Growth and Habits of the Sea Mullet, Mugil dobula Gnnther, in Western Australia

1951 ◽  
Vol 2 (2) ◽  
pp. 193 ◽  
Author(s):  
JM Thomson
Keyword(s):  
Fresh Water ◽  
Western Australia ◽  
Age Groups ◽  
Age Determination ◽  
River System ◽  
The Mean ◽  
Pass Through ◽  
Considerable Individual Variation ◽  
Incomplete Sampling ◽  
Western Australian

Morphologically and physiologically, the sea mullet of Western Australia seems to be identical with that of the eastern Australian coast. No raciation can be detected either within Western Australian waters or between the stocks of eastern and Western Australia. However, the mean growth rate varies from one estuary to another and from year to year within any particular river system. Growth is isometric and shows considerable individual variation though tending to a mean rate. Increase in length is seasonal, practically stopping in midwinter and reaching a peak in midsummer. The seasons of fish and scale growth are contemporaneons. The annuli form at the end of September or the beginning of October, when growth recommences after the winter cessation. Mullet mature at a size of 31–35 cm. (12 1/2-13 3/4 in. length to caudal fin) at the end of their third year. The movement of mullet from the fishing grounds as they increase in size leads to an incomplete sampling of the population so that Petersen's method of age determination is inappIicable owing to the apparent nonprogression of the modes. Of 7110 mullet tagged, only 97 or 1.35 per cent. were returned. The return for separate tagging operations varied from nil to 25 per cent. and according to localities from nil to 16 per cent. Only three fish were retaken outside the rivers in which they were tagged. These showed a northerly movement. Inside the rivers the young fish spread out over the estuary and into the fresh water; but the older age-groups remain in the slightly brackish or fresh water except during the migration season, when they pass through the saline estuaries on the way to the sea.

Prevalence of blackleg (Leptosphaeria maculans) on canola (Brassica napus) in Western Australia

2001 ◽  
Vol 41 (1) ◽  
pp. 71 ◽  
Author(s):  
R. K. Khangura ◽  
M. J. Barbetti
Keyword(s):  
Western Australia ◽  
Disease Incidence ◽  
Leptosphaeria Maculans ◽  
Sowing Date ◽  
Blackleg Disease ◽  
The Mean ◽  
Seed Yields ◽  
Blackleg Fungus ◽  
Western Australian

Canola crops were monitored throughout the Western Australian wheatbelt during 1996–99 to determine the incidence and severity of crown cankers caused by the blackleg fungus (Leptosphaeria maculans). All crops surveyed had blackleg. The incidence of crown canker was 48–100%, 15–100%, 9–94% and 48–100% during 1996, 1997, 1998 and 1999, respectively. The mean incidence of crown cankers statewide was 85, 63, 55 and 85% in 1996, 1997, 1998 and 1999, respectively. The severity of crown canker (expressed as percentage disease index) ranged between 30 and 96%, 3 and 94%, 5 and 78% and 21 and 96% during 1996, 1997, 1998 and 1999, respectively. These high levels of blackleg can possibly be attributed to the accumulation of large amounts of infested canola residues. In 1999, there were effects of variety, application of the fungicide Impact, distance to last year’s canola residues and rainfall on the incidence and severity of blackleg. However, there were no effects of sowing date or region on the disease incidence or severity once the other factor effects listed above had been considered. In 1995, an additional survey of 19 sites in the central wheatbelt of Western Australia assessed the survival of the blackleg fungus on residues from crops grown in 1992–94. The residues at all sites carried blackleg. However, the extent of infection at any particular site varied from 12 to 100% of stems with the percentage of stems carrying pseudothecia containing ascospores varying between 7 and 96%. The high levels of blackleg disease found in commercial crops are indicative of significant losses in seed yields, making it imperative that management of blackleg be improved if canola is to remain a viable long-term cropping option in Western Australia.

The Population of a Trout Stream and the Survival of Released Fish

1958 ◽  
Vol 9 (3) ◽  
pp. 319 ◽  
Author(s):  
AG Nicholls
Keyword(s):  
Salmo Trutta ◽  
Age Groups ◽  
River System ◽  
Fish Population ◽  
Curvilinear Relationship ◽  
Growth And Survival ◽  
Younger Age ◽  
Brown Trout Salmo Trutta ◽  
Preceding Season ◽  
The Mean

