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

Observations on the biology of the common torpedo (Torpedo torpedo, Linnaeus, 1758) and marbled... <jats:p>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.</jats:p> http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Marine and Freshwater Research CrossRef

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

Marine and Freshwater Research , Volume 45 (4): 693 – Jan 1, 1994

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


Abstract

<jats:p>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.</jats:p>

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Publisher
CrossRef
ISSN
1323-1650
DOI
10.1071/mf9940693
Publisher site
See Article on Publisher Site

Abstract

<jats:p>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.</jats:p>

Journal

Marine and Freshwater ResearchCrossRef

Published: Jan 1, 1994

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