Fisheries ecology of sand flathead in Port Phillip Bay

Age data revealed that growth of sand flathead samples caught within Port Phillip Bay is very different compared to those caught from outside the Bay. Results also show that recruitment is variable (dependent of several environmental parameter), and that this variability is largely responsible for trends in abundance.

Fish and fisheries of large and medium-sized reservoirs in Vietnam

The study was undertaken in view of the importance of reservoir fisheries for Vietnam, and to fill gaps in the current knowledge in order to introduce affective management measures to optimise the fish yields from the reservoirs. Eight large and medium sized reservoirs , representing a cross section of reservoirs in Vietnam in the different climatic zones were studied.

Fishways in Australia

In Australian regulated rivers, dams and weirs have contributed to serious declines in the distribution and abundance of migratory fish. This thesis has evaluated four fishways in Victoria, New South Wales and Queensland and provided new information for 51 migratory fish species. Fishways will be crucial for management and conservation of biodiversity.

The potential use of otoliths for pilchard stock discrimination

Pilchards were collected from south-eastern Australian waters and aged by counting growth rings on their ear bones (otoliths). Differences in growth and population age structures were compared between regions. The shape characteristics of the ear bones were also examined using rapid, objective, semi-automated methods. Differences between the areas were shown.

Reproduction and ageing of Australian holocephalans and white-fin swell shark

The holocephalans are a slow growing, long lived group with a conservative life history strategy and require similarly conservative fishery management strategies to ensure their sustainable exploitation. White-fin swell shark are relatively short lived, highly fecund and likely to be more capable of withstanding intensive fishing.

Catch and selectivity parameters of the anastomid fish Schizodon nasutus using gillnets in the Jurumirim reservoir (São Paulo, Brazil)

Catch and selectivity parameters using gillnets were calculated for Schizodon nasutus in the Jurumirim reservoir on the Parana-panema River in southern Brazil. The simple gillnets used were made of monofilament nylon of 30 to 140 mm mesh size an of different heights. The relative abundance of the S. nasutus caught was analysed monthly and a positive relationship was found between catches per unit effort in number and biomass. The relative catches were more abundant for the nets of 40 and 50 mm, mesh size. Catches were characterized by clear temporal variations and a predominance of medium size fish throughout the study period. The selectivity curve of gillnets for S. nasutus in this ecosystem was obtained. The catch obtained was compared with the available catch for each mesh size, and the available catch for a certain length of fish was calculated starting from the theoretical selectivity curve. The 50 mm mesh size gillnet showed the best fit between real and available captures and was considered the most suitable, because a smaller mesh size resulted in a catch of predominantly immature specimens. It is expected that these results will contribute to improving management strategies for conservation of resources. Parameters such as the minimum catch length advisable or the mesh size permitted for a given species are indispensable for such decision-making.

Discrimination of Shark species by simple PCR of 5S rDNA repeats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phylogeography and genetic population structure of Caribbean sharpnose shark Rhizoprionodon porosus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Species delimitation in sharpnose sharks (genus Rhizoprionodon) in the western Atlantic Ocean using mitochondrial DNA

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetics of neotropical fish: from chromosomes to populations

The Neotropical freshwater fish fauna is very rich-according to the most recent catalogue 71 families and 4,475 species have been described. However, only a small amount of general information is available on the composition of Neotropical marine fishes. In Brazil, 1,298 marine species have been recorded. General analysis of available cytogenetic and population genetic data clearly indicates research has been mainly concentrated on freshwater fishes. Thus, today, cytogenetic information is available for 475 species of Characiformes, 318 species of Siluriformes, 48 species of Gymnotiformes, 199 freshwater species that do not belong to the superorder Ostariophysi, and only 109 species of marine fishes. For the species studied, only about 6% have sex chromosomes and about 5% have supernumerary or B chromosomes. A review of the cytogenetic studies shows that these data have provided valuable information about the relationships between fish groups, the occurrence of cryptic species and species complexes, the mechanism of sex determination and sex chromosome evolution, the distribution of nucleolus organizer regions, the existence supernumerary chromosomes, and the relationship between polyploidy and evolution. In relation to populations in Neotropical marine waters, the studies have shown the presence of cryptic species, which has important implications for fishery management. Different levels of genetic structuring can be found among Neotropical freshwater migratory fish species. This raises important implications for fish population genetic diversity and consequently its sustainable utilization in inland fisheries and aquaculture, specifically for conservation of ichthyo-diversity and survival.

