Recruitment and survival of Northeast Pacific Ocean fish stocks: temporal trends, covariation, and regime shifts

2007 ◽  
Vol 64 (6) ◽  
pp. 911-927 ◽  
Author(s):  
Franz J Mueter ◽  
Jennifer L Boldt ◽  
Bernard A Megrey ◽  
Randall M Peterman
Keyword(s):  
Bering Sea ◽  
Regime Shift ◽  
Temporal Trends ◽  
Gulf Of Alaska ◽  
Regime Shifts ◽  
Environmental Forcing ◽  
Fish Stocks ◽  
Large Marine Ecosystems ◽  
Decadal Scale ◽  
Climatic Regime

Two measures of productivity for fish stocks (recruitment and stock–recruit residuals) within two large marine ecosystems (Gulf of Alaska and eastern Bering Sea – Aleutian Islands) showed significant positive covariation within several groups of species and significant negative covariation between certain others. For example, stock–recruit residuals of gadids (Gadidae) in the Bering Sea were inversely related to those of shelf flatfishes (Pleuronectidae), suggesting that environmental forcing affects these groups in opposite ways. Salmon (Oncorhynchus spp.), Pacific herring (Clupea pallasii), and groundfish stocks each showed strong patterns of covariation within these taxonomic groups and within ecosystems, and both salmon and groundfish stocks showed positive covariation between the two ecosystems. However, we found little evidence of covariation between salmon and herring stocks or between these stocks and demersal stocks. Recruitment and stock–recruit residuals in individual stocks did not show a consistent response to known climatic regime shifts. However, combined indices of productivity across stocks showed decadal-scale variability (regime-like patterns), suggesting that both pelagic productivity (mostly salmon) and demersal productivity increased in response to the well-documented 1976–1977 climatic regime shift, whereas the 1988–1989 regime shift produced inconsistent or short-lived responses.

Application of a sequential regime shift detection method to the Bering Sea ecosystem

2005 ◽  
Vol 62 (3) ◽  
pp. 328-332 ◽  
Author(s):  
Sergei Rodionov ◽  
James E. Overland
Keyword(s):  
Bering Sea ◽  
Regime Shift ◽  
Poor Performance ◽  
Regime Shifts ◽  
Test Analysis ◽  
Eastern Bering Sea ◽  
Time Signals ◽  
Shift Detection ◽  
Changes Over Time ◽  
The Bering Sea

Abstract A common problem of existing methods for regime shift detection is their poor performance at the ends of time-series. Consequently, shifts in environmental and biological indices are usually detected long after their actual appearance. A recently introduced method based on sequential t-test analysis of regime shifts (STARS) treats all incoming data in real time, signals the possibility of a regime shift as soon as possible, then monitors how perception of the magnitude of the shift changes over time. Results of a STARS application to the eastern Bering Sea ecosystem show how the 1989 and 1998 regime shifts manifest themselves in biotic and abiotic indices in comparison with the 1977 shift.

scholarly journals Characteristics and Variability of Storm Tracks in the North Pacific, Bering Sea, and Alaska*

2010 ◽  
Vol 23 (2) ◽  
pp. 294-311 ◽  
Author(s):  
Micheld S. Mesquita ◽  
David E. Atkinson ◽  
Kevin I. Hodges
Keyword(s):  
Bering Sea ◽  
North Pacific ◽  
Temporal Trends ◽  
Storm Track ◽  
Gulf Of Alaska ◽  
Relative Vorticity ◽  
Reanalysis Data ◽  
Storm Tracks ◽  
The North ◽  
The North Pacific

