Reproductive biology of the protogynous hermaphrodite Achoerodus viridis (Labridae) from south-eastern Australia

1995 ◽  
Vol 46 (7) ◽  
pp. 999 ◽  
Author(s):  
BM Gillanders
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Age Classes ◽  
South Eastern ◽  
Eastern Australia ◽  
Protogynous Hermaphrodite ◽  
Mature Fish ◽  
A Site ◽  
Gonadal Structure

Achoerodus viridis (Pisces : Labridae) was sampled over two years at Little Bay, NSW, Australia, and comparative material was taken from a site 4.5 km away at Cape Solander. Population structure and gonadal structure showed that A. viridis was protogynous and monandric (i.e. no primary males were found). Histological sections of male gonads showed a gonadal lumen, general ovarian lamellar form and multiple sperm ducts running longitudinally through the gonad wall. Males dominated the larger size and age classes, whereas females predominated in the smaller size and age classes. The sex ratio of mature fish and the whole population was biased in favour of females. Individuals at both sites matured as females at 1+-2+ years. Fish at Little Bay functioned as females at ages ranging from 8+ to 18+ years before changing sex at a size between 480 and 580 mm SL. Fish at Cape Solander may function as females for up to 18+' years and change sex between 500 and 520 mm SL. Spawning occurred between July and October (1991-93).

The Rabbit in Subalpine South-eastern Australia. I. Population Structure and Productivity

1974 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Dunsmore
Keyword(s):  
Population Structure ◽  
National Park ◽  
Initial Level ◽  
Adult Survival ◽  
South Eastern ◽  
Breeding Group ◽  
Eastern Australia ◽  
Domestic Livestock ◽  
A Site ◽  
Better Than

An unconfined, almost completely tagged rabbit population on a site of about 100 ha was studied by observation and trapping for 5 years. The commencement of the study coincided approximately with the incorporation of the area into the Kosciusko National Park, the elimination of grazing by domestic livestock, and the cessation of the previously almost annual burning of the area. During the 5-yr study the fecundity of the rabbits declined to little more than half the initial level. This was not a result of the concurrently increasing age of the population, which was shown to be quite unrelated. It was also shown that the 1yr old rabbits were less fecund than the older rabbits, whose fecundity remained constant. Although it appeared subjectively to be so, the area was not uniformly suitable for the survival of rabbits. In one of its four subdivisions adult survival was much better than in the others; and in one of the others it was much the worst. During the study there was considerable immigration to the area, presumably balanced by migration. Females tended to remain where they were born and in no case changed from one breeding group to another. Males were considerably less sedentary than the females.

Abundance and biology of warty oreo (Allocyttus verrucosus) and spiky oreo (Neocyttus rhomboidalis) (Oreosomatidae) off south-eastern Australia

1997 ◽  
Vol 48 (2) ◽  
pp. 91 ◽  
Author(s):  
J. M. Lyle ◽  
D. C. Smith
Keyword(s):  
Continental Slope ◽  
Reproductive Biology ◽  
Size Structure ◽  
Depth Range ◽  
South Eastern ◽  
Species Overlap ◽  
Eastern Australia ◽  
Prey Items ◽  
South Eastern Australia ◽  
Depth Distributions

The distribution, abundance, size structure, reproductive biology and diet of warty oreo, Allocyttus verrucosus (Gilchrist), and spiky oreo, Neocyttus rhomboidalis (Gilchrist), from the continental slope region (400-1200 m depth) of south-eastern Australia are described. The depth distributions of the two species overlap, with spiky oreo being more abundant in intermediate depths (600-800 m) and warty oreo abundance peaking at greater depths (900-1200 m). There was evidence of size structuring with depth. Warty oreo juveniles and subadults were comparatively more abundant in depths of less than 1000 m and adults dominated at greater depths. In spiky oreo, juveniles were largely restricted to the depth range of 700-900 m. Size at 50% maturity in females was 28 and 35 cm for warty and spiky oreos, respectively. Males mature at slightly smaller sizes. Spawning occurs in May–June for warty oreo and between August and October for spiky oreo. Just prior to spawning in warty oreo the sexes appear to segregate by depth, with females becoming progressively more dominant with depth. Both species are benthopelagic feeders, consuming a range of prey items including crustaceans, fish and squid. Salps were also an important component of the diet of spiky oreo.

scholarly journals Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil

2016 ◽  
Vol 64 (1) ◽  
pp. 69 ◽  
Author(s):  
Matheus Tenorio Baumgartner ◽  
Pedro Rogério Leandro da Silva ◽  
Gilmar Baumgartner
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
River Basin ◽  
Reproductive Biology ◽  
Body Length ◽  
Fish Species ◽  
Energy Allocation ◽  
Influence Area ◽  
Endemic Fish ◽  
Iguaçu River

