bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loss of and damage to scallops due to storms in the Sea of Okhotsk
Authors: MIYAKE HIDEO , MATSUOKA MITSUAKI , FURUYA KUNIO 
Published: October 2007

ABSTRACTIn the coastal zone of the Sea of Okhotsk off Hokkaido, Japan, the giant ezo scallop (Patinopecten yessoensis) is widely cultivated on the sea bed, making its fishery a major industry. However, the area experiences intense cyclones, including typhoons, about once a decade and the scallop resources appear to have received severe damage from the storms. Such an event occurred on 29 October 1988. The storm caused 12‐m‐high wind waves, which appeared to be fully developed sea waves. The water above the sea bed repeatedly moved back and forth at speeds of 1∼2 m s‐1 causing damage to the scallops due to collisions and rubbing with gravel and other scallops. From a comparison of wind data with the annual catch of scallops, intense cyclones seem to play an important role on the year‐to‐year fluctuations in the scallop fishery.
A three‐dimensional numerical model for a mariculture nitrogen cycle: case study in Shizugawa Bay, Japan
Authors: KISHI MICHIO J. , UCHIYAMA MASATO 
Published: October 2007

ABSTRACTA numerical model is developed for mariculture management, which consists of: (1) calculation of spatial distribution of PON (particulate organic nitrogen) using simulated current, (2) calculation of spatial distribution of DO (dissolved oxygen), (3) calculation of DON (dissolved organic nitrogen), (4) calculation of spatial distribution of DIN (dissolved inorganic nitrogen), and (5) calculation of the horizontal distribution of accumulated matter which is supplied by deposits from the mariculture of fish. This model is capable of calculating the detailed spatial distribution of PON, DON, DIN and DO by dividing the bay into many grid points. It also takes into consideration the effects of feed and fish in each raft, and the loading of DIN from rivers. The model is applied to Shizugawa Bay, in Miyagi Prefecture, Japan. The model elucidated the oxygen cycle among ecological compartments. The amount of dissolved oxygen supplied by photosynthesis is much greater than the consumption through respiration by fish and all other conditions for mariculture of fish are favourable in this bay.
Recruitment strategy of swimming crab, Portunus trituberculatus, in Hiuchi‐Nada, Japan
Authors: YANAGI TETSUO , TSUKAMOTO HIDESHI , IGAWA SHUJO , SHIOTA KOHJI 
Published: October 2007

ABSTRACTThe recruitment strategy of swimming crabs, Portunus trituberculatus, was investigated by field observations and numerical experiments in Hiuchi‐Nada, Japan. Calculated dispersal patterns of zoeal and megalopal stages in a three‐dimensional numerical model reproduce observed patterns accurately. The temporal change of vertical migration patterns between the 1st and 2nd zoeas and the 3rd and 4th zoeas plays an important role in the process of recruitment of P. trituberculatus from spawning ground to nursery ground.
Stability of water masses‐impact on cod recruitment off West Greenland
Authors: LLORET M. STEIN AND J. 
Published: October 2007

ABSTRACTBased upon the hypothesis of Meyer (1968: Hansa, 16:2–4) that periods of low stability of the water column in autumn should parallel good cod year‐classes in the following year, the paper analyzes available time series of cod recruitment, subsurface oceanographic stability data and wind stress data off West Greenland. No significant correlations were found between stability, wind stress and recruitment when considering the entire. length of available time series. However, splitting the autumn‐based oceanographic data set into a pre‐ 1970s part (when warm climatic conditions and high recruitment prevailed), and a recent part (for the past 20 years of cooling climate) yields significant coherence of recruitment and environmental conditions for the cold climate period. For the warm climate period, only occasional consistency is shown. The possible influence of the Great Salinity Anomaly on recruitment of cod is discussed. It is suggested that during the past 20 years a new correlation mechanism, an advective coupling instead of low stability coupling, may explain the variability of recruitment.
Possible mechanisms underlying fluctuations in the Far Eastern sardine population inferred from time series of two biological traits
Authors: KAWASAKI TSUYOSHI , OMORI MICHIO 
Published: October 2007

