Abstract Scomberomorus brasiliensis is the most important fish species of the small-scale fishery off the southwestern Atlantic north of the La Plata estuary. For management purposes, this study evaluated their reproductive biology, size, age and growth along the Paraná coast. Monthly samples (March 2018-June 2020) from the fishery comprised 933 specimens (413 males, 520 females), 210-779 mm fork length, corresponding to a size smaller than in the northern areas. It presented negative allometry (b = 2.69159, length-weight relationship). Specimens in all stages of maturity occurred during the study period, indicating spawning in the area from October to June, peaking from January to March. The gonad-length relationship was suitable to confirm this assessment. Individual fecundity varied between 34,484 and 390,786 oocytes. Maturity occurred at L50 = 446.46 mm, t50 = 1.4 years, and L100 = 588.79 mm, and t100 = 2.3 years. The growth parameters were L∞ = 771.68 mm, k = 0.65 year-1 and t0 = -0.102 years, with cohorts aged from 0.5 to 6.5 years. Scomberomorus brasiliensis along the Paraná coast constitutes a self-sustaining group, not directly related to that from northeastern Brazil. This small-scale fishery is not currently negatively affecting stock level; it is essential to monitor these attributes to detect future changes or impacts.

Resumo É comum a ocorrência de flutuadores extraviados, provenientes de redes de pesca do tipo emalhe. Geralmente apresentam-se quebrados e apresentam sinais de terem sido reparados. A análise desses flutuadores e entrevistas com pescadores sugerem duas causas principais para o extravio. Primeira, colisões entre equipamentos ativos, as redes de arrasto camaroeiras, ou equipamentos passivos, as redes de emalhe para peixes, com destruição e perda de materiais em ambos os casos. Como segunda causa destaca-se o método precário com que flutuadores são inseridos na tralha superior das redes de emalhe na época em que os recursos-alvo são predominantemente pelágicos. Tal inserção ocorre para substituir unidades danificadas ou perdidas ou ainda, em caráter sazonal, as que foram removidas na época em que a pesca era dirigida a recursos demersais. Este trabalho descreve um novo desenho de flutuador e testa sua eficácia, visando aumentar a retenção nos cabos e reduzir a perda.

Abstract Plastic floats from fishing nets are commonly found washed up on beaches in southern Brazil. They are usually broken and show signs of having been repaired. Characteristics of floats and interviews with fishermen suggest two main causes of float loss. First, collisions between active gear, bottom trawl nets for shrimp, and passive gear, drift nets for fish, destroy nets and release fragments of them, including floats. Second, the difficulty with which floats are inserted on the float rope of the nets when they are used near the surface. Floats are inserted to replace damaged or lost floats, or they may be removed if it is desired that the nets be used in deeper waters. Floats may thus be poorly fixed to the cables and lost. Here a new float design that offers greater safety in use and for the replacement of floats is described and tested.

Estrutura e organização das assembléias de peixes de águas rasas (<1,5 m) foram estudadas em dois ecossistemas sul-brasileiros sob influências marinhas ou continentais, uma laguna e uma baía. Dados abióticos foram obtidos para definir a hidrologia dos locais, e descritores bióticos foram avaliados para caracterizar a estrutura das assembléias. Transparência, salinidade e matéria orgânica melhor distinguem os locais. Foram capturadas 69 espécies distribuídas em três guildas ecológicas. Descritores como densidade, diversidade e equitabilidade foram diferentes em cada local. Hidrodinamismo e geomorfologia determinaram a estrutura e a organização das assembléias de peixes nestas águas rasas. Observou-se que variações nos atributos hidrológicos gerados por aportes marinhos ou continentais podem alterar mais rapidamente, e em freqüências mais regulares, as condições na lagoa do que aquelas na baía.

The general structure and organization of the shallow water (<1.5 m) fish assemblages were studied in two southern Brazilian ecosystems, a bay and a lagoon, under different marine or continental influences. The abiotic factors were measured to define the hydrology of the sites and the biotic descriptors were evaluated to characterize the assemblage structures. Transparency, salinity and organic matter were the abiotic factors which best distinguished the sites. A total richness of 69 species was observed. Ecological guilds, density, diversity and evenness indices values were different at each site. The hydrodynamism and geomorphology determined the structure and the organization of the fish assemblages in these shallow waters. It was observed that the variations in the hydrological attributes generated by the marine or continental water movements were able to alter the conditions in the lagoon more quickly and at more regular frequencies than those in the bay.

