Jana Menegassi del Favero

The ichthyofauna of upper rio Capivari: defining conservation strategies based on the composition and distribution of fish species

Although the rio Capivari basin is recognized as an area of great importance for the ichthyofauna, it lacks virtually every basic requirement for the definition of appropriate conservation strategies, since not even its species composition is known. The objective of this work is to determine the composition and distribution of fish species in the upper rio Capivari basin, relating them to the local physical features, and to evaluate the effectiveness of proposed conservations units, delimited based on areas of native vegetation remains, on the conservation of local ichthyofauna. During 2007, 50 different watercourses were sampled with gillnets, cast nets and kick nets. A total of 1308 individuals belonging to 41 species were captured. Degree of conservation, altitude and width were the parameters that best explained fish species richness. Considering the recently proposed boundaries for potential conservation units in the region only 15 or 20 out of 41 species would be found in the State Park and Environmental Protection Area respectively. In practice, the proposed conservation units would not be effective tools for fish conservation, since it would be located in mountainous areas of high altitude, of headwaters streams and where few species are found. In such context, the conservation of specific stretches of larger rivers is critical.

Biologia reprodutiva de Heros efasciatus Heckel, 1840 (Pisces, Cichlidae) na Reserva de Desenvolvimento Sustentável Amanã-AM, visando seu manejo sustentável

The aim if the present work is to supply basic information that may help the management of ornamental fishes in the Amana Sustainable Reserve, State of Amazonas, Brazi. A study of the reproductive biology of Heros efasciatus, a cichlid fish with ornamental potential, was performed using specimens collected bi-monthly between February 2006 and January 2007 in ten creeks contributing to Lakes Amana and Urini. The sample collection gear included hand net, seine and traps. In addition, artificial tree branches were used for sampling near the lakes. A total of 140 specimens of H. efasciatus were captured, which corresponded to only 0.07% of all specimens collected. Of this total, 50 were male, 42 were female, and 46 individuals could not be sexed due to their small size. The type of growth founded was isometric; with individuals’ sizes varying from 14 mm to 174 mm. Average fecundity was estimated at 2,502 oocytes. The results of this study will help in implementing several sustainable management measures, such as establishing a minimum size for capture (higher than 97 mm) and imposing a no-fishing restriction during the spawning season of this species (from October till January). To ensure stock continuity due to the low density and low fecundity of H. efasciatus, we suggest that exploitation of this species for ornamental trade be kept to a small number of individuals per year.

Juvenile fish use of the shallow zone of beaches of the Cananéia-Iguape coastal system, southeastern Brazil

The purpose of the present study is to describe the juvenile fish use of the shallow zone of beaches of the Cananeia-Iguape coastal system, Sao Paulo, Brazil, analyzing its occurrence period and the patterns of utilization for the most abundant species. Using a beach seine monthly for one year, we sampled 13861 individuals, of 57 species and 24 families. The fish species used the study area for different proposes: Atherinella brasiliensis was sampled in all phases of gonadal development and considered as resident, juveniles of Trachinotus goodei used the beaches for growth and juveniles of Mugil curema and Mugil liza used the beaches as a route from the ocean to the estuary. Our results showed the importance of the sandy beaches for juvenile fish, especially in spring and summer when most juveniles occur and recruit. Unfortunately, this is the period of the most intense tourist activity. As many of the species studied are commercially important, this study highlighted the necessity of coastal habitat preservation for better fishery management.

Using new tools to identify eggs of Engraulis anchoita (Clupeiformes, Engraulidae)

Efficiency of the identification of eggs of Engraulis anchoita can be greatly improved by a method developed from egg measurements, using photography and the ImageJ programme, analysed by discriminant analysis using R software.

Comparison of the effects of two bongo net mesh sizes on the estimation of abundance and size of Engraulidae eggs

Studies of ichthyoplankton retention by nets of different mesh sizes are important because they help in choosing a sampler when planning collection and the establishment of correction factors. These factors make it possible to compare studies performed with nets of different mesh sizes. In most studies of mesh retention of fish eggs, the taxonomic identification is done at the family level, resulting in the loss of detailed information. We separated Engraulidae eggs, obtained with 0.333 mm and 0.505 mm mesh bongo nets at 172 oceanographic stations in the southeastern Brazilian Bight, into four groups based on their morphometric characteristics. The difference in the abundance of eggs caught by the two nets was not significant for those groups with highest volume, types A and B, but in type C (Engraulis anchoita), the most eccentric, and in type D, of the smallest volume, the difference was significant. However, no significant difference was observed in the egg size sampled with each net for E. anchoita and type D, which exhibited higher abundance in the 0.333 mm mesh net and minor axis varying from 0.45-0.71 mm, smaller than the 0.505 mm mesh aperture and the mesh diagonal.