Distribution, size and sex composition, reproductive biology and diet of sharks from Northern Australia

1991 ◽  
Vol 42 (2) ◽  
pp. 151 ◽  
Author(s):  
JD Stevens ◽  
KJ McLoughlin
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Annual Cycle ◽  
Post Partum ◽  
Austral Summer ◽  
Size Composition ◽  
Maximum Size ◽  
Northern Australia ◽  
Average Size ◽  
Size At Birth

The distribution, size composition, sex ratio, reproductive biology and diet of 17 species of shark from the families Triakidae, Hemigaleidae and Carcharhinidae from northern Australia were examined. In most of these species the sex ratio of the embryos is 1 : 1, whereas in the post-partum populations there were significantly more males than females. The results indicate four broad reproductive strategies among these sharks. In most species reproduction was distinctly seasonal with individual females giving birth each Austral summer (annual cycle) after a gestation period of 9-12 months. A second group had a very similar cycle except that individual females gave birth every second year (biennial cycle). A third group had an annual cycle but breeding was continuous throughout the year, these were mostly small bottom-associated sharks. One species had a seasonal cycle but gave birth twice each year (biannual cycle) after a 6-month gestation. The average size at birth varied from 27 to 75 cm and the average litter size varied from 2 to 34. The size at birth was about 40% of the size at maturity, which in turn was about 70% of the maximum size. Diets ranged from omnivorous to highly selective. Fish was an important component of the diet in all but one species. There was evidence of partitioning of food resources among sympatric, morphologically similar, sharks.

Reproductive biology and diet of the longtail butterfly ray Gymnura poecilura (Shaw, 1804) along western Bay of Bengal

2020 ◽  
Vol 100 (3) ◽  
pp. 461-470
Author(s):  
Muktha Menon ◽  
G. Maheswarudu ◽  
K. Sree Ramulu ◽  
Shoba Joe Kizhakudan
Keyword(s):  
Reproductive Biology ◽  
Maximum Size ◽  
Female Size ◽  
Feeding Intensity ◽  
Disc Width ◽  
The Mean ◽  
Index Of Relative Importance ◽  
Western Bay Of Bengal ◽  
Gravid Females ◽  
Size At Birth

AbstractThe reproductive biology and diet of the longtail butterfly ray Gymnura poecilura is described based on 630 specimens (N = 377 females and 253 males). The mean disc width (WD) of females and males was 576.7 mm (range = 190–920 mm) and 416.3 mm (230–550 mm), respectively. Sexual dimorphism in size was seen, with the maximum size of males being only 60% of the maximum female size. The disc widths at 50% maturity (WD50) were estimated to be 506.5 mm (females) and 435.9 mm (males). The mean uterine fecundity was 3.3 (range = 1–8). The size at birth was between 190 and 220 mm WD. Year-round reproduction was indicated, due to the presence of mature males and gravid females throughout the year, neonates in multiple months and large variations in embryo size within months. Feeding intensity increased with body size. Fish accounted for 80.9% of the diet (Index of Relative Importance, IRI), followed by crustaceans (18.9%) and molluscs. The species was found to be a specialized feeder.

Reproductive biology of the pelagic stingray, Pteroplatytrygon violacea (Bonaparte, 1832), in the equatorial and south-western Atlantic Ocean

2014 ◽  
Vol 65 (11) ◽  
pp. 1035 ◽  
Author(s):  
D. P. Veras ◽  
F. H. V. Hazin ◽  
I. S. L. Branco ◽  
M. T. Tolotti ◽  
G. H. Burgess
Keyword(s):  
Sex Ratio ◽  
Atlantic Ocean ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Pregnant Female ◽  
Longline Fishery ◽  
Western Atlantic ◽  
Pregnant Females ◽  
Size At Birth ◽  
Tuna Longline

