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  • 1
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 72, No. 10 ( 2015-10), p. 1552-1564
    Abstract: Pathways linking climate to population dynamics of higher-trophic-level fish species such as Pacific salmon often involve a hierarchy in which regional-scale physical and biological processes mediate the effects of large-scale climate variability. We used probabilistic networks to investigate 17 potential ecological pathways linking climate to Oregon coho salmon (Oncorhynchus kisutch) recruitment. We found that pathways originating with the Pacific Decadal Oscillation were the most influential on recruitment, with the net effect being two to four times greater than for pathways originating with the North Pacific Gyre Oscillation or the Oceanic Niño Index. Among all environmental variables, sea surface temperature and an index of juvenile salmon prey biomass had the greatest effects on recruitment, with a 76% chance of recruitment being equal to or below average given that ocean temperatures were above average and a 34% chance of recruitment being below average given that prey biomass was above average. Our results provide evidence that shifts in climate patterns could strongly influence recruitment simultaneously through multiple ecological pathways and highlight the importance of quantifying cumulative effects of these pathways on higher-trophic-level species.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2015
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    detail.hit.zdb_id: 1473089-3
    SSG: 21,3
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2017
    In:  Fisheries Oceanography Vol. 26, No. 3 ( 2017-05), p. 268-281
    In: Fisheries Oceanography, Wiley, Vol. 26, No. 3 ( 2017-05), p. 268-281
    Abstract: Horizontal ocean transport can influence the dynamics of higher‐trophic‐level species in coastal ecosystems by altering either physical oceanographic conditions or the advection of food resources into coastal areas. In this study, we investigated whether variability in two North Pacific Current (NPC) indices was associated with changes in productivity of North American Pacific salmon stocks. Specifically, we used Bayesian hierarchical models to estimate the effects of the north‐south location of the NPC bifurcation (BI) and the NPC strength, indexed by the North Pacific Gyre Oscillation (NPGO), on the productivity of 163 pink, chum, and sockeye salmon stocks. We found that for salmon stocks located in Washington (WA) and British Columbia (BC), both the BI and NPGO had significant positive effects on productivity, indicating that a northward‐shifted bifurcation and a stronger NPC are associated with increased salmon productivity. For the WA and BC regions, the estimated NPGO effect was over two times larger than the BI effect for pink and chum salmon, whereas for sockeye salmon the BI effect was 2.4 times higher than the NPGO. In contrast to WA and BC stocks, we found weak effects of both horizontal ocean transport processes on the productivity of salmon stocks in Alaska. Our results indicated that horizontal transport pathways might strongly influence population dynamics of Pacific salmon in the southern part of their North American ranges, but not the northern part, suggesting that different environmental pathways may underlie changes in salmon productivity in northern and southern areas for the species under consideration.
    Type of Medium: Online Resource
    ISSN: 1054-6006 , 1365-2419
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1214985-8
    detail.hit.zdb_id: 2020300-7
    SSG: 21,3
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Canadian Science Publishing ; 2015
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 72, No. 5 ( 2015-05), p. 697-708
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 72, No. 5 ( 2015-05), p. 697-708
    Abstract: We investigated spatial and temporal components of phytoplankton dynamics in the Northeast Pacific Ocean to better understand the mechanisms linking biological oceanographic conditions to productivity of 27 pink salmon (Oncorhynchus gorbuscha) stocks. Specifically, we used spatial covariance functions in combination with multistock spawner–recruit analyses to model relationships among satellite-derived chlorophyll a concentrations, initiation date of the spring phytoplankton bloom, and salmon productivity. For all variables, positive spatial covariation was strongest at the regional scale (0–800 km) with no covariation beyond 1500 km. Spring bloom timing was significantly correlated with salmon productivity for both northern (Alaska) and southern (British Columbia) populations, although the correlations were opposite in sign. An early spring bloom was associated with higher productivity for northern populations and lower productivity for southern populations. Furthermore, the spring bloom initiation date was always a better predictor of salmon productivity than mean chlorophyll a concentration. Our results suggest that changes in spring bloom timing resulting from natural climate variability or anthropogenic climate change could potentially cause latitudinal shifts in salmon productivity.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2015
    detail.hit.zdb_id: 7966-2
    detail.hit.zdb_id: 1473089-3
    SSG: 21,3
    SSG: 12
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Canadian Science Publishing ; 2011
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 68, No. 5 ( 2011-05), p. 880-897
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 68, No. 5 ( 2011-05), p. 880-897
    Abstract: Conservation objectives aimed at maintaining the diversity of Pacific salmon ( Oncorhynchus spp.) are often expressed as a desire to ensure that spawner abundance is spread out over a number of spawning sites. However, sampling is not usually possible at all sites or in all years. For such incomplete data sets, rotating panel sampling designs and hierarchical estimation models have been suggested as ways to improve monitoring performance. To evaluate the potential benefits of using these approaches to assess the conservation status of coho salmon ( O. kisutch ), we developed a simulation procedure that modelled spatial and temporal variation in salmon abundance at multiple sites within a region. Results show that both approaches were largely unsuccessful at reducing classification errors for conservation status. Furthermore, indicators describing distributions of abundance levels and temporal trends in abundance within a region were more sensitive to missing data than to observation error variance on annual abundance estimates. Thus, sampling effort might be better spent reducing the level of missing data within a regional data set, as opposed to obtaining more precise estimates for only a few site–year combinations. Our results also show that the best monitoring plans for regions depend on monitoring objectives as well as the relative magnitudes of spatial and temporal variability.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2011
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    detail.hit.zdb_id: 1473089-3
    SSG: 21,3
    SSG: 12
    Location Call Number Limitation Availability
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