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Dams and reservoirs are often needed to provide environmental water and maintain suitable water temperatures for downstream ecosystems. Here, we evaluate if water allocated to the environment, with storage to manage it, might allow environmental water to more reliably meet ecosystem objectives than a proportion of natural flow. We use a priority-based water balance operations model and a reservoir temperature model to evaluate 1) pass-through of a portion of reservoir inflow versus 2) allocating a portion of storage capacity and inflow for downstream flow and stream temperature objectives. We compare trade-offs to other senior and junior priority water demands. In many months, pass-through flows exceed the volumes needed to meet environmental demands. Storage provides the ability to manage release timing to use water efficiently for environmental benefit, with a co-benefit of increasing reservoir storage to protect cold-water at depth in the reservoir. Allocating a proportion of water and storage for the environment allows water to efficiently meet environmental needs. This reduces inefficiencies caused by instream flows exceeding environmental demands. [ABSTRACT FROM AUTHOR]

Abstract: Developed countries are increasingly dependent on international trade to meet seafood requirements, which has important social, environmental, and economic implications. After becoming an independent coastal state following Brexit, the UK faces increased trade barriers and changes in seafood availability and cost. We compiled a long-term (120-year) dataset of UK seafood production (landings and aquaculture), imports, and exports, and assessed the influence of policy change and consumer preference on domestic production and consumption. In the early twentieth century, distant-water fisheries met an increasing demand for large, flaky fish such as cod and haddock that are more abundant in northerly waters. Accordingly, from 1900 to 1975, the UK fleet supplied almost 90% of these fish. However, policy changes in the mid-1970s such as the widespread establishment of Exclusive Economic Zones and the UK joining the European Union resulted in large declines in distant-water fisheries and a growing mismatch between seafood production versus consumption in the UK. While in 1975, UK landings and aquaculture accounted for 89% of seafood consumed by the British public, by 2019 this was only 40%. The combination of policy changes and staunch consumer preferences for non-local species has resulted in today's situation, where the vast majority of seafood consumed in the UK is imported, and most seafood produced domestically is exported. There are also health considerations. The UK public currently consumes 31% less seafood than is recommended by government guidelines, and even if local species were more popular, total domestic production would still be 73% below recommended levels. In the face of climate change, global overfishing and potentially restrictive trade barriers, promoting locally sourced seafood and non-seafood alternatives would be prudent to help meet national food security demands, and health and environmental targets. [ABSTRACT FROM AUTHOR]

Chemical analysis of calcified structures continues to flourish, as analytical and technological advances enable researchers to tap into trace elements and isotopes taken up in otoliths and other archival tissues at ever greater resolution. Increasingly, these tracers are applied to refine age estimation and interpretation, and to chronicle responses to environmental stressors, linking these to ecological, physiological, and life-history processes. Here, we review emerging approaches and innovative research directions in otolith chemistry, as well as in the chemistry of other archival tissues, outlining their value for fisheries and ecosystem-based management, turning the spotlight on areas where such biomarkers can support decision making. We summarise recent milestones and the challenges that lie ahead to using otoliths and archival tissues as biomarkers, grouped into seven, rapidly expanding and application-oriented research areas that apply chemical analysis in a variety of contexts, namely: (1) supporting fish age estimation; (2) evaluating environmental stress, ecophysiology and individual performance; (3) confirming seafood provenance; (4) resolving connectivity and movement pathways; (5) characterising food webs and trophic interactions; (6) reconstructing reproductive life histories; and (7) tracing stock enhancement efforts. Emerging research directions that apply hard part chemistry to combat seafood fraud, quantify past food webs, as well as to reconcile growth, movement, thermal, metabolic, stress and reproductive life-histories provide opportunities to examine how harvesting and global change impact fish health and fisheries productivity. Ultimately, improved appreciation of the many practical benefits of archival tissue chemistry to fisheries and ecosystem-based management will support their increased implementation into routine monitoring. [ABSTRACT FROM AUTHOR]

Context: Cross-boundary subsidies create important growth opportunities for a range of taxa. In modified river systems, remnant patches of floodplain and flood bypasses become ephemeral hotspots of zooplankton production, however, the extent to which these prey items are (or could be) transported downstream is unclear. Objectives: We investigated the diet of juvenile salmon under varying hydroclimatic conditions to assess the importance of floodplain-produced prey subsidies in an otherwise food-scarce region. Methods: Juvenile salmon (n = 3033) and zooplankton were sampled across the California Central Valley Sacramento-San Joaquin River Delta in 2014–2018, incorporating a range of climatic conditions including drought and flood. Salmon stomach fullness and diet composition, and ambient zooplankton densities were used to assess spatiotemporal patterns in prey production and consumption. Results: Floodplain-produced cladocerans provided ephemeral food pulses to juvenile salmon in downstream riverine habitats. Salmon had the fullest stomachs in wetter years (2016–2017) and the emptiest stomachs in the final year of a multi-year drought (2015). Cladoceran abundances in the water column and salmon diets were highest during wet periods and below floodplains, and decreased with increasing distance downstream, consistent with flow-mediated trophic subsidies. Conclusions: These data emphasize the importance of maintaining diverse, interconnected habitats to support resilient fish populations and the potential for managing floodplains to boost prey production and delivery. Here, the inundation of a flood bypass (or lack of) played a pivotal role shaping the juvenile salmon foodscape. As freshwater ecosystems are increasingly transformed by large-scale engineering, it is important to coordinate infrastructure, habitat and flow modifications to maximize climate resilience and trophic benefits to target species. [ABSTRACT FROM AUTHOR]

In the manuscript and reference list, Charapata et al 2020 should read, respectively, "Charapata et al (2022)", and "Charapata P, Oxman D, McNeel K, Keith A, Mansouri F, Trumble S (2022) Lifetime hormone profiles for a long-lived teleost: Opercula reveal novel estimates of age-specific reproductive parameters and stress trends in yelloweye rockfish ( I Sebastes ruberrimus i ). The end of the caption of Figure 3 should read: "(Charapata, Oxman, and Trumble, unpublished)". [Extracted from the article]