61 research outputs found

    Marine Survival of Puget Sound Chinook salmon-New studies on size-selective mortality and critical growth periods

    Get PDF
    Size-selective mortality (SSM) is a significant force regulating recruitment at multiple stage during the life cycle of anadromous salmon, but the early marine life stages are consistently implicated as critical periods for growth and survival which influence SSM. The life stage(s) and habitat(s) when and where SSM is imposed can vary considerably among species, stocks, and life history strategies, and the relationship between size, growth, and condition in freshwater and marine life stages to overall life cycle survival is unclear for most stocks of salmon. Starting in Spring 2014, we will initiate a field sampling program is 4 Puget Sound watersheds that methodically tracks the timing, duration, and relative abundance of juvenile Chinook salmon at hatchery release, river outmigration (smolt traps), rearing in estuarine delta (tidal channel traps) nearshore marine (beach seines) and offshore marine habitats (purse seining and midwater trawling) of Puget Sound from April through October. The timing and relative magnitude of SSM will be determined by serial sampling of size distributions over a progression of life stages using both direct measurements of body size and back-calculated estimates from scales or otoliths. Disproportionate reductions in the contribution of smaller members to subsequent life stages, especially to adult returns, can be used to determine the timing and magnitude of SSM and identify critical periods of growth and survival. We will then diagnose which factors most affect growth during critical periods through bioenergetics modeling simulations that are linked to directed sampling of diet, growth and environmental conditions. This approach could potentially improve run forecasting and focus restoration efforts

    Size-selective mortality during freshwater and marine life stages of steelhead related to freshwater growth in the Skagit River, Washington

    Get PDF
    Wild steelhead trout, Oncorhynchus mykiss, in the Puget Sound are currently in decline, and very little is known about the early life history of these threatened fish. This study evaluated consequences of early growth and survival to smolt or adult stages in different precipitation zones of the Skagit River Basin, Washington. The objectives of this study were to determine whether significant size-selective mortality (SSM) in wild steelhead could be detected between freshwater stages and returning adults; and if so, how the magnitude of SSM varied among juveniles rearing in different precipitation zones (snow and mixed rain-snow). Wild steelhead were sampled as juveniles, smolts, and adults, and scales were measured to compare back-calculated size distributions and growth rates of rearing juveniles with individuals that survived from an earlier life stage to the smolt and adult stages. Back-calculated size-at-annulus comparisons indicated that steelhead in the snow zone were significantly larger at annulus-1 than those in the mixed zone. Steelhead sampled as adults were significantly larger than those sampled as juveniles at annuli-1, -2, and -3, and larger than those sampled as smolts at annuli-2 and -3, Steelhead sampled as smolts were larger than those sampled as juveniles at annuli-1 and -2, but smolts and juveniles were the same size at annulus-3. The disparity in size-at-age-2 and -3 between steelhead sampled at earlier and later life stages suggested that fast growth during the second or third freshwater growing seasons was vitally important for survival to adulthood, and that both freshwater and marine survival could be attributed, in part, to size attained at earlier life stages in freshwater. Efforts for recovery of threatened Puget Sound steelhead could benefit by considering SSM in freshwater environments, and identifying factors that limit growth during early life stages

    Impact of pulsed direct current on embryos, larvae, and young juveniles of Atlantic cod and its implications for electrotrawling of brown shrimp

    Get PDF
    The application of electrical pulses in fishing gear is considered a promising option to increase the sustainability of demersal trawl fisheries. In the electrotrawl fishery for brown shrimp Crangon crangon, an electrical field selectively induces a startle response in the shrimp. Other benthic organisms remain mainly on the seafloor and escape underneath a hovering trawl. Previous experiments have indicated that this pulse has no short-term major harmful effects on adult fish and invertebrates. However, the impact on young marine life stages is still unknown. Because brown shrimp are caught in shallow coastal zones and estuaries, which serve as important nurseries or spawning areas for a wide range of marine species, electrotrawling on these grounds could harm embryos, larvae, and juveniles. We carried out experiments with different developmental stages of Atlantic Cod Gadus morhua, which are considered vulnerable to electrical pulses. Three embryonic stages, four larval stages, and one juvenile stage of Atlantic Cod were exposed to a homogeneous electrical field of 150 V-peak/m for 5 s, mimicking a worst-case scenario. We detected no significant differences in embryo mortality rate between control and exposed groups. However, for the embryonic stage exposed at 18 d postfertilization, the initial hatching rate was lower. Larvae that were exposed at 2 and 26 d posthatch exhibited higher mortality rates than the corresponding nonexposed control groups. In the other larval and juvenile stages, no short-term impact of exposure on survival was observed. Morphometric analysis of larvae and juveniles revealed no differences in measurements or deformations of the yolk, notochord, eye, or head. Although exposure to a worst-case electrical field did not impact survival or development for six of the eight young life stages of Atlantic Cod, the observed delayed hatching rate and decreased survival for larvae might indicate an impact of electric pulses and warrant further research

    Climate vulnerability assessment for Pacific salmon and steelhead in the California Current Large Marine Ecosystem.

