Bishop M.A.,Prince William Sound Science Center |
Reynolds B.F.,Prince William Sound Science Center |
Powers S.P.,Dauphin Island Sea Laboratory
PLoS ONE | Year: 2010
As modern fishery assessments change in an effort to be more accurate and encompass the range of potential ecosystem interactions, critical information on the ecology of species including life history, intra and inter-specific competitive interactions and habitat requirements must be added to the standard fishery-dependent and independent data sets. One species whose movements and habitat associations greatly affects exploitation patterns is lingcod, Ophiodon elongatus, which support an economically important fishery along the coastal waters of the Pacific Coast of North America. High site fidelity and limited movements within nearshore areas are hypothesized to have resulted in high catchability, a major factor that has contributed to overfished stocks. Thus, assessing the level of movement and connectivity among lingcod subpopulations inhabiting nearshore habitats is a prerequisite to determining the condition of lingcod stocks. We used the Pacific Ocean Shelf Tracking (POST) Project acoustic receiver array in Alaska's Prince William Sound to monitor movements and residency of 21 acoustic-tagged lingcod for up to 16 months. Eight of sixteen lingcod (50%) initially aged at 2.5- to 3.5- years-old dispersed from their tag site. Dispersal was highly seasonal, occurring in two, five-week periods from mid- December through January and from mid-April through May. Dispersal in winter may be related to sexually immature lingcod or newly-mature male lingcod being displaced by territorial males. Spring dispersal may be indicative of the onset of migratory behavior where lingcod move out into Prince William Sound and possibly the offshore waters of the Gulf of Alaska. Our results reveal a pattern of ontogenetic dispersal as lingcod approach 4-years-old and exceed 50 cm total length. The large proportion of tagged fish migrating out of Port Gravina, their tagging site, reflects a high level of connectivity among Prince William Sound subpopulations. Our results also support the hypotheses that these subpopulations may be highly susceptible to overfishing because most fish show long residence times. © 2010 Bishop et al.
Kline T.C.,Prince William Sound Science Center
Progress in Oceanography | Year: 2010
Northern lampfish (NLF), Stenobrachius leucopsarus (Myctophidae), the dominant pelagic fish taxon of the subarctic North Pacific Ocean, were sampled opportunistically in MOCNESS tows made on continental slope waters of the Gulf of Alaska (GOA) as well as in deep areas of Prince William Sound (PWS) during 1997-2006. The overall mean whole-body lipid-corrected stable carbon isotope value of NLF from the GOA was -21.4 (SD = 0.7) whereas that from PWS was -19.5 (SD = 0.9). This pattern is similar to that observed for late feeding stage Neocalanus cristatus copepods thus confirming a mean cross-shelf carbon stable isotope gradient. As well, there was a statistically significant positive correlation between the considerable temporal variation in the monthly mean carbon stable isotope composition of GOA Neocalanus and GOA NLF (r=0.69, P<0.001). In contrast, NLF nitrogen stable isotope values were bi-modal with most data fitting the upper mode value of ~+11.5. NLF nitrogen stable isotope values are a better indicator of trophic level or food chain length whereas carbon stable isotopes reflect organic carbon production. The carbon stable isotope values of NLF, measured in May, were positively correlated to marine survival rate of PWS hatchery salmon cohorts entering the marine environment the same year (r=0.84, P<0.001). The carbon stable isotope values for Neocalanus in May were also positively correlated to salmon marine survival (r=0.82, P<0.001). Processes thus manifested through the carbon stable isotope value of biota from the continental slope more closely predicted marine survival rate than that of the salmon themselves. The incipient relationships suggested by the correlations are consistent with the hypothesis that exchange between coastal and oceanic waters in the study area is driven by meso-scale eddies. These eddies facilitate the occurrence of slope phytoplankton blooms as well as drive oceanic zooplankton subsidies into coastal waters. The strong as well as more significant correlations of salmon marine survival rate to NLF as well as slope Neocalanus carbon stable isotope values point to processes taking place at the slope (i.e., interactions driven by meso-scale eddies when at the edge of the shelf) as being the driving force to inter-annual variability in the coastal Gulf of Alaska study area. © 2010 Elsevier Ltd.
