Growth and Age Determination of the Pacific Edible Crab Cancer magister Dana

1961 ◽  
Vol 18 (5) ◽  
pp. 873-891 ◽  
Author(s):  
T. H. Butler
Keyword(s):  
British Columbia ◽  
Carapace Width ◽  
Age Groups ◽  
Age Determination ◽  
Cancer Magister ◽  
Larval Instars ◽  
Frequency Distributions ◽  
Queen Charlotte Islands ◽  
The Pacific

Of 2,820 early post-larval unsexed crabs collected by small-meshed trawl in two regions of the Queen Charlotte Islands, 1,175 were measured and the 1st and 2nd post-larval instars were identified as modes at 6.9 and 10.0 mm, respectively. Increments of 5 unsexed moulted crabs, carapace widths 6.80 to 9.96 mm, were from 36.3 to 46.5%. A total of 284 males, from 83 to 186 mm, moulted in crab traps, live-wells, and while at large as tagged specimens; 44 females, from 88 to 145 mm, moulted in traps. Using equations of regression of new carapace width on old width for both sexes and starting at the 2nd instar, average carapace widths were calculated for instars 3 to 15. In the width-frequency distributions of 8,145 crabs, separation of stages was sufficient for identification of age-groups. It is estimated that a year after hatching, males reach stage 5 or 6 (24.2 or 31.1 mm); after 2 years stage 11 or 12 (96.6 or 119.5 mm) is attained; after 3 years stage 13 (146.9 mm); after 4 years most males are in the 14th stage (176.2 mm) and above the British Columbia legal size of 165 mm; and generally after 5 years males are in stage 15 (207.5 mm). Growth of females is similar for 2 years, but afterwards is slower.

Maturity and Breeding of the Pacific Edible Crab, Cancer magister Dana

1960 ◽  
Vol 17 (5) ◽  
pp. 641-646 ◽  
Author(s):  
T. H. Butler
Keyword(s):  
Sexual Activity ◽  
Carapace Width ◽  
Cancer Magister ◽  
Male And Female ◽  
Breeding Activity ◽  
Queen Charlotte Islands ◽  
The Pacific

The breeding procedure of C. magister is described. Contact between the male and female in the pre-mating embrace causes marks on the exoskeletons. These "mating marks" are used as an indicator of breeding activity of male crabs. Differences in intensity of mating marks are discerned, and these are interpreted as evidence of polygamy under natural conditions.Examination of vasa deferentia and sampling of male breeding crabs has indicated that onset of maturity in the Queen Charlotte Islands occurs at a carapace width of about 110 mm, or at approximately three years of age. However, sexual activity is not appreciable until the width is about 140 mm.Female crabs are mature at a carapace width of 100 mm, at about two years.

The Growth of the Pacific Edible Crab, Cancer magister Dana

1935 ◽  
Vol 1 (3) ◽  
pp. 191-212 ◽  
Author(s):  
Donald C. G. MacKay ◽  
Frank W. Weymouth
Keyword(s):  
British Columbia ◽  
Average Duration ◽  
Maximum Size ◽  
Cancer Magister ◽  
Larval Instars ◽  
Larval Stages ◽  
The Third ◽  
The Pacific ◽  
Size Of Animals ◽  
Males And Females

Approximately 20,000 measurements were made of crabs and cast exoskeletons, chiefly from Boundary bay, southern British Columbia. From size frequencies of crabs under 3 cm. seven modes have been identified as representing the early post-larval instars. Increase in size of animals in the laboratory or in live wells is significantly less than in nature, and leads to erroneous results when applied to growth. The increase per moult decreases from about 40 per cent in the early post-larval stages to about 15 per cent in males of 13.5 cm. and 10 per cent in females of 13.0 cm. Above 10 cm. the males increase more per moult. The intervals between moults become progressively longer with increasing size, and tagging experiments indicate that large crabs moult yearly. Probably to reach the maximum size, seventeen and sixteen post-larval instars are required for males and females respectively. Sexual maturity in female crabs is probably attained during the fourth or fifth year but may occur in the third or the sixth year. The legal size in British Columbia (6½ inches, or 16.5 cm.) is probably attained during the seventh or eighth year. The average duration of life is probably about eight years and the maximum age not more than ten years.

