scholarly journals The critical first year of life of walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea: Implications for recruitment and future research

2016 ◽  
Vol 134 ◽  
pp. 283-301 ◽  
Author(s):  
J.T. Duffy-Anderson ◽  
S.J. Barbeaux ◽  
E. Farley ◽  
R. Heintz ◽  
J.K. Horne ◽  
...  
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Future Research ◽  
First Year ◽  
Eastern Bering Sea ◽  
First Year Of Life

scholarly journals The Social Origins of Human Prosociality

2019 ◽  
Vol 28 (3) ◽  
pp. 274-279 ◽  
Author(s):  
Audun Dahl ◽  
Celia A. Brownell
Keyword(s):  
Prosocial Behavior ◽  
Social Interactions ◽  
Early Development ◽  
Future Research ◽  
First Year ◽  
Social And Emotional ◽  
Caregiver Behavior ◽  
The Social ◽  
Second Year ◽  
First Year Of Life

From early in life, children help, comfort, and share with other people. Recent research has deepened scientific understanding of the development of prosociality—efforts to promote the welfare of others. In this article, we discuss two key insights about the emergence and early development of prosocial behavior, focusing on the development of helping. First, children’s motivations and capabilities for helping change in quality as well as quantity over the opening years of life. Specifically, helping begins in participatory activities without prosocial intent in the first year of life, becoming increasingly autonomous and motivated by prosocial intent over the second year. Second, helping emerges through bidirectional social interactions starting at birth: Caregivers and other individuals support the development of helping in a variety of ways, and young children play active roles that often influence caregiver behavior. The question now is not whether but how social interactions contribute to the development of prosocial behavior. Recent methodological and theoretical advances provide exciting avenues for future research on the social and emotional origins of human prosociality.

scholarly journals Comparison of the biophysical and trophic characteristics of the Bering and Barents Seas

2005 ◽  
Vol 62 (7) ◽  
pp. 1245-1255 ◽  
Author(s):  
George L. Hunt ◽  
Bernard A. Megrey
Keyword(s):  
Bering Sea ◽  
Barents Sea ◽  
Single Species ◽  
Atlantic Water ◽  
Walleye Pollock ◽  
Fish Stocks ◽  
Eastern Bering Sea ◽  
The Barents Sea ◽  
Shelf Seas ◽  
Bottom Waters

Abstract The eastern Bering Sea and the Barents Sea share a number of common biophysical characteristics. For example, both are seasonally ice-covered, high-latitude, shelf seas, dependent on advection for heat and for replenishment of nutrients on their shelves, and with ecosystems dominated by a single species of gadoid fish. At the same time, they differ in important respects. In the Barents Sea, advection of Atlantic Water is important for zooplankton vital to the Barents Sea productivity. Advection of zooplankton is not as important for the ecosystems of the southeastern Bering Sea, where high levels of diatom production can support production of small, neritic zooplankton. In the Barents Sea, cod are the dominant gadoid, and juvenile and older fish depend on capelin and other forage fish to repackage the energy available in copepods. In contrast, the dominant fish in the eastern Bering Sea is the walleye pollock, juveniles and adults of which consume zooplankton directly. The southeastern Bering Sea supports considerably larger fish stocks than the Barents. In part, this may reflect the greater depth of much of the Barents Sea compared with the shallow shelf of the southeastern Bering. However, walleye pollock is estimated to occupy a trophic level of 3.3 as compared to 4.3 for Barents Sea cod. This difference alone could have a major impact on the abilities of these seas to support a large biomass of gadoids. In both seas, climate-forced variability in advection and sea-ice cover can potentially have major effects on the productivity of these Subarctic seas. In the Bering Sea, the size and location of pools of cold bottom waters on the shelf may influence the likelihood of predation of juvenile pollock.

scholarly journals Evaluating total uncertainty for biomass- and abundance-at-age estimates from eastern Bering Sea walleye pollock acoustic-trawl surveys

2016 ◽  
Vol 73 (9) ◽  
pp. 2208-2226 ◽  
Author(s):  
Mathieu Woillez ◽  
Paul D. Walline ◽  
James N. Ianelli ◽  
Martin W. Dorn ◽  
Christopher D. Wilson ◽  
...  
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Target Strength ◽  
Acoustic Backscatter ◽  
Trawl Survey ◽  
Data Types ◽  
Total Uncertainty ◽  
Functional Relationships ◽  
Eastern Bering Sea ◽  
Trawl Surveys