From October 2005 to March 2010, a total of 480 pelagic stingray, Pteroplatytrygon violacea, specimens, 188 females and 292 males (0.64 female : 1 male), were taken in the equatorial and south-western Atlantic by the commercial tuna longline fishery and their reproductive biology was studied. Disc widths (DW) ranged from 28.0 to 66.0 cm for females and from 34.0 to 59.6 cm for males. Size at first sexual maturity was estimated at ~48.0 cm DW (first pregnant female) for females and ~41.0 cm DW for males. Ovarian fecundity, considering only follicles larger than 0.5 cm in diameter, ranged from 1 to 17 follicles per female, while the uterine fecundity of embryos in pregnant females in Stages 2 and 3 ranged from 1 to 5 embryos per female. The sex ratio between the embryos was almost equal (1.08 female : 1 male) and the size at birth was 19.0 cm DW.

scholarly journals SEBARAN UKURAN PANJANG DAN NISBAH KELAMIN IKAN MADIDIHANG (Thunnus albacares) DI SAMUDERA HINDIA BAGIAN TIMUR

2015 ◽  
Vol 7 (3) ◽  
pp. 175
Author(s):  
Arief Wujdi ◽  
Bram Setyadji ◽  
Budi Nugraha
Keyword(s):  
Sex Ratio ◽  
Size Composition ◽  
Thunnus Albacares ◽  
Chi Square ◽  
Resources Management ◽  
Fisheries Resources ◽  
The Mean ◽  
Average Size ◽  
Chi Square Analysis ◽  
Size Mode

Ikan madidihang atau tuna sirip kuning (Thunnus albacares) merupakan salah satu komoditas penting bagi industri perikanan di Indonesia dengan hasil tangkapan tertinggi dibandingkan jenis tuna lainnya. Sebagai dasar pengelolaan sumberdaya ikan yang berkelanjutan, diperlukan data dan informasi tentang komposisi ukuran layak tangkap yaitu membandingkan proporsi rata-rata ikan tertangkap (Lc) dan matang gonad (Lm), serta nisbah kelamin sebagai indikator pendugaan kemampuan memijah. Pengumpulan data dilakukanmelalui program observasi diatas kapal rawai tuna yang berbasis di Benoa, Pelabuhanratu dan Bungus dari bulan Agustus 2005 hingga November 2013. Penghitungan nisbah kelamin menggunakan uji Chi-Square (X2) dengan tingkat kepercayaan 95%. Hasil penelitian menunjukkan bahwa distribusi ukuran panjang cagak ikan madidihang berkisar antara 30-179 cm, modus ukuran 106-110 cm dan rata-rata 101,65 cm. Sebanyak 81,03% madidihang yang tertangkap berukuran lebih besar daripada Lm yang berarti telah layak tangkap. Nisbah kelamin betina:jantan adalah 1:1,45 mengindikasikan dominansi ikan jantan. Hubungan antara nisbah kelamin dengan panjang ikan menunjukkan signifikansi dimana ikan betina semakin berkurang pada ukuran 120-180 cm, serta tidak ditemukan lagi pada ukuran lebih dari 170 cm. Korelasi nisbah kelamin dan panjang cagak dapat dideskripsikan dengan persamaan regresi sebagai berikut: 1,8013 - 0,0099 FL dengan nilai R2=0,8058.Yellowfin tuna or YFT (Thunnus albacares) is one of the important commodity for the fishing industry in Indonesia because it has the highest catches compared with other tunas. In order to fisheries resources management, it was necessary to monitor the size composition compared between proportion average size captured (Lc) and maturity size (Lm) to meets the size eligibility, as well as the sex ratio as an indicator to estimate the ability of spawn. Data collected by scientific observers program which was following tuna longline operation mainly based in Benoa, Palabuhanratu and Bungus Fishing Port, from August 2005 to November 2013. Chi-Square analysis with 95%confidence level also implemented to determine sex ratio between female and male. The result indicated that YFT were caught has size ranged between 30-179 cm, size mode ranged between 106-110 cm and the mean was 101,65 cm.Mostly YFT (81,03%) was greater than its maturity size (Lm) and that’s mean have been worthy to be captured. Sex ratio of (F:M) 1:1,45 was observed which indicates male was dominant. Correlation between sex ratio and length proved to be significant where the female was diminishing in size between 120-180 cm, even female was no longer found in size more than 170 cm. Correlation between sex ratio and length can described as a regression equation=1,8013 - 0,0099 FL; R2=0,8058.