    Get PDF
    Major ecological realignments are already occurring in response to climate change. To be successful, conservation strategies now need to account for geographical patterns in traits sensitive to climate change, as well as climate threats to species-level diversity. As part of an effort to provide such information, we conducted a climate vulnerability assessment that included all anadromous Pacific salmon and steelhead (Oncorhynchus spp.) population units listed under the U.S. Endangered Species Act. Using an expert-based scoring system, we ranked 20 attributes for the 28 listed units and 5 additional units. Attributes captured biological sensitivity, or the strength of linkages between each listing unit and the present climate; climate exposure, or the magnitude of projected change in local environmental conditions; and adaptive capacity, or the ability to modify phenotypes to cope with new climatic conditions. Each listing unit was then assigned one of four vulnerability categories. Units ranked most vulnerable overall were Chinook (O. tshawytscha) in the California Central Valley, coho (O. kisutch) in California and southern Oregon, sockeye (O. nerka) in the Snake River Basin, and spring-run Chinook in the interior Columbia and Willamette River Basins. We identified units with similar vulnerability profiles using a hierarchical cluster analysis. Life history characteristics, especially freshwater and estuary residence times, interplayed with gradations in exposure from south to north and from coastal to interior regions to generate landscape-level patterns within each species. Nearly all listing units faced high exposures to projected increases in stream temperature, sea surface temperature, and ocean acidification, but other aspects of exposure peaked in particular regions. Anthropogenic factors, especially migration barriers, habitat degradation, and hatchery influence, have reduced the adaptive capacity of most steelhead and salmon populations. Enhancing adaptive capacity is essential to mitigate for the increasing threat of climate change. Collectively, these results provide a framework to support recovery planning that considers climate impacts on the majority of West Coast anadromous salmonids

    Preliminary investigations into the response of O+ twaite shad (alosa fallax) to ultrasound and its potential as an entrainment deterrent

    Get PDF
    Water is abstracted from riverine, estuarine and marine environments to supply potable water, power stations, hydroelectric facilities and industry. Such abstractions inevitably carry with them the risk of fish entrainment, defined as „the drawing in of fish of any life stage at a water intake‟ (Turnpenny & O‟Keeffe, 2005). It is possible, however, that entrainment losses can be reduced to an acceptable level with the use of appropriate fish screening technologies. Fish protection solutions for water intakes are manifold and include: alterations to intake design; management of the abstraction regime; modification of existing screens to make them “fish friendly”; provision of fish return systems; and the installation of physical screens or behavioural deterrents to prevent or minimise entrainment. There are however a range of site specific constraints which influence the suitability of each solution

    A Trait‐Based Framework for Assessing the Vulnerability of Marine Species to Human Impacts

    Get PDF
    Marine species and ecosystems are widely affected by anthropogenic stressors, ranging from pollution and fishing to climate change. Comprehensive assessments of how species and ecosystems are impacted by anthropogenic stressors are critical for guiding conservation and management investments. Previous global risk or vulnerability assessments have focused on marine habitats, or on limited taxa or specific regions. However, information about the susceptibility of marine species across a range of taxa to different stressors everywhere is required to predict how marine biodiversity will respond to human pressures. We present a novel framework that uses life-history traits to assess species’ vulnerability to a stressor, which we compare across more than 44,000 species from 12 taxonomic groups (classes). Using expert elicitation and literature review, we assessed every combination of each of 42 traits and 22 anthropogenic stressors to calculate each species’ or representative species group’s sensitivity and adaptive capacity to stressors, and then used these assessments to derive their overall relative vulnerability. The stressors with the greatest potential impact were related to biomass removal (e.g., fisheries), pollution, and climate change. The taxa with the highest vulnerabilities across the range of stressors were mollusks, corals, and echinoderms, while elasmobranchs had the highest vulnerability to fishing-related stressors. Traits likely to confer vulnerability to climate change stressors were related to the presence of calcium carbonate structures, and whether a species exists across the interface of marine, terrestrial, and atmospheric realms. Traits likely to confer vulnerability to pollution stressors were related to planktonic state, organism size, and respiration. Such a replicable, broadly applicable method is useful for informing ocean conservation and management decisions at a range of scales, and the framework is amenable to further testing and improvement. Our framework for assessing the vulnerability of marine species is the first critical step toward generating cumulative human impact maps based on comprehensive assessments of species, rather than habitats