Reynolds B.F.,Dauphin Island Sea Laboratory |
Reynolds B.F.,Prince William Sound Science Center |
Powers S.P.,Dauphin Island Sea Laboratory |
Bishop M.A.,Dauphin Island Sea Laboratory
PLoS ONE | Year: 2010
Loss and/or degradation of nearshore habitats have led to increased efforts to restore or enhance many of these habitats, particularly those that are deemed essential for marine fishes. Copper rockfish (Sebastes caurinus) and lingcod (Ophiodon enlongatus) are dominant members of the typical reef fish community that inhabit rocky and high-relief substrates along the Pacific Northwest. We used acoustic telemetry to document their residency and movements in the nearshore waters of Prince William Sound, Alaska in order to assess use of created reef habitat in an individual-based manner. A total of 57 fish were surgically implanted with acoustic transmitters. Forty-five fish were captured and monitored in three habitats: artificial reef, low-relief natural reef, and patchy high-relief natural reef. Within each habitat, both rockfish and lingcod exhibited long periods of residency with limited movements. Twelve rockfish were captured at the natural reefs and displaced a distance of 4.0 km to the artificial reef. Five of the 12 rockfish returned within 10 d of their release to their initial capture site. Another five of the 12 displaced fish established residency at the artificial reef through the duration of our study. Our results suggest the potential for artificial reefs to provide rockfish habitat in the event of disturbances to natural habitat. © 2010 Reynolds et al.
Wille M.,Memorial University of Newfoundland |
Robertson G.J.,Environment Canada |
Whitney H.,Natural Resources Canada |
Bishop M.A.,Prince William Sound Science Center |
And 2 more authors.
PLoS ONE | Year: 2011
Due to limited interaction of migratory birds between Eurasia and America, two independent avian influenza virus (AIV) gene pools have evolved. There is evidence of low frequency reassortment between these regions, which has major implications in global AIV dynamics. Indeed, all currently circulating lineages of the PB1 and PA segments in North America are of Eurasian origin. Large-scale analyses of intercontinental reassortment have shown that viruses isolated from Charadriiformes (gulls, terns, and shorebirds) are the major contributor of these outsider events. To clarify the role of gulls in AIV dynamics, specifically in movement of genes between geographic regions, we have sequenced six gull AIV isolated in Alaska and analyzed these along with 142 other available gull virus sequences. Basic investigations of host species and the locations and times of isolation reveal biases in the available sequence information. Despite these biases, our analyses reveal a high frequency of geographic reassortment in gull viruses isolated in America. This intercontinental gene mixing is not found in the viruses isolated from gulls in Eurasia. This study demonstrates that gulls are important as vectors for geographically reassorted viruses, particularly in America, and that more surveillance effort should be placed on this group of birds. © 2011 Wille et al.
Schroth A.W.,University of Vermont |
Crusius J.,University of Washington |
Hoyer I.,Woods Hole Coastal and Marine Science Center |
Campbell R.,Prince William Sound Science Center
Geophysical Research Letters | Year: 2014
While recent work demonstrates that glacial meltwater provides a substantial and relatively labile flux of the micronutrient iron to oceans, the role of high-latitude estuary environments as a potential sink of glacial iron is unknown. Here we present the first quantitative description of iron removal in a meltwater-dominated estuary. We find that 85% of "dissolved" Fe is removed in the low-salinity region of the estuary along with 41% of "total dissolvable" iron associated with glacial flour. We couple these findings with hydrologic and geochemical data from Gulf of Alaska (GoA) glacierized catchments to calculate meltwater-derived fluxes of size and species partitioned Fe to the GoA. Iron flux data indicate that labile iron in the glacial flour and associated Fe minerals dominate the meltwater contribution to the Fe budget of the GoA. As such, GoA nutrient cycles and related ecosystems could be strongly influenced by continued ice loss in its watershed. © 2014. American Geophysical Union. All Rights Reserved.