ABSTRACTA cycle of fluctuation in the Far Eastern sardine, Sardinops sagax, population is accompanied by an abrupt drop and recovery of fish size and lipid content of parent fish, which may reflect a phase variation from coastal to oceanic and its reverse. The cycle begins with the survival success of a smaller number of eggs produced by high‐quality parents, which is triggered by a global climate change (density‐independent process), and finally ends in the survival failure resulting from an overexpansion of an enormous number of fish produced by low‐quality parents (density‐dependent process).
Declines in chinook salmon catches in the Strait of Georgia in relation to shifts in the marine environment
Authors: BEAMISH RICHARD J. , RIDDELL BRIAN E. , NEVILLE CHRYS‐ELLEN M. , THOMSON BARBARA L. , ZHANG ZIYANG 
Published: October 2007

ABSTRACTChinook, Oncurhynchus tshawytscha, catches in the Strait of Georgia increased in the 1970s and reached maximum levels from 1976 to 1978. Catches then declined until they stabilized through regulation at levels approximately one‐quarter of the 1976 to 1978 levels. The timing of the decline in catch was synchronous with an increase in the mean temperature of the Strait of Georgia, a decline in annual Fraser River flows, and an abrupt decrease in the marine survival of hatchery‐reared chinook released into the Strait of Georgia. Surprisingly, the number of young chinook salmon (smolts) more than doubled over the period of declining catches compared with the number produced during the period of high catches. The increase in smolt abundance was a consequence of the production from hatcheries that was approximately equal to wild production.We conclude that there was a change in the carrying capacity for chinook salmon in the Strait of Georgia in the late 1970s that contributed to the declines in abundance and that rebuilding stocks to the high abundance of the late 1970s is unlikely until the carrying capacity for chinook salmon changes either naturally or through manipulation. Although we did not separate density‐dependent and density‐independent effects on marine survival, the current total number of chinook smolts produced appears larger than required for the current marine carrying capacity.
Characterization of the pelagic ecosystem in surface waters of the northern Gulf of St, Lawrence in early summer: the larval redfish‐Calanus‐microplankton interaction
Authors: RUNGE JEFFREY A. , LAFONTAINE YVES DE 
Published: October 2007

ABSTRACTIn June 1989, the water column along a transect in the north‐central Gulf of St Lawrence was thermally stratified (10–14oC at the surface; 0‐loC at 30 m). In the surface layer, nitrate and chlorophyll concentrations were very low; the mean concentration of chlorophyll a > 5 μm in the subsurface maximum was 0.26 μg1‐1. Autotrophic and (presumably) heterotrophic flagellates and dinoflagellates were the most abundant micro‐plankton. In this system, redfish (Sebastes spp.) larvae and the planktonic copepod Calanus finmarchicus overwhelmingly dominated the ichthyoplankton and zoo‐plankton, respectively. Redfish larvae, Calanus females and Calanus eggs were most abundant in the surface layer (0–25 m) day and night. Daily specific egg production rates of Calanus, calculated from shipboard incubations of females, approached the predicted maximal level for this species at the ambient temperature of the surface layer, indicating no or little food limitation. The redfish larvae were feeding almost exclusively on the Calanus eggs and were found in greatest abundance along the transect where Calanus egg production rates (eggs m‐2 day‐1), calculated from the product of the specific egg production rate and female concentration, were highest. The mono‐specificity of the larval redfish diet and the codom‐
Locations of early fishing grounds of saury in the northwestern Pacific
Authors: YASUDA ICHIRO , KITAGAWA DAIJI 
Published: October 2007

ABSTRACTIn the north‐western Pacific, we found that locations of early fishing grounds of Pacific saury, Cololabis saira, are affected by two factors, the size composition and the meridional shift of the offshore Oyashio Front (OOF). Early fishing grounds are formed nearshore from the central Kuril Islands to Hokkaido in northward OOF years. In southward OOF years, they are far from the coasts. There also exists a tendency that early fishing grounds are formed south‐westward (north‐eastward) in years when a large (medium or small) size class of saury is dominant and when the OOF shifts north (south). These results support the hypothesis that saury migration is considerably influenced by oceanographic conditions, and that a large size class of saury leads to migration that can reach the vicinity of Japan early in the fishing season.
Interannual variability of the early life history of walleye pollock near Shelikof Strait as inferred from a spatially explicit, individual‐based model
Authors: HERMANN ALBERT J. , HINCKLEY SARAH , MEGREY BERNARD A. , STABENO PHYLLIS J. 
Published: October 2007

