Reproductive cycles in the eastern subspecies of the Australian salmon, Arripis trutta marginata (Cuvier & Valenciennes)

1977 ◽  
Vol 28 (3) ◽  
pp. 287 ◽  
Author(s):  
CA Stanley ◽  
WB Malcolm
Keyword(s):  
Sexual Activity ◽  
New South ◽  
Juvenile Fish ◽  
Gonad Weight ◽  
Spawning Activity ◽  
Similar Work ◽  
South Wales ◽  
Younger Age ◽  
Reproductive Cycles ◽  
Weight Data

To complement similar work carried out on the western subspecies of the Australian salmon (Arripis trutta esper), the known data on the reproductive cycle of the eastern subspecies (A. t. marginata) are summarized. The data (collected between 1961 and 1963) consisted of ovary and testis welghts, fish lengths, oocyte diameters from preserved ovaries, and information from histological material. The gonad weight data were analysed to show increases in ovary and testls weights, which were indicative of sexual activity. Supporting information was extracted from changes in maximum oocyte diameters, and from examination of histological sections. The onset of sexual maturity for juvenile fish in Tasmanian waters occurred at a length of approximately 39 cm (equivalent to the end of the fourth year of life). The corresponding length for the western subspecies is 54 cm (at approximately the same age), and 52-54 cm for New Zealand fish. There was no evidence of spawning activity in Tasmanian waters. Cycles of sexual activity were observed in fish from the Lakes Entrance area of Victoria and the Eden and Bermagul areas of southern New South Wales. Spawning activity was deduced to occur between December and January in the Lakes Entrance area, between January and February in the Eden area, and between November and February in the Bermagui area. Sexual maturation may commence in males at a slightly younger age than in females.

Growth of four species of juvenile fish associated with the Seagrass Zostera capricorni, in Botany Bay, NSW

1992 ◽  
Vol 43 (5) ◽  
pp. 1189 ◽  
Author(s):  
DG Worthington ◽  
DJ Ferrell ◽  
SE NcNeill ◽  
JD Bell
Keyword(s):  
Sea Water ◽  
New South ◽  
Juvenile Fish ◽  
Natural Populations ◽  
Length Frequency ◽  
Frequency Distributions ◽  
South Wales ◽  
Time Period ◽  
Flow Through ◽  
Sampling Programme

Populations of four species of juvenile fish- Rhabdosargus sarba, Acanthopagrus australis, Achoerodus viridis and Girella tricuspidata-were sampled from a seagrass bed in Botany Bay, New South Wales. Fish were collected eight times between 22 March 1990 and 22 February 1991, using a small seine-net. Growth rates were calculated from the progression of cohorts in length-frequency distributions. Cohorts of R. sarba, A. australis and A. viridis grew most slowly during winter (0.02, 0.04 and 0.21 mm day-1, respectively); growth then increased, peaking just prior to the loss of the cohort from the habitat (0.3 1, 0.24 and 0.39 mm day-1). Populations of R. sarba, A. australis and A. viridis were comprised of one or two cohorts that remained in the habitat for at least 3-4 months. Conversely, up to seven cohorts of G. tricuspidata were found between October and February, and most cohorts did not remain in the habitat for more than 2 months. As a result, there were only two confident estimates of growth for G. tricuspidata: 0.23 mm day-1 between October and November, and 0.34 mm day-1 between January and February. Individuals of each species were also kept in a flow-through 4000-L tank of sea water. Growth of cohorts of fish kept in the tank was very similar to that found in natural populations during the same time period. The rates of recruitment and loss of cohorts from seagrass can be rapid and these factors must be considered in designing a sampling programme to assess growth by analysis of length-frequency distributions.

Reproductive cycles, fat body cycles and socio-sexual behaviour in the Mallee dragon, Amphibolurus fordi (Lacertilia : Agamidae)

1978 ◽  
Vol 26 (4) ◽  
pp. 653 ◽  
Author(s):  
HG Cogger
Keyword(s):  
Life Cycle ◽  
Sex Ratio ◽  
Fat Body ◽  
New South ◽  
Reproductive Period ◽  
South Wales ◽  
Behavioural Types ◽  
Fat Bodies ◽  
Reproductive Cycles ◽  
Sexually Mature

A field study of the reproductive and fat cycles of the small agamid lizard Amphibolurus fordi was undertaken in two areas of mallee in central western New South Wales. The development of the gonads, including the histology of the testicular cycle, is described, together with correlated changes in the size of the inguinal fat bodies. The males emerge from winter torpor some 4-5 weeks before the females. The sex ratio approximates unity throughout the life cycle. Mating occurs from October to December; up to three clutches each of two or three eggs are laid in a season. The eggs hatch in 7-9 weeks after laying. The construction of the nesting chamber by the female is described. Apart from behaviour specifically geared to thermoregulation, two other behavioural types have been identified: male-female interactions involving only sexually mature individuals during the reproductive period, and non-sex-specific patterns which occur in both immature and mature individuals of either sex. Males are not territorial.