Halverson M.J.,Prince William Sound Science Center
Dynamics of Atmospheres and Oceans | Year: 2014
Current meter data from a series of oceanographic moorings spanning a total of five years was analyzed to quantify the tidal and subtidal exchange of water between Prince William Sound and the adjacent continental shelf in the northern Gulf of Alaska. Velocity profiles were used to quantify the exchange in terms of a transport through each of the two largest passages: Montague Strait and Hinchinbrook Entrance. Buoy wind and atmospheric pressure observations, as well as bottom pressure records, are then used to elucidate the role of atmospheric forcing on the exchange.An EOF analysis shows that the barotropic component accounts for 62% or more of the variance in the velocity profiles even after tides are removed by low-pass filtering, and thus the analysis is concerned primarily with depth-integrated transport. The estimated depth-integrated transport can reach ±0.6. Sv in Montague Strait, and ±1.5. Sv in Hinchinbrook Entrance. The largest fluctuations occur in response to the semidiurnal tides. Transport variations on subtidal time scales, which can reach -0.2. Sv in Montague Strait, and +0.6. Sv in Hinchinbrook Entrance, are shown by a frequency domain analysis to be dominated by easterly wind stress events which occur at periods of 2-5 days in both summer and winter. Atmospheric pressure has much less impact on transport, but there is some evidence that it might play a small role on time scales of a few weeks.Bottom pressure records suggest that easterly wind events set up a sea level height gradient in Hinchinbrook Entrance such that it tilts up to the east, which under geostrophy drives a barotropic flow into Prince William Sound. The same winds also raise the sea level in Hinchinbrook Entrance relative to Montague Strait, encouraging an outflow there in agreement with the ADCP observations. There is no evidence that the wind drives a vertically sheared bi-directional flow in either entrance, as has been observed in some estuaries. It is hypothesized that the lack of such a flow is possible because Prince William Sound has two major connections to the shelf, which alters the mass conservation requirement for each passage when compared to a system with just one entrance. © 2013 Elsevier B.V.
Crawford R.E.,Prince William Sound Science Center |
Vagle S.,Canadian Department of Fisheries and Oceans |
Carmack E.C.,Canadian Department of Fisheries and Oceans
Polar Biology | Year: 2012
Relatively little is known about the distribution of fish in deep water (<200 m) in the Beaufort Sea. Data collected by an Acoustic Doppler Current Profiler operated in the Chukchi and Beaufort seas in summer were examined for evidence of fish biomass detections between 18 and 400 m. The presence of fish in waters between 1 and 30 m was explored opportunistically with a non-scientific echo sounder. Evaluation of findings was enhanced by measurements of water column properties (temperature, salinity, fluorescence and transmissivity). Relatively small shoals of fish were detected on the Chukchi shelf and eastern Chukchi shelf break, and also on the Alaskan and Canadian Beaufort shelves in the upper 20 m (T = 2-5°C). Much larger shoals (putative polar cod) were detected within Atlantic Water along the Beaufort continental slope (250-350 m) and near the bottom of Barrow and Mackenzie canyons, where temperatures were above 0°C. A warm-water plume of Alaska Coastal Current water with high concentrations of phytoplankton, zooplankton, and fish was found extending along the shelf 300 km eastward of Barrow Canyon. In contrast to the warm surface and Atlantic Water layers, very few fish were found in colder, intermediate depth Pacific-origin water between them. The large biomass of fish in the Atlantic Water along the continental slope of the Chukchi and Beaufort seas represents previously undescribed polar cod habitat. It has important implications with regard to considerations of resource development in this area as well as understanding impacts of climate change. © 2011 The Author(s).
