Maturation and reproduction of Squalus cubensis and Squalus cf. quasimodo (Squalidae, Squaliformes) in the southern Caribbean Sea
Tagliafico, A, Rangel, S & Broadhurst, MK 2018, 'Maturation and reproduction of Squalus cubensis and Squalus cf. quasimodo (Squalidae, Squaliformes) in the southern Caribbean Sea', Ichthyological Research.
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Specimens of Squalus cubensis (n = 137; 38.5–67.3 cm total length–TL) and Squalus cf. quasimodo (n = 183; 41.1–93.2 cm TL) were opportunistically collected from the catches of artisanal gillnetters working in the southern Caribbean Sea off Venezuela between January 2006 and December 2007 and assessed for maturation and reproductive biology. Catches of each species comprised considerably more, and mostly larger, females (n = 124 and 174, for S. cubensis and S. cf. quasimodo, respectively) than males (n = 13 and 9). Based on changes to the reproductive organs, both species were partitioned into four maturation stages for females (juvenile, ovulating, gravid and post-partum) and two stages for males (juvenile and adult). Squalus cubensis and S. cf. quasimodo both were least represented by juveniles (n = 10 and 13, respectively) and most by ovulating females (n = 74 and 120, respectively). Formal assessments of 50% sizes at sexual maturity (± SE) were restricted to females, and were 44.5 ± 0.5 TL for S. cubensis and 59.9 ± 0.2 cm TL for S. cf. quasimodo. All sampled male S. cubensis were mature above 43.8 cm TL, while only one adult male S. cf. quasimodo (82.4 cm TL) was recorded. Gravid females of both species had each uteri functional with between one and five embryos—the numbers of which were not correlated to the TLs of the mothers. A common observation of gravid females for both species during many of the sampled months, and an absence of clear temporal progression in embryo size implied asynchronous reproduction, although the few post-partum individuals (n = 5 and 4 for S. cubensis and S. cf. quasimodo, respectively) were restricted to December. Because of their low reproductive output and apparent potential for exploitation, further life-history studies are warranted for both species.