Seasonal changes in Pelage of Miniopterus schreibersi blepotis (Chiroptera) in north-eastern NSW.

1963 ◽  
Vol 11 (3) ◽  
pp. 290 ◽  
Author(s):  
PD Dwyer
Keyword(s):  
Seasonal Changes ◽  
New South ◽  
New South Wales ◽  
Age Groups ◽  
Adult Females ◽  
Early Autumn ◽  
South Wales ◽  
North Eastern ◽  
Reproductive Cycles

In M. s. blepotis, of north-eastern New South Wales, the annual moult occurs during the summer and early autumn and lasts about 14.5 weeks. Yearlings having their first moult usually initiate this some 3 weeks after the adults commence. In many adult females the moult is inhibited during lactation and again during the winter so that some individuals may be found moulting in all months of the year. The importance of considering annual pelage characters when using colour taxonomically in bats is emphasized, and possible relationships between moult and reproductive cycles are indicated. In addition the use of pelage characteristics, in conjunction with reproductive criteria as a means of recognizing age groups of M. s. blepotis, is discussed.

Evaluation of the Condom Distribution Program in New South Wales Prisons, Australia

2004 ◽  
Vol 32 (1) ◽  
pp. 124-128 ◽  
Author(s):  
Kate Dolan ◽  
David Lowe ◽  
James Shearer
Keyword(s):  
General Population ◽  
Condom Use ◽  
Sexual Activity ◽  
Sex Workers ◽  
Drug Users ◽  
Hiv Transmission ◽  
New South ◽  
South Wales ◽  
Homosexual Activity ◽  
Sexual Health Behaviors

Male to male unprotected anal sex is the main route of HIV transmission in Australia. The Australian Study of Health and Relationships, a large, representative population survey of sexual health behaviors, found that six percent of males in the general population have engaged in homosexual activity. These findings were consistent with studies in Europeand North America. Condoms have been shown to reduce the transmission of HIV in the community. Barriers to the use of condoms include access,stigma,and cost? Nevertheless, increased condom use has been reported among homosexual males, sex workers and injecting drug users although recent declines in condom use among homosexuals has presented new challenges in HIV prevention.The prevalence of male to male sexual activity may be higher in prison than in the general population. Sexual activity in prison can be consensual and non-consensual involving both homosexual / bisexual and heterosexual men.

Drifting objects as habitat for pelagic juvenile fish off New South Wales, Australia

2004 ◽  
Vol 55 (7) ◽  
pp. 675 ◽  
Author(s):  
Tim Dempster ◽  
Michael J. Kingsford
Keyword(s):  
New South ◽  
Juvenile Fish ◽  
New South Wales ◽  
Weather Conditions ◽  
Small Fish ◽  
Drift Algae ◽  
Odour Source ◽  
South Wales ◽  
Fish Aggregation ◽  
Drifting Algae

The importance of drifting objects to small juvenile pelagic fish was investigated off the coast of New South Wales, Australia. Distance-related and temporal patterns in the distribution of clumps of drifting algae were investigated with 5000 m2 transects at five distances from shore (0.1, 0.5, 1, 5 and 10 km), two to three times per season for 2 years. Juvenile fish associated with drift algae were collected. Clumps of algae, predominantly Sargassum spp., were most abundant in spring, which coincided with the highest abundance of alga-associated post-flexion juvenile fish. Drift algae were also most abundant close to shore, probably due to the proximity to source and the dominant onshore winds. Fish were quickly attracted to drifting artificial objects (fish aggregation device; FADs), although the magnitude of attraction varied greatly among days. The relative abundance of small fish in open waters available to colonise FADs and differing weather conditions may explain much of this variability. More fish colonised FADs with an odour source than unscented control FADs, indicating small fish may use chemical cues to locate drifting structures. We conclude that juvenile fish actively seek drifting objects as pre-settlement habitat, which may reduce predation and enhance settlement opportunities.

