Breeding and Fecundity of the Glass Shrimp, (Pasiphaea multidentata (Decapoda, Caridea), in the Gulf of Maine

1969 ◽  
Vol 26 (8) ◽  
pp. 1969-1983 ◽  
Author(s):  
S. Apollonio
Keyword(s):  
Linear Function ◽  
Growth Rates ◽  
Carapace Length ◽  
Gulf Of Maine ◽  
Sex Ratios ◽  
Decapod Crustacean ◽  
Deep Waters ◽  
Age Of Maturity ◽  
Males And Females ◽  
Second Clutch

About 1450 specimens of the decapod crustacean Pasiphaea multidentata were collected in deep waters of the Gulf of Maine in 1966–69, and were examined for size, sex, weight, breeding, fecundity, and feeding. The sizes and sex ratios of the catches vary with the egg-bearing seasons, suggesting that ovigerous females are susceptible to greater predation. The data do not permit estimates of growth rates or age of maturity. The ratios of carapace length to total length differ in males and females. Two egg clutches per female per year were produced, the second clutch being smaller in numbers, probably because of "reproductive fatigue" in the female. In each clutch the number of eggs produced is a linear function of carapace length. About 50% of the stomachs were empty. Eighteen per cent contained crustacean remains of which about half could be identified as remains of the copepods Metridia longa, M. lucens, and Euchaeta norvegica. Epizoic suctorians were found on a few shrimps.

The Winter Flounder (Pseudopleuronectes americanus) in Long Pond, Conception Bay, Newfoundland

1971 ◽  
Vol 28 (8) ◽  
pp. 1153-1165 ◽  
Author(s):  
V. S. Kennedy ◽  
D. H. Steele
Keyword(s):  
Food Intake ◽  
Growth Rates ◽  
Plant Material ◽  
Early Growth ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Food Items ◽  
Fish Remains ◽  
Males And Females ◽  
Conception Bay

Monthly samples of winter flounder taken in Long Pond from November 1962 to October 1963 indicated that the flounder moved into deeper water (7–10 m) during the summer and returned to shallow water (1–2 m) from September to June. These movements corresponded to the end of the spawning season and the ripening of the gonads respectively. Spawning occurred from March until early June, most of it in May and early June. Most males were mature at age 6 and most females at age 7. Fifty percent of the males and females were mature at 21 and 25 cm respectively. The growth rates of the males and females were similar until the age of 8, after which the females apparently outgrew the males. Early growth and fecundity were similar to those reported for other areas. No feeding took place in December or January but the flounder fed in March and continued to feed throughout the summer; food intake decreased in the fall. They were omnivorous and the type of food eaten varied with the locality. Polychaetes, plant material, and molluscs were the most common food items throughout the year. Capelin eggs and fish remains were found only during a few months of the year but were eaten in great quantities.

Size–Maturity Relationships and Related Observations in Newfoundland Populations of the Lobster (Homarus americanus)

1980 ◽  
Vol 37 (6) ◽  
pp. 945-956 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Carapace Length ◽  
Size Range ◽  
Sex Ratios ◽  
Weight Ratio ◽  
Homarus Americanus ◽  
Spawning Season ◽  
Length Ratio ◽  
Maturity Indices

Female maturity ogives for five Newfoundland populations of the lobster (Homarus americanus) gave 50% maturities ranging from 71- to 76-mm carapace length. Sizes at which distinct inflections (indicating onset of maturity) and asymptotes (indicating 100% mature) are present in the abdomen width/carapace length ratio vs. carapace length relationships coincide with the smallest ovigerous and largest immature specimens, respectively, observed in those particular samples. Inflection in the crusher claw weight/whole weight ratio vs. carapace length relationships (used in this paper to indicate onset of maturity in males) occurred at larger sizes than inflections in the abdomen width/carapace length ratios of females.The percentage of nonovigerous females that spawn in a given year generally increases with increasing size. The highest percentage of nonovigerous females tagged with sphyrion tags prior to the spawning season that were ovigerous when recaptured 10–12 mo later was 83.8%. The percentage of ovigerous females with new shells (i.e. molted and spawned in same year) varied between areas and years and ranged from 0 to 38.5% of the total number of ovigerous females in fall samples. The percentage of ovigerous females in samples also varied between areas and years and ranged from 2.6 to 30.4% of the total number of females greater than the size at 50% maturity. In general a greater percentage of females was ovigerous at sizes between the size at 50% maturity and 80 mm (largest subcommercial size) than at commercial sizes.In a sample of nonovigerous females, the size range at which 50% were fertilized (76–80 mm) coincided closely with the size at 50% maturity (75 mm) for the area.At subcommercial sizes (< 81 mm) the sexes were approximately equally represented in fall trap-caught samples but females heavily outnumbered males in diver-caught samples taken over the same period. At commercial sizes, however, males heavily outnumbered females in the trap-caught samples while in diver-caught samples the sexes were equally represented.Key words: lobster (Homarus americanus), maturity ogives, maturity indices, percent ovigerous, sex ratios