scholarly journals Reproductive biology aspects of Alopias pelagicus and A. superciliosus (Lamniformes: Alopiidae) in the Ecuadorian Pacific

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Jesús Briones-Mendoza ◽  
Pol Carrasco-Puig ◽  
Daniel Toala-Franco
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Inflection Point ◽  
Maximum Size ◽  
Size Class ◽  
Shark Species ◽  
Thresher Shark

ABSTRACT The reproductive biology of thresher shark species of the Ecuadorian Pacific was analysed based on 1236 specimens of Alopias pelagicus (711 females and 525 males) and 354 of A. superciliosus (164 females and 190 males) landed in “Playita Mía”, from January to December of 2019. The length of A. pelagicus females ranged between 67.2 and 184 cm PCL (precaudal length) and the males between 69.0 and 178.4 cm PCL, A. superciliosus registered a minimum and maximum size of 76.0 and 202.2 cm PCL for females and 94.0 and 204.8 cm PCL for males. The most frequently captured size class for A. pelagicus was 147.2−157.2 cm PCL and for A. superciliosus was 156.0-166.0 cm PCL. The sex ratio (F:M) for A. pelagicus and A. superciliosus was 1.35F:1M and 0.86F:1M respectively. For A. pelagicus males the inflection point of the clasper length adjustment, was 134.2 cm PCL and size at first sexual maturity (L 50 ) was estimated at 136.0 cm PCL. For A. superciliosus males the inflection point of the clasper length adjustment, was 136.8 cm PCL, and the first sexual maturity (L 50 ) was estimated at 138.7 cm PCL.

Reproductive biology of the eastern shovelnose stingaree Trygonoptera imitata from south-eastern Australia

2009 ◽  
Vol 60 (8) ◽  
pp. 845 ◽  
Author(s):  
Fabian I. Trinnie ◽  
Terence I. Walker ◽  
Paul L. Jones ◽  
Laurie J. Laurenson
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Rapid Growth ◽  
Extended Period ◽  
In Utero ◽  
Anthropogenic Pressures ◽  
Eastern Australia ◽  
The Family ◽  
Mean Size ◽  
Size At Birth

In applying a quantitative approach to the reproduction of Trygonoptera imitata, the present study contributes to understanding the wide diversity in the reproductive biology of the family Urolophidae and provides insights to help determine phylogenetic relationships. This localised species is taken as bycatch in several inshore fisheries and potentially impacted by a range of other anthropogenic pressures, including introduced species, particularly in shallow-water pupping areas. T. imitata can be characterised as a species of comparatively low matrotrophic histotrophy with an extended period of relatively large eggs in utero (5–8 months) followed by rapid growth of the embryos (4–6 months). The reproductive cycle is annual with parturition occurring during late-February–April, followed immediately by ovulation. Mean size-at-birth is ~225 mm total length and there is a ~1000% gain in mean wet mass from egg (15 g) to full-term embryo in utero (150 g), the lowest reported for any viviparous batoid. Litter size increases with maternal length, reaching a maximum of seven, and sex ratio of embryos is 1 : 1. Maximum length and estimates of the maturity–ogive parameters l50 and l95 are similar for females and males.

