scholarly journals Seasonal migrations of morphometrically mature male snow crab (Chionoecetes opilio) in the eastern Bering Sea in relation to mating dynamics

2015 ◽  
Vol 113 (3) ◽  
pp. 313-326 ◽  
Author(s):  
Daniel G. Nichol ◽  
David A. Somerton
Keyword(s):  
Bering Sea ◽  
Mature Male ◽  
Snow Crab ◽  
Chionoecetes Opilio ◽  
Eastern Bering Sea ◽  
Seasonal Migrations

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 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.

Spatial dynamics of female snow crab (Chionoecetes opilio) in the eastern Bering Sea

2005 ◽  
Vol 62 (2) ◽  
pp. 250-268 ◽  
Author(s):  
Billy Ernst ◽  
JM (Lobo) Orensanz ◽  
David A Armstrong
Keyword(s):  
Bering Sea ◽  
Environmental Gradients ◽  
Condition Index ◽  
Mature Female ◽  
Temperature Fields ◽  
Snow Crab ◽  
Bottom Temperature ◽  
Eastern Canada ◽  
Chionoecetes Opilio ◽  
Eastern Bering Sea

Snow crab (Chionoecetes opilio) migrations in the eastern Bering Sea have long been ignored. Based on preliminary information, we hypothesized that females undergo an extensive ontogenetic migration, tracking down environmental gradients. We analyzed a 25-year time series of survey data and defined ontogenetic stages in terms of a "shell condition index" calibrated with radiochemical methods. "Pseudo-cohorts" of mature females (groups of females that undergo puberty molt in a given year) "recruit" to the mature female pool in the Middle Domain (50–100 m) of the intermediate shelf. Females undergo puberty molt and primiparous mating in winter. Over the next year, they migrate an average net distance of 73.5 nautical miles towards the shelf edge following a predominantly northeast–southwest direction. Maximum post-terminal molt life span is 6–7 years. Results support the hypothesis that the variable tracked is near-bottom temperature. Although near-bottom temperature fields vary from year to year, the corresponding vector field is a conservative template, which explains the consistency observed in the pattern of migration. Elucidation of the life history schedule of mature female snow crabs in the eastern Bering Sea revealed that it is very similar to that reported for eastern Canada, although patterns of migration may differ substantially between the two systems.

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