Abstract The North Pacific and Bering Sea regions represent loci of cyclogenesis and storm track activity. In this paper climatological properties of extratropical storms in the North Pacific/Bering Sea are presented based upon aggregate statistics of individual storm tracks calculated by means of a feature-tracking algorithm run using NCEP–NCAR reanalysis data from 1948/49 to 2008, provided by the NOAA/Earth System Research Laboratory and the Cooperative Institute for Research in Environmental Sciences, Climate Diagnostics Center. Storm identification is based on the 850-hPa relative vorticity field (ζ) instead of the often-used mean sea level pressure; ζ is a prognostic field, a good indicator of synoptic-scale dynamics, and is directly related to the wind speed. Emphasis extends beyond winter to provide detailed consideration of all seasons. Results show that the interseasonal variability is not as large during the spring and autumn seasons. Most of the storm variables—genesis, intensity, track density—exhibited a maxima pattern that was oriented along a zonal axis. From season to season this axis underwent a north–south shift and, in some cases, a rotation to the northeast. This was determined to be a result of zonal heating variations and midtropospheric moisture patterns. Barotropic processes have an influence in shaping the downstream end of storm tracks and, together with the blocking influence of the coastal orography of northwest North America, result in high lysis concentrations, effectively making the Gulf of Alaska the “graveyard” of Pacific storms. Summer storms tended to be longest in duration. Temporal trends tended to be weak over the study area. SST did not emerge as a major cyclogenesis control in the Gulf of Alaska.

scholarly journals A palaeolimnological perspective to understand regime-shift dynamics in two Yangtze-basin lakes

2019 ◽  
Vol 15 (11) ◽  
pp. 20190447 ◽  
Author(s):  
Min Xu ◽  
Rong Wang ◽  
Xuhui Dong ◽  
Xiangdong Yang
Keyword(s):  
Regime Shift ◽  
Nutrient Loading ◽  
Stable State ◽  
Regime Shifts ◽  
Alternative Stable State ◽  
Human Disturbances ◽  
Environmental Forcing ◽  
Ecological Threshold ◽  
Yangtze Basin ◽  
Shift Dynamics

Natural and human disturbances have caused widespread regime shifts in shallow lakes of the lower Yangtze basin (LYB, China) resulting in a severe decline of ecosystem services. Improved understanding of the relationship between environmental forcing and ecosystem response, and the mechanisms behind regime shifts has significant implications for management. However, the patterns of these regime shifts and the underlying internal mechanisms are less known. In this study, two typical lakes (Chaohu and Zhangdu) from the LYB were selected to determine the trajectories of ecological regime shifts, both of which transitioned from vegetation- to plankton-dominated states several decades ago. Ecological trajectories since the 1900s in both lakes were reconstructed using palaeolimnological proxies, mainly diatom assemblages. Although results show that regime shifts occurred in both lakes in the 1970s and the 1950s, respectively, their inherent mechanisms were different. In Lake Zhangdu, altered hydrological conditions pushed the ecosystem across an ecological threshold, providing an example of a driver-mediated regime shift. In Lake Chaohu, ongoing nutrient loading influenced ecosystem processes and drove the lake to an alternative stable state, potentially presenting an example of a critical transition after a loss of resilience. This research indicates that palaeolimnological perspectives can provide insights into regime shift changes, as well as important information regarding which restoration methods should be tailored to individual lakes.

scholarly journals Climate regime shifts and community reorganization in the Gulf of Alaska: how do recent shifts compare with 1976/1977?

2006 ◽  
Vol 63 (8) ◽  
pp. 1386-1396 ◽  
Author(s):  
Michael A. Litzow
Keyword(s):  
Regime Shift ◽  
Rapid Change ◽  
Gulf Of Alaska ◽  
Regime Shifts ◽  
The Arctic ◽  
Climate Regime ◽  
Local Climate ◽  
The North ◽  
Spatial Reorganization ◽  
Catch Composition