ABSTRACTA coupled biophysical model is used to hindcast the early life history of a population of walleye pollock (Theragra chalcogramma), to assess possible physical causes of interannual variability in recruitment. The modelling approach combines a primitive equation, rigid'lid hydrodynamic model with a probabilistic, individual‐based biological model of growth, development, and mortality. Individuals are tracked through space using daily velocity fields generated from the hydrodynamic model, along with self‐directed vertical migrations appropriate to each life stage in the biological model. The hydrodynamic model is driven with wind and runoff time series appropriate to each year. Biological model output compares favourably with observed spatial distributions for specific years. Lloyd's index of patchiness, calculated from model output, was similar to values calculated from field data. Five noncontiguous years were chosen for hindcasts to span a wide range of meteorological conditions (winds, runoff) and recruitment success. Interannual comparisons suggest that two years of above average recruitment (1978 and 1988), and one year of below average recruitment (1991), experienced flow fields which carried many individuals into the Alaskan Stream. At the same time, the vigorous flow fields generated in each of these years carried some individuals onto the shelf area to the south‐west of the spawning site. A year with low runoff and weak winds (1989) exhibited weak circulation, with extended retention of larvae near the spawning site. A year with high runoff (1987) was notable for the strength and frequency of mesoscale eddy activity. Eddies appear capable of both enhancing patchiness of early larvae (through retention) and dissipating patchiness of juveniles (through mesoscale mixing). Larvae retained in an eddy feature exhibit a narrower range of sizes than the population outside that feature.
Acoustic detection of mesoscale biophysical features in the Shelikof sea valley, and their relevance to pollock larvae in the Gulf of Alaska
Authors: BRODEUR RICHARD D. , NAPP JEFFREY M. , WILSON MATTHEW T. , BOGRAD STEVEN J. , COKELET EDWARD D. , SCHUMACHER JAMES D. 
Published: October 2007

ABSTRACTMesoscale features such as fronts and eddies can act to retain larval walleye pollock (Theragra chalcogramma) within the continental shelf zone in the western Gulf of Alaska. During two May cruises, we observed unusual patterns of backscattering with a 38 kHz acoustic system. Characteristics of this signal were a strong scattering layer at the surface and in midwater, with the water column between nearly void of sound scattering organisms. This signal appeared in several transects where satellite remote sensing indicated the presence of an eddy. Analysis of concomitant water properties and ADCP (153 kHz) data confirmed the existence of an anomalous physical feature at this location. Biological properties (chlorophyll and zooplankton) showed marked changes across the edge of the feature. Larval pollock densities were estimated to be an order of magnitude higher within this feature compared to those outside. Acoustic backscatter signals can be used to identify and characterize mesoscale biophysical features in the ocean, thereby enabling real‐time studies of these features.
Variations in larval walleye pollock feeding and condition: a synthesis
Authors: THEILACKER GAIL H. , BAILEY KEVIN M. , CANINO MICHAEL F. , PORTER STEVEN M. 
Published: October 2007

ABSTRACTThere was a strong association among concentrations of microzooplankton prey sampled from the walleye pollock, Theragra chalcogramma, larval habitat, gut contents of larvae, and their nutritional condition. Subsequently, hypothesized survival potentials linked to food availability were validated by independently determined mortality rates. We present evidence that a significant number of walleye pollock larvae were starving in 1991 but that fewer were starving in 1992. At some stations where prey levels were anomalously low in 1991, up to 40% of the larvae were in poor condition. There appears to be a 2‐week period after first feeding when walleye pollock are vulnerable to starvation.
Interannual variability in growth of larval and juvenile walleye pollock Theragra chalcogramma in the western Gulf of Alaska, 1983–91
Authors: BAILEY KEVIN M. , BROWN ANNETTE L. , YOKLAVICH MARY M. , MIER KATHRYN L. 
Published: October 2007

