Larvae diversity of Istiophoridae and Xiphiidae (Perciformes, Xiphoidei) in Southeast Brazil

Abstract

In the Atlantic the billfish belong to the families and Istiphoridae Xiphiidae, and are commonly known as sailfish (Istiophorus platypterus), white marlin (Kajikia albida), blue marlin (Makaira nigricans), spearfish (Tetrapturus pfluegeri) roundscale spearfish (Tetrapturus georgii) and swordfish (Xiphias gladius). They are caught in commercial fishing and Brazilian sport fishery. Fish stock of K. albida and M. nigricans are over-exploited with little information about their reproductive biology in relation to the area and spawning season in the West South Atlantic. These species occupy important ecological niche in their environment using the southeastern and southern Brazil as a migratory route for feeding and reproduction. Previously, were observed with female gonads mature I. platypterus, K. albida, M. nigricans, and X. gladius, from November to March. This work intends to capture, identify and quantify larvae of these species, to determine the geographic and temporal spawning these fish in southeastern Brazil, generating additional data on the reproductive biology. Also contributing to the database Biota - FAPESP and OBIS (Ocean biogeographic Information System) and subsidizing management measures in the region. Will be made approximately 20 scientific cruises with the support of the sport fishery boats of "Iate Clube de Espírito Santo, Iate Clube do Rio de Janeiro and Yacht Club de Ilhabela", yielding approximately 80 collection points in major areas of occurrence of billfish (Espírito Santo to São Paulo), from November 2013 to February 2014. Will be performed trawl net surface ichthyoplankton. The samples will be fixed in 95% ethanol. After screening there is a selection of probable larvae and Istiophoridae Xiphiidae, based on the main taxonomic characteristics for identification. It is intended to perform the further identification of the larvae through DNA analysis at the "Universidade de Mogi das Cruzes" (Laboratório de Biologia Molecular) and "Nova Southeastern University (Oceanographic Center)" Florida, USA. Preliminarily, the fishing seasons (2011/2012 and 2012/2013) were conducted pilot samples totaling 45 points hauls, yielding 98 probable larvae K. albida (Vitória-ES), 53 probable larvae of I. platypterus (Cabo Frio-RJ and Rio de Janeiro-RJ) and six larvae of I. platypterus (Ilhabela-SP). The project also has the support of the "Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de Sao Paulo", using scanning electron microscopy, for better identification of anatomic structures of billfish larvae. (AU)