Abstract Climate regime shifts have recently occurred in the North Pacific (1998–1999) and the Arctic (2000), but the nature of biological reaction to these events is poorly understood. An index of local climate (1960–2005), and data from commercial fishery catches (1960–2004) and from small-mesh trawl surveys (1972–2005) are used to assess the impacts of these climate events in the Subarctic Gulf of Alaska. Non-linear regression showed that survey catch composition strongly responded to local climate at lags of 2 and 4 years, providing evidence of rapid ecological response to climate change in the system. A sequential regime shift detection method identified rapid change in local climate, and in survey and commercial catches following the well-documented regime shift to a positive state of the Pacific Decadal Oscillation (PDO) in 1976/1977. However, the analysis failed to detect the 1998/1999 regime shift in local climate, or in survey or commercial catches. This result is consistent with the view that the 1998/1999 climate regime shift did not represent a reversion to a negative PDO state. Local temperature increased and local sea level pressure decreased in the Gulf of Alaska during the years 2001–2005, consistent with anthropogenic warming and recent spatial reorganization in Arctic climate. There was no evidence of community reorganization following this climate event. Further observation will be required to evaluate the persistence of this new climate pattern, and the nature of community reaction to it.

scholarly journals Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska

2013 ◽  
Vol 70 (6) ◽  
pp. 1220-1232 ◽  
Author(s):  
Megan J. Peterson ◽  
Franz Mueter ◽  
Dana Hanselman ◽  
Chris Lunsford ◽  
Craig Matkin ◽  
...  
Keyword(s):  
Bering Sea ◽  
Killer Whale ◽  
Temporal Trends ◽  
Gulf Of Alaska ◽  
Orcinus Orca ◽  
Future Research ◽  
Fish Stock ◽  
Anoplopoma Fimbria ◽  
Catch Rates ◽  
Longline Fisheries

Abstract Peterson, M. J., Mueter, F., Hanselman, D., Lunsford, C., Matkin, C., and Fearnbach, H. 2013. Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska. – ICES Journal of Marine Science, 70: 1220–1232. Killer whale (Orcinus orca) depredation occurs when whales damage or remove fish caught on longline gear. This study uses National Marine Fisheries Service longline survey data from 1998–2011 to explore spatial and temporal trends in killer whale depredation and to quantify the effect of killer whale depredation on catches of six groundfish species within three management areas in Alaska: the Bering Sea, Aleutian Islands and Western Gulf of Alaska. When killer whales were present during survey gear retrieval, whales removed an estimated 54–72% of sablefish (Anoplopoma fimbria), 41–84% of arrowtooth flounder (Atheresthes stomias) and 73% (Bering Sea only) of Greenland turbot (Reinhardtius hippoglossoides). Effects on Pacific halibut (Hippoglossus stenolepis) and Pacific cod (Gadus macrocephalus) were significant in the Western Gulf only with 51% and 46% reductions, respectively. Overall catches (depredated and non-depredated sets) for all groundfish species significantly impacted by killer whale depredation were lower by 9–28% (p < 0.05). Effects on shortspine thornyhead (Sebastolobus alascanus) catches were not significant in any management area (p > 0.05). These results provide insight into the potential impacts of killer whale depredation on fish stock abundance indices and commercially important fisheries in Alaska and will inform future research on apex predator–fisheries interactions.

scholarly journals Laminated sediments in the Bering Sea reveal atmospheric teleconnections to Greenland climate on millennial to decadal timescales during the last deglaciation

2014 ◽  
Vol 10 (6) ◽  
pp. 2215-2236 ◽  
Author(s):  
H. Kuehn ◽  
L. Lembke-Jene ◽  
R. Gersonde ◽  
O. Esper ◽  
F. Lamy ◽  
...  
Keyword(s):  
Bering Sea ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Gulf Of Alaska ◽  
Laminated Sediments ◽  
Last Deglaciation ◽  
Export Production ◽  
Decadal Scale ◽  
The Last Deglaciation ◽  
The Bering Sea