Abstract A comprehensive evaluation of the uncertainty of acoustic-trawl survey estimates is needed to appropriately include them in stock assessments. However, this evaluation is not straightforward because various data types (acoustic backscatter, length, weight, and age composition) are combined to produce estimates of abundance- and biomass-at-age. Uncertainties associated with each data type and those from functional relationships among variables need to be evaluated and combined. Uncertainty due to spatial sampling is evaluated using geostatistical conditional (co-) simulations. Multiple realizations of acoustic backscatter were produced using transformed Gaussian simulations with a Gibbs sampler to handle zeros. Multiple realizations of length frequency distributions were produced using transformed multivariate Gaussian co-simulations derived from quantiles of the empirical length distributions. Uncertainty due to errors in functional relationships was evaluated using bootstrap for the target strength-at-length and the weight-at-length relationships and for age–length keys. The contribution of each of these major sources of uncertainty was assessed for acoustic-trawl surveys of walleye pollock in the eastern Bering Sea in 2006–2010. This simulation framework allows a general computation for estimating abundance- and biomass-at-age variance–covariance matrices. Such estimates suggest that the covariance structure assumed in fitting stock assessment models differs substantially from what careful analysis of survey data actually indicate.

scholarly journals Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision

2007 ◽  
Vol 64 (3) ◽  
pp. 559-569 ◽  
Author(s):  
Paul D. Walline
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Geostatistical Simulation ◽  
Normal Space ◽  
Total Biomass ◽  
Spatial Distributions ◽  
Acoustic Data ◽  
Eastern Bering Sea ◽  
Abundance Estimates ◽  
Length Frequency Data

Abstract Walline, P. D. 2007. Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision. – ICES Journal of Marine Science, 64: 559–569. Sequential Gaussian and sequential indicator geostatistical simulation methods were used to estimate confidence intervals (CIs) for biomass estimates from six echo-integration trawl surveys of eastern Bering Sea walleye pollock (Theragra chalcogramma) biomass. Uncertainty in the acoustic and the length frequency data was combined in the calculation of CIs. Sampling in 2002 provided evidence for isotropy in the spatial distribution. Variogram models were characterized by long ranges (75–122 nautical miles for non-zero acoustic data, for example) compared with the smallest dimension of the survey area (∼100 nautical miles) and small nugget effects (∼20% of the semi-variance in transformed normal space for acoustic data). The 95% CIs obtained for the abundance estimates did not vary greatly between years and were similar to those from a one-dimensional transitive geostatistical analysis, i.e. ± 5–9% of estimated total biomass.

scholarly journals Feeding and food supply of juvenile fishes in the eastern Bering Sea in 2003-2012

2015 ◽  
Vol 181 (2) ◽  
pp. 129-140
Author(s):  
Natalia A. Kuznetsova
Keyword(s):  
Bering Sea ◽  
Cold Water ◽  
Walleye Pollock ◽  
Feeding Intensity ◽  
Sand Lance ◽  
Food Ration ◽  
Eastern Bering Sea ◽  
Fish Juveniles ◽  
Calanus Marshallae ◽  
Atka Mackerel

Feeding of fish juveniles in the eastern Bering Sea is investigated for the periods of 2003-2006 considered as relatively «warm» and 2007-2012 considered as relatively «cold». Small- and medium-sized zooplankton was the dominant prey in the 2003-2006, in particular copepods prevailed in the food of walleye pollock (41.5 %), pacific herring (48.3 %), and sand lance (71.7 %) juveniles, which in turn were the prey for pollock, herring and cod yearlings and other predators. On the contrary, large-sized zooplankton was more abundant in the 2007-2012, so arrowwarms ( Sagitta sp.), large-sized copepods (in particular Calanus marshallae ), euphausiids (mainly Thysanoessa raschii ), hyperiids, and pteropods were the prey for young fish: C. marshallae - for juveniles of pollock (40-45 % by weight) and capelin (32-34 %), Th. raschii - for yearlings of pollock (51 %) and herring (36-46 %), cold-water hyperiid T. libellula - for adult pollock (24 %), juvenile cod (9-18 %) and juvenile herring (9-11 %), whereas portion of fish in the diets was insignificant. In the warm period (2003-2006), juvenile pollock, herring, sand lance and capelin were zooplankton-eaters with the diets similarity 67 %, while yearlings of pollock and juveniles of cod, herring, sandfish, and atka mackerel were fish-eaters preying upon pollock juveniles. In the cold period (2007-2012), the diets of juvenile pollock, juvenile and adult capelin, and juvenile sand lance were also similar at 85-70 % but they preferred large-sized copepods and euphausiids ( C. marshallae and Th. raschii ), while yearlings of pollock, yearlings and adults of herring, and juveniles of sand fish and cod had the diets of 70 % similarity with Th. raschii prevalence. Feeding intensity was high for all species: the mean stomach fullness was 150-200 ‱ for pollock juveniles and yearlings, 200-250 ‱ for cod juveniles, 200-258 ‱ for sand lance juveniles, 302 ‱ for herring juveniles, and 178-250 ‱ for juvenile atka mackerel. The fullness had diurnal rhythm with three peaks: at noon - up to 179 ‱, in evening - up to 213 ‱, and at night - up to 204 ‱ (the data for walleye pollock juveniles in «cold» years only). Daily food ration of juvenile pollock is estimated as 6.7 % of its body weight in the «warm» years and 7.0 % in the «cold» years.

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