2015/01/01 by José Augusto Negreiros Aragão, Aragão, José Augusto Negreiros, Israel Hidenburgo Aniceto Cintra +3
Environmental Science · Agricultural and Biological Sciences · #Fish biology, ecology, and behavior #Marine and fisheries research #Aquaculture Nutrition and Growth
paper · doi:10.2312/actafish.2015.3.1.77-90
Resumo O camarao-rosa ( Farfantepenaeus subtilis ) possui um ciclo de vida curto, mas complexo, habitando areas oceânicas, mais ao norte da area de ocorrencia, na fase adulta e larval, e areas estuarinas e lagunares na fase de pos-larva e juvenil. O pico de reproducao se estende de maio a setembro e, logo apos, as larvas eclodem e iniciam sua migracao para areas costeiras, onde se assentam e residem principalmente entre junho e outubro. A partir de setembro ate janeiro do ano seguinte e maior a intensidade de recrutamento de juvenis as areas oceânicas, onde passam a amadurecer e, a partir de dezembro, comecam a ser alvo da pesca industrial. A maior abundância da populacao adulta em termos de biomassa vai de marco a agosto quando tambem se verificam as maiores capturas. As femeas crescem mais que os machos e estao presentes sempre em maior proporcao nas capturas (61%). Os comprimentos assintoticos foram estimados em 231 mm (machos) e 205 mm (femeas). A populacao apresenta taxa de mortalidade relativamente elevada com acentuadas flutuacoes de recrutamento e abundância, com evidencias de que sao fortemente governadas pelas condicoes ambientais. A vazao do rio Amazonas e o fator ambiental que governa com mais intensidade as condicoes do ambiente costeiro na regiao e verificou-se que suas flutuacoes influenciam a abundância populacional. Postula-se que o aporte e sobrevivencia das larvas e pos-larvas no ambiente costeiro seja influenciada pela intensidade da vazao do rio. O periodo em que se assentam nos bercarios na zona costeira coincide com a estacao de vazante do rio, sendo a sobrevivencia favorecida por vazoes abaixo da media e vice-versa. Portanto, medidas de ordenamento voltadas para o uso sustentavel do recurso devem estar associadas ao conhecimento das condicoes ambientais, bem como a estudos sobre a abundância de pos-larvas e juvenis na faixa costeira. Abstract The brown shrimp ( Farfantepenaeus subtilis ) has a short but complex life cycle, inhabiting oceanic areas, at the north of its distribution during the adult and larval stages, and at estuarine areas and lagoons in post-larval and juvenile stages. Highest intensity of reproduction extends from May to September. Soon after the hatch, the larvae start their migration to coastal areas, passing throughout several stages, where they settle and remain resident between June and October. From September to January of the following year the intensity of recruitment to ocean areas is higher, where they start to mature and from December on they are captured by the industrial fishery. The highest abundance of the adult population in terms of biomass was observed from March to August when the largest catches also occur. Females grow larger than males and are always present in greater proportion in catches (61%). Asymptotic lengths were estimated at 231 mm and 205 mm, for females and males respectively. The population has a natural mortality rate relatively high, 2.53 year -1 for females and 1.83 years -1 for males, and pronounced fluctuations in recruitment and abundance are observed, with evidence of being strongly governed by environmental conditions. The flow of the Amazon River is the main environmental factor that determines the conditions of the coastal environment in the region and it was found that the fluctuations are correlated with with the brown shrimp population abundance. It is postulated that the uptake and survival of larvae and post larvae in the coastal environment is influenced by the intensity of river flow. The settling period at the nurseries in the coastal zone coincides with the dry season and their survival is favored when the flow of the river is below the average, and vice versa. Therefore, management measures facing the sustainable use of the resource must be associated with the knowledge of environmental conditions during this period, as well as studies on the abundance of post-larvae and juveniles in the coastal zone.