The fish population of a river system was studied by electro-fishing in 25 places, after which 1000 marked yearling brown trout, Salmo trutta L., were released at each of 10 sites. In a re-examination 8 to 9 months after the release it was estimated that about 10 per cent. of these were surviving; the survival after 18 months was estimated to be below 5 per cent., and the survival to takable size, at about 3 years of age, at 2 per cent. At no site were the younger age groups of the natural population truly represented in either season, but the numbers of older fish in the second season were greater than those of the corresponding year classes in the preceding season, showing that the streams receive recruitment of younger fish from other sources. Some evidence is produced to show that "nursery" streams provide the source of recruitment. The average annual mortality for fish of 2 and 3 years of age is estimated at from 70 to 80 per cent. for the system. It is estimated that there were about 45,000 takable fish in this river system at the beginning of each season. It is shown that the mean lengths of trout decrease with increasing density of population, and that there is a curvilinear relationship between population density and total weight of all fish per acre. The standing crop of trout at different sites ranged from 1 to 182 lb/acre over the two seasons. The condition factor showed a decrease with increasing age of the fish, and the released fish had a lower factor than resident fish of the same age at all sites. In general there was a relationship between the depth of water and the length of the fish, sections over 14 in. deep having greater populations of larger fish. A study of the ability of each section of stream to carry fish, based on the lengths and condition factors of the fish, the number and weight of the population per acre, and the ability of each section to absorb additions to the population, shows that where populations were low, conditions were Iess favourable to the growth and survival of fish.

STUDIES ON THE INFLUENCE OF AGE ON OESTROGENS IN POST-MENOPAUSAL WOMEN WITH ATROPHIC ENDOMETRIUM AND NORMAL LIVER FUNCTION

1969 ◽  
Vol 62 (3) ◽  
pp. 461-467 ◽  
Author(s):  
B.-J. Procopé ◽  
H. Adlercreutz
Keyword(s):  
Age Groups ◽  
Normal Liver ◽  
Time Lapse ◽  
Mean Value ◽  
Vaginal Smear ◽  
Normal Liver Function ◽  
Menopausal Women ◽  
The Mean ◽  
Post Menopausal ◽  
Considerable Individual Variation

ABSTRACT A group of 104 post-menopausal women, who were at least 50 years old and with a time lapse of at least 2 years since the last menstruation, were investigated for their urinary oestrogen content. All the women had an atrophic endometrium as judged by histological investigation of a biopsy specimen. In 66 of the subjects the mean value of the karyopyknotic and eosinophilic indices in the vaginal smear was also calculated. The women, whose ages ranged from 50 to 79 years, were divided into 6 age groups. The median values for the excretion of oestrone, oestradiol, oestriol and total oestrogens and the mean karyopyknotic and eosinophilic indices for all age groups were very constant though there was considerable individual variation. It was also shown that the median values for all subjects were practically identical with those of 57 ovariectomized women reported in a previous study. It is concluded that in the majority of post-menopausal women with atrophic endometrium the ovarian contribution to the production of oestrogens is insignificant. It can also be concluded that with increasing age the normal liver does not significantly change the metabolism of oestrogens in post-menopausal women, as judged by the excretion of oestrone, oestradiol and oestriol, and the oestrogenic effect on the vaginal smear.

Variability in the drinking behaviour of individual emus Dromaius novaehollandiae

2016 ◽  
Vol 38 (5) ◽  
pp. 489
Author(s):  
S. J. J. F. Davies ◽  
T. A. Knight
Keyword(s):  
Western Australia ◽  
Individual Variation ◽  
Maximum Temperature ◽  
Drinking Behaviour ◽  
Time And Space ◽  
Water Influx ◽  
Dromaius Novaehollandiae ◽  
Mean Size ◽  
The Mean ◽  
Considerable Individual Variation

The drinking behaviour of four captive emus Dromaius novaehollandiae Latham 1790 was examined at the CSIRO Laboratory, Helena Valley, Western Australia. Considerable individual variation was found in the amount of water each emu drank daily, but for each bird the amount drunk was positively correlated with daily ambient maximum temperature. There was also considerable variation between individual birds in the number of sips of water taken daily, in the mean size of each sip and in the distribution of the size of sips taken in each drinking bout. Variability in drinking behaviour has been reported in other species of bird when their water influx has been calculated using double-labelled water. The availability of water to emus varies greatly in both time and space. More thirsty emus may do well when water is plentiful, whereas more abstemious ones may be favoured when water is scarce. Hence, variability in drinking behaviour would be maintained in populations.

scholarly journals Estimation of Age Using Dimensions of Apical Foramina of Teeth

2021 ◽  
Vol 10 (10) ◽  
pp. 705-710
Author(s):  
Aklesha Behera ◽  
Archana Santhanam ◽  
Herald J. Sherlin ◽  
Gifrina Jayaraj ◽  
Don K.R.
Keyword(s):  
Age Estimation ◽  
Age Groups ◽  
Age Determination ◽  
Forensic Odontology ◽  
Estimation Methods ◽  
P Value ◽  
Age Group ◽  
Human Beings ◽  
Mean Diameter ◽  
The Mean