Rubidium and Strontium age determination of some Pre-Cambrian granitic rocks, S.E. Uganda

1971 ◽  
Vol 108 (5) ◽  
pp. 353-360 ◽  
Author(s):  
R. A. Old ◽  
D. C. Rex
Keyword(s):  
Age Groups ◽  
Age Determination ◽  
Granitic Rocks ◽  
Age Limit ◽  
Age Determinations

SummaryWhole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.

scholarly journals Moral Development in Structure of Legal and Cultural Organisation of Adolescent Personality with Critical Social Deviations

2019 ◽  
Vol 9 (2) ◽  
pp. 264-275
Author(s):  
N.A. Slavova ◽  
V.A. Chvyakin
Keyword(s):  
Moral Development ◽  
Age Groups ◽  
Age Determination ◽  
Moral Judgments ◽  
Criminal Proceedings ◽  
Moral Consciousness ◽  
Illegal Behavior ◽  
Region Of Residence ◽  
Critical Social

The article describes the moral development in the structure of the legal and cultural organization of the personality of an adolescent with criticla social deviations. The problem of the study is a moral field of the personality of adolescents. The process of formation of moral judgments with regard to its dynamics from preconventional to postconventional levels of development in adolescents with illegal behavior is considered. A total of 60 adolescents with aggressive asocial behavior between the age of 14 and 17 were examined; they were suspected of committing various offenses; the criminal proceedings were instituted against them. The subjects were divided into two age groups: the first group is 14–15 years old, the second - 16–17 years old. The factor of residence of the subjects was taken into account (residents of Moscow and those who came from different regions of the Russian Federation). L. Kohlberg's technique was used to reveal the peculiarities of moral consciousness in the examined persons. The attention was paid to the levels of development of moral consciousness (preconventional, conventional and postconventional levels). The finding of the study is data about the development degree of moral judgments of adolescents with critical social deviations. The information on the age determination of moral development and depending on the region of residence of the subject is obtained.

Age and stock structure of gemfish (Rexea solandri) in New Zealand waters

1999 ◽  
Vol 50 (2) ◽  
pp. 103 ◽  
Author(s):  
P. L. Horn ◽  
R. J. Hurst
Keyword(s):  
Growth Parameters ◽  
Age Determination ◽  
Natural Mortality ◽  
Stock Structure ◽  
Von Bertalanffy ◽  
Length Frequency ◽  
Frequency Distributions ◽  
The North ◽  
Spawning Areas

Age determination of gemfish by counting hyaline zones in otoliths was validated by following the progression of modes in length–frequency distributions and the progression of strong and weak year classes in age–frequency distributions. Length–frequency and otolith samples were examined from four areas (west Northland, east Northland and Bay of Plenty, Wairarapa coast, and the Stewart- Snares shelf). Age–frequency distributions and von Bertalanffy growth parameters were calculated and compared between areas. Two gemfish stocks are indicated on the basis of patterns of year class strengths, trends in commercial landings and likely spawning areas; one off the east and north of the North Island, and another off the west and south of the South Island. Estimates of natural mortality are presented for the two stocks.

Why is age determination of Baltic cod (Gadus morhua) so difficult?

2010 ◽  
Vol 67 (6) ◽  
pp. 1198-1205 ◽  
Author(s):  
Karin Hüssy
Keyword(s):  
Gadus Morhua ◽  
Age Determination ◽  
Zone Formation ◽  
Frequency Distributions ◽  
Daily Increment ◽  
Reading Frequency ◽  
Traditional Age ◽  
Age Reading ◽  
Baltic Cod

Abstract Hüssy, K. 2010. Why is age determination of Baltic cod (Gadus morhua) so difficult? – ICES Journal of Marine Science, 67: 1198–1205. The aim of this study was to evaluate the consistency of three methods for assigning annuli in adult Baltic cod otoliths. The methods examined were (i) daily increment patterns, (ii) opacity profiles, and (iii) traditional age reading. Frequency distributions of the distance from the nucleus to the different zones showed that the first annulus of traditional age reading missed the first zone of both increment and opacity methods, but overlapped with the second zone identified by these methods. This pattern did not continue over subsequent zones. Frequency distributions of increment patterns were similar to opacity patterns. However, within individual fish, the co-occurrence of overlap between the two patterns was random. In cases where there was overlap, translucent zone formation started just before the disappearance of visible increments. Overlap in 1 year did not necessarily lead to a consistent pattern the following year, and overlap was not influenced by sex or fish size. The results suggest that otolith opacity in Baltic cod is not associated with seasonal patterns in daily increment structure and that traditional age determination based on otolith opacity yields highly uncertain estimates of age.

