Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences
RESEARCH ARTICLE

Reproductive biology of the Magellan skate, Bathyraja magellanica (Chondrichthyes, Rajidae), in the south-western Atlantic

Lorena B. Scenna A B D and Juan M. Díaz de Astarloa B C

A Laboratorio de Ictiología, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata, Funes 3350, B7602AYL, Mar del Plata, Argentina.

B Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ, Cuidad Autónoma de Buenos Aires, Argentina.

C Laboratorio de Biotaxonomía Morfológica y Molecular de Peces, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata, Funes 3350, B7602AYL, Mar del Plata, Argentina.

D Corresponding author. Email: lscenna@mdp.edu.ar

Marine and Freshwater Research 65(9) 766-775 http://dx.doi.org/10.1071/MF13144
Submitted: 8 June 2013  Accepted: 13 November 2013   Published: 16 June 2014

Abstract

The knowledge of reproductive parameters is essential to develop effective management and conservation plans. The present study provides the first information on the reproductive biology of an abundant and important trawl by-catch skate, Bathyraja magellanica, along its geographic range in the south-western Atlantic (43–55°S). In total, 81 males (205–738 mm total length, TL) and 104 females (157–768 mm TL) were analysed. Length–frequency distributions were significantly different between sexes, with females being larger than males. However, no sexual dimorphism was observed in TL–total body weight relationship and liver size. Length at maturity was similar between males (638 mm TL) and females (653 mm TL), ~85% of maximum observed size. The mean number of vitellogenic oocytes per skate was 14.37 (±4.43), increasing with female TL. Egg cases of B. magellanica had striated surface, broad lateral keels, extremely long posterior horns, and its wall consisted of three layers. An important area for the reproduction of B. magellanica was found between 48°50′S and 50°30′S. The present results indicated that this species has a low reproductive efficiency, suggesting that the B. magellanica population should be monitored closely to avoid large-scale changes in skate community structure of the south-western Atlantic.

Additional keywords: egg cases, egg-laying area, elasmobranchs, maturity, Patagonian Shelf, vitellogenic oocytes.


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