Annual cycle of growth and population structure of the estuarine crab Hemigrapsus crenulatus (Brachyura: Varunidae) off central Chile

2021 ◽  
pp. 1-15
Author(s):  
Ramiro A. Riquelme-Bugueño ◽  
Tomás Luppi ◽  
Gonzalo S. Saldías ◽  
Marcelo E. Lagos ◽  
Mauricio A. Urbina ◽  
...  
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Size Distribution ◽  
Annual Cycle ◽  
Linear Models ◽  
Environmental Variability ◽  
Growth Parameters ◽  
Austral Summer ◽  
Size Frequency Distribution ◽  
Central Chile

Abstract Estuaries and saltmarshes play a fundamental role in the life cycle of many crab species. Diverse studies show that temperature and salinity modulate abundance, size frequency distribution (SFD), sex ratio and growth in crustaceans. These population parameters are usually challenging to estimate due to the high environmental variability of estuaries. Monthly samples of the estuarine crab Hemigrapsus crenulatus were taken from October 2003 to October 2004 (except July 2004) in the Tubul estuary, central Chile. We quantified temporal changes in abundance, size distribution, sex ratio and monthly growth through the annual cycle. A total of 1025 individuals were collected. Sizes ranged from 7.72–33.51 mm carapace length (CL) with a growth rate ranging between 2.13–30.5% mm CL mo−1. Size and growth rates were greater in spring-summer, suggesting a faster growth of younger crabs correlated with increasing sea temperatures in the austral summer. Overall, sex ratio was 1.75:1 in favour of males. Modal analysis identified at least seven cohorts cohabiting throughout the annual cycle. Growth parameters for males and females were the following, respectively: L∞ = 33.6 and 29.6, k = 0.69 and 0.91, t0 = –0.39 and −0.28. Changes in size distribution suggested a recruitment period during autumn and winter seasons when there are lower salinities and temperature fluctuations stresses. Generalized linear models indicated that sea temperature, salinity and chlorophyll were the environmental variables that better predicted the annual patterns in the population structure.

Life history and reproductive biology of the invasive amphipod Melita palmata (Amphipoda: Melitidae) in the Mar Chiquita coastal lagoon, Argentina

2006 ◽  
Vol 86 (6) ◽  
pp. 1381-1387 ◽  
Author(s):  
S. Obenat ◽  
E. Spivak ◽  
L. Garrido
Keyword(s):  
Life History ◽  
Body Size ◽  
Population Density ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Coastal Lagoon ◽  
Brood Size ◽  
Maximum Size ◽  
The Body ◽  
Invasive Amphipod

The life history and reproductive biology of the gammaridean amphipod Melita palmata was studied in the Mar Chiquita coastal lagoon (Argentina). The animals were collected fortnightly or monthly from Ficopomatus enigmaticus reefs from December 2000 to March 2002. The population density reached a maximum of 1556.67±1560 ind/m3 (mean±SD) in March 2001, decreased dramatically after intense rainfalls in winter 2001, and had a minimum value of 141.67±27.54 ind/m3 (mean±SD) in March 2002. Size differed significantly between sexes. The maximum size of males was 11.5 mm and this was 1.4 times longer than the length of females. The average sex ratio (0.44) did not differ significantly from an expected 1:1 value. Ovigerous females were present from December to March, when the temperature was above 18°C. The body size of ovigerous females ranged from 2.9 to 6.81 mm. There was a positive correlation between the brood size and body length of ovigerous females, and the maximum number of eggs per female was ten. Recruitment took place during the whole breeding season; juveniles recruited at the beginning of the season matured at the end of the same season, those recruited late would probably reach maturity in the following season.

scholarly journals Population structure of the shrimp Palaemon pandaliformis (Stimpson, 1871) (Caridea: Palaemonidae) in the river Rio Itapemirim, in Southeastern Brazil

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Pedro de Souza Laino ◽  
Joelson Musiello-Fernandes ◽  
Adriane Araujo Braga
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Water Temperature ◽  
Frequency Distribution ◽  
Reproductive Biology ◽  
Southeastern Brazil ◽  
Winter Period ◽  
Spring Period ◽  
Average Size ◽  
Almost All

