scholarly journals Fishery collapse, recovery, and the cryptic decline of wild salmon on a major California river

2018 ◽  
Vol 75 (11) ◽  
pp. 1836-1848 ◽  
Author(s):  
Malte Willmes ◽  
James A. Hobbs ◽  
Anna M. Sturrock ◽  
Zachary Bess ◽  
Levi S. Lewis ◽  
...  
Keyword(s):  
Oncorhynchus Tshawytscha ◽  
Temporal Trends ◽  
River System ◽  
Wild Salmon ◽  
Hatchery Fish ◽  
Relative Contribution ◽  
Feather River ◽  
The Status ◽  
Fishery Collapse ◽  
Salmon Fishery

Fall-run Chinook salmon (Oncorhynchus tshawytscha) from the Sacramento–San Joaquin River system form the backbone of California’s salmon fishery and are heavily subsidized through hatchery production. Identifying temporal trends in the relative contribution of hatchery- versus wild-spawned salmon is vital for assessing the status and resiliency of wild salmon populations. Here, we reconstructed the proportion of hatchery fish on natural spawning grounds in the Feather River, a major tributary to the Sacramento River, using strontium isotope (87Sr/86Sr) ratios of otoliths collected during carcass surveys from 2002 to 2010. Our results show that prior to the 2007–2008 salmon stock collapse, 55%–67% of in-river spawners were of hatchery origin; however, hatchery contributions increased drastically (89%) in 2010 following the collapse. Data from a recent hatchery marking program corroborate our results, showing that hatchery fish continued to dominate (∼90%) in 2011–2012. Though the rebound in abundance of salmon in the Feather River suggests recovery of the stock postcollapse, our otolith chemistry data document a persistent decline of wild spawners, likely leading to the erosion of locally adapted Feather River salmon populations.

scholarly journals A comparison of infectious agents between hatchery-enhanced and wild out-migrating juvenile chinook salmon (Oncorhynchus tshawytscha) from Cowichan River, British Columbia

FACETS ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 695-721 ◽  
Author(s):  
Krishna K. Thakur ◽  
Raphaël Vanderstichel ◽  
Shaorong Li ◽  
Emilie Laurin ◽  
Strahan Tucker ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
River System ◽  
Infectious Agents ◽  
Juvenile Chinook Salmon ◽  
Hatchery Fish ◽  
Juvenile Chinook

Infectious diseases are likely contributing to large-scale declines in chinook salmon stocks in the Pacific Northwest, but the specific agents and diseases involved, and the prevalences in migratory salmon, are mostly unknown. We applied a high-throughput microfluidics platform to screen for 45 infectious agents in 556 out-migrating juvenile chinook salmon, collected from freshwater (FW) and saltwater (SW) locations in the Cowichan River system on Vancouver Island, Canada, during 2014. Nineteen agents (5 bacterial, 2 viral, and 12 parasitic) were detected, with prevalences ranging from 0.2% to 57.6%. Co-infections between Candidatus Branchiomonas cysticola Toenshoff, Kvellestad, Mitchell, Steinum, Falk, Colquhoun & Horn, 2012, Paranucleospora theridion Nylund, Nylund, Watanabe, Arnesen & Kalrsbakk, 2010, and gill chlamydia, all associated with gill disease, were observed in SW samples. We detected agents known to cause large-scale mortalities in Pacific salmon ( Ceratonova shasta (Noble, 1950), Parvicapsula minibicornis Kent, Whitaker & Dawe, 1977), and agents only recently reported in Pacific salmon in BC ( Ca. B. cysticola, P. theridion, Facilispora margolisi Jones, Prosperi-Porta & Kim, 2012 and Parvicapsula pseudobranchicola Karlsbakk, Saether, Hostlund, Fjellsoy & Nylund, 2002). Wild and hatchery fish were most divergent in agent profiles in FW, with higher agent diversity in wild fish. Differences in prevalence largely dissipated once they converged in the marine environment, although hatchery fish may be infected by a greater diversity of agents sooner after ocean entry by virtue of their more rapid migration from nearshore to offshore environments.

Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta

2014 ◽  
Vol 70 (4) ◽  
pp. 671-677 ◽  
Author(s):  
Xiaomin Ji ◽  
Youpeng Xu ◽  
Longfei Han ◽  
Liu Yang
Keyword(s):  
River Basin ◽  
River System ◽  
Yangtze River Delta ◽  
System Structure ◽  
River Channels ◽  
Stream Structure ◽  
Impervious Area ◽  
The Status ◽  
Urbanized Areas ◽  
Qinhuai River

Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.

