Abstract
Squalus megalops and Squalus mitsukurii are recognized as the most abundant Squalus species in the southern Brazil region. Currently, S. megalops is listed as 'least concern' (LC) and S. mitsukurii as 'endangered' (EN). However, at the regional level, both species are classified as 'data deficient' - DD, due to the lack of population local data. In this context, the present study aimed to determine the reproductive biology parameters of these species. In addition, insights on their abundance were provided. Research cruises using bottom trawls were conducted on the continental shelf off southern Brazil between 2001 and 2002. A total of 298 specimens of S. megalops (♂143|♀156) and 297 specimens of S. mitsukurii (♂129|♀166) were captured. For S. megalops, the L50 was 38.2 cm for males and 50.22 cm for females, with ovarian fecundity ranging from 1 to 4 vitellogenic follicles and uterine fecundity from 1 to 4 embryos. S. mitsukurii presented an L50 of 54.12 cm for males and 66.4 cm for females, with ovarian fecundity ranging from 1 to 8 vitellogenic follicles and uterine fecundity ranging from 1 to 8 embryos. The highest catch per unit of effort (CPUE) for S. megalops was in zone B (2360.43 ind/mn(2)) and for S. mitsukurii in zone A (5287.97 ind/mn(2)). The study observed differences in the reproductive stages and fecundity of both species compared to other studies for the same species. In southern Brazil, the calculated L50 sizes were smaller than those obtained in the northeast, potentially due to higher fishing pressure. Obtaining data on poorly known species reinforces the importance of monitoring fisheries in the region. The maturity data presented are crucial for species classified as DD, such as S. megalops and S. mitsukurii in southern Brazil, potentially generating new information to support local fisheries management.