scholarly journals Older but not wider. Impacts of molt frequency variation on age and growth dynamics of Newfoundland & Labrador snow crab (Chionoecetes opilio) toward corroborating gastric mill 2 age estimations

2021 ◽  
Author(s):  
Darrell Mullowney ◽  
Nicole O’Connell ◽  
Rémy Rochette ◽  
Raouf Kilada
Keyword(s):  
Estimation Error ◽  
Growth Dynamics ◽  
Age And Growth ◽  
Future Research ◽  
Snow Crab ◽  
Frequency Variation ◽  
Gastric Mill ◽  
Age At Maturity ◽  
Chionoecetes Opilio ◽  
Size At Age

Abstract Aging specimen and survey data from a heterogeneous stock range are combined to investigate effects of molt frequency variation on age and growth dynamics and efficacy of gastric mill age band estimations in snow crab. A central assumption that bands form independent of molting is examined through analyses of molt frequency variation with an overall result of support for the hypothesis that gastric mill bands form independent of molting. This is based on an applied review approach, demonstrating blind age estimation results within and across population units featuring different rates of molt frequency interruptions in context of literature-based expected outcomes of age and growth dynamics. The comprehensive analyses overall supports the ability of gastric mill bands to track chronological ages, but non-fully explained outcomes of growth delays into sexual maturity stages in males and potential estimation error in 1-3 year old crab preclude a conclusion that absolute ages are consistently tracked throughout ontogeny. The results suggest gastric mill bands continue to form during both skip-molts and after terminal molt. Despite uncertainties, the research highlights that males originating from populations where skip-molting is prominent are older reaching fishery size than previously thought (9-10 years), with tentative average estimates of 10-12 years. The study presents novel observations of size-at-age and age-at-maturity in Newfoundland & Labrador (NL) snow crab and broadens life history knowledge for the species. Along with corroborating gastric mill age band estimations, the study reveals future research streams to further help advance the discipline of aging crustaceans [247].

Evaluation of a direct age estimation method for terminally molted male snow crab Chionoecetes opilio (Fabricius 1788) (Decapoda: Brachyura: Oregoniidae)

2020 ◽  
Vol 40 (5) ◽  
pp. 549-555
Author(s):  
April L Rebert ◽  
Gordon H Kruse ◽  
Joel B Webb ◽  
Sherry L Tamone ◽  
Dion Oxman ◽  
...  
Keyword(s):  
Fishery Management ◽  
Estimation Method ◽  
Growth Patterns ◽  
Annual Growth ◽  
Snow Crab ◽  
Gastric Mill ◽  
Age Composition ◽  
Thin Sections ◽  
Chionoecetes Opilio ◽  
Growth Increments

Abstract Recent research suggests that calcified eyestalks and gastric mill ossicles (stomach teeth) can be used to estimate the age of some crustacean species. Along with annual growth of the endocuticle, bipartite bands in the hard tissue are believed to reflect annual growth patterns (similar to fish scales or otoliths) that are retained through repeated molt cycles. Similar bands are observed in the zygocardiac ossicles of the gastric mill from the snow crab (Chionoecetes opilioFabricius 1788). If these bands reflect annual growth, they may be used to estimate age, which could enhance understanding growth, mortality, recruitment, and age composition and improve fishery management. While some studies show that the number of bands correlates to other estimates of age for C. opilio, little evidence suggests that bands accumulate annually as growth increments independent of molting. Male C. opilio terminally molt at maturity, after which they can survive for seven years or more. Shell condition, i.e., degree of wear and epibionts on their exoskeleton, is used here and by other carcinologists as a proxy for age subsequent to the terminal molt. We estimated band counts and endocuticle thickness from thin sections of the zygocardiac ossicle of terminally molted male C. opilio across a range of shell conditions from a wild, fished stock. We found no differences in band counts (P = 0.41) or endocuticle thickness (P = 0.13) across varying shell conditions and size. These results do not support the hypothesis that band counts can be used to estimate the age of this species after the terminal molt.

