scholarly journals Recent shifts in northern Bering Sea snow crab (Chionoecetes opilio) size structure and the potential role of climate-mediated range contraction

2020 ◽  
Vol 181-182 ◽  
pp. 104878 ◽  
Author(s):  
Erin J. Fedewa ◽  
Tyler M. Jackson ◽  
Jon I. Richar ◽  
Jennifer L. Gardner ◽  
Michael A. Litzow
Keyword(s):  
Bering Sea ◽  
Potential Role ◽  
Size Structure ◽  
Snow Crab ◽  
Chionoecetes Opilio ◽  
Range Contraction ◽  
Northern Bering Sea

Catchability of snow crab (Chionoecetes opilio) by the eastern Bering Sea bottom trawl survey estimated using a catch comparison experiment

2013 ◽  
Vol 70 (12) ◽  
pp. 1699-1708 ◽  
Author(s):  
David A. Somerton ◽  
Kenneth L. Weinberg ◽  
Scott E. Goodman
Keyword(s):  
Experimental Data ◽  
Bering Sea ◽  
Weighted Average ◽  
Assessment Model ◽  
Bottom Trawl ◽  
Snow Crab ◽  
Trawl Survey ◽  
Chionoecetes Opilio ◽  
Bottom Trawl Survey ◽  
Eastern Bering Sea

Catchability of the eastern Bering Sea (EBS) bottom trawl survey for snow crab (Chionoecetes opilio) was estimated from experimental data to provide a constraint on the survey catchability parameters in the stock assessment model. The experiment utilized a second fishing vessel to conduct side-by-side trawling with each of two survey vessels at 92 stations using an experimental trawl assumed to capture all crabs in its path. Trawl efficiency, or the captured proportion of crabs in the trawl path, was estimated for the 83-112 Eastern otter trawl from experimental data using a nonparametric smooth function of carapace width, sediment size, and depth. Survey catchability was then estimated as the catch-weighted average of the predicted trawl efficiency at all 275 survey stations where snow crabs were captured. The fitted model indicated that trawl selectivity was greater in sand than mud and greater in shallow water than deep. At a carapace widths >95 mm, the minimum commercial size limit, the estimated survey catchability of males is considerably less than previously reported.

Life history schedule and periodic recruitment of female snow crab (Chionoecetes opilio) in the eastern Bering Sea

2012 ◽  
Vol 69 (3) ◽  
pp. 532-550 ◽  
Author(s):  
Billy Ernst ◽  
David A. Armstrong ◽  
Julián Burgos ◽  
J.M. (Lobo) Orensanz
Keyword(s):  
Bering Sea ◽  
Mature Female ◽  
Snow Crab ◽  
Age At Maturity ◽  
Eastern Canada ◽  
Chionoecetes Opilio ◽  
Frequency Distributions ◽  
Eastern Bering Sea ◽  
Crab Abundance ◽  
Mean Size

Snow crab ( Chionoecetes opilio ) populations have fluctuated cyclically in eastern Canada and the eastern Bering Sea, where recruitment to the mature female pool has occurred over a period of three decades (1978–2007) in pulses with a mean period of 7 years. It has been hypothesized that this was the result of a parent–offspring relation between sequentially linked strong cohorts of mature primiparous females, which requires that periodicity matches the time lapsed between egg extrusion by the maternal broodstock and the offspring reaching maturity. We show that female age at maturity (post-settlement) varies between 4.5 and 7.5 years, with most females maturing at 5.5–6.5 years (7–8 years after egg extrusion). Pulses of female recruitment to the mature population do not show a latitudinal trend, consistent with uniformity in age-at-maturity. Results of tracking crab abundance and size–frequency distributions in cod stomach and trawl samples between successive pulses of the cycle are consistent with the hypothesis of serial linkage among pulses. Periodicity is reflected in trends of clutch fullness and average shell condition and in the negative correlation between the strength of primiparous female cohorts and the mean size of their members.

scholarly journals Discard mortality rates in the Bering Sea snow crab, Chionoecetes opilio, fishery

