Montevideo, Uruguay
Montevideo, Uruguay

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Mantelatto F.L.,University of Sao Paulo | Pezzuto P.R.,Vale do Itajai University | Masello A.,Recursos Bentonicos | Rossi Wongtschowski C.L.D.B.,University of Sao Paulo | And 2 more authors.
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2014

Deep-sea red crabs Chaceon ramosae and Chaceon notialis are commercially and ecologically important crustaceans in South Atlantic waters. With some overlapping occurring at the edge of the crabs' distribution, the fisheries are managed separately in Brazil and Uruguay, with some differences in the regulations, although the stock is supposedly shared between the two countries. To assess genetic information on these two species, we examined the nucleotide sequence of the mitochondrial 16S rDNA and CO1 mtDNA genes in samples from the southern region. We also compared these data to sequences from other congeners. The genetic analysis revealed a clear separation between C. notialis and C. ramosae. In addition, we detected the existence of at least two different groups within the species that is currently recognized as C. notialis. This might indicate the existence of cryptic species, leading us to speculate about the presence of two different taxonomic entities, although further research is needed to resolve this issue. © 2013 Elsevier Ltd.

Gutierrez N.L.,University of Washington | Masello A.,Recursos Bentonicos | Uscudun G.,Recursos Bentonicos | Defeo O.,Recursos Bentonicos
Fisheries Research | Year: 2011

Spatial heterogeneity is a conspicuous feature in life history traits of the deep sea red crab Chaceon notialis in the Southwestern Atlantic Ocean. However, a quantitative assessment of its spatial distribution in Uruguayan waters is lacking. A fishing survey was conducted in 2005 between latitudes 35°00'S and 37°00'S, water depth ranging from 300 to 1600. m. A likelihood-based geostatistical approach showed a persistent spatial structure of the red crab for both the whole population and the harvestable stock, with global biomass estimates of 55,054. t and 34,870. t respectively. Similar estimates were provided by the " effective fishing area" technique (53,800. t and 36,400. t, respectively). C. notialis showed clear large-scale patterns: (1) concerning latitude, the highest density and CPUE were found between 35°40'S and 36°20'S. Males were mainly concentrated between 35°20'S and 36°00'S, whereas the relative representation of both ovigerous and non-ovigerous females increased at the northern end of the study area. Male individual weight increased asymptotically towards higher latitudes, while females followed the reverse pattern. (2) Bathymetric analysis showed the highest density and CPUE at depths close to 900-1100. m, coinciding with the highest representation of males. By contrast, females mainly occurred in shallower waters (300-500. m), and ovigerous females only between 300 and 400. m. Individual weight of males and females consistently decreased from 300 to 1600. m. Proportion of molting males increased with latitude and depth, whereas molting females followed the reverse trend. Spatially explicit management tools are suggested, including fishing closures between 300 and 500. m depth and between latitudes 35°00'S and 35°40'S (main spawning area with the highest proportion of females) and at depths > 1200. m (recruitment area). © 2011 Elsevier B.V.

Masello A.,Recursos Bentonicos | Defeo O.,Recursos Bentonicos
Fisheries Research | Year: 2016

The deep-sea crab Chaceon notialis is distributed along the continental shelf and slope of the SW Atlantic Ocean, mainly in Uruguayan waters, supporting a male-only fishery of high commercial value since 1993. A long-term study of catch per unit of effort (CPUE), population structure and individual weight was carried out before and after the onset of exploitation. Some 23,000 individuals were collected at 300–900 m depth and between latitudes 35°00′ and 36°40′S during seven fishery-independent trap surveys. Additional data on weight and individuals with signs of molting were gathered from 1000 to 1600 m south to 37°00′S after the start of the fishery. Individual weight decreased markedly over time, particularly after the start of the fishery, and decreased with depth for both sexes, with opposite patterns with latitude. CPUE peaked at 900 m and 35°40′S and remained stable over time, suggesting that it does not reflect the condition of the stock. Ovigerous females were found between 300 and 500 m and in the northernmost edge of the distribution range (35°00′S–35°40′S). The number of females decreased exponentially with depth and linearly with latitude. Molting males and females followed opposite latitudinal patterns, with highest percentages of molting individuals found between 600 and 900 m depth. A spatial management framework is proposed, which includes closing areas to fishing where ovigerous females, juvenile crabs and largest males are concentrated. © 2016 Elsevier B.V.

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