scholarly journals Seasonal variability of near-surface hydrography and frontal features in the northern Gulf of Alaska and Prince William Sound

2005 ◽  
Vol 32 (11) ◽  
Author(s):  
Stephen R. Okkonen
Keyword(s):  
Seasonal Variability ◽  
Gulf Of Alaska ◽  
Prince William Sound ◽  
Near Surface

scholarly journals An empirical Bayesian approach to incorporate directional movement information from a forage fish into the Arnason-Schwarz mark-recapture model

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Mary A. Bishop ◽  
Jordan W. Bernard
Keyword(s):  
Bayesian Approach ◽  
Gulf Of Alaska ◽  
Forage Fish ◽  
Pacific Herring ◽  
Prince William Sound ◽  
Modeling Framework ◽  
Empirical Bayesian ◽  
Directional Information ◽  
Directional Movement ◽  
Empirical Bayesian Approach

Abstract Background Over the past two decades, various species of forage fish have been successfully implanted with miniaturized acoustic transmitters and subsequently monitored using stationary acoustic receivers. When acoustic receivers are configured in an array, information related to fish direction can potentially be determined, depending upon the number and relative orientation of the acoustic receivers. However, it can be difficult to incorporate directional information into frequentist mark-recapture methods. Here we show how an empirical Bayesian approach can be used to develop a model that incorporates directional movement information into the Arnason-Schwarz modeling framework to describe survival and migration patterns of a Pacific herring (Clupea pallasii) population in coastal Alaska, USA. Methods We acoustic-tagged 326 adult Pacific herring during April 2017 and 2018 while on their spawning grounds in Prince William Sound Alaska, USA. To monitor their movements, stationary acoustic receivers were deployed at strategic locations throughout the Sound. Receivers located at the major entrances to the Gulf of Alaska were arranged in parallel arrays to determine the directional movements of the fish. Informative priors were used to incorporate the directional information recorded at the entrance arrays into the model. Results A seasonal migratory pattern was found at one of Prince William Sound’s major entrances to the Gulf of Alaska. At this entrance, fish tended to enter the Gulf of Alaska during spring and summer after spawning and return to Prince William Sound during the fall and winter. Fish mortality was higher during spring and summer than fall and winter in both Prince William Sound and the Gulf of Alaska. Conclusions An empirical Bayesian modeling approach can be used to extend the Arnason-Schwarz modeling framework to incorporate directional information from acoustic arrays to estimate survival and characterize the timing and direction of migratory movements of forage fish.

Relationship of water column stability to the growth, condition, and survival of pink salmon (Oncorhynchus gorbuscha) in the northern coastal Gulf of Alaska and Prince William Sound

2012 ◽  
Vol 69 (5) ◽  
pp. 955-969 ◽  
Author(s):  
Sara E. Miller ◽  
Milo Adkison ◽  
Lewis Haldorson
Keyword(s):  
Water Column ◽  
Growth Condition ◽  
Pink Salmon ◽  
Gulf Of Alaska ◽  
Oncorhynchus Gorbuscha ◽  
Biological Parameters ◽  
Prince William Sound ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Fish Condition ◽  
Water Column Stability

Water column stability has been hypothesized to affect growth and ultimately survival of juvenile fish. We estimated the relationships between stability and the growth, condition, and marine survival of several stocks of pink salmon ( Oncorhynchus gorbuscha ) within Prince William Sound (PWS), Alaska, USA, and the northern coastal Gulf of Alaska (GOA) shelf. There was a stronger correlation among the biological parameters of the fish than between the biological parameters and physical conditions. While stability and fish condition during early marine residence in PWS were important to year-class survival, stability of the water column that juveniles experienced as they migrated to the open waters of the GOA did not play a key role in determining survival to adulthood. Below-average stability just prior to capture within PWS combined with positive fish condition was related to increased year-class survival. Our results are similar to previous studies that concluded that slower and weaker development of stratification with a deeper mixed layer depth may be important for juvenile pink salmon survival in PWS.

scholarly journals On the changes in the sea surface temperature in the Benguela upwelling region. Part 1: season cycle

2019 ◽  
pp. 33-44
Author(s):  
A. B. Polonsky ◽  
A. N. Serebrennikov
Keyword(s):  
Surface Temperature ◽  
Seasonal Variability ◽  
Surface Wind ◽  
Water Layer ◽  
Hydrodynamic Characteristics ◽  
Entire Area ◽  
Near Surface ◽  
Sea Level Anomalies ◽  
Benguela Upwelling ◽  
Upwelling Index

Based on daily ocean surface temperature values for 1982–2017, near-surface wind for 1988–2017. and sea level anomalies for 1993–2017, obtained from satellite data, the seasonal variability of the hydrodynamic characteristics of the upper water layer in the vicinity of the Benguela upwelling is investigated. It is shown that the thermal upwelling index averaged over the entire area with lower temperature values does not give a correct idea on the seasonal course of the water lifting rate in the upwelling zone due to the significant horizontal advection of waters of upwelling origin. The seasonal variations of the vertical velocity of wind origin in the Benguela upwelling zone are characterized by the presence of two extremes from October to March, which is manifested in the predominance of the semiannual harmonic. At the same time, the thermal upwelling index in the zone of distribution of upwelling waters is subject to seasonal variability with an annual period.