ABSTRACTInterannual variability in growth of larval walleye pollock Theragra chalcogramma was examined from 1983 to 1991 and of juveniles from 1985 to 1990. ANCOVA was used to assess differences in population growth rates, and an alternate method was developed to examine variations between annual length‐at‐age data and average ‘expected’ values over different age groupings. For larvae, the years 1986, 1987, 1989 and 1990 had higher than average length‐at‐age, and 1988 and 1991 had lower than average values. Relationships between growth and SST and larval density were not clear. A tentative relationship between copepod nauplii abundance and larval length‐at‐age was noted. The consequence of larval growth to larval mortality, late larval abundance or recruitment was not clear. We conclude that larval mortality rates are highly variable and tend to mask effects of moderate variability in growth on later abundance. For juveniles, 1987 had significantly lower than average length‐at‐age and 1988 had higher than average values. Although there are few years of data, they tend to support the importance of juvenile growth in the recruitment process. Conditions for the large 1988 year class are documented and discussed, including warm SST, calm winds, relatively low larval growth rates, low abundances of potential predators on larvae, low larval mortality rates, and high juvenile growth rates.
Behavioural determinants of distribution and survival in early stages of walleye pollock, Theragra chalcogrammai a synthesis of experimental studies
Authors: OLLA BORI L. , DAVIS MICHAEL W. , RYER CLIFFORD H. , SOGARD SUSAN M. 
Published: October 2007

ABSTRACTThis review summarizes results of an extensive series of laboratory studies on the behavioural responses of early life stages of walleye pollock, Theragra chakogramma to key environmental factors including light, temperature, gravity, turbulence, food availability and predator presence. Experiments focused on vertical distribution of egg through 0‐age stages, and social interactions of age‐0 juveniles. Key factors were modified either singly or in concert to determine their direct and indirect influence on fish behaviour. The observed results suggest that the behaviour of individual fish depends on the integration of a continually changing hierarchy of both intrinsic and extrinsic factors, with the relative importance of a specific factor varying with ontogeny and over time and space. The broad range of responses displayed by early life stages suggests that behaviour plays an important role in determining the consequences of environmental variability on walleye pollock populations. In general, results from our laboratory experiments are consistent with patterns observed in field studies, supporting the efficacy of using experimental behavioural research to define some of the underlying mechanisms controlling distribution and survival in the field, and eventual recruitment to adult populations.
Contributions of FOCI research to forecasts of year‐class strength of walleye pollock in Shelikof Strait, Alaska
Authors: MEGREY BERNARD A. , HOLLOWED ANNE B. , HARE STEVEN R. , MACKLIN S. ALLEN , STABENO PHYLLIS J. 
Published: October 2007

ABSTRACTNOAA's Fisheries Oceanography Coordinated Investigations (FOCI) contributes information to help forecast year‐class strength of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska. Quantitative estimates of recruitment are obtained from models of stock assessment and stock projection employing information supplied by FOCI. To generate its information, FOCI convenes specialists in marine biology, physical and fisheries oceanography, meteorology, and statistics to assemble and analyse relevant biological and physical time series with respect to recruitment and processes hypothesized to influence fish survival. Statistical methods encompass linear and nonlinear regression, stochastic simulation modelling, transfer function time series modelling, and tree‐modelling regression. The current database consists of 31 years of data, and analyses have identified factors that affect ocean stratification and circulation during spring and summer of the fish's birth year as being important to recruitment. A conceptual model of the recruitment process serves as the framework for a recruitment forecast scheme. A stochastic mathematical simulation model of the conceptual model produces similarities between simulated and observed recruitment time series. FOCI has successfully forecast recruitment observed over the past several years.
Spatial variations in feeding and condition of juvenile pink and chum salmon off Vancouver Island, British Columbia
Authors: PERRY R. IAN , HARGREAVES N. BRENT , WADDELL BRENDA J. , MACKAS DAVID L. 
Published: October 2007

