ABSTRACT Specimens of Hippocampus patagonicus obtained in the bycatch of trawling in the states of Rio Grande do Sul (RS) and Rio de Janeiro (RJ) were collected in 2012 (n = 199) and 2014 (n = 157), respectively. Mean height of females of reproductive age in RS was 8.89 ± 1.9 cm, with the fecundity of 366 ± 195.8 eggs per clutch, and for males of reproductive age, height was 8.79 ± 1.86 cm and weight 2.3 ± 1.67 g, with 404 ± 99 embryos at each gestation. In RJ, height was 9.69 ± 1.05 cm and weight 2.9 ± 0.9 g, with the fecundity of 277 ± 95.06 eggs per clutch, and for males, height was 10.06 ± 1.02 cm and weight 3.68 ± 1.18 g, with the fecundity of 156.38 ± 66 embryos at each gestation. The equations obtained from the weight (W) to height (H) ratio were: W = 0.002 H3.182, R2 = 0.947 (RS males); W = 0.004 H2.914, R2 = 0.949 (RS females); W = 0.0050 H2.838, R2 = 0.793 (RJ males); W = 0.014 H2.355, R2 = 0.733 (RJ females). RS females produced more eggs (P = 0.023), and males incubated more embryos (P = 0.000) than those of RJ. The mean height of brood pouch formation in males was 4.69 ± 0.48 cm, 95% CI [4.53; 4.86], while the mean height at first sexual maturity was 8.34 cm (95% CI [7.481; 9.046]). Alternative strategies need to be developed for the conservation of H. patagonicus in Brazil.

ABSTRACT Hippocampus patagonicus is classified as endangered in the vulnerable category by Brazilian law (MMA, 2014), and by IUCN (International Union for Conservation of Nature) criteria. Thirteen boats from the commercial fishing fleet of southern Brazil were monitored for 17 months to supplement data for the evaluation of this species. Three seahorse collection points were established, where the fish are landed: port of Imbé/Tramandaí and port of Passo de Torres (northern coast (NC) of Rio Grande do Sul) and the port of Rio Grande (southern coast (SC) of Rio Grande do Sul). The presence of H. patagonicus was recurrent, and the collected animals were between 22 and 130 mm in height. The species was captured from 11 to 57 m deep as bycatch of significant transboundary marine resources (Brazil, Uruguay, and Argentine). In bycatch of gillnet fishing (NC), estimated capture was 0.68 ± 0.97 seahorses/month/vessel, annually, an average of 89.76 seahorses would be removed from the sea by the 11 vessels involved. In trawling (SC), it was 49.66 ± 64.86 seahorses/month/double-rig trawl. It is estimated that 8,342 seahorses are removed annually as bycatch, only in this mode of fishing. The information obtained reinforces the need to apply ecosystem management to fisheries for the recovery of stocks that are over-exploited and accompanying fauna as well, especially small species with poorly known life histories such as H. patagonicus.

The sequence of events of the ossification process in the newly bom specimens of Hippocampus reidi Ginsburg, 1933 up to 37 days of life has been described, mainly the ossification in the ethmoid plate, palatine, pectoral girdle, and postorbital bones and bony structures such as mesoethmoid, articular and six suborbitals. Observation on adult specimens are presented too.

The cartilaginous Structures of the cmbryos of Hippocampus reidi Ginsburg, 1933, were described as well as the beginning of the ossification process in the dentary, angular, retroarticular, operculum, frontal, supraoccipital bonés and neural end hemal arches. The viteline sac is well developed. The results show that cartilaginous structures are predominam in specimens with an average of 4.85 mm in total length.