Mixed model estimation of age and month of calving adjustment factors for milk and butterfat yields of New South Wales dairy cattle

1982 ◽  
Vol 33 (4) ◽  
pp. 731 ◽  
Author(s):  
RW Everett ◽  
JF Taylor ◽  
K Hammond
Keyword(s):  
Mixed Model ◽  
New South ◽  
New South Wales ◽  
South Wales ◽  
Younger Age ◽  
Adjustment Factors ◽  
June July ◽  
Jersey Cows ◽  
Genetic Trends ◽  
Friesian Cows

Month-age adjustment factors for milk and butterfat yields were estimated from 504063 lactations on 239 518 cows located in 6 145 herds in New South Wales by mixed model methods, which eliminate biases due to genetic trends, environmental trends and culling. June, July and August are the most favourable months for calving, and December and January are the least favourable, resulting in 8 to 22% less production. Friesian cows are less affected by calendar month of calving than the other breeds. Results indicate the existence of large differences between breeds in rate of maturity. Ayrshire and Jersey cows attain mature yields at a younger age than AIS, Guernsey, Friesian and AMZ cows.

Feeding ecology of the temperate marine fish Achoerodus viridis (Labridae): Size, seasonal and site-specific differences

1995 ◽  
Vol 46 (7) ◽  
pp. 1009 ◽  
Author(s):  
BM Gillanders
Keyword(s):  
Feeding Ecology ◽  
Feeding Rate ◽  
New South ◽  
Juvenile Fish ◽  
Rocky Reef ◽  
Rocky Reefs ◽  
South Wales ◽  
Labrid Fish ◽  
Harpacticoid Copepods ◽  
Rocky Reef Fish

Fish were collected from localities in the Sydney region, New South Wales, Australia, from March 1991 to September 1993. Achoerodus viridis is a benthic carnivore and consumes a wide variety of prey items. Size-specific differences in diet were found. The diet of recruits (17-26 mm SL) collected in seagrass environments was dominated by tanaids, whereas that of rocky reef recruits was dominated by harpacticoid copepods. The diet of rocky reef fish then shifted to gammarid amphipods and other crustaceans (fish 50-150 mm SL) and to mussels and urchins (fish >300 mm SL). Juvenile fish on rocky reefs (450 mm SL) foraged in shallow fringing habitat, whereas adult fish (>200 mm SL) foraged in deeper turf and barrens habitats, reflecting the depth distribution of the species. Feeding rate of larger fish tended to be less than that of smaller fish. Variations in diet and feeding rate were also detected over the year but the patterns were not consistent between years. Among sites, there were differences in diet but these were not related to the position of sites inside an estuary or on the open coast. The results of this study provide information on the feeding ecology of a large labrid fish; this information will aid in understanding the population dynamics of the species.

Area of Distribution, Movements, Age Composition and Mortality Rates of the Australian Salmon Population in Tasmania, Victoria and New South Wales

1978 ◽  
Vol 29 (4) ◽  
pp. 417 ◽  
Author(s):  
CA Stanley
Keyword(s):  
New South ◽  
New South Wales ◽  
Age Groups ◽  
South Australia ◽  
South Wales ◽  
Younger Age ◽  
Salmon Population ◽  
Show Evidence ◽  
Western Victoria ◽  
Age Range

Two subspecies of the Australian salmon, a perciform fish, occur in eastern Australian waters. The western subspecies, Arripis trutta esper (Whitley), is found only in Tasmania and Victoria. In Tasmanian waters fish do not occur above an age of 2+ years. In Victoria about 300 000 fish (180 tonnes) of an age range from of to 5+ years are caught annually. The younger age groups are found in sheltered areas, and the older age groups along the open coastline, especially in western Victoria. Returns of tags from fish thought to be of the western subspecies indicate that movement towards Western Australia takes place via western Victoria and South Australia, rather than by a direct seawards movement. For the eastern subspecies, Arripis trutta marginata (Cuvier & Valenciennes), young fish from 0+ to 2+ years are found predominantly in Tasmania and Victoria, and older fish from 4+ years in New South Wales. Recaptures of tagged fish indicate that there is a continual movement at all stages of the life cycle from Tasmania to Victoria and then to New South Wales. Fish within New South Wales also show evidence of a movement southwards, which probably occurs only once, to the eastern Bass Strait area. Fish older than 5+ years move increasingly northwards in New South Wales waters. For the eastern subspecies estimates of M, the instantaneous annual natural mortality coefficient, range from 0.5 to 1.0, and estimates of F, the instantaneous annual fishing mortality coefficient, range from 0.3 to 0.7. It is suggested that in the present eastern subspecies fishery greater yields should result from increasing the fishing pressure up to about twice the present value.

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