TETRA CARDINAL: UM SÍMBOLO AMAZÔNICO DE ECONOMIA, CULTURA E CONSERVAÇÃO AMBIENTAL

Abstract

The pressure of anthropic activities directed towards a reduced number of species can make economic activities unfeasible and suppress ecological functions. The ornamental fishery in the state of Amazonas traded over 140 million individuals between 2006 and 2015, of which approximately 100 million were cardinal tetras (Paracheirodon axelrodi). The species symbol of the activity has been exploited since the 1950s, representing 70% of the number of individuals traded by Brazil. Despite the significant numbers, little is known about the levels of stock exploitation, the vulnerability of the species to fishing, or the effects of the activity on ecosystem functioning. Seeking to fill these knowledge gaps and create scientific subsidies to guide fishery management strategies, this study gathered information on the life history of the cardinal tetra, analyzed population parameters, evaluated the condition of the fishery stock, the vulnerability of the species to fishing, and analyzed possible effects of ornamental overfishing on fish assemblage functional structures. The results obtained by evaluating data from 22,031 cardinal tetras show that the species has rapid growth (k= 0.76 year-1, L∞ of 27.37mm, Ф 2.75 year-1), with a life expectancy between 3 and 5 years, and 10 cohorts were observed in the analyses, reinforcing the conclusion that the species has a short life cycle. The total, natural, and fishing mortality rates were 2.45, 1.11, and 1.34 year-1, respectively. The relationship between of fishing mortality during the analyzed period to maximum sustainable yield was greater than 1, and the stock exploitation rate was estimated at 0.53, demonstrating good condition. Through stock reduction analysis, mild biomass trajectories were observed. The intrinsic population growth rate shows rapid resilience, taking approximately 16 months for the population to double in size. These results show that the stock is not overfished, and regardless of the exploitation levels found between 2006 and 2020, the support capacity of the environment limits the size of the stock. In hypothetical scenarios of ornamental species extinction, we observed losses of up to 12% in functional redundancy in the studied streams, highlighting the importance of regulating the activity. In summary, this study provides data demonstrating that the cardinal tetra stock is not overfished and shows rapid recovery, ensured by the integrity of the environments exploited by ornamental fishing, but the activity must be carried out in an orderly manner to avoid the loss of fish assemblage resilience. Thus, maintaining the activity proves to be an important conservation tool for the middle Negro River.