Seventy years of diminishing biocomplexity of California Central Valley hatchery steelhead, Oncorhynchus mykiss

Canadian Journal of Fisheries and Aquatic Sciences, Journal Year: 2024, Volume and Issue: 81(4), P. 355 - 367

Published: Jan. 31, 2024

The California Central Valley steelhead ( Oncorhynchus mykiss) has declined precipitously since Euro-American colonization and been listed as threatened under the United States Endangered Species Act 1998. Hatchery-origin fish now dominate population, hatchery management is a key listing factor. However, scant release metric information available. We compiled time series of O. mykiss data for all four hatcheries releasing between 1948 2017. biocomplexity released early 1980s. Individuals have at increasingly similar numbers, biomass, body sizes, times, locations over time. Moreover, yearling larger leading to near-exclusive age-1 smolts in February March late 1990s 2000s. Pervasive reductions portfolios likely occurred other hatchery-supported Pacific salmonid stocks throughout Rim region. In an variable environment, such intraspecific diversity could significantly affect population stability resilience.

Language: Английский

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Dispersal and gene flow in anadromous salmonids: a systematic review

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Feb. 15, 2024

Abstract Dispersal is a ubiquitous ecological process that has been extensively studied in many plants and animals. Anadromous salmonids are an interesting system for examining dispersal, part because of their well-known philopatric behavior, but also the conservation challenges related to dispersal hatchery-origin fish. Building on earlier work, we provide updated systematic review gene flow anadromous salmonids. In particular, compared studies from wild hatchery origins, including providing estimates rates, observations results modelling studies. We reviewed 228 found these were unevenly distributed among species, with Atlantic salmon, Chinook sea trout being well-represented. Our showcase considerable variability estimated rates within across studies, which likely different methodologies, propensities species populations, spatial extents considered. Overall, our confirmed higher tendency fish disperse relative fish, some variation warrants further study. Moreover, propensity tended decline exponentially distance, drivers varied considerably Additionally, highlight various facets captured this suite terminology, methods metrics characterizing spatio-temporal scales Finally, revealed few considered, even fewer assessed, implications management

Language: Английский

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A Review of Factors Potentially Contributing to the Long-Term Decline of Atlantic Salmon in the Conne River, Newfoundland, Canada

Reviews in Fisheries Science & Aquaculture, Journal Year: 2024, Volume and Issue: 32(3), P. 479 - 504

Published: April 18, 2024

Species extinction and population extirpation are now widespread across aquatic ecosystems with many diadromous species, including Atlantic salmon (Salmo salar), in decline throughout much of the North Atlantic. Declines can occur simultaneously at both large small regional scales rendering factors driving decreases more elusive. On south coast Newfoundland abundance Conne River fell by 92% over a period almost four decades contrast most other populations region suggesting local may be contributing to decline. Here potentially long-term reviewed (1) examining trends survival different life stages, (2) presenting synopsis on presence absence impacting productivity this population, (3) using semi-quantitative two dimensional classification system, based expert opinion, rank decline, (4) utilizing quantitative Random Forest analysis complement opinion approach identifying possibly affecting population. Results from qualitative analyses identified associated aquaculture as possible driver Additional include influence climate change predation freshwater marine habitats. As various native range extirpation, results further highlight necessity river-specific addition monitoring fine-scale demographic threat information prioritization research necessary for conserving or restoring endangered populations.

Language: Английский

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Challenges of implementing a multi-agency monitoring and adaptive management strategy for federally threatened Chinook salmon and steelhead trout during and after dam removal in the Elwha River

Frontiers in Environmental Science, Journal Year: 2024, Volume and Issue: 12

Published: July 19, 2024

Adaptive management, a process of planning, implementing, and evaluating management strategies, is often recommended for monitoring ecological systems. However, few examples successful implementation retrospective case studies exist. We provide study adaptively managing hatchery-assisted protection recovery Chinook salmon ( Oncorhynchus tshawytscha ) winter steelhead trout O. mykiss during after the removal two large mainstem dams in Elwha River, WA. summarize key aspects adaptive plan over last decade highlight successes, challenges, complications plan’s implementation. The Monitoring Management Guidelines included trigger-based system moving through four phases that preservation, recolonization, local adaptation, viable natural population, each with differing levels hatchery production as actions. component has been very successful, providing critical data to guide actions otherwise may not have occurred and, opportunistically, provided other native species River. Implementing mixed results was at times hindered by divergent goals among project partners, inflexibility Endangered Species Act regulatory requirements implemented this project, conflicting information guidance documents. learned some metrics triggers were ill-defined or too difficult measure field. In cases, performance indicators and/or successfully modified incorporate what learned; however, we unable revise values due opinions partners. ability reach consensus on revised appeared be influenced trajectory involved. strategy resulted substantial collaboration learning, which but imperfect. Sufficient long-term funding necessary implement well-designed program could benefit from including defined leadership position shepherd facilitate multi-stakeholder program. Additionally, incorporating into legally binding conditions under feasible, requires pre-planning close coordination agencies.

Language: Английский

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Rehabilitation of whitefish fisheries in lakes Geneva and Bourget during the eutrophication period: assessing socio-economic impacts through large collaborative research

International Journal of Limnology, Journal Year: 2024, Volume and Issue: 60, P. 13 - 13

Published: Jan. 1, 2024

Lakes provide ecosystem services such as water resources, tourism, biodiversity, and fishing, therefore their management represents important societal challenges. Since the early 1960s, significant anthropogenic pressures (human population growth industrial agricultural development) have accelerated degradation of lake ecosystems, leading to eutrophication subsequent increased sedimentation on fish spawning grounds decreased dissolved oxygen concentrations. This negatively affects natural recruitment whitefish ( Coregonus lavaretus ), an emblematic species peri-alpine lakes. Over years, processes resulted in a decline stock, thereby drastic drop catch causing major economic losses. From beginning 1980s, alongside restoration quality, professional fishers, recreational anglers, state services, researchers from INRA worked together develop applied research program called ‘Pacage Lacustre’ improve optimise salmonid stocking. The goal was counterbalance low juvenile maintain populations. Here, we retrospectively retrace key stages this its main impacts society. Collaborative efforts played role rehabilitating populations lakes Geneva Bourget, particularly when abundances were lowest. Therefore, these had substantial impact preserving commercial fishery activities, addition favorable impacts, highlighting importance collaborative work.

Language: Английский

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