Permafrost, tectonics, and past and future regional climate change, Yukon and adjacent Northwest Territories

1994 ◽  
Vol 31 (1) ◽  
pp. 182-191 ◽  
Author(s):  
C. R. Burn
Keyword(s):  
Northwest Territories ◽  
General Circulation ◽  
Regional Climate ◽  
Gulf Of Alaska ◽  
General Circulation Models ◽  
Yukon Territory ◽  
Early Pleistocene ◽  
Tectonic Activity ◽  
Near Surface ◽  
Late Tertiary

Late Tertiary changes in the general circulation of the atmosphere, regionally enhanced by uplift of the Wrangell – Saint: Elias and Coast mountains, were sufficient to promote permafrost development in the western Arctic. Permafrost developed in Yukon Territory and adjacent Northwest Territories during early Pleistocene glacial periods, after continued tectonic activity led to further modification of regional climate, but degraded in the interglacials. Permafrost has been present in northern parts of the region since the Illinoian glaciation, but most ground ice in central Yukon formed in the Late Wisconsinan. The present interglacial is the only one with widespread evidence of permafrost, which is maintained in the valleys of central and southern Yukon by the Saint Elias Mountains blocking continental penetration of maritime air from the Gulf of Alaska. This reduces snow depth in winter, while cold-air drainage in the dissected terrain of the Yukon Plateaus enhances the near-surface inversion, leading to continental minimum temperatures. General circulation models used to simulate climate represent the physiography of northwest Canada crudely. As a result, the simulations are unable to reproduce conditions responsible for the development and preservation of permafrost in the region.

Temporal and spatial variability of 13C/12C and 15N/14N in pelagic biota of Prince William Sound, Alaska

1999 ◽  
Vol 56 (S1) ◽  
pp. 94-117 ◽  
Author(s):  
Thomas C Kline, Jr.
Keyword(s):  
Stable Isotope ◽  
Phytoplankton Bloom ◽  
Gulf Of Alaska ◽  
Prince William Sound ◽  
Large Herbivore ◽  
Clupea Pallasi ◽  
Carbon Cycles ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Isotope Tracer

Stable isotope ratios of carbon and nitrogen were used to identify seasonal and spatial patterns in carbon and nitrogen and to determine source of energy (Prince William Sound (PWS) versus the Gulf of Alaska (GOA)) for juvenile fishes in PWS. PWS-wide samples of bulk net zooplankton (all noncalcareous zooplankton collected in 335-µm-mesh nets), individual late copepodid stage of the large herbivore Neocalanus cristatus, juvenile Pacific herring (Clupea pallasi), and juvenile walleye pollock (Theragra chalcogramma) were collected in spring, summer, and fall in 1994 and 1995. For bulk zooplankton and N. cristatus, there was a strong 13C/12C gradient but weak 15N/14N gradient within PWS and GOA. Zooplankton 15N/14N was positively correlated with 13C/12C during the phytoplankton bloom but was not correlated during the zooplankton bloom, suggesting a decoupling of nitrogen and carbon cycles. Plankton isotopic signatures suggested a diagnostic 13C/12C for GOA carbon. For juvenile fishes and diapausing copepods in PWS, 13C/12C varied between years, suggesting that the origin of carbon differed between years (GOA more so in 1995 than in 1994). Use of a natural stable isotope tracer provided evidence for biophysical coupling via inferred fluctuations in oceanographic processes.

BIOLOGICAL CONDITIONS OF SHORELINES FOLLOWING THE EXXON VALDEZ SPILL1

1993 ◽  
Vol 1993 (1) ◽  
pp. 287-292
Author(s):  
Sam W. Stoker ◽  
Jerry M. Neff ◽  
Thomas R. Schroeder ◽  
Deborah M. McCormick
Keyword(s):  
Marine Mammals ◽  
Gulf Of Alaska ◽  
Prince William Sound ◽  
Residual Oil ◽  
Exxon Valdez ◽  
Biological Communities ◽  
Upper Intertidal ◽  
Abundance And Diversity ◽  
Environmentally Sound ◽  
Almost All