ABSTRACTSpatial variations in feeding and condition of juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon, and their implications for growth, were examined on the Vancouver Island continental shelf in early summer 1992. Juvenile pink salmon off northern Vancouver Island had more material in their stomachs, were in better condition, and had higher potential growth rates (from a bioenergetics model) than pink salmon off southern Vancouver Island. These variations were consistent with spatial differences in zoo‐plankton biomass, there being more plankton in the northern region. There was a significant positive relationship between condition of pinks and the amount of material in their stomachs, suggesting a positive feedback on feeding success. Juvenile chum in the north also had more material in their stomachs than chum to the south. However, condition factor was not significantly different between southern and northern regions nor was there a significant relationship between condition factor and the weight of stomach contents for chum on the southern shelf. A bioenergetics model suggests that chum in the south were food limited. Stable carbon isotope data also indicated different feeding histories for some chum in the southern region, which may have been recent migrants onto the continental shelf from near‐shore areas, or possibly a nearby hatchery. Estimation of the energy required by juvenile salmon to migrate north in a continental shelf area with low zooplankton biomass and a weak northerly current (inner shelf), compared with an area with higher zooplankton biomass but a strong southerly current (outer shelf), indicated sufficient surplus energy only in the inner shelf, consistent with observations of northward migrations predominantly through this area. Spatial variations in current velocity and zooplankton biomass can affect feeding, condition, and potential growth of juvenile pink and chum salmon off Vancouver Island.
Skipjack velocity, dwell time and migration
Authors: GAULDIE R. W. , SHARP G. D. 
Published: October 2007

ABSTRACTApparent velocities (distance travelled/time at liberty) of tagged Pacific skipjack tuna, Katsuwonus pelamis, observed over the 1978 to 1982 Skipjack Survey and Assessment Program (SSAP) of the South Pacific Commission (SPC) were very low (less than 10 cm s‐1in 90% of observations) compared with the minimum swimming speed of skipjack tunas of 70–100 cm s‐1. Such low apparent velocities are not biologically meaningful and therefore the extrapolation of biological properties from mathematical models, such as diffusion and advection models, based on the tagging data is difficult, if not impossible. This paper explores alternative approaches to the 1978 to 1982 SSAP data set. Dwell time and migration analysis indicate a north to south seasonal migratory pattern with the skipjack home range located along an arc from the Solomon Islands, through Fiji and Samoa, to the Marquesas. Ancillary evidence supports a purposeful rather than advective migration pattern that oscillates between southern feeding areas and northern breeding areas. many hands. Most of the previous analyses have focused on the issue of interactions between fisheries for K. pelamis that are in different political jurisdictions (Kleiber et al., 1984) and estimates of the size of the standing crop of K. pelamis (Kleiber et al., 1983; Kearney et al., 1984). Models of interactions between fisheries for K. pelamis in different jurisdictions (Sibert, 1984; Hilborn, 1990) have pointed towards the use of diffusion and advection models in studying fish movements (Sibert and Fournier, 1994; Sibert et al., 1995).
The distribution of sea birds relative to their fish prey off Vancouver Island: opposing results at large and small spatial scales
Authors: LOGERWELL ELIZABETH A. , HARGREAVES N. BRENT 
Published: October 2007

ABSTRACTWe investigated the distribution of common murres, Uria aalge, and shearwaters, Puffinus griseus and P. tenuirostris, relative to their fish prey at two spatial scales, one of hundreds of kilometres and the other of kilometres. Data on oceanographic conditions, the distribution of sea birds and the distribution of fish in the upper water column were collected during three research surveys off Vancouver Island (British Columbia, Canada). At the large spatial scale, we found that both murres and shearwaters were more abundant inshore than offshore of the shelf break and that their fish prey were likewise more abundant in the inshore habitat. At the smaller scale, we investigated the relative importance of fronts and fish density. In contrast to what we expected based on our finding at the large spatial scale, there was a significant negative relationship between fish and both murre and shearwater density. We found that fronts, independent of fish density, did not have an effect on small‐scale murre density and had only a weak effect on small‐scale shearwater density. We suggest that the negative relationship between fish and sea bird density at the scale of kilometres may have been due to fish diving to escape foraging sea birds and thus avoiding capture in the near‐surface trawl used in this study. If this avoidance behaviour is common in pelagic fish, then sea birds may affect fish populations by driving fish away from plankton‐rich surface waters and thus negatively affecting the feeding and growth rates of their fish prey.