Success in fish breeding depends on reproduction intensity, periodicity and the place where it occurs. Information about fish species reproduction is important to assist managers, and to determine conservation and management strategies. The fish assemblage of the Iguaçu River basin is already known for its high endemism, and despite this privilege, the large number of dams built along it, threat this particular biodiversity. Astyanax gymnodontus is an endemic fish species and studies on its population structure and reproductive biology are important, since they represent the first step for further community studies. Our objective was to evaluate some aspects of the population structure and reproductive biology of A. gymnodontus in the influence area of Salto Santiago dam, Iguaçu River, Paraná State, Brazil. Sampling was made monthly from July 2003 to June 2005, and bimonthly from July 2005 to March 2013, at five sites in the influence area of Salto Santiago dam. Fishes were collected using 10 m length gillnets with meshes ranging from 2.5 to 6.0 cm between non-adjacent knots and trammel nets with inner meshes of 6.0 cm between non-adjacent knots. Nets were arranged on surface, bottom and margins of each site, exposed for 24 h. Additional drags on littoral areas were performed from January to March and October to December from 2009 to 2011, with 50.0 m nets, 0.5 cm mesh size, for juveniles capture. We captured and analyzed 21 932 individuals, being 9 249 females and 12 683 males, representing 42.2 % and 57.8 %, respectively. The average body length was 8.8 cm for females and 8.3 cm for males. The average weight was 18.8 g for females and 16.0 g for males. Sex ratio calculated for the entire period was 1.8 males/female. Males were more abundant than females in 73.2 % of samples and significant differences were observed in 35.3 % of samples. The estimated length at first maturity (SL50) was 6.4 cm for females and 6.2 cm for males. We suggest that sexual differences in body length and weight, and sex ratio occurred as a result of sexual differences in energy allocation. Females spend more energy on body growth, which means more eggs production and higher fecundity. As an integrated response, males spend more energy on sperm production, in competition with other males, leading to a smaller body size. Differences in estimated SL50 might be an indicator of this sexual difference in energy allocation. The reproduction period was from September to February, with greater intensity at the beginning of this period, and the sites of highest reproductive intensity were those immediate downstream from dams, and therefore with more riverine characteristics.

scholarly journals Reproductive biology of female blue swimmer crabs in the temperate estuaries of south-eastern Australia

2021 ◽  
Author(s):  
Samuel E. F. Nolan ◽  
Daniel D. Johnson ◽  
Roshan Hanamseth ◽  
Iain M. Suthers ◽  
Matthew D. Taylor
Keyword(s):  
Reproductive Biology ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

scholarly journals Population Structure and Reproductive Biology of the Endangered Crab Deiratonotus japonicus (Brachyura, Camptandriidae) Surveyed for Nine Years in the Kita River, Japan

2020 ◽  
Vol 8 (11) ◽  
pp. 921
Author(s):  
Il-Kweun Oh ◽  
Seung-Woo Lee
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Carapace Width ◽  
River Mouth ◽  
Sampling Period ◽  
Sampling Station ◽  
Egg Number ◽  
Kanagawa Prefecture ◽  
The Mean

Deiratonotus japonicus (D. japonicus) is known as a near-threatened species, because of the changing conditions of its habitat. This species resides in isolated locations and in upstream, brackish waters from Kanagawa Prefecture to Okinawa Prefecture in Japan. In this study, we investigated the population structure and reproductive biology of D. japonicus in the Kita River, Japan. The distribution, sex ratio, breeding season, and fecundity were assessed at bimonthly intervals during spring low-tide periods from May 2001 to November 2008 and from November 2014 to January 2016 for approximately nine years. A total of 3525 crabs were collected during the sampling period: 1806 (51.2%) males, 1240 (35.2%) non-ovigerous females, and 479 (13.6%) ovigerous females. The overall sex ratio (1:0.95) did not differ significantly from the expected 1:1 ratio. The mean maximum density was 26.1 and 36.5 indiv./m2 for the first and second sampling periods, respectively, in the sampling station 5.2 km from the Kita River mouth, and all individuals were typically found approximately 4.4–6.8 km (13.2 ± 7.8 indiv./m2) from the Kita River mouth. Carapace width (CW) ranged from 2.6 to 13.5 mm in males and from 2.8 to 13.4 mm in females and was significantly different between the two sexes (p < 0.05). Ovigerous females were found almost throughout the entire sampling period, with breeding peaks between July and September. The smallest ovigerous female had a CW of 3.9 mm. The seasonal frequency distribution suggested the continuous recruitment of young juveniles (CW < 3.9 mm) throughout the year, with peaks from September to November. The mean fecundity was 1008.3 ± 183.1 (8.3 ± 1.6 mm) eggs. Egg number in relation to CW was calculated by the formula egg number (EN) = 110.36 × CW + 90.96 (R2 = 0.948, n = 41, p < 0.0001). Regression analysis showed that fecundity was closely associated with female CW. Our results indicate that the performance of reproductive biology depends not only on continuous breeding but also on recruitment throughout the year in our study area.