BACKGROUND Forensic odontology is an ever growing and a flourishing science. The science deals in criminal laws by using dental knowledge. People who practice forensic odontology are called as forensic dentists. They are asked to determine the age, sex, race, occupation, previous dental history and various other determinants like DNA verification in unidentified human beings. Teeth are a very special tissue in the human body. Teeth are the only tissue which can survive through extreme climatic and environmental conditions like heat, cold etc. hence many a times retains its morphology. Age estimation has been studied by many researchers but age estimation methods have been incapable of providing the age estimation in older age groups. The study aims to determine the age using the dimensions of the apical foramen from middle age to old age groups. METHODS A descriptive ex vivo study, was done from December 2019 to March 2020. Freshly extracted teeth were collected and cleaned using hydrogen peroxide. The teeth selected were single rooted teeth like incisors, canine and premolars in the age group of 30 to 40 years, 41 - 50 years, 51 - 60 years and 61 - 70 years. Apical one third of the teeth was sectioned, mounted over a slide and placed perpendicular to the lens of the stereomicroscope. Using Mag Vision and Image J software, photomicrographs and measurements were taken. Data procured was tabulated and statistical analysis was done using Statistical Package for the Social Sciences (SPSS) version 20. RESULTS In 30 - 40 years age group, the mean diameter of all single rooted teeth was 0.35 mm. Among the 41 - 50 years age group, the mean diameter was 0.43mm. In 51 - 60 years age group it was 0.41mm and in the 61 - 70 years age group, the mean diameter was 0.36 mm. Pearson chi square P value for incisor is 0.280, canine is 0.223 and premolar is 0.326. CONCLUSIONS Age estimation can be done using physiological dimensions of apical foramen. From the present study, dimensions of apical foramen decreases with increasing age due to cementum deposition. KEY WORDS Age Determination, Apical Foramen Diameter, Single Rooted Teeth

Salinization of southwestern Western Australian rivers and the implications for the inland fish fauna - the Blackwood River, a case study

2003 ◽  
Vol 9 (3) ◽  
pp. 161 ◽  
Author(s):  
David L. Morgan ◽  
Dean C. Thorburn ◽  
Howard S. Gill
Keyword(s):  
Western Australia ◽  
Fish Fauna ◽  
River System ◽  
Main Channel ◽  
Gambusia Holbrooki ◽  
River Catchment ◽  
Low Salinity ◽  
Western Australian ◽  
Freshwater Teleosts

Increasing salinities throughout southwestern Western Australia, facilitated by extensive land clearing, have compromised the region's highly endemic freshwater fishes. Salinization of the Blackwood River has resulted in the main channel and upper cleared catchment being dominated by estuarine and halotolerant teleosts. The non-halotolerant species are restricted to the forested non-saline tributaries of the lower catchment. Of the 12 943 fish (13 species) captured in 113 sites, the halotolerant introduced Mosquitofish Gambusia holbrooki was widespread and the most abundant, representing almost 52% of fish caught. The estuarine Western Hardyhead Leptatherina wallacei, which was also widespread throughout the main channel and upper catchment, was the next most abundant, representing ca. 24% of fish caught. Freshwater endemics represented ca. 23% of captures, with the Western Minnow Galaxias occidentalis and Western Pygmy Perch Edelia vittata accounting for most (i.e., ca. 20%). There were significant differences in teleost communities among the naturally vegetated, low salinity tributaries of the river compared with the main channel and upper cleared catchment. While the forested tributaries still contain populations of E. vittata, Nightfish Bostockia porosa and Mud Minnow Galaxiella munda, the elevated salinities in the upper reaches of the Blackwood River system appear to have caused a massive decline in, or extinction of, populations of these species. The protection of the region's unique freshwater teleosts relies on the preservation of their remaining habitat in both the uncleared catchments of the region and in the low salinity forested tributaries within largely cleared systems, such as those in the Blackwood River catchment.

Mortality and Morbidity in Western Australia Due to Alcohol, Tobacco and other Drug Related Conditions during 1980–1984

1989 ◽  
Vol 19 (3) ◽  
pp. 101-104
Author(s):  
Karen Manning ◽  
Colin Binns
Keyword(s):  
Drug Abuse ◽  
Western Australia ◽  
Age Groups ◽  
Data Sources ◽  
Mortality And Morbidity ◽  
Preliminary Results ◽  
Geographical Variations ◽  
National Centre ◽  
Morbidity Data ◽  
Western Australian

The National Centre for Research into the Prevention of Drug Abuse has initiated a mortality/morbidity analysis with a view to: identifying geographical variations in drug related deaths/hospitalisations; identifying at risk sex/age groups for drug related diseases; illustrating the magnitude and diversity of drug related deaths/hospitalisations in Western Australia; and examining the patterns of drug related discharges. An overview of the study is presented, with a brief description of the computer packages used, preliminary results of geographical variations in drug related deaths, and a discussion of the Western Australian mortality and morbidity data sources available for this study. (AMRJ, 1989, 19(3), 101–104).