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 Size-at-maturity shift in a male-only fishery: factors affecting molt-type outcomes in Newfoundland and Labrador snow crab (Chionoecetes opilio)

2020 ◽  
Author(s):  
Darrell R J Mullowney ◽  
Krista D Baker
Keyword(s):  
Population Density ◽  
Newfoundland And Labrador ◽  
Cold Water ◽  
Large Male ◽  
Snow Crab ◽  
Size At Maturity ◽  
Chionoecetes Opilio ◽  
Factors Affecting ◽  
Male Density ◽  
Process Factors

Abstract A sex-asymmetric downward shift in size-at-terminal-molt has recently occurred in males in some portions of the Newfoundland and Labrador (NL) snow crab stock range, a first known occurrence for such processes in snow crab (Chionoecetes opilio) stocks. This study examines plausible factors promoting the shift in size-at-terminal-molt [synonymous with size-at-maturity (SaM)] including individual size, temperature, population density, and sex ratio. Analyses highlight expanse of cold water and large male density as being significant predictors of molt-type outcomes. A confluence of cold conditions and low density of large males promoted the SaM shift. In turn, the low male density was associated with recently elevated fishery exploitation rates under quota-controlled management. It remains unknown the extent to which the reduction in terminal size reflects a phenotypic vs. genotypic process. Factors affecting skip-molting in male snow crab are investigated, and we find that skip-molting occurs most frequently under extreme cold and high population density conditions. Potential complications arising from altered growth dynamics are discussed. Overall, the results advance knowledge on intraspecific competition processes within snow crab populations and inform fisheries management systems that male-only harvest strategies do not provide full protection from biological harm to aquatic resources through fishing.

scholarly journals Panmixia in Alaskan populations of the snow crab Chionoecetes opilio (Malacostraca: Decapoda) in the Bering, Chukchi, and Beaufort Seas

2014 ◽  
Vol 34 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Gregory T. Albrecht ◽  
Kris J. Hundertmark ◽  
Alexandra E. Valentin ◽  
Sarah M. Hardy
Keyword(s):  
Snow Crab ◽  
Chionoecetes Opilio

SHELL STRENGTH AND CARAPACE SIZE IN NON-ADULT AND ADULT MALE SNOW CRAB (CHIONOECETES OPILIO)

2000 ◽  
Vol 20 (2) ◽  
pp. 399-406 ◽  
Author(s):  
J-D. Dutil ◽  
C. Rollet ◽  
R. Bouchard ◽  
W. T. Claxton
Keyword(s):  
Adult Male ◽  
Snow Crab ◽  
Chionoecetes Opilio

Age and growth of the Patagonian lizard Phymaturus patagonicus

2006 ◽  
Vol 27 (3) ◽  
pp. 385-392 ◽  
Author(s):  
Carla Piantoni ◽  
Victor Cussac ◽  
Nora Ibargüengoytía
Keyword(s):  
Body Length ◽  
Cross Sections ◽  
Growth Dynamics ◽  
Strong Relationship ◽  
Age And Growth ◽  
Adult Males ◽  
Patagonian Steppe ◽  
The North ◽  
Sigmoidal Curve ◽  
Reproductive Cycles

AbstractThe growth dynamics of Phymaturus patagonicus, a diurnal, herbivorous and viviparous lizard from the Argentinean Patagonian steppe, was studied using eight juveniles (two born in the laboratory), 11 adult females and eight adult males. Histological cross sections of femoral bones were analysed to determine if individuals show osseous growth marks and if these marks provide useful age estimates. Individual ages were assessed after estimating the reabsorbed rings in relation to snout-vent length. There was a strong relationship between body length and estimated age, modelled by a sigmoidal curve. Sexual maturity was found to be reached at seven years in females and nine in males and the maximum life span was estimated to be 16 years. No difference in body length was observed between the same-age females and males. We postulate that severe environments such as the north Patagonian steppe play a significant role in the selection of not only modes of reproduction but also delayed maturity and prolonged reproductive cycles, a combination that results in low fecundity.

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