Determination of Larval Instars of Semanotus bifasciatus (Coleoptera: Cerambycidae) Based on Frequency Distributions of Morphological Variables

2020 ◽  
Vol 55 (3) ◽  
pp. 405-415
Author(s):  
Na Li ◽  
Lei Wu ◽  
Yongxin Geng ◽  
Danfeng Wei ◽  
Min Chen
Keyword(s):  
Body Length ◽  
Larval Instar ◽  
Head Capsule ◽  
Larval Instars ◽  
Frequency Distributions ◽  
Larval Stages ◽  
Field Investigations ◽  
Mandible Length ◽  
Morphological Variables

Abstract Semanotus bifasciatus Motschulsky (Coleoptera: Cerambycidae) is one of the most destructive pests of Platycladus trees in China. Morphological measurements, such as head capsule (HC) width, can be very useful and practical indicators for identifying larval instars of coleopteran species. In this study, six morphological variables, including HC width, pronotum width, mandible length and width, and body length and width were measured to determine the instars of field-collected larvae of S. bifasciatus. Both the HC width and pronotum width were reliable parameters for determining the instar and stage. Larvae of S. bifasciatus were divided into eight instars; we detected strong relationships between larval instar and both the HC width (R2 = 0.9640) and pronotum width (R2 = 0.9549). The ranges of body widths and lengths for each instar are provided as reference values for distinguishing among larval stages in field investigations.

Sediment transfer by shallow landsliding in the Queen Charlotte Islands, British Columbia

2002 ◽  
Vol 39 (2) ◽  
pp. 189-205 ◽  
Author(s):  
Yvonne Martin ◽  
Kenneth Rood ◽  
James W Schwab ◽  
Michael Church
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Probability Distributions ◽  
Sampling Period ◽  
Sampling Bias ◽  
Drainage Basins ◽  
Physical Mechanisms ◽  
Queen Charlotte Islands ◽  
The Pacific ◽  
Sediment Transfer

Despite the importance of landsliding in routing sediment through mountainous drainage basins, few studies have documented landsliding rates over extended time and space scales. We have investigated landsliding in surficial material in the Queen Charlotte Islands using a large inventory of events, derived from aerial photography, covering an area of 166.7 km2. The mean erosion rate for shallow landsliding is 0.10 mm·a–1, which is at the upper end of shallow landsliding rates observed in the Pacific Northwest and coastal British Columbia, but several orders of magnitude lower than rock-based landsliding rates reported in the literature. Probability distributions for landslide area and volume are somewhat convex in form. Flattening of the curve found at low magnitudes may be due to sampling bias or physical mechanisms inhibiting failure, and the steepening for high values may exist because the sampling period is not long enough to adequately represent large events. Landslides generally initiate on hillslope gradients greater than 0.50–0.60. The largest numbers of landslides occur on south- to southwest-facing slopes and east- to northeast-facing slopes. Most events occur on concave and straight hillslopes in upper-slope positions. Landsliding rates were found not to be affected by rock type. Hillslopes in the Queen Charlotte Islands are often mantled by weathered Quaternary deposits and, hence, landsliding events are not directly controlled by weathering of bedrock. About 31% of landslides identified in this study deposited material in stream reaches, with about 83% of these landslides deposited in reaches with gradients between 3% and 10%.

New evidence for the age of the Skonun Formation, Queen Charlotte Islands, British Columbia

1981 ◽  
Vol 18 (12) ◽  
pp. 1900-1903 ◽  
Author(s):  
N. Champigny ◽  
C. M. Henderson ◽  
G. E. Rouse
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Middle Miocene ◽  
Early Miocene ◽  
Queen Charlotte Islands ◽  
The Pacific ◽  
New Evidence

Recent palynological, megafaunal, and intrusive evidence from a section low in the Skonun Formation in the Cinola deposit on Graham Island indicates that it was deposited in the late Early Miocene, and that the age of the Skonun ranges up to the early Middle Miocene in outcrop sections on northeastern Graham Island. Correlations are made with several Miocene series of the Pacific Northwest and Alaska.

scholarly journals Relative age determination of the skull of the chacma baboon (Papio ursinus)

1983 ◽  
Vol 2 (4) ◽  
pp. 215-223
Author(s):  
J. P. Van Niekerk ◽  
O. B. Kok ◽  
L. P. Stoltz
Keyword(s):  
Nature Reserve ◽  
Age Groups ◽  
Age Determination ◽  
Permanent Teeth ◽  
Reliable Estimate ◽  
Papio Ursinus ◽  
Relative Age ◽  
Complete Set ◽  
General Size

Relative age determination was carried out on the skulls of 261 chacma baboons (Papio ursinus), 117 from the Loskopdam Nature Reserve and 144 from the Messina district in the Northern Transvaal. Seven age groups were distinguished, of which classes I-IV were based on the eruption and displacement of milk and permanent teeth. Adults with a complete set of permanent dentition were subdivided into three additional classes (V- VII), mainly on the basis of the degree of molar attrition. For comparative purposes the pattern of maturation of craniometric parameters which reflect the general size and shape of the skull, as well as the degree of closure of ectocranial sutures, were treated on the same basis. From this it is apparent that a most reliable estimate of relative age can be obtained by using all the above-mentioned criteria.

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