E90 ranged between 4 and 95 h, depending upon conditions. E90 was slower than those estimated previously for another predator of salmon, the stomachless northern squawfish (Ptychocheilus oregonensis).

A Climate-Mediated Shift in the Estuarine Habitat Mosaic Limits Prey Availability and Reduces Nursery Quality for Juvenile Salmon

2021 ◽  
Author(s):  
Melanie J. Davis ◽  
Isa Woo ◽  
Christopher S. Ellings ◽  
Sayre Hodgson ◽  
David A. Beauchamp ◽  
...  
Keyword(s):  
Prey Availability ◽  
Juvenile Salmon ◽  
Estuarine Habitat ◽  
Habitat Mosaic ◽  
Nursery Quality

Reconstructing habitat use by juvenile salmon sharks links upwelling to strandings in the California Current

2015 ◽  
Vol 525 ◽  
pp. 217-228 ◽  
Author(s):  
AB Carlisle ◽  
SY Litvin ◽  
EL Hazen ◽  
DJ Madigan ◽  
KJ Goldman ◽  
...  
Keyword(s):  
Habitat Use ◽  
California Current ◽  
Juvenile Salmon

Kidney Disease in Juvenile Atlantic Salmon (Salmo salar) in the Margaree River

1969 ◽  
Vol 26 (9) ◽  
pp. 2535-2537 ◽  
Author(s):  
J. H. C. Pippy
Keyword(s):  
Kidney Disease ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
River System ◽  
Juvenile Salmon ◽  
Wild Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
Bacterial Kidney Disease ◽  
Juvenile Atlantic Salmon

Bacterial kidney disease was presumptively identified in each of 25 hatchery-reared juvenile salmon (Salmo salar) but in only 2 of 235 wild juveniles in the Margaree River system. Apparently spread of disease from the hatchery to wild salmon in the river is very gradual.

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

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.

scholarly journals Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2403 ◽  
Author(s):  
Rachel L. Malison ◽  
Kirill V. Kuzishchin ◽  
Jack A. Stanford
Keyword(s):  
Fish Assemblages ◽  
Coho Salmon ◽  
Fish Passage ◽  
Main Channel ◽  
Habitat Connectivity ◽  
Juvenile Salmon ◽  
Negative Consequences ◽  
Alluvial Rivers ◽  
Beaver Ponds ◽  
Beaver Dams

Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3–12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99–1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically could produce 2× the biomass (between June–August, 1,174 vs. 667 kg) and rear 3× the number of salmon (370,000 vs. 140,000) compared to the existing condition with dams present. The highly productive Kol river produces an order of magnitude more salmon biomass and rears 40× the individuals compared to the Kwethluk. If beavers were introduced to the Kol River, we estimate that off-channel habitats would produce half as much biomass (2,705 vs. 5,404 kg) and 3× fewer individuals (1,482,346 vs. 4,856,956) owing to conversion of inter-connected, productive springbrooks into inaccessible pond complexes. We concluded that beaver dams may limit the total amount of floodplain habitat available for salmon rearing in the Kwethluk river and that the introduction of beavers to the Kol river could be detrimental to salmon populations. The introduction of beavers to other large alluvial rivers like those found in Kamchatka could have negative consequences for salmon production.

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