Abstract The present study analyzes the population structure of Palaemon pandaliformis, based on sex ratio, the frequency distribution in defined size classes and the reproductive biology of samples captured in seasonal collections (winter 2011 to autumn 2012) with sieves under marginal vegetation. A total of 1,043 specimens were obtained, 222 juveniles, 465 males and 356 females, being that of this total of females, 58.42% were in the ovigerous condition. The average size of the carapace for both sexes varied between 4 and 6 mm (p> 0.05) only the ovigerous females had higher averages (p <0.0001). The sex ratio differed with 1:0.76 for males (p = 0.0001), although juvenile individuals and females were present in all sampled periods, except ovigerous females in autumn. Highest abundances were observed during the winter and spring period (p = 0.0001), decreasing in the periods with higher water temperature and salinity (summer and autumn). Was observed a continuous recruitment due to the presence of juveniles in all seasons, with greater abundance in winter and spring. Thus, based on the presence of ovigerous females in almost all seasons and juveniles in all, the reproduction for P. pandaliformis can be defined as seasonal-continuous with peak in winter period.

scholarly journals Reproductive biology of Astyanax janeiroensis (Osteichthyes, Characidae) from the Ubatiba River, Maricá, RJ, Brazil

2005 ◽  
Vol 65 (4) ◽  
pp. 643-649 ◽  
Author(s):  
R. Mazzoni ◽  
R. S. Mendonça ◽  
E. P. Caramaschi
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Annual Cycle ◽  
Seasonal Variations ◽  
Standard Length ◽  
Environmental Variables ◽  
Weight Ratio ◽  
Reproductive Period ◽  
Monthly Basis ◽  
Expected Frequency

Aspects of the reproductive biology of Astyanax janeiroensis in the Ubatiba river in Maricá, RJ, Brazil were evaluated in order to ascertain whether the strategy adopted by the species is causally related to environmental variables. Specimens were collected on a monthly basis from October 1994 to September 1995, through electrofishing. The Sex ratio was not significantly different from the expected frequency of 1:1 (G = 1.29; p > 0.50); nonetheless, considering three standard length classes, significantly larger numbers of females were recorded for the higher SL class (G = 11.07; p < 0.01). Size at first maturation showed no significant differences between sexes. Length-weight ratio analyses showed negative allometry for males and isometry, for females. Length structure was significantly different between sexes, suggesting that females are larger than males (D = 0.027, p < 0.01). Reproductive specimens were recorded during nine months of the annual cycle. Seasonal variations of reproductive specimens belonging to two different standard length classes displayed an asynchronous behavior, with larger specimens having a longer reproductive period and smaller ones reproducing for fewer months during the annual cycle. High values of fecundity (F), varying from 3169 to 18714 oocytes, were recorded for fish of 9.1 and 10.2 cm lengths, respectively. The correlation between weight and number of oocytes/unit of weight was positive, indicating that larger specimens produced more eggs.

Breeding of Philander frenata (Didelphimorphia, Didelphidae) in captivity

1998 ◽  
Vol 32 (4) ◽  
pp. 434-438 ◽  
Author(s):  
Erika Hingst ◽  
Paulo Sergio D'Andrea ◽  
Ricardo Santori ◽  
Rui Cerqueira
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Litter Size ◽  
Breeding Success ◽  
Gestation Period ◽  
Sex Ratio At Birth ◽  
Laboratory Management ◽  
Sensory Contact ◽  
In Captivity ◽  
Size At Birth

Data on the reproductive biology and laboratory management of Philander frenata are presented here. Sensory contact before pairing increased breeding success and reduced aggression between pairs. Gestation period was 13–14 days, with a post-lactation oestrous. Births occurred only between August and February. Mean litter size at birth and at weaning was 5.5 (SD=2.4) and 4.0 (SD=1.9), respectively. Sex ratio at birth was statistically biased toward males. The timing of weaning was established at between 70 and 80 days old, with the young weighing from 24 g to 49 g.

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