Fish eggs are often excluded from identification analysis since at this stage of development there are few morphological characters. The correct identification of eggs can provide important information about spawning areas of species. The current work aimed to identify fish eggs in the Tibagi and Cinzas Rivers using the DNA barcode to obtain information on richness and diversity, adding to the existing data in the area. Of the 928 sequences analyzed using the BOLD Systems database, 99.78% were able to be identified at a specific level, demonstrating a high success rate for egg identification. The samples resulted in 25 species, 11 families, and 2 orders. Of the 25 species found, more than half (60%) present reproductive migration behavior, indicating that the tributaries of the Capivara reservoir are being used as a migratory route by these species. Eggs of rare and endangered species were found, indicating these tributaries as spawning grounds for these species. The results demonstrate the importance of identifying fish eggs in reservoir-influenced environments to recognize breeding areas of native and endangered species, as well as the importance of the Tibagi and Cinzas Rivers for the maintenance of native fish species in the Paranapanema River.

Eggs and larvae of the species were found in the region of the middle Paranapanema River in an analysis study on reproductive activity (Garcia et al., 2016) and are present in the region of the lower and middle Paranapanema River when considering a compilation of fish fauna (Jarduli et al., 2020). Thus, it can be understood that P. microstoma is present in regions with high anthropic influence, making it of great importance for diversity and

Knowledge about reproductive biology is critical for understanding species ecology and evolution, hence their conservation. However, such information remains elusive for many species due to the difficulty of observing mating in nature. Herein, we coupled population and sociogenetic analysis to assess the reproductive biology of an important South American catfish, the “painted catfish” Pimelodus maculatus. We analysed the genetic diversity and kinship patterns of three wild ichthyoplankton samples identified by DNA barcoding and screened with microsatellite loci. We found the same trend in the three samples analysed: a high number unrelated larvae (r < 0.25) and potential parents involved (Ca1, 24♀:24♂; Ca2, 21♀:23♂; Cin, 24♀:25♂), as well as a high number of familial clusters (ML: 19‐21; MCMC: 23‐26). The data indicate a parental sexual proportion close to 1:1 and a polygynandrous mating system. We found high levels of genetic diversity, low GST values (GST < 0.014), but moderate DEST values between the tributary and reservoir samples (DEST > 0.25; Cin x Ca1 or Cin x Ca2), a similar pattern to the observed in adult populations. These results indicate that the mating system of P. maculatus has played an important role in minimising the loss of genetic diversity, a condition that may have favoured the species in a highly fragmented landscape.

Mixed stocks are described for Chelonia mydas and the frequency of haplotypes in feeding areas can aid understanding of the genetic and ecological diversity, since with this information it is possible to identify the origin of the individuals. The current study aims to characterize and compare genetic diversity along the coast of Paraná with 17 other feeding areas in the Atlantic Ocean. A total of 285 samples from juveniles were DNA sequenced in the control region, resulting in the identification of 12 haplotypes, with a predominance of the CMA8 haplotype (69%) and the first registration of CMA23. For the study subjects, haplotypic and nucleotide diversity were 0.469 ± 0.032 and 0.00189 ± 0.00020, respectively, and comparisons with other feeding areas presented significant values for the majority of FST and ΦST. The results point to the importance of this region and provide evidence that over the years a mixed stock has used the region as a feeding area. This variation could be related to sea currents, climatic changes, and oceanographic characteristics that may alter the availability of food, water temperature, and the presence of turtles. The current results can be considered in conservation plans for Chelonia mydas.