Paternity analysis with microsatellites in a Danish Abies nordmanniana clonal seed orchard reveals dysfunctions

2006 ◽  
Vol 36 (4) ◽  
pp. 1054-1058 ◽  
Author(s):  
O K Hansen ◽  
E D Kjær
Keyword(s):  
Asymptotic Variance ◽  
Seed Orchard ◽  
Paternity Analysis ◽  
Effective Population ◽  
Population Number ◽  
Clonal Seed Orchard ◽  
Relative Contribution ◽  
Male Gametes ◽  
Abies Nordmanniana ◽  
The Status

A paternity analysis using five microsatellite markers was conducted in a Danish clonal seed orchard with 13 Abies nordmanniana (Stev.) Spach clones. The purpose was to investigate potential seed-orchard dysfunctions, with special emphasis on nonequal pollen contributions and selfing. Male paternity was found for 232 seedlings germinated from seeds collected on three ramets, each of eight clones, and the relative contribution of each clone to the gene pool of male gametes was calculated. Furthermore, 49 ramets were genotyped to check for erroneous grafting. The effect of an unbalanced male contribution was quantified by means of two measures: (1) the status number (NS), which reflects buildup of coancestry in the seed-orchard crop as a result of a low number of clones and an unequal male contribution, and (2) the asymptotic variance effective population number (Ne(v)). The contributions by pollen donors from the 13 clones were highly skewed. Three clones were fathers to more than 75% of the progenies, while making up only 24% of the ramets in the seed orchard. Four clones sired no progenies at all. The unequal contribution on the male side corresponded to NS = 4.2 and Ne(v) = 5.8. Some selfing was observed, which may give rise to concern if clonal seed orchards with few clones are established. The estimated maximum pollen contamination from outside the seed orchard was 4.3%. No grafting–labelling errors were identified.

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.

Advances in Fisheries Bioengineering

2008 ◽  
Author(s):  
Keyword(s):  
River Flow ◽  
Oncorhynchus Tshawytscha ◽  
Prolonged Exposure ◽  
Likelihood Function ◽  
Predictor Variable ◽  
Passage Time ◽  
Fish Length ◽  
River Temperature ◽  
Relative Contribution ◽  
The Face

<em>Abstract.</em>—Although many hydroelectric dams have fishways for upstream passage of migratory fish, passage delays often occur at these sites. Migrational delay may affect fish detrimentally in several ways, including depletion of energy reserves, suboptimal arrival timing at spawning sites, and prolonged exposure to hazardous conditions at the face of dams. We applied time-to-event analyses to passage times of radio-tagged adult Chinook salmon <em>Oncorhynchus tshawytscha </em>at four dams on the lower Columbia River, where many fish require several days to pass each dam. The analysis allowed us to determine instantaneous passage rates in response to fluctuating river conditions. By relating variability in passage rate to the predictor variables river temperature, river flow, and fish size, we determined the relative contribution of various factors to the passage time of migrating fish. We fit the model by maximizing the likelihood function that incorporated information from individuals rather than aggregated groups of fish. We used Akaike’s Information Criterion to distinguish among several competing models, each of which used a different predictor variable. We found that daytime passage rates were significantly greater than nighttime passage rates. Also, the influence of river flow, river temperature, and fish length on passage rates varied at the four dams. However, when a factor had a significant influence on passage time, the direction of the relationship was consistent across dams: river flow and fish length were positively related to passage time (greater values led to longer passage time), and river temperature was negatively related. This method is easily adaptable to study passage time of any fish population facing a broad range of obstacles to migration, whether natural or man-made.

Within-river straying: sex and size influence recovery location of hatchery Chinook salmon (Oncorhynchus tshawytscha)

2020 ◽  
Vol 77 (2) ◽  
pp. 226-235 ◽  
Author(s):  
Amanda M.M. Pollock ◽  
Maryam Kamran ◽  
Andrew H. Dittman ◽  
Marc A. Johnson ◽  
David L.G. Noakes
Keyword(s):  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Classification Tree ◽  
River System ◽  
Classification Tree Analysis ◽  
Spawning Grounds ◽  
Natural Origin ◽  
Elk River ◽  
In The Wild

Salmon straying is often defined as the failure of adults to return to their natal river system. However, straying within a river basin can be problematic if hatchery salmon do not return to their hatchery of origin and subsequently spawn in the wild with natural-origin salmon. We examined within-river straying patterns from 34 years of coded-wire tag data, representing 29 941 hatchery fall Chinook salmon (Oncorhynchus tshawytscha) in the Elk River, Oregon, USA. Using classification tree analysis, we found that females and larger salmon were more likely to be recovered on the spawning grounds than males and smaller fish. Females larger than 980 mm had a 51.6% likelihood of recovery on the spawning grounds rather than at the Elk River Hatchery. Our findings raise questions about the behavior of straying adults and implications for management of these stocks, with a focus on methods to reduce within-river straying. We recommend further studies to determine whether carcass recoveries are fully representative of hatchery salmon that stray within the Elk River basin.

scholarly journals The Ocean Pout, Zoarces americanus, and the Ocean Sunfish, Mola mola: Additions to the Marine Ichthyofauna of the Lower Saint John River System, New Brunswick, with a Summary of Marine Fish Reported from the Estuary