    PICES Press, Vol. 7, No. 1, January 1999

    Get PDF
    Taking stock and looking to the future - note from former PICES Chairman The state of the western North Pacific in the first half of 1998 The status of the Bering Sea in the first eight month of 1998 The state of the eastern North Pacific since February 1998 Highlights of PICES VII, review of SB activities and future workplan The second PICES Workshop on the Okhotsk Sea and ajacent area PICES-GLOBEC Climate Change and Carrying Capacity Program: A report from PICES VII Data management for the CCCC Program Report on GOOS Living Marine Resource Panel Meeting Photos from PICES VII Vjatcheslav Petrovich Shuntov GLOBEC Canada: Who we are, what we’ve been doing and where we’re headed The Ocean Carrying Capacity Research Program (OCC) at the Alaska Fisheries Science Center, Auke Bay Laboratory, Juneau, Alaska JAMSTEC research activities in the northern North Pacific People and event

    Important areas at sea for adult loggerhead sea turtles in the Mediterranean Sea: satellite tracking corroborates findings from potentially biased sources

    Get PDF
    Sea turtle populations worldwide suffer from reduced survival of immatures and adults due to fishery bycatch. Unfortunately, information about the whereabouts of turtles outside the breeding habitat is scarce in most areas, hampering the development of spatially explicit conservation plans. In the Mediterranean, recoveries of adult females flipper-tagged on nesting beaches suggest that the Adriatic Sea and Gulf of Gabès are important foraging areas for adults, but such information could be heavily biased (observing and reporting bias). In order to obtain unbiased data, we satellite-tracked seven loggerhead sea turtles after they completed nesting in the largest known Mediterranean rookery (Bay of Laganas, Zakynthos, Greece). Three females settled in the north Adriatic Sea, one in the south Adriatic Sea and two in the Gulf of Gabès area at the completion of their post-nesting migrations (one individual did not occupy a distinct foraging area). The concordance of tracking results with information from recoveries of flipper-tagged turtles suggests that the north Adriatic Sea and the Gulf of Gabès represent key areas for female adult Mediterranean loggerhead sea turtle

    PICES Press, Vol. 20, No. 2, Summer 2012

    Get PDF
    •The 2012 Inter-sessional Science Board Meeting: A Note from Science Board Chairman (pp. 1-4) ◾PICES Interns (p. 4) ◾2012 Inter-sessional Workshop on a Roadmap for FUTURE (pp. 5-8) ◾Second Symposium on “Effects of Climate Change on the World’s Oceans” (pp. 9-13) ◾2012 Yeosu Workshop on “Framework for Ocean Observing” (pp. 14-15) ◾2012 Yeosu Workshop on “Climate Change Projections” (pp. 16-17) ◾2012 Yeosu Workshop on “Coastal Blue Carbon” (pp. 18-20) ◾Polar Comparisons: Summary of 2012 Yeosu Workshop (pp. 21-23) ◾2012 Yeosu Workshop on “Climate Change and Range Shifts in the Oceans" (pp. 24-27) ◾2012 Yeosu Workshop on “Beyond Dispersion” (pp. 28-30) ◾2012 Yeosu Workshop on “Public Perception of Climate Change” (pp. 31, 50) ◾PICES Working Group 20: Accomplishments and Legacy (pp. 32-33) ◾The State of the Western North Pacific in the Second Half of 2011 (pp. 34-35) ◾Another Cold Winter in the Gulf of Alaska (pp. 36-37) ◾The Bering Sea: Current Status and Recent Events (pp. 38-40) ◾PICES/ICES 2012 Conference for Early Career Marine Scientists (pp. 41-43) ◾Completion of the PICES Seafood Safety Project – Indonesia (pp. 44-46) ◾Oceanography Improves Salmon Forecasts (p. 47) ◾2012 GEOHAB Open Science Meeting (p. 48-50) ◾Shin-ichi Ito awarded 2011 Uda Prize (p. 50

    The influence of migratory distance on Atlantic salmon Salmo salar population responses to interannual variation in sea surface temperature.

    Get PDF
    As a species, the Atlantic salmon Salmo salar is undergoing a range wide population decline. In the last 40 years alone, wild stocks have specifically declined due to continuing human pressures and global climate change. During the marine life stages, North Atlantic Sea surface temperatures (SST) have specifically impacted stocks, inducing range wide declines in abundance and morphometrics as temperature rises. Recent studies have indicated that SST’s effects on S. salar are more severe at the southernmost ranges, however we lack an explanation for why this may be the case. Acknowledging this trend, we hypothesise that while declines in returning abundance and size are explained by SST rise, the population’s response is moderated by their migration distance. Following, this thesis aims to investigate this hypothesis by examining whether the distance that S. salar migrates during their marine inhabitancy influences their population responses to changes in SST. To address this aim, this thesis includes two critical areas of research vital to the understanding of how migratory distance could influence a populations response to SST rise. 1st a literature review section comprised of two review chapters to outline SST influence on S. salar responses and possible marine migratory routes, and 2nd a quantitative analysis of the impact of migratory distance on population responses. In conclusion, the results document considerable declines and variations between populations across the southern and northern European species range
    corecore