The Founding Population - the Effect of Differences in Its Size, Nature and Season of Establishment on the Subsequent Dynamics of Populations of House Mice, Mus-Musculus L

1990 ◽  
Vol 38 (5) ◽  
pp. 479
Author(s):  
PR Pennycuik ◽  
AH Reisner
Keyword(s):  
Age Structure ◽  
Wide Band ◽  
Age Classes ◽  
South Eastern ◽  
Founding Population ◽  
Eastern Australia ◽  
Agricultural Areas ◽  
Ephemeral Habitats ◽  
Dynamics Of Populations ◽  
South Eastern Australia

In south-eastern Australia, house mouse numbers in agricultural areas often reach plague proportions in the year following the breaking of a drought but numbers are usually low in subsequent years. The effects of differences in the size and nature of the groups invading ephemeral habitats on sub- sequent numbers, and on the time taken for the population to peak, were investigated by introducing groups of different size, age structure and composition into out-door pens where food supplies were abundant. The effects of differences in the season of invasion and the effects of allowing mice from one or two sources to invade empty home sites were also investigated. Varying the size of the founding groups had little effect on peak numbers or on the length of the establishment-peak interval. Peak numbers were usually higher in populations established with mice from a narrow band of age classes than in those established with mice from a wide band of age classes, and the establishment-peak interval was usually shorter in populations established with mice from one source than in populations established with mice from two sources. The establishment-peak interval was also shorter in populations established in spring than in those established at other seasons. When established groups were allowed access to empty home sites, the groups colonising the sites varied in size, age structure and composition. Peak heights in these colonies, too, appeared to be affected by the age structure of the founding group, and the establishment-peak interval was affected by the composition of the group. These results suggest that both between-year differences in the nature of the groups moving from the refuge areas to the growing crops, and between-year differences in the season at which the crops are colonised, could contribute to the observed differences in mouse numbers in the agricultural areas of south-eastern Australia. Possible reasons for between-year differences in the nature of the groups colonising the ephemeral habitats are discussed.

scholarly journals Iheringichthys labrosus (Siluriformes: Pimelodidae) in the Piquiri River, Paraná, Brazil: population structure and some aspects of its reproductive biology

2009 ◽  
Vol 7 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Arlei J. Holzbach ◽  
Éder A. Gubiani ◽  
Gilmar Baumgartner
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Standard Length ◽  
Length Distribution ◽  
Temporal Distribution ◽  
Spatial And Temporal Distribution ◽  
Night Time ◽  
Reproduction Period ◽  
Iheringichthys Labrosus

The purpose of this study was to analyze the population structure (spatial and temporal distribution, sex ratio, length distribution and length/weight relationship) and reproductive biology of Iheringichthys labrosus. This species is of importance as fisheries resource in the Paraná River basin. Fish were sampled, bimonthly, with gill and trammel nets at three sampling sites (Campina, Apertado and Altônia), located in the Piquiri River, between November 2002 and September 2003. In this study, 164 individuals were collected; the largest capture occurred in Campina site, with 209.88 individuals/1000 m² of net for 24 hours, while the shift of largest capture was night time (N) and the month was July. Females occurred in larger numbers than males in all periods. The growth was allometric positive and the reproduction period was from the beginning of September to the end of December, with the majority of the individuals showing a standard length between 13.0 and 20.0 cm.

Reproductive biology of blue mackerel, Scomber australasicus, off southern and eastern Australia: suitability of the Daily Egg Production Method for stock assessment

2009 ◽  
Vol 60 (2) ◽  
pp. 187 ◽  
Author(s):  
P. J. Rogers ◽  
T. M. Ward ◽  
L. J. McLeay ◽  
M. Lowry ◽  
R. J. Saunders ◽  
...  
Keyword(s):  
Reproductive Biology ◽  
Egg Production ◽  
Stock Assessment ◽  
Fork Length ◽  
Production Method ◽  
Spawning Season ◽  
Batch Size ◽  
Batch Fecundity ◽  
Eastern Australia ◽  
Mature Fish

The present study investigated the reproductive biology of blue mackerel (Scomber australasicus) off southern and eastern Australia and assessed the suitability of the Daily Egg Production Method (DEPM) for future stock assessment. This analysis revealed that S. australasicus is a serial spawner with asynchronous oocyte development and indeterminate fecundity. S. australasicus spawns between November and April off southern Australia and between July and October off eastern Australia. In southern Australia, ~50% of males and females were mature at 236.5 and 286.8 mm fork length (FL), respectively. Size at ~50% maturity could not be estimated reliably for eastern Australia owing to the smaller proportion of mature fish in samples. Mean spawning frequencies ranged from 2 to 11 days off southern Australia. Batch fecundity was related to fish size and mean batch size was 69 894 ± 4361 oocytes per batch and 134 oocytes per g of weight. The timing and duration of the spawning season, size at maturity, spawning frequency and batch fecundity of S. australasicus off southern Australia were consistent with those of S. japonicus in the northern Pacific Ocean. The present study’s estimates of adult reproductive parameters of S. australasicus off southern Australia were suitable for the application of the DEPM for estimating spawning biomass. Collecting representative samples of mature fish from waters off eastern Australia during the spawning season is a high priority for future stock assessment of this species.

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