A new male-killing parasitism:Spiroplasmabacteria infect the ladybird beetleAnisosticta novemdecimpunctata(Coleoptera: Coccinellidae)

Parasitology ◽  
2006 ◽  
Vol 132 (6) ◽  
pp. 757-765 ◽  
Author(s):  
M. C. TINSLEY ◽  
M. E. N. MAJERUS
Keyword(s):  
Phylogenetic Analysis ◽  
Sex Ratio ◽  
High Efficiency ◽  
Sex Ratios ◽  
Egg Hatch ◽  
Hatch Rate ◽  
Male Killing ◽  
Offspring Sex ◽  
Novel Host ◽  
Males And Females

Whilst most animals invest equally in males and females when they reproduce, a variety of vertically transmitted parasites has evolved the ability to distort the offspring sex ratios of their hosts. One such group of parasites are male-killing bacteria. Here we report the discovery of females of the ladybirdAnisosticta novemdecimpunctatathat produced highly female-biased offspring sex ratios associated with a 50% reduction in egg hatch rate. This trait was maternally transmitted with high efficiency, was antibiotic sensitive and was infectious following experimental haemolymph injection. We identified the cause as a male-killingSpiroplasmabacterium and phylogenetic analysis of rDNA revealed that it belongs to theSpiroplasma ixodetisclade in which other sex ratio distorters lie. We tested the potential for interspecific horizontal transfer by injection from an infectedA. novemdecimpunctataline into uninfected individuals of the two-spot ladybirdAdalia bipunctata. In this novel host, the bacterium was able to establish infection, transmit vertically and kill male embryos.

VARIATION, SEXUAL DIMORPHISM, AND MATURITY IN A QUEBEC POPULATION OF THE COMMON SNAPPING TURTLE, CHELYDRA SERPENTINA

1960 ◽  
Vol 38 (1) ◽  
pp. 19-38 ◽  
Author(s):  
James E. Mosimann ◽  
J. Roger Bider
Keyword(s):  
Carapace Length ◽  
Relative Rate ◽  
Analysis Of Covariance ◽  
Head Width ◽  
Posterior Lobe ◽  
Chelydra Serpentina ◽  
Single Population ◽  
Species Analysis ◽  
The Common ◽  
Males And Females

An analysis was made of a sample of 55 snapping turtles, Chelydra serpentina, from a single locality in southern Quebec. The variation studied is regarded as being representative of that of a single population of the species. Analysis of covariance was used in studying dimorphism in various measurements. Conclusions reached are: (a) the sex ratio is one; (b) males grow to a larger size than females; (c) males and females become mature at a carapace length of about 200 millimeters; (d) the ratio precloacal distance over posterior lobe of the plastron gives a practical index for sex determination in adults; (e) there is a set of small but interrelated changes correlated with a greater precloacal distance in the male: These are that males have the plastron shifted forward slightly, have the bridge slightly longer relative to plastron length, and have the posterior lobe of the plastron slightly shorter relative to plastron length; (f) the precloacal length of the male (which area accommodates the penis) grows relatively faster than carapace length; the precloacal length of the female grows at the same relative rate as carapace length; (g) there is virtually no dimorphism in shell dimensions nor in head width.

scholarly journals A multivariate study of variation in two species of rock crab of the genus Leptograpsus

1974 ◽  
Vol 22 (3) ◽  
pp. 417 ◽  
Author(s):  
NA Campbell ◽  
RJ Mahon
Keyword(s):  
Carapace Length ◽  
Carapace Width ◽  
The Body ◽  
Canonical Variate ◽  
Multivariate Approach ◽  
Maximum Width ◽  
Multivariate Study ◽  
Rock Crab ◽  
Males And Females ◽  
Colour Form

