Reproductive biology of the angular angel shark Squatina guggenheim (Chondrichthyes: Squatinidae) off Patagonia (Argentina, southwestern Atlantic)

Abstract

The reproductive biology of the angel shark Squatina guggenheim was described based on 584 animals sampled in the San Matías Gulf, Argentina, between January and December 1996. Both sexes of S. guggenheim reached similar total length and matured at similar sizes (between 73 and 76 cm total length). In males, testes were paired and showed diametric development. Adult males were predominant in the austral autumn and winter, and were capable of mating all year round. In females, only the left ovary was functional. The maximum follicular diameter recorded (6 cm) was observed during the austral autumn and winter, with ovulation occurring during spring and summer. The size distribution of the follicles indicated that adult females presented different maturational stages in all the seasons. No post-ovulatory follicles were distinguished in any of the females examined. The seasonal analysis showed significant differences in sex abundance. Adult males were predominant in autumn and winter, juvenile males in spring, and adult females in summer. Only a few pregnant animals were caught in January, May and September. The results suggest that S. guggenheim females show a biannual reproductive cycle with gestation taking at least one year, and that the San Matías Gulf is not one of their main breeding areas.

Reproductive parameters of the Pacific angel shark Squatina californica (Selachii: Squatinidae)

“…Females were larger than males; sexual dimorphism has previously been reported among squatinids (Capapé et al, 1990(Capapé et al, , 2002(Capapé et al, , 2005Awruch et al, 2000;Colonello et al, 2007). This condition could be an adaptation to the greater energy demands of their viviparous reproductive mode (Goodwin et al, 2002).…”

“…In California, size at maturity was estimated at 90-100 cm L T (Natanson & Cailliet, 1986), suggesting different life-history parameters for these two S. californica populations. Latitudinal differences between sexes in L T50 have also been observed for Squatina guggenheim Marini 1936 (Awruch et al, 2000;Colonello et al, 2007). The differences have been explained by the fact that Squatina have low dispersal capability, making identification of differences in life-history parameters at small geographic scales possible (Colonello et al, 2007).…”

Population structure, distribution and habitat use of the Critically Endangered Angelshark, Squatina squatina, in the Canary Islands

“…Despite the reproductive behaviour of the angelshark being poorly understood, Narvaez (2013) and Osaer (2009) have also indicated that active males were predominantly found during winter and that the pupping season started in spring at Gran Canaria Island, as has been demonstrated here. Sexual segregation, either seasonal or spatial, has also been observed for other species of the same genus, including Squatina californica (Pittenger, 1984), Squatina tergocellata (Bridge, Mackay, & Newton, 1998) and Squatina guggenheim (Awruch, Nostro, Somoza, & Di Giacomo, 2008). For example, similar to S. squatina, adult S. guggenheim females migrate to shallow coastal areas (< 40 m depth) to breed (Vooren & Da Silva, 1991).…”

Chondrichthyans of the San Matías Gulf, Patagonia, Argentina

“…Since then, studies on distribution, biology and commercial exploitation have been carried out on several fish species (Di Giácomo, 1992;Di Giácomo & Perier, 1991;1996;2009;Van der Molen et al, 1998;Awruch et al, 2008;Perier et al, 2010;Coller et al, 2011;Estalles et al, 2011). However, basic information such as species composition has remained unpublished.…”