Genetic Diversity of an Imperiled Neotropical Catfish and Recommendations for Its Restoration

Abstract

The long-whiskered catfish Steindachneridion parahybae (Family Pimelodidae) is endemic to the Paraíba do Sul River basin in southeastern Brazil. This species was heavily exploited by artisanal fisheries and faces challenges posed by dams, introduced species, and deterioration of critical habitat. The remaining populations are small and extirpated from some locales, and the species is listed as critically endangered in Brazil. Screening variation at a partial mitochondrial control region sequence (mtCR) and 20 microsatellite loci, we: (i) describe the patterns of genetic diversity along its current distributional range; (ii) test the null hypothesis of panmixia; (iii) investigate the main factors driving its current population structure, and (iv) propose management of broodstock for fostering recovery of wild populations through genetically cognizant restocking. Our microsatellite data for 70 individuals from five collections indicate moderate levels of heterozygosity (HO = 0.45) and low levels of inbreeding (FIS = 0.016). Individual-based cluster analyses showed clear genetic structure, with three clusters of individuals over the collection area with no mis-assigned individuals, suggesting no recent migration among the three clusters. Pairwise DEST values showed moderate and significant genetic differentiation among all populations so identified. The MUR population may have suffered a recent demographic reduction. mtCRs for 70 individuals exhibited 36 haplotypes resulting from 38 polymorphic sites. Overall, mitochondrial haplotype diversity was 0.930 (±0.023) and nucleotide diversity was 0.011 (±0.002). Significant population structure was observed, with ϕST = 0.226. Genetic markers could be used in a hatchery-based restoration program emphasizing breeding of pairs with low kinship values in order to promote retention of genetic diversity and avoid inbreeding. Individual average kinship relationships showed 87.3% advised matings, 11.0% marginal matings, and 1.7% advised against. While these results comprise a contribution toward planning better breeding management and monitoring, parallel actions to be undertaken include surveying healthy riverine habits for reintroduction and continued searching for wild individuals to introduce new variation into the captive broodstock to avoid adaptation to captivity and to minimize inbreeding.

Genetic Structure and Diversity of the Endemic Carolina Madtom and Conservation Implications

“…2012; da Fonseca et al. 2017). Research on the Caddo Madtom Noturus taylori has also shown similarly low genetic diversity due to small, fragmented populations (Turner and Robison 2006).…”

“…Acipenser brevirostrum, Yazoo Darter E. raneyi, and the Neotropical catfish Steindachneridion parahybae have shown that anthropogenic habitat alteration has negatively affected the genetic diversity of the species (Quattro et al 2002;Sterling et al 2012;da Fonseca et al 2017). Research on the Caddo Madtom Noturus taylori has also shown similarly low genetic diversity due to small, fragmented populations (Turner and Robison 2006).…”

GENETIC IMPLICATIONS OF RESTOCKING PROGRAMS ON WILD POPULATIONS OF STREAKED PROCHILOD <i>Prochilodus lineatus<i>

“…In general, all fish farms presented some crosses not indicated, due to the high degree of kinship among some broodstock. According to Fonseca et al (2017), the successful restocking programs depends upon keeping levels of inbreeding low and optimizing genetic variability, resultant of genetic information of broodstock and breeding designs The genetic composition of the freshwater broodstock is generally formed by exchange of matrices between fish farmers, regardless of the river basin where they are found, and guidelines are available for this commercialization. In addition to compromising the genetic composition of natural populations (Vaini et al, 2016), crosses among fish from different hydrographic basins may result in non-intentional, as well as intentional, interspecific crosses, as detected in several species of fish in previous studies (Hashimoto et al, 2014a,b;Scaranto et al, 2018).…”

“…Thus, limited genetic diversity and effective population size of broodstock may pose a risk to wild populations restocked under these conditions (Small et al, 2009;Fonseca et al, 2017;Prado et al, 2018). In addition, restocking programs that avoid introduction of genotypes unrepresentative of the augmented population, low genetic diversity and inbreeding can have negative effects (Ward, 2006;Roques et al, 2018).…”

Dynamics of ovarian maturation during the annual reproductive cycle of the endangered fish Steindachneridion parahybae (Siluriformes: Pimelodidae) in captivity

“…Currently, it is known that this population decline of S. parahybae was probably caused by industrial pollution and mainly the construction of a dam in this basin (Honji et al ., 2017). Since 2003, the CESP ( Companhia Energética de São Paulo , Brazil) has supported research studies on the biology and production of S. parahybae , including the maintenance of wild and captivity broodstock to obtain fingerlings in captivity and subsequently rear larvae successfully, guaranteeing the success of genetic diversity and recommendations for its restoration in this species' conservation programme (Fonseca et al ., 2017). S. parahybae is under a conservation programme by the CESP and a partner institution.…”