2015 ◽  
Vol 72 (5) ◽  
pp. 1525-1529 ◽  
Author(s):  
J. Daniel Urban
Keyword(s):  
Mortality Rate ◽  
Bering Sea ◽  
Fishery Management ◽  
Stock Assessment ◽  
Mortality Rates ◽  
Snow Crab ◽  
Commercial Fishing ◽  
Chionoecetes Opilio ◽  
Discard Mortality ◽  
The Bering Sea

Abstract Fish and invertebrates that are unintentionally captured during commercial fishing operations and then released back into the ocean suffer mortality at unknown rates, introducing uncertainty into the fishery management process. Attempts have been made to quantify discard mortality rates using reflex action mortality predictors or RAMP which use the presence or absence of a suite of reflexes to predict discard mortality. This method was applied to snow crab, Chionoecetes opilio, during the 2010–2012 fisheries in the Bering Sea. Discard mortality in the fishery is currently assumed to be 50% in stock assessment models, but that rate is not based on empirical data and is widely recognized to be in need of refinement. Over 19 000 crab were evaluated using the RAMP method. The estimated discard mortality rate was 4.5% (s.d. = 0.812), significantly below the rate used in stock assessment models. Predicted discard mortality rates from the 2010 to 2012 study were strongly correlated with the air temperature at the St Paul Island airport in the Pribilof Islands. Using this relationship, the discard mortality rate from 1991 to 2011 was estimated at 4.8% (s.d. = 1.08).

scholarly journals Why does the pollock (Theragra chalcogramma) abundance change

2016 ◽  
Vol 185 (2) ◽  
pp. 31-48
Author(s):  
Vyacheslav P. Shuntov
Keyword(s):  
Bering Sea ◽  
Food Supply ◽  
Global Changes ◽  
Winter Mortality ◽  
Migration Timing ◽  
Northern Bering Sea ◽  
Class Strength ◽  
Strength Dependence ◽  
The Bering Sea

Some common ideas about environmental factors that determine the patterns of migration (including timing) and stock dynamics of walleye pollock are critically analyzed with particular attention to the Bering Sea. There is shown that the conception of the migration timing dependence on food supply in the northern Bering Sea does not represent the real facts, as well as the conception of year-class strength dependence on winter mortality of fingerlings determined by food supply, especially in conditions of its deficiency. Periodicity of the pollock stocks dynamics associated with global changes of climatic and oceanographic factors is also called in question. Role of provincial factors in dynamics of the pollock populations is discussed and emphasized.

scholarly journals The contribution of fecundity and embryo quality to reproductive potential of eastern Bering Sea snow crab (Chionoecetes opilio)

2016 ◽  
Vol 73 (12) ◽  
pp. 1800-1814 ◽  
Author(s):  
Joel B. Webb ◽  
Laura M. Slater ◽  
Ginny L. Eckert ◽  
Gordon H. Kruse
Keyword(s):  
Bering Sea ◽  
Embryo Quality ◽  
Stock Assessment ◽  
Reproductive Potential ◽  
Large Male ◽  
Reference Points ◽  
Snow Crab ◽  
Eastern Canada ◽  
Chionoecetes Opilio ◽  
Eastern Bering Sea

Development of refined indices of female reproductive potential is needed for estimation of alternative biological reference points for the eastern Bering Sea (EBS) snow crab (Chionoecetes opilio) fishery, which is managed with large male-only harvest regulations. Females were collected from 2007 to 2009 to investigate seasonal and interannual variation in fecundity with maternal size, shell condition (a proxy for age after maturity), and recent mating and again in 2010 to examine biochemical measures (carbon, hydrogen, and nitrogen) of embryo quality. Mean model-adjusted fecundity was highest for primiparous and young multiparous females and declined with advancing shell condition, presumably from senescence. This pattern was also found for clutch fullness indices evaluated from 20 years of stock assessment survey data. Indicators of low female sperm reserves were associated with decreased (∼10%) fecundity for multiparous females. Seasonal comparison of size–fecundity relationships suggested that embryo loss during brooding was minimal, and embryo quality analyses suggested that strong variation with maternal characteristics was unlikely. Finally, fecundity-at-size of EBS females may be lower than that of conspecifics in Japan and eastern Canada.

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