Eiler J.H.,National Oceanic and Atmospheric Administration |
Bishop M.A.,Prince William Sound Science Center
Transactions of the American Fisheries Society | Year: 2016
Pacific Herring Clupea pallasii are an important forage fish in the northern Pacific Ocean and support commercial fisheries throughout the region, although numerous populations have experienced pronounced declines in abundance. Acoustic telemetry can enhance our understanding of the spatial and temporal distribution of depressed herring populations. However, herring are extremely sensitive to handling. During 2012–2013, we tagged 94 adult herring with acoustic transmitters on their spawning grounds in Prince William Sound, Alaska. The handling and tagging methods were specifically designed to minimize physical injuries and stress. Receiver arrays located near the spawning area (2012–2013) and at the principal entrances into the sound from the Gulf of Alaska (2013) were used to track the postspawning movements of the fish. The herring responded well to the tagging procedures. Most were subsequently detected by the arrays, ranging from 88.0% in 2012 to 92.8% in 2013, when the entire tracking system was operational. Forty-three (67.2%) of the 64 fish detected during 2013 were recorded near entrances to the sound, representing minimum travel distances of 50–180 km. Initial movements during the spring and summer were generally to the southwest and mirrored the prevailing currents, but a number of fish were subsequently observed moving east, including one individual detected near the spawning area during the late fall and winter. Larger herring were more frequently detected near the entrances to the sound. Although it is possible that smaller fish exhibit different migratory patterns, the lower detection rate may also suggest that these individuals were adversely affected by the tagging. Our findings suggest that large-scale telemetry studies on pelagic forage fish such as herring are feasible. These data provide new insights into the migratory patterns of herring and present an opportunity to address ongoing questions related to the factors affecting the status and recovery of depressed populations. Received June 19, 2015; accepted November 24, 2015 © 2016 American Fisheries Society.
Musgrave D.L.,Musgrave Oceanographic Analysis |
Halverson M.J.,Prince William Sound Science Center |
Scott Pegau W.,Oil Spill Recovery Institute
Continental Shelf Research | Year: 2013
Salinity, temperature, and depth profiles from 1973 to 2010 were used to construct a seasonal climatology of surface temperature, surface salinity, mixed layer depth (MLD), potential energy of mixing, and surface geostrophic circulation in Prince William Sound (PWS) and the adjacent Gulf of Alaska. Surface salinity is greatest in winter and least in summer due to the influence of increased freshwater runoff in summer. It is generally lowest in the northwest and highest in the Gulf of Alaska. The surface temperature is lowest in the winter and highest in the summer when surface heating is greatest, with little spatial variability across the Sound. The MLD is deepest in winter (9-27. m) and shallowest in summer (4-5. m). The work by winds was estimated from meteorological buoy data in central PWS and compared to the potential energy of mixing of the upper water column. The potential depth to which winds mix the upper water column was generally consistent with the MLD. The surface geostrophic circulation in the central Sound has: a southerly flow in the western central Sound in the winter; a closed, weak anticyclonic cell in spring; a closed, cyclonic cell in the summer; an open, cyclonic circulation in the fall. In the western passages, a southerly flow occurs in spring, summer, and fall. These results have important implications for oil spill response in PWS, the use of oil dispersants, and for comparison to numerical studies. © 2012 Elsevier Ltd.
Head E.J.H.,Bedford Institute of Oceanography |
Ringuette M.,Bedford Institute of Oceanography |
Campbell R.W.,Prince William Sound Science Center
Journal of Plankton Research | Year: 2013
Egg production rates (EPRs) were measured for Calanus finmarchicus from the Labrador Sea during annual cruises between May and July from 1997 to 2010. EPRs ranged between 0 and 91 eggs f-1 day-1 at 95 stations. Clutch size (CS) was related to female size (prosome length, PL) and both were smallest on the Greenland (2.76 mm, 55.2 eggs) and Labrador (2.86 mm, 60.1 eggs) shelves and largest in the central basin (2.94 mm, 73.0 eggs). CS and spawning frequency (SF, the proportion of females spawning during a 24 h experiment) both increased with increasing female nitrogen content and decreased with increasing C:N ratio. CS and SF were also positively correlated and both increased with an increasing in situ chlorophyll concentration. The relationships between SF (% day-1) and EPR (as eggs f-1 day-1 or % body C or N day-1) and in situ chlorophyll concentration were well described by Ivlev functions (r2 = 0.30-0.34). The residuals from the Ivlev correlations for EPR (but not SF) were significantly negatively correlated with temperature for the central basin (r2 = 0.14), but unrelated over all sub-regions. Over the course of the bloom, as in situ nitrate concentrations decreased, the female N content and the CS decreased and the female C content and C:N increased. Overall, the EPR was most influenced by (i) local feeding conditions (in situ chlorophyll concentration), (ii) the state of the bloom (via effects on female age/condition) and (iii) long-term feeding and temperature history (via effects on female size), although a significant amount of variability remains unexplained. © The Author 2013. Published by Oxford University Press. All rights reserved.