A multivariate approach has been used to study morphological variation in the blue and orange-form species of rock crab of the genus Leptograpsus. Objective criteria for the identification of the two species are established, based on the following characters: width of the frontal region of the carapace; width of the posterior region of the carapace (rear width); length of the carapace along the midline; maximum width of the carapace; and the depth of the body. The first canonical variate, which differentiates between the two species, represents a contrast between the carapace width relative to the width of the front lip and the depth of the body; the blue-form species has a greater relative carapace width than has the orange form. The second canonical variate, which presents a contrast between the rear width and the carapace length, identifies males and females within each species; males have a greater relative carapace length than have females. All individuals, including 20 not used in the study, were correctly identified for colour form. The clear separation of the blue and orange forms achieved by canonical analysis supports the previously determined specific status of the two forms.

scholarly journals Analysis of the sex ratio in Bradysia matogrossensis (Diptera, Sciaridae)

2000 ◽  
Vol 23 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Lincoln S. Rocha ◽  
André Luiz P. Perondini
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
X Chromosome ◽  
Control Mechanism ◽  
Sex Ratios ◽  
Laboratory Strain ◽  
Chromosome Elimination ◽  
Common Control ◽  
Males And Females ◽  
Successive Generations

In sciarid flies, the control of sex determination and of the progeny sex ratio is exercised by the parental females, and is based on differential X-chromosome elimination in the initial stages of embryogenesis. In some species, the females produce unisexual progenies (monogenic females) while in others, the progenies consist of males and females (digenic females). The sex ratio of bisexual progenies is variable, and departs considerably from 1:1. Bradysia matogrossensis shows both monogenic and digenic reproduction. In a recently established laboratory strain of this species, 15% of the females were digenic, 10% produced only females, 13% produced only males, and 62% produced progenies with one predominant sex (33% predominantly of female and 29% predominantly male progenies). These progeny sex ratios were maintained in successive generations. Females from female-skewed progenies yielded female- and male-producing daughters in a 1:1 ratio. In contrast, daughters of females from male-skewed progenies produce bisexual or male-skewed progenies. The X-chromosome of B. matogrossensis shows no inversion or other gross aberration. These results suggest that the control of the progeny sex ratio (or differential X-chromosome elimination) involves more than one locus or, at least, more than one pair of alleles. The data also suggest that, in sciarid flies, monogeny and digeny may share a common control mechanism.

Panulirus echinatus population in the Brazilian oceanic ecosystem Rocas Atoll

Crustaceana ◽  
2019 ◽  
Vol 92 (2) ◽  
pp. 221-232 ◽  
Author(s):  
Juliana Gaeta ◽  
Raúl Cruz
Keyword(s):  
Sex Ratio ◽  
Carapace Length ◽  
Reproduction Period ◽  
Males And Females ◽  
The Mean ◽  
Oceanic Ecosystem ◽  
Abundant Population ◽  
Future Information

Abstract In Rocas Atoll (03°51′S 033°48′W) a most abundant population of Panulirus echinatus Smith, 1869 was observed during free dives. Numbers of males and females were almost the same, with an overall sex ratio M : F = 1.1. In addition, males are larger than females, with a mean male carapace length (CL) of 92.6 ± 1.8 mm, while the female mean CL was 72.7 ± 1.0 mm and for both sex combined the mean CL was 83.1 ± 1.4 mm. The percentage of females breeding, i.e., with a spermatophore mass or eggs, was 75.1%. More information is needed to better understand the fluctuation in densities over a year cycle, the reproduction period, and differences in CL between males and females, as well as other aspects of the biology of this species. The present work and future information could help to formulate fisheries policies aimed at protecting P. echinatus stocks.

Age, Growth, and Sexual Maturity of the Shorthorn Sculpin, Myoxocephalus scorpius, in Newfoundland Waters

1970 ◽  
Vol 27 (12) ◽  
pp. 2155-2158 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Growth Rates ◽  
Sexual Maturity ◽  
Average Length ◽  
Maximum Size ◽  
Age Group ◽  
Younger Age ◽  
Shorthorn Sculpin ◽  
Males And Females ◽  
The Difference ◽  
Myoxocephalus Scorpius

In Newfoundland waters, shorthorn sculpins, Myoxocephalus scorpius (L.), live to age 15 and attain a maximum size of just over 50 cm. The growth rates of males and females are little different below age 4, but above age 4 the females grow faster than the males, and the difference between average length-at-age for males and females gets progressively larger with age. Males mature at a younger age and at a smaller size than females. In any age-group where there are mature and immature individuals the mature ones are larger.

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