In science news this week: Poor returns: The 2017 salmon season; Sierra Nevada Bighorn: A 21st century wildlife success story; White abalone’s cousin helps researchers recover its endangered relative; Cal Water Fix and juvenile salmon; and more …
Poor returns: The 2017 salmon season: “Every year, the Pacific Fishery Management Council (PFMC) publishes a report on the previous year’s salmon fisheries along the West Coast. The report details harvest totals and socioeconomic benefits for the California ocean fishery, and escapement totals, or the number of salmon that “escaped” the fishery and returned to the Sacramento and San Joaquin rivers. The report also provides an opportunity to compare these numbers with the preseason prediction that was used to set harvest regulations for that year. Inaccurate preseason predictions can have severe consequences: underestimating the salmon population can lead to excessively restrictive fishing regulations, while overestimating can lead to over-harvest, and fewer salmon returning to rivers. In 12 of the last 15 years, PFMC predictions have overestimated the size of the population (Figure 1), leading to higher than expected harvest rates and reduced escapement to Central Valley streams. … ” Read more from FishBio here: Poor returns: The 2017 salmon season
Sierra Nevada Bighorn: A 21st century wildlife success story: “Seven animals. Can just seven Sierra Nevada bighorn sheep really make much of an impact on the species’ future? CDFW scientists believe so, which is why they came away pleased with the results of their annual spring helicopter capture this past March. Limited to three days of work due to strong winds and bad weather, the effort resulted in the capturing, collaring and relocation of seven sheep to new herds high in the Eastern Sierra. … ” Read more from CDFW here: Sierra Nevada Bighorn: A 21st century wildlife success story
All in the Family: White Abalone’s Cousin Helps Researchers Recover its Endangered Relative: “NOAA Fisheries researchers working to recover the critically endangered white abalone need to answer one basic question: How does a healthy abalone population behave in the wild? Once so plentiful that commercial fishermen harvested them by the thousands, white abalone have virtually disappeared from the wild. Now researchers are planning to reintroduce some of the imperiled shellfish to their native California waters in the next few years, and want to give them the best odds of survival. To do that, they need to know what a healthy population looks like. NOAA Fisheries has designated white abalone a “Species in the Spotlight,” one of eight marine species nationwide at high risk of extinction. Researchers have developed a special Action Plan of concerted recovery efforts by NOAA Fisheries and its partners to pull white abalone back from the brink and revive their numbers. ... ” Read more from NOAA here: All in the Family: White Abalone’s Cousin Helps Researchers Recover its Endangered Relative
Report: Analysis of Limiting Factors Across the Life Cycle of Delta Smelt (Hypomesus transpacificus): Scott A. Hamilton, Dennis D. Murphy: Abstract: “We developed a mechanistic life-cycle model derived from the elicitation of multiple factors influencing the success of individual life-stages of the imperiled delta smelt (Hypomesus transpacificus). We discuss the relevance of limiting factors in population ecology and problems with additive models in detecting them. We identify limiting factors and assess their significance using a non-linear optimization routine, combined with traditional metrics to assess the value of covariates and model performance. After reviewing previous conceptual models and multivariate analyses, we identified a set of factors that were consistent with conceptual models and useful in explaining the erratic fluctuations in a common abundance index: food at certain times in certain locations, predation by introduced species primarily in the spring, and entrainment. The analytical approach provides a transparent and intuitive framework in which to consider the contribution of covariates and consequences for population trends, and has the potential to assist with the evaluation of proposed recovery measures.” Read the report here: Report: Analysis of Limiting Factors Across the Life Cycle of Delta Smelt (Hypomesus transpacificus)
Report: Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California: “The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft3/s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta. … ” Read abstract and download the report here: Report: Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California
Twin spacecraft launch to track Earth’s movement: “A joint U.S./German space mission to track the continuous movement of water and other changes in Earth’s mass on and beneath the planet’s surface successfully launched at 12:47 p.m. PDT (3:47 p.m. EDT) Tuesday from the California coast. The twin spacecraft of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), a joint NASA/German Research Centre for Geosciences (GFZ) mission, lifted off on a SpaceX Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California, sharing their ride into space with five Iridium NEXT communications satellites. … ” Read more from NASA here: Twin spacecraft launch to track Earth’s movement
Maven’s XKCD Comic Pick of the Week …
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About Science News and Reports: This weekly feature, posted every Thursday, is a collection of the latest scientific research and reports with a focus on relevant issues to the Delta and to California water, although other issues such as climate change are sometimes included. Do you have an item to be included here? Submissions of relevant research and other materials is welcome. Email Maven
