Closing in on the genetics of Uruguay’s narrownose smooth-hounds
The Critically Endangered narrownose smooth-hound shark is found only in the south-western Atlantic Ocean. It is one of the most exploited sharks in the Argentine–Uruguayan Common Fishing Zone (AUCFZ) and adjacent territorial waters of both countries, targeted by artisanal fisheries and caught as bycatch in industrial bottom-trawl fisheries. Sofia’s research is updating and improving the availability of genetic information for this overfished shark, closing a critical gap in effectively managing the fishery and providing much-needed input for improving the outlook for this struggling smooth-hound.
Sofia Ariosa Fontana
As a young Uruguayan scientist, I recently earned my Bachelor’s degree in biological sciences. Throughout my academic journey I have developed a deep curiosity for aquatic organisms, particularly sharks, which led me to explore the intersection between marine biology and genetics, my main area of interest. I am especially interested in applying population genetic analysis to aquatic species, to support their conservation and to provide information for the development of management measures.
Population genomics of the endangered narrownose smooth-hound shark (Mustelus schmitti) in Uruguayan waters
Our goal is to address the lack of genetic information for the narrownose smooth-hound shark, a Critically Endangered species. From samples obtained between 2006 and 2008 and between 2020 and 2025, we will perform population genomic analysis to evaluate population structure and genetic diversity, and generate useful information for the conservation of the species.
Given the fishing pressure on the narrownose smooth-hound shark, the lack of genetic information for the species and the potential problem of mismatches between natural populations and stock delimitation, the results of our project will be relevant to the government entities responsible for Uruguay’s fishing policies. They will provide important information to be considered when management measures aimed at the conservation and sustainable use of the species are implemented.
The narrownose smooth-hound shark Mustelus schmitti is endemic to the south-western Atlantic Ocean. It is the most exploited chondrichthyan species in the Argentine–Uruguayan Common Fishing Zone and the adjacent territorial waters of both countries. The species is targeted by artisanal fisheries and is caught indiscriminately along with other species in bottom-trawl industrial fisheries that harvest coastal resources. Given the past and current exploitation of this species throughout its range in the south-western Atlantic and the consequent decline in its population, the narrownose smooth-hound shark was assessed as Critically Endangered by the IUCN. This species, like other sharks, presents life-history characteristics that result in a low population growth rate, which makes the population vulnerable to overfishing. Another threat that fishery resources face is the mismatches between population structure and stock units. Previous research intended to inform the setting of stock limits for the narrownose smooth-hound shark has been inconclusive. A study based on the mitochondrial marker cytochrome b found no evidence of population structure for the species in Uruguayan waters. This study also found low genetic diversity, which raises concerns about the viability of the species as a fishery resource, as individuals would be less likely to be able to adapt to disease or environmental change. However, the authors highlight the limitations of the molecular marker utilised, which only reconstructs the evolutionary history of females. The scarcity of studies employing robust molecular markers led our group to investigate the species by developing a set of nuclear microsatellite markers, a task that formed part of my Bachelor’s thesis. The markers showed a lack of population structure. The presentation of this project was motivated by the need to resolve the population structure of the narrownose smooth-hound shark in Uruguayan waters and to address the lack of genetic information for the species.
- To reveal the current and past population structure of the narrownose smooth-hound shark in Uruguayan waters.
- To characterise the genetic diversity and effective population size of the species.
- To evaluate the changes between populations over a period of 15 years.
- To identify selection fingerprints in the genome of the narrownose smooth-hound shark that are associated with local adaptation to environmental variables.