Reproductive Cycle, Size at Maturity, and Sexual Composition of Commercially Harvested Weathervane Scallops (Patinopecten caurinus) in Alaska

1970 ◽  
Vol 27 (11) ◽  
pp. 2112-2119 ◽  
Author(s):  
Daniel P. Hennick
Keyword(s):  
Reproductive Cycle ◽  
Size At Maturity ◽  
Annual Rings ◽  
Island Growth ◽  
Kodiak Island ◽  
Sexual Composition

Findings of this study indicated that scallops spawn in the summer, primarily during early June, and also through mid-July. Spawning is complete, and only one annual spawning occurs. Sexual composition of mature scallops appeared as a 50:50 ratio. Most scallops were mature when three or more concentric rings (annual rings) were present on the upper valve and all after four or more were present. Scallops off Yakutat grow slower and are smaller at maturity than scallops off Kodiak Island. Growth and size differences did not seem directly related to time of maturity.

The reproductive cycle and size at maturity observed in Cancer pagurus in the Shetland Islands, Scotland

2007 ◽  
Vol 87 (5) ◽  
pp. 1181-1189 ◽  
Author(s):  
Shelly M.L. Tallack
Keyword(s):  
Reproductive Cycle ◽  
Carapace Width ◽  
Biological Indicators ◽  
Size At Maturity ◽  
Mating Period ◽  
Spawning Period ◽  
Functional Maturity ◽  
Shetland Islands ◽  
Egg Capsules ◽  
Cancer Pagurus

Seasonality of the reproductive cycle for Cancer pagurus was determined using three biological indicators: extruding sperm plugs (mating period), extrusion of eggs (spawning period) and presence of empty egg capsules (hatching period). Sperm plugs were found only in recently moulted females, indicating that mating coincides with moulting periods. Cancer pagurus mating indicators were observed during the summer months and into autumn; spawning occurred in winter, and broods were hatching throughout the summer into early autumn. Size at maturity, was assessed using a variety of reproductive and morphometric criteria; estimates from reproductive criteria are generally larger than those from morphometric criteria and these differences are often indicative of ‘functional’ vs ‘behavioural’ maturity. In C. pagurus, size at maturity estimates ranged from 101.6–125.0 mm carapace width (CW) in males and 110.7–147.3 mm CW in females; the sizes at functional maturity proposed are larger than those from morphometric indicators.

Reproductive cycle, age, and body size at maturity and fecundity of female willowy flounder Tanakius kitaharai

2007 ◽  
Vol 73 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Yoji NARIMATSU ◽  
Akibumi YAMANOBE ◽  
Masakazu TAKAHASHI
Keyword(s):  
Body Size ◽  
Reproductive Cycle ◽  
Size At Maturity

Observations on the biology of the common torpedo (Torpedo torpedo, Linnaeus, 1758) and marbled electric ray (Torpedo marmorata, Risso, 1810) from Egyptian Mediterranean waters

1994 ◽  
Vol 45 (4) ◽  
pp. 693 ◽  
Author(s):  
SH Abdel-Aziz
Keyword(s):  
Reproductive Biology ◽  
Breeding Season ◽  
Reproductive Cycle ◽  
Strong Correlation ◽  
Maximum Size ◽  
Size At Maturity ◽  
Torpedo Marmorata ◽  
Food Items ◽  
The Common ◽  
Males And Females

The reproductive biology and diets of Torpedo torpedo and T. marmorata from Egyptian Mediterranean waters are described. Males and females reached a maximum size of 39.1 and 40.8 cm total length (TL), respectively, in T. torpedo and 38.6 and 61.2 cm TL, respectively, in T. marmorata. The size at maturity of males of T. torpedo and T. marmorata is 18 and 25.5 cm TL, respectively, and of females, is 22 and 35.5 cm TL, respectively. Both species exhibit aplacental viviparity. T. torpedo has a restricted breeding season, and individual females appear to breed annually, whereas T. marmorata females appear to have a more extended reproductive cycle (probably breeding every two years). In both species, males are capable of mating every year. In T. torpedo, mating occurs between December and February, ovulation in March-April, and parturition in late August and September after five to six months of gestation. Individuals of T. marmorata mate between November and January, ovulate between December and February, and give birth the following December after 10-12 months of gestation. Mean embryos sizes are 7.3 cm TL (range 4.6-8.2 cm TL) for T. torpedo and 8.5 cm TL (range 5.8-10.1 cm TL) for T. marmorata. Observations in Egyptian Mediterranean waters show a strong correlation between ovarian and uterine fecundity and the length of the mother in both species. Fish are an important component of the diet of the two species, as, to a lesser extent, are crustaceans for T. torpedo and cephalopods for T. marmorata. Juveniles eat a wide variety of food items, whereas adults feed only on fish.