Abstract. During the last glacial termination, the upper North Pacific Ocean underwent dramatic and rapid changes in oxygenation that lead to the transient intensification of oxygen minimum zones (OMZs), recorded by the widespread occurrence of laminated sediments on circum-Pacific continental margins. We present a new laminated sediment record from the mid-depth (1100 m) northern Bering Sea margin that provides insight into these deglacial OMZ maxima with exceptional, decadal-scale detail. Combined ultrahigh-resolution micro-X-ray-fluorescence (micro-XRF) data and sediment facies analysis of laminae reveal an alternation between predominantly terrigenous and diatom-dominated opal sedimentation. The diatomaceous laminae are interpreted to represent spring/summer productivity events related to the retreating sea ice margin. We identified five laminated sections in the deglacial part of our site. Lamina counts were carried out on these sections and correlated with the Bølling–Allerød and Preboreal phases in the North Greenland Ice Core (NGRIP) oxygen isotope record, indicating an annual deposition of individual lamina couplets (varves). The observed rapid decadal intensifications of anoxia, in particular within the Bølling–Allerød, are tightly coupled to short-term warm events through increases in regional export production. This dependence of laminae formation on warmer temperatures is underlined by a correlation with published Bering Sea sea surface temperature records and δ18O data of planktic foraminifera from the Gulf of Alaska. The rapidity of the observed changes strongly implies a close atmospheric teleconnection between North Pacific and North Atlantic regions. We suggest that concomitant increases in export production and subsequent remineralization of organic matter in the Bering Sea, in combination with oxygen-poor waters entering the Being Sea, drove down oxygen concentrations to values below 0.1 mL L−1 and caused laminae preservation. Calculated benthic–planktic ventilation ages show no significant variations throughout the last deglaciation, indicating that changes in formation rates or differing sources of North Pacific mid-depth waters are not prime candidates for strengthening the OMZ at our site. The age models established by our correlation procedure allow for the determination of calendar age control points for the Bølling–Allerød and the Preboreal that are independent of the initial radiocarbon-based chronology. Resulting surface reservoir ages range within 730–990 yr during the Bølling–Allerød, 800–1100 yr in the Younger Dryas, and 765–775 yr for the Preboreal.

scholarly journals Marine regime shifts in ocean biogeochemical models: a case study in the Gulf of Alaska

2015 ◽  
Vol 12 (16) ◽  
pp. 14003-14048 ◽  
Author(s):  
C. Beaulieu ◽  
H. Cole ◽  
S. Henson ◽  
A. Yool ◽  
T. R. Anderson ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Regime Shift ◽  
Mixed Layer Depth ◽  
Gulf Of Alaska ◽  
Regime Shifts ◽  
Sea Surface ◽  
Abrupt Increase ◽  
Layer Depth ◽  
Biogeochemical Models

Abstract. Regime shifts have been reported in many marine ecosystems, and are often expressed as an abrupt change occurring in multiple physical and biological components of the system. In the Gulf of Alaska, a regime shift in the late 1970s was observed, indicated by an abrupt increase in sea surface temperature and major shifts in the catch of many fish species. This late 1970s regime shift in the Gulf of Alaska was followed by another shift in the late 1980s, not as pervasive as the 1977 shift, but which nevertheless did not return to the prior state. A thorough understanding of the extent and mechanisms leading to such regime shifts is challenged by data paucity in time and space. We investigate the ability of a suite of ocean biogeochemistry models of varying complexity to simulate regime shifts in the Gulf of Alaska by examining the presence of abrupt changes in time series of physical variables (sea surface temperature and mixed layer depth), nutrients and biological variables (chlorophyll, primary productivity and plankton biomass) using change-point analysis. Our study demonstrates that ocean biogeochemical models are capable of simulating the late 1970s shift, indicating an abrupt increase in sea surface temperature forcing followed by an abrupt decrease in nutrients and biological productivity. This predicted shift is consistent among all the models, although some of them exhibit an abrupt transition (i.e. a significant shift from one year to the next), whereas others simulate a smoother transition. Some models further suggest that the late 1980s shift was constrained by changes in mixed layer depth. Our study demonstrates that ocean biogeochemical can successfully simulate regime shifts in the Gulf of Alaska region, thereby providing better understanding of how changes in physical conditions are propagated from lower to upper trophic levels through bottom-up controls.

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