ABSTRACT Following the Exxon Valdez oil spill of March 24, 1989, in Prince William Sound, Alaska, Exxon conducted a comprehensive shoreline survey program in cooperation with federal and state authorities. Objectives of surveys during the spring and summer of 1989 were to assess the distribution and magnitude of oiling, to evaluate impacts of the oil on key shoreline biological communities, and to identify ecological and archaeological resources requiring special care during the massive cleanup effort that followed. Similar shoreline surveys were performed during the springs of 1990, 1991, and 1992 on all shorelines in Prince William Sound and the Gulf of Alaska suspected of having residual oil. These subsequent surveys were conducted to provide information on the distribution and amounts of residual shoreline oil and to assess the condition of intertidal biological communities in order to make environmentally sound decisions regarding the need for additional cleanup. The following report is based primarily on survey results from Prince William Sound, where most of the heavy shoreline oiling occurred. Although not strictly quantitative, the shoreline surveys provide an unprecedented, broad base of professional observations covering the entire spill-affected area from 1989 through 1992 by which to evaluate spill impacts and recovery. Shoreline surveys documented that the extent of shoreline oiling declined substantially from 1989 to 1992. In 1989, oil was found on about 16 percent of the 3,000 miles of shoreline in Prince William Sound; by the spring of 1991, oil was found on only about 2 percent of the shoreline; and by May of 1992, on only 0.2 percent. In all years, most of this oil was located in the biologically least productive upper intertidal and supratidal zones. In both 1991 and 1992, small, isolated pockets of subsurface oil were found on some boulder/cobble beaches. Most of these deposits were also located in the upper intertidal and were usually buried beneath clean sediments. In almost all cases, the condition of intertidal biological communities improved correspondingly from 1989 to 1992. By the spring of 1991, recovery appeared to be well under way on virtually all previously oiled shores, with species composition, abundance, and diversity levels usually comparable to those of nearby shores that were not oiled in 1989. Recruitment of intertidal plants and animals was observed as early as the summer of 1989, and increasingly through 1991 and 1992. Recruitment was evident even in areas with remnant deposits of surface and subsurface oil, indicating that toxicity levels of the oil had declined substantially and that, in most cases, the residual oil no longer interfered with biological recovery. Observations of birds and marine mammals on or near shorelines surveyed during 1991 and 1992 confirmed that species present before the spill were still present and were feeding and reproducing in areas affected by oil in 1989. In most cases, observed densities were comparable to those recorded prior to the spill, and to those found in similar unaffected areas.

EVOLUTION OF A WORLD-CLASS TANKER ESCORT SYSTEM

2001 ◽  
Vol 2001 (2) ◽  
pp. 1167-1172
Author(s):  
Vincent B. Mitchell
Keyword(s):  
Oil Spill ◽  
Gulf Of Alaska ◽  
Prince William Sound ◽  
The Disabled ◽  
Oil Spill Response ◽  
Subarctic Climate ◽  
World Class ◽  
Best Available Technology ◽  
Pass Through ◽  
Available Technology

ABSTRACT The Ship Escort Response Vessel System (SERVS) of Alyeska Pipeline Service Company (Alyeska) in Valdez Alaska is responsible for overseeing the prevention, preparedness, and response activities for the safe transportation of oil through Prince William Sound. Since the inception of SERVS in 1989, escort vessels have accompanied laden tankers through Prince William Sound from the Valdez Marine Terminal to the Gulf of Alaska, a distance of approximately 70 miles. The tankers pass through the pristine Prince William Sound, which encompasses over 2,500 square miles, with fjord-like topography and a subarctic climate. The evolution of the tanker escort system began with the emergency order issued by the state of Alaska in 1989 immediately after the grounding of the Exxon Valdez. A fleet of 12 vessels, each singular in purpose, was quickly developed: three dedicated pairs of escorts (comprised of an escort response vessel and tug), response barge standby vessels, and four dedicated docking tugs. The emphasis was more on oil spill response than prevention, and there was little interchangeability between vessels and their missions. In subsequent years, a variety of factors has caused changes to the escort system and vessel mix. These included the Disabled Tanker Towing Study, Prince William Sound Risk Assessment Promulgation of Federal Escort Requirements, oil spill response responsibility in the Gulf of Alaska, tanker vapor recovery, reduction in pipeline throughput, and weather restrictions. Additionally, industry instituted voluntary measures such as ice scouts and sentinel standby escorts for inbound tankers in ballast have affected the escort system, in addition to the experience gained in the operation the system. As the escort system matured, there was a marked emphasis and focus on oil spill prevention, fleet modernization, and multipurpose vessels to increase capabilities while maximizing efficiencies. Alyeska/SERVS embarked on a dedicated strategy to upgrade the specialized vessel fleet of 12 vessels to a fleet composed of fewer multipurpose vessels. This strategy encompassed a technological and operational enhancement of the fleet, significantly improving the prevention posture while maintaining the necessary response capabilities. Today, the Alyeska/SERVS escort fleet consists of nine multipurpose vessels. The cornerstones of the escort fleet are the two 10,192 horsepower Voith Schneider enhanced tractor tugs and the three 10,192 horsepower ? drive Prevention and Response Tugs, all specifically designed, constructed, and outfitted for tanker escorting. The combination of these vessels for tanker escorting utilizes complimentary best available technology to ensure the safe transit of tankers through Prince William Sound.

Seasonal transport variations in the straits connecting Prince William Sound to the Gulf of Alaska

2013 ◽  
Vol 63 ◽  
pp. S63-S78 ◽  
Author(s):  
Mark J. Halverson ◽  
Claude Bélanger ◽  
Shelton M. Gay
Keyword(s):  
Gulf Of Alaska ◽  
Prince William Sound
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