Population genetic structure revealed by a school of the freshwater migratory fish, Brycon hilarii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fishing resources in the rio Cuiabá basin, Pantanal do Mato Grosso, Brazil

O recurso pesqueiro da bacia do rio Cuiabá, um dos mais importantes tributários da bacia do Alto Paraguai, formadora do Pantanal, foi estudado a partir dos dados de desembarque de pescado obtidos no Mercado do Porto de Cuiabá, Mato Grosso, Brasil. São descritas a composição e procedência das capturas para os anos de 2000 e 2001. O rio Cuiabá é a fonte dominante de pescado para a cidade de Cuiabá, mas uma parte do pescado comercializado localmente é oriunda do rio Paraguai. Além disso, atualmente o pescado vem de regiões mais distantes da zona urbana. Constatou-se que a pesca incide basicamente sobre espécies migradoras. As principais espécies capturadas foram os pimelodídeos pintado -Pseudoplatystoma corruscans, cachara -Pseudoplatystoma fasciatum e jaú -Paulicea luetkeni e os caraciformes pacu -Piaractus mesopotamicus, piraputanga -Brycon microlepis, piavuçu -Leporinus macrocephalus e dourado -Salminus brasiliensis. Os grandes bagres (Pimelodidae) foram os responsáveis por 70% do pescado desembarcado no período de estudo, dentre os quais o pintado foi a espécie mais capturada. Os dados indicam que as capturas atuais estão bem aquém daquelas registradas no início da década de 80. Além disso, apesar do número e composição de espécies capturadas serem similares àqueles da década de 80, a distribuição da abundância mudou. Atualmente a pesca captura mais espécies carnívoras do que espécies de níveis tróficos inferiores. Estes achados não podem ser creditados somente a sobrepesca, mas parecem resultar de uma complexa interação entre degradação ambiental, mudanças na preferência de mercado e medidas legais restritivas à pesca.

Fee - fishing operation evaluation at Nothwest São Paulo State, Brazil

Os lagos de pesca recreativa, pesque-pague, surgiram no Brasil em um cenário agrícola denominado como novo rural brasileiro. Este estudo conduzido no noroeste paulista teve como foco o desempenho produtivo dos lagos de pesca recreativa. Foram feitas visitas mensais a nove empreendimentos de pesca recreativa durante seis meses. A cada visita foi aplicado um questionário contendo 13 indicadores de desempenho. Os dados levantados foram submetidos à análise multivariada (MANOVA), análise de componente principal (ACP) e análise de agrupamento. A MANOVA indicou diferenças significativas entre os lagos de pesca recreativa. A ACP revelou, a partir do coeficiente dos autovalores, três atributos: sistema produtivo, gerenciamento pesqueiro e administração operacional. A análise de agrupamento classificou os lagos de pesca recreativa em quatro grupos. Freqüência de pescadores (FP), densidade de estocagem (DE), biomassa de estocagem (BE), captura total (CT) e captura lago dia (CLD), os quais fazem parte do atributo sistema produtivo, mostrando-se os indicadores mais importantes para a avaliação de desempenho dos lagos de pesca recreativa neste estudo.

A bio-economic appraisal of pair trawl fisheries off southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diversity of fish species in the River Paranapanema Jurumirim Reservoir transition region (São Paulo, Brazil)

The diversity of fish species in an transition zone between the River Paranapanema and the head mouth of the Jurumirim Reservoir was evaluated. Fish samples were collected from October 1995 to September 1996, by experimental fishing (gill-nets and sieve), in three marginal shallow lagoons and two channel river zones, Gill-net collections resulted in 21 taxons of native fishes. Detritivorous Characiformes such as Steindachnerina insculpta were predominant Sieve collections resulted in 31 taxa and the Tetragonopterinae subfamily was the most representative group, which included small species as Cheirodon stenodon. The equitability index characterized the high heterogeneity of fish numeric abundance, reflecting the dominance of a few groups. A significant relationship between biotic and abiotic variables was indicated by the first canonical function. In comparison with other regions of the drainage basin, the ecotone zone studied indicated a higher species richness and, in the case of some species, fishes in all stages of development. This study demonstrated the necessity to preserve the ecological zone for the fishing and fishery management in the reservoir.