The Reproductive Cycle and the Size at Maturity of Tupinambis rufescens (Sauria: Teiidae) in the Dry Chaco of Argentina

1993 ◽  
Vol 27 (1) ◽  
pp. 70 ◽  
Author(s):  
Lee A. Fitzgerald ◽  
Felix B. Cruz ◽  
Gabriela Perotti
Keyword(s):  
Reproductive Cycle ◽  
Size At Maturity

scholarly journals Reproductive biology of the eyespot skate Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae) an endemic species of the Southwestern Atlantic Ocean (34ºS - 42ºS)

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Anahí Wehitt ◽  
Jorge H. Colonello ◽  
Gustavo J. Macchi ◽  
Elena J. Galíndez
Keyword(s):  
Atlantic Ocean ◽  
Reproductive Cycle ◽  
Seasonal Pattern ◽  
Gonadosomatic Index ◽  
Reproductive Activity ◽  
Size At Maturity ◽  
Southwestern Atlantic ◽  
Disc Width ◽  
Southwestern Atlantic Ocean ◽  
By Catch

ABSTRACT Atlantoraja cyclophora is an endemic skate to the continental shelf of the Southwestern Atlantic Ocean (22ºS-47ºS) and a by-catch species in commercial bottom trawl fisheries. The morphometric relationships, the size at maturity and the reproductive cycle of this species were analyzed, with samples collected between 34ºS and 42ºS. The size range was 190 to 674 mm total length (TL) for males and 135 to 709 mm TL for females. Sexual dimorphism between the relationships TL - disc width and TL - total weight was found, with females wider and heavier than males. The mean size at maturity for males was estimated in 530 mm TL and for females in 570 mm TL. The gonadosomatic index (GSI) in mature females varied seasonally and showed the highest value in December. The maximum follicular diameter and oviductal gland width did not show any seasonal pattern. Females with eggs in the uterus were present most of the year. The reproductive activity in males would be continuous throughout the year, evidenced by the lack of variation in the GSI between seasons. The results obtained suggest that A. cyclophora might undergo an annual reproductive cycle, in coincidence to that reported for this species in Brazilian populations.

scholarly journals Reproductive aspects of the oceanic whitetip shark, Carcharhinus longimanus (Elasmobranchii: Carcharhinidae), in the equatorial and southwestern Atlantic Ocean

2013 ◽  
Vol 61 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Mirna Regina dos Santos Tambourgi ◽  
Fábio H.V. Hazin ◽  
Paulo G.V. Oliveira ◽  
Rui Coelho ◽  
George Burgess ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Reproductive Biology ◽  
Reproductive Cycle ◽  
Size At Maturity ◽  
Southwestern Atlantic ◽  
Total Length ◽  
Southwestern Atlantic Ocean ◽  
Longline Fisheries ◽  
Fishing Area ◽  
Pelagic Longline

The present study sought to study the reproductive biology of the oceanic whitetip shark, Carcharhinus longimanus, in the equatorial and southwestern Atlantic Ocean. A total of 234 specimens were collected as bycatch during pelagic longline fisheries targeting tunas and swordfish, between December 2003 and December 2010. The fishing area was located between latitudes 10N and 35S and longitudes 3E and 40W. Of the 234 individuals sampled, 118 were females (with sizes ranging from 81 to 227 cm TL, total length) and 116 males (ranging from 80 to 242 cm TL). The reproductive stages of the females were classed as immature, mature, preovulatory and pregnant, while males were divided into immature, maturing and mature. The size at maturity for females was estimated at 170.0 cm TL, while that for males was between 170.0 and 190.0 cm TL. Ovarian fecundity ranged from 1 to 10 follicles and uterine fecundity from 1 to 10 embryos. The reproductive cycle of this species is most likely biennial, with parturition occurring once every two years.

The reproductive cycle and size at maturity observed in the velvet swimming crab, Necora puber, in the Shetland Islands, Scotland

2007 ◽  
Vol 87 (5) ◽  
pp. 1161-1168 ◽  
Author(s):  
Shelly M.L. Tallack
Keyword(s):  
Reproductive Cycle ◽  
Biological Indicators ◽  
Size At Maturity ◽  
Swimming Crab ◽  
Mating Period ◽  
Spawning Period ◽  
Functional Maturity ◽  
Shetland Islands ◽  
Late Autumn ◽  
Egg Capsules

Seasonality of the reproductive cycle for Necora puber was determined using three biological indicators: extruding sperm plugs (mating period), extrusion of eggs (spawning period) and presence of empty egg capsules (hatching period). Sperm plugs were found only in recently moulted females, indicating that mating coincides with moulting periods. Necora puber mating indicators were observed during the summer months and into autumn; spawning was observed year-round but peaked in the summer; hatching was observed throughout the summer into late autumn. Size at maturity was assessed using a variety of reproductive and morphometric criteria; estimates from reproductive criteria are generally larger than those from morphometric criteria and these differences are often indicative of ‘functional’ vs ‘behavioural’ maturity. Size at maturity estimates for N. puber in Shetland ranged from 40.0–49.9 mm CW in males and 51.8–59.5 mm CW in females; sizes at functional maturity were larger than sizes derived from morphometric indicators.

Polar Magnetic Field Reversals of the Sun in Maunder Minimum

2000 ◽  
Vol 179 ◽  
pp. 193-196
Author(s):  
V. I. Makarov ◽  
A. G. Tlatov
Keyword(s):  
Magnetic Field ◽  
Maunder Minimum ◽  
The Sun ◽  
Annual Rings ◽  
Field Reversal ◽  
Polar Magnetic Field ◽  
Pine Trees ◽  
Using Data ◽  
Magnetic Field Reversal

AbstractA possible scenario of polar magnetic field reversal of the Sun during the Maunder Minimum (1645–1715) is discussed using data of magnetic field reversals of the Sun for 1880–1991 and the14Ccontent variations in the bi-annual rings of the pine-trees in 1600–1730 yrs.

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