scholarly journals Comparative Study of Young Open Clusters: Age Determination and Stellar Content

1980 ◽  
Vol 85 ◽  
pp. 245-245
Author(s):  
J. C. Mermilliod
Keyword(s):  
Comparative Study ◽  
Age Groups ◽  
Age Determination ◽  
Open Clusters ◽  
Red Giants ◽  
Be Stars ◽  
Stellar Content ◽  
Blue Stragglers ◽  
The Mean ◽  
Hr Diagram

75 young open clusters have been divided into 14 age groups on the basis of their MV/U-B diagrams. Composite HR diagrams have been constructed and empirical isochronous curves estimated (Figure 1). The left envelope defines a ZAMS. The mean position of the red giants in the HR diagram has been investigated, as well as the occurrence and location of Ap, Am and Be stars and of blue stragglers. Red giants appear mainly in clumps (shaded area).

The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. I. Characteristics of nest trees and nest hollows.

2013 ◽  
Vol 19 (2) ◽  
pp. 121 ◽  
Author(s):  
R E Johnstone ◽  
T Kirby ◽  
K Sarti
Keyword(s):  
Social Interactions ◽  
Western Australia ◽  
Wildlife Conservation ◽  
Breeding Habitat ◽  
Breast Height ◽  
Linear Distance ◽  
Wide Range ◽  
The Mean ◽  
Old Trees ◽  
Western Australian

The Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso (FRTBC) is a large, iconic forest cockatoo, endemic to the south-west corner of Western Australia. It is currently listed as Vulnerable under the State Western Australian Wildlife Conservation Act and under the Commonwealth Environment Protection and Biodiversity Conservation Act. In this paper, we provide details of nest tree and nest hollow requirements based on details of hollows in 128 nest trees studied over 17 years. FRTBC are monogamous and pairs nest in tree hollows from 6.5–33 m above ground. Most nests are in very large and very old, mature Marri Corymbia calophylla, a long-lived endemic tree species, which is the most important nesting tree throughout the FRTBC range. Nest trees of all species had a mean circumference at breast height of 2.79 m, a mean estimated age of 222 years and a mean overall height of 20.24 m. Marri nest trees had an mean circumference at breast height of 2.76 m, a mean estimated age of 220 years (95% confidence limit 209–231 years) and an average overall height of 20.04 m. The rate of fall or loss of nest trees was high, c. 16.6% per decade. A wide range of hollow types, defined by position of the hollow in the tree, were found. Hollow aspects were also diverse. The mean height to a hollow was 14.49 m. Mean hollow depth was 1.44 m, mean floor space (the longest linear distance across the bottom of the hollow) was 33.2 cm and the mean hollow entrance area was 30 x 34 cm. FRTBC nests are typically, but not always, clustered in the landscape and social interactions within the flock are likely to play a part in the clustering of nests. Nest competitors, including feral European Honey Bee Apis mellifera, Carnaby’s Cockatoo Calyptorhynchus latirostris, Baudin’s Cockatoo C. baudinii and the Regent Parrot Polytelis anthopeplus were recorded using nest hollows once used by FRTBC. In the past Marri was harvested commercially, especially the largest and oldest trees, for timber and woodchips. In recent times the volume of Marri logs has been reduced due to a decline in markets e.g. between 2004 and 2010 a total of 95,436 m³ was harvested (K. Whitford, pers. comm.). Given the importance of large, old trees for FRTBC breeding habitat, conservation of these trees

The Movements and Migrations of Mullet (Mugil cephalus L.)

1955 ◽  
Vol 6 (3) ◽  
pp. 328 ◽  
Author(s):  
JM Thomson
Keyword(s):  
Fresh Water ◽  
Age Groups ◽  
Late Summer ◽  
River System ◽  
Mugil Cephalus ◽  
Moreton Bay ◽  
Direction Of Movement ◽  
Real Entity ◽  
Mature Fish ◽  
Considerable Period

The mullet school (Mugil cephalus L.) has a real entity. The same fish remain associated in a group for a considerable period. Some emigration from (and inferentially immigration to) the school takes place. Some schools remain in one locality (within a river system) for some months. Others appear to move more or less continually. A sojourn in fresh water does not appear to be essential though many fish are found there. It is impossible to generalize about age preferences for salinity. Fish of all age groups can be found at all times of year from fresh water to the lower saline estuaries. Some seasonal difference in the direction of movement is evident in Moreton Bay, Qld.; but this movement lacks the persistence of the seaward spawning migration of adult fish in late summer and autumn. There is some evidence to support the hypothesis that the majority of mature fish do not migrate every spawning season, but at greater intervals.

Sign in / Sign up

Export Citation Format

Share Document