أشلاق (القروش و الشفانين) (sharks and rays) >
Rajiformes (Skates and rays) >
Rajidae (Skates)
Etymology: Rostroraja: Latin, rostrum = beak + Latin, raja, -ae = a sting ray (Ref. 45335).
Environment: milieu / climate zone / depth range / distribution range
البيئة
بحري; مياه مخلوطة القاع; محيطية (Ref. 51243); نطاق العمق 0 - 330 m (Ref. 92298), usually 0 - 50 m (Ref. 55280). Subtropical; 48°N - 22°N, 91°W - 59°W (Ref. 55280)
Western Atlantic: Massachusetts to southern Florida (USA) and eastern Gulf of Mexico. Also northern Gulf of Mexico (Ref. 26938).
Length at first maturity / الحجم / وزن / العمر
Maturity: Lm 53.5, range 49 - 60 cm
Max length : 84.0 cm TL ذكر/ مختلط الجنس; (Ref. 1125)
Small skate, with irregular darker spots and bars on dorsal surface. Translucent area on each side of mid-dorsal ridge on snout (Ref. 26938). Single row of thorns along the midridge of the back (Ref. 6902). Disk with dark brown bars and streaks and some spots. Front edges nearly straight or slightly concave (Ref. 7251).
Found from saltwater parts of estuaries and bays of 330 m (Ref. 26938). Inhabit inshore areas. Prefer waters of 10°-21°C. Feed mainly on decapod crustaceans, bivalves, polychaetes, squids and fishes (Ref. 3824). Breed while inshore (Ref. 6902). Oviparous. Distinct pairing with embrace. Young may tend to follow large objects, such as their mother (Ref. 205). Eggs are oblong capsules with stiff pointed horns at the corners deposited in sandy or muddy flats (Ref. 205). Egg capsules are 5.1-8.9 cm long and 3.8-5.7 cm wide (Ref. 41249, 41307, 41301, 41358).
Life cycle and mating behavior
النضج | التكاثر | وضع البيض | بيض | الخصوبة | Larvae
Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). Distinct pairing with embrace. Young may tend to follow large objects, such as their mother (Ref. 205).
From the work of Libby and Gilbert (1960) (Ref. 51117) and Luer and Gilbert (1985) (Ref. 38742) male and female clearnose skates mate side by side in an upright position (Ref. 49562). Actual copulation occurs when the male bites the caudal margin of the female's pectoral, bends his tail 75 degrees beneath hers and inserts one clasper, flexed ('splayed') medially 90 degrees, into her oviduct (Ref. 49562). A female displays 'back arching' and 'pectoral fin undulations' as precopulatory behavior to attract males (Ref. 49562).
McEachran, J.D. and K.A. Dunn, 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes: Rajidae). Copeia 1998(2):271-290. (Ref. 27314)
IUCN Red List Status (Ref. 130435: Version 2024-2)
استخدامات بشرية
مصائد: غير مهمة تجارياً; طعم: occasionally
أدوات
تقارير خاصة
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مصادر علي الأنترنت
Estimates based on models
Preferred temperature (Ref.
123201): 9.6 - 25.7, mean 23.5 °C (based on 342 cells).
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00158 (0.00101 - 0.00248), b=3.27 (3.14 - 3.40), in cm total length, based on LWR estimates for this species & (Sub)family-body (Ref.
93245).
مستوى غذائي (Ref.
69278): 3.9 ±0.3 se; based on diet studies.
Generation time: 5.5 ( na - na) years. Estimated as median ln(3)/K based on 1
growth studies.
المرونه (Ref.
120179): منخفض, الحد الزمني الأدني لتضاعف عدد أفراد المجتمع 4.5-14 سنة (K=0.20; Fec assumed to be <100).
Prior r = 0.07, 95% CL = 0.04 - 0.10, Based on 1 full stock assessment.
Fishing Vulnerability (Ref.
59153): Moderate to high vulnerability (51 of 100).
