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A record of abortion in the school shark Galeorhinus galeus (Carcharhiniformes, Triakidae) captured on the continental shelf off southern Brazil

GETULIO RINCON1 & CAROLUS MARIA VOOREN2

1UNESP-Rio Claro. Instituto de Biociências. Departamento de Ecologia. Av 24-A s/n, Bela Vista. Rio Claro-SP. Brasil. E-mail: zazan143@terra.com.br. 2Fundação Universidade de Rio Grande (FURG). Laboratório de Elasmobrânquios e Aves Marinhas. Departamento de Oceanografia. CP 474, Rio Grande-RS. Brasil.

( 3 3 Abortion in elasmobranch fishes is a well known post-capture stress behavior with a long historical series of reports and superficial descriptions (Babel 1967, Cousseau 1973, Sunyé & Vooren 1997, Fahy et al. 2007). In fact, the whole process and physiological mechanism is completely unknown and it can be only speculated that the intrauterine decrease in oxygen level is the main stimulus to start embryos’ motion and consequent abortion. However, mechanical stress due to removal from the water and loss of water pressure are certainly important factors on the abortion process. The present note and the associated video record the abortion of Galeorhinus galeus (Linnaeus 1758) almost immediately after capture. The specimen was caught at the mid-continental shelf (80-100 m deep) off southern Brazil, Rio Grande do Sul State, between Rio Grande (32o 03’S-52o 10’W) and Chuí o 4 5 S - 5 3 o 2 2 W ) i n e a r l y s p r i n g ( O c t o b e r 2 8 t h t o N o v e m b e r 2 n d ) o f 1 9 9 2 b y t h e F U R G s ( F u n d a ç ã o Universidade de Rio Grande) R.V. “Atlântico Sul” (Project Diadema). Several specimens (about 14) of G. galeus were captured along with Squalus mitsukurii, S. megalops and Squatina spp in one single bottom otter trawl. Although the presence of G. galeus in the area was unexpected at this time of the year (Peres & Vooren 1991, Vooren 1997, Lucifora et al. 2004), the record of pregnant females was not considered relevant due to the very punctual occurrence. Although well recorded, abortion in elasmobranches lacks a fully description and systematic research in order to determine its physiology and variation among species. This video intends to illustrate this process in G. galeus and provides visual support for a future study. The video

was recorded in VHS-C by Dr. Alexandre Matthiensen (FURG) as part of the project and subsequently digitalized without sound by the first author.

CLICK HERE TO WATCH THE VIDEO (7,799 Kb)

References Babel, J. S. 1967. Reproduction, life history, and ecology of the round stingray, Urolophus halleri Cooper. Fisheries Bulletin of the California Department of Fish and Game, 137: 1-104. Cousseau, M. B. 1973. Taxonomía y biología del pez ángel, Squatina argentina Marini 1936 (Pisces-Squatinidae). Physis A 32: 175-195. Fahy, D. P., Spieler, R. E. & Hamlett, W. C. 2007. Preliminary observations on the reproductive cycle and uterine fecundity of the yellow

stingray,

Urobatis

jamaicensis

(Elasmobranchii:

Myliobatiformes:

Urolophidae) in southeast Florida, USA. The Raffles Bulletin of Zoology, 14: 131-139. Lucifora, L. O., Menni, R. C. & Escalante, A. H.

2004. Reproductive biology of the school shark, Galeorhinus galeus, off Argentina:

support for population

a single south western Atlantic

with

synchronized

migratory

movements. Environmental Fishes, 71: 199-209.

Biology

of

Peres, M. B. & Vooren, C. M. 1991. Sexual development, reproductive cycle, and fecundity of the school shark Galeorhinus galeus off Southern Brazil. Fishery Bulletin, 89: 655-667.

Pan-American Journal of Aquatic Sciences (2007) 2 (1): 53-54

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