2013 ◽  
Vol 127 (1) ◽  
pp. 38 ◽  
Author(s):  
Donald F. McAlpine
Keyword(s):  
New Brunswick ◽  
River System ◽  
Marine Species ◽  
Sensu Stricto ◽  
Marine Fishes ◽  
Ocean Sunfish ◽  
System A ◽  
Mola Mola ◽  
Saint John ◽  
The Status

Recent records for the Ocean Pout, Zoarces americanus (collected 11 February 2011), and the Ocean Sunfish, Mola mola (photograph taken 24 June 2012), in the lower Saint John River system, New Brunswick, add to the list of marine fishes reported from this oceanographically unique estuary system. A total of 62 species of strictly freshwater, anadromous, catadromous, and marine fishes have now been recorded in the Saint John River system, with 49 of these in the Saint John River sensu stricto. The Acadian Redfish, Sebastes faciatus, a species assessed as threatened by the Committee on the Status of Endangered Wildlife in Canada, appears to be among these. While strictly marine fishes may contribute relatively little to the overall biomass of fishes in the Saint John River system, marine species account for 30.6% of the biodiversity of fishes in the river to date. This suggests that marine fishes may be a more significant component of the ichthyofauna of the lower Saint John River system than is generally recognized.

Research productivity in neurosurgery: trends in globalization, scientific focus, and funding

2011 ◽  
Vol 115 (6) ◽  
pp. 1262-1272 ◽  
Author(s):  
Jason S. Hauptman ◽  
Daniel S. Chow ◽  
Neil A. Martin ◽  
Michael W. Itagaki
Keyword(s):  
Case Reports ◽  
Bibliometric Study ◽  
Funding Sources ◽  
Relative Contribution ◽  
Steady Growth ◽  
Review Articles ◽  
The Us ◽  
The Status ◽  
Relative Decline ◽  
Nih Funding

Object While research is important for the survival, growth, and expansion of neurosurgery, little work has been done to quantify the status and trends of neurosurgical publications. The purpose of this bibliometric study was to quantitatively analyze trends in neurosurgical publications, including changes in worldwide productivity, study methodology, subspecialty topic, and funding. Methods This was a retrospective bibliometric study using MEDLINE to record all publications between 1996 and 2009 by first authors affiliated with neurosurgical departments. Country of origin, MEDLINE-defined methodology, study topic, and funding sources (for US articles) were recorded. Linear regression was used to derive growth rates. Results Total articles numbered 53,425 during the study period, with leading global contributors including the US with 16,943 articles (31.7%) and Japan with 10,802 articles (20.2%). Countries demonstrating rapid growth in productivity included China (121.9 ± 9.98%/year, p < 0.001), South Korea (50.5 ± 4.7%/year, p < 0.001), India (19.4 ± 1.8%/year, p < 0.001), and Turkey (25.3 ± 2.8%/year, p < 0.001). While general research articles, case reports, and review articles have shown steady growth since 1996, clinical trials and randomized controlled trials have declined to 2004 levels. The greatest overall subspecialty growth was seen in spine surgery. Regarding funding, relative contribution of National Institutes of Health (NIH)–funded publications decreased from 30.2% (290 of 959) to 22.5% (356 of 1229) between 1996 and 2009. Conclusions Neurosurgical publications demonstrate continued increases in productivity as well as in global expansion, although US contributions remain dominant. Two challenges that the neurosurgical community is facing include the preponderance of case reports and review articles and the relative decline in NIH funding for US neurosurgical publications, as productivity has outpaced government financial support.

In a warming river, natural-origin Chinook salmon spawn later but hatchery-origin conspecifics do not

2021 ◽  
Vol 78 (1) ◽  
pp. 68-77
Author(s):  
Catherine S. Austin ◽  
Timothy E. Essington ◽  
Thomas P. Quinn
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River System ◽  
Local Environment ◽  
Washington State ◽  
Human Intervention ◽  
Timing Of Reproduction ◽  
Natural Origin ◽  
Skagit River

Median timing of reproduction in salmonid populations is generally consistent among years, reflecting long-term patterns of natural selection from characteristics of the local environment. However, altered selection from factors related to climate change or human intervention might shift timing over generations, with implications for the population’s persistence. To study these processes, we modeled median timing of redd (nest) counts as an index of spawning timing by natural-origin Chinook salmon (Oncorhynchus tshawytscha) in the Skagit River system in Washington State, USA. Over the last 2–6 decades, natural-origin salmon have been spawning later by 0.03–0.52 days·year–1, while a naturally spawning group that is influenced by strays from a hatchery has been spawning earlier by 0.19 days·year–1. Trends in the spawning timing of hatchery-origin strays may reflect opposing selection from the hatchery, where egg take for propagation has become earlier by 0.58 days·year–1. As mean August river temperatures have risen over the period of record, hatchery timing trends may be moving in the opposite direction from the plastic or adaptive patterns expressed by natural-origin fish.

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