Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: “cação.” The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, “cação” samples available in local markets from Southern Brazil. We collected 63 samples traded as “cação,” which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47% of the elasmobranch species found are threatened at the global level, while 53% are threatened and 47% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as “cação” is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.
Dinâmica de Populações da Espécie Invasora Zaprionus indianus (Gupta) (Diptera: Drosophilidae) emComunidades de Drosofilídeos da Cidade de Porto Alegre, RS RESUMO -Estudos em populações de espécies invasoras permitem entender como os invasores reagem às novas condições bióticas e abióticas, e como espécies nativas reagem à invasão. Avaliou-se a eficiência de colonização da invasora Zaprionus indianus (Gupta), na área urbana da cidade de Porto Alegre, RS. Amostras de moscas foram tomadas de três parques urbanos, e índices ecológicos foram usados baseados na freqüência das espécies amostradas. Os índices foram calculados para sítios de oviposição e alimentação separadamente. A maior freqüência de Z. indianus comparada aos outros drosofilídeos foi registrada nas estações de temperaturas médias maiores, tanto para o componente sítio de alimentação como o de oviposição. Nessas mesmas estações, e para ambos os componentes, foram encontrados os maiores valores do índice de dominância (D) e os menores valores de diversidade (H'). Uma análise dos valores do índice de similaridade de Morisita mostrou que o Jardim Botânico e o Parque Farroupilha apresentam maior similaridade em termos de diversidade para o componente sítio de oviposição. Para o componente sítio de alimentação a maior similaridade foi entre Parque Farroupilha e Parque Gabriel Knijnik. Apesar de os três parques apresentarem algumas particularidades, a facilidade de estabelecimento de Z. indianus nesses locais parece ter sido a mesma. A chegada da invasora parece estar promovendo ajustes nas estratégias de sobrevivência das espécies residentes, pelo menos em certos períodos quando a freqüência das populações da invasora aumenta significantemente. Entretanto, pelo menos a maioria das espécies parece ter condições de coexistir com a invasora.
PALAVRAS-CHAVE: Invasão biológica, índice ecológico, parque urbanoABSTRACT -Population studies of invasive species allow us to understand how invaders react to new biotic and abiotic conditions, and how native species react to invasion. We evaluated the colonisation efficiency of the invader Zaprionus indianus (Gupta), in the urban area of Porto Alegre city, southern of Brazil. Samples of flies were taken from three urban parks, and ecological indexes were used based on the frequency of the sampled species. The indexes were calculated for breeding and feeding sites separately. The highest frequencies of Z. indianus compared to the other drosophilids were registered during seasons of highest mean temperatures, both for the feeding and the breeding sites. The highest values for the dominance index (D) and the lowest values for diversity (H') were found at the same seasons and for both components. An analysis of the values for Morisita similarity index shows that the Botanical Garden and Farroupilha Park had higher similarity in terms of diversity of the breeding sites. For the feeding sites the highest similarity was between Farroupilha Park and Gabriel Knijnik Park. Despite the three parks have some particularities, the eas...
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