Peixes são conhecidos pela grande plasticidade fenotípica com que respondem às características do meio, o que lhes permite aumentar as chances de sucesso frente a variações ambientais. No presente trabalho foram examinadas as respostas biológicas de teleósteos após uma abrupta modificação no ambiente provocada pelo represamento dos rios. Dois reservatórios de diferentes idades, situados no norte da América do Sul, foram investigados: um mais jovem (14 anos), Petit-Saut, na Guiana Francesa, e outro mais antigo (44 anos), Brokopondo, no Suriname. Em 14 espécies de peixes foram avaliados seis atributos biológicos, os quais foram comparados com a situação apresentada no rio Sinnamary antes do enchimento do Reservatório Petit-Saut. Avaliamos o tamanho máximo dos indivíduos, os comprimentos absoluto e relativo de primeira maturação, a proporção de ovócitos maduros em gônadas desovantes, a fecundidade por lote, e o tamanho médio dos ovócitos maduros. Os resultados indicam ter havido aumento do esforço reprodutivo com a formação dos reservatórios. Todas as espécies tiveram redução de tamanho. Comparados aos valores observados antes da formação dos reservatórios, oito espécies tiveram ovócitos maiores e três espécies mostraram aumento da fecundidade por lote. A constatação dessas mudanças aponta para a adoção de estratégias de ocupação pioneira. Aquelas observadas no Reservatório Petit-Saut parecem também aplicar-se ao Reservatório Brokopondo, 30 anos mais antigo, sugerindo que esses reservatórios mantêm-se em condição imatura por muito tempo

Fish species are known for their large phenotypic plasticity in life-history traits in relation to environmental characteristics. Plasticity allows species to increase their fitness in a given environment. Here we examined the life-history response of fish species after an abrupt change in their environment caused by the damming of rivers. Two reservoirs of different age, both situated on the Guiana Shield, were investigated: the young Petit-Saut Reservoir in French Guiana (14 years) and the much older Brokopondo Reservoir in Suriname (44 years). Six life-history traits in 14 fish species were studied and compared to their value in the Sinnamary River prior to the completion of Petit-Saut Reservoir. The traits analyzed were maximum length, absolute and relative length at first maturation, proportion of mature oocytes in ripe gonad, batch fecundity and mean size of mature oocytes. The results revealed a general increase of reproductive effort. All species showed a decrease in maximum length. Compared to the values observed before the dam constructions, eight species had larger oocytes and three species showed an increased batch fecundity. These observed changes suggest a trend towards a pioneer strategy. The changes observed in Petit-Saut Reservoir also seemed to apply to the 30 years older Brokopondo Reservoir suggesting that these reservoirs remain in a state of immaturity for a long time.

O presente estudo avaliou: 1) se a diversidade da ictiofauna de águas rasas do Rio Formoso (Pernambuco) varia entre as zonas estuarinas superior e inferior, e entre os períodos seco e chuvoso e 2) se houve diferenças espaciais e temporais nas categorias tróficas dessa ictiofauna. Os peixes foram coletados bimestralmente com rede-de-arrasto tipo mangote. Foram coletados 5475 indivíduos pertencentes a 78 espécies, sendo 51,3% de origem recifal. Carangidae e Gerreidae tiveram a maior riqueza específica, enquanto Clupeidae, Engraulidae e Gerreidae a maior abundância. Entre as espécies dominantes (89%), destaca-se Rhinosardinia amazonica (36%). A maioria da ictiofauna é predadora (75%) e com hábito alimentar carnívoro de 2ª. ordem (37,5%). A diversidade foi significativamente mais elevada na zona superior do estuário. A zona superior do estuário é, provavelmente, mais produtiva devido a sua maior complexidade morfológica, à maior abundância de Rhizophora mangle (abrigo e refúgio para vários peixes) e ao sedimento lamoso. O Fator de Contribuição Trófica (FCT) de detritos foi maior na zona estuarina superior, onde há maior teor de silte e argila. O FTC para a produção primária foi mais elevado na zona estuarina média, onde há uma maior biomassa fitoplanctônica. A maioria das espécies encontrava-se em ecofase jovem, evidenciando a importância das águas rasas deste estuário tropical como criadouro natural e abrigo para vários peixes de importância ecológica e econômica.

The goals of the present study were: 1) to test whether the shallow water ichthyofaunal diversity in the Formoso river (Pernambuco) varies between the upper and lower estuarine zones and between the dry and rainy season; and 2) to assess spatial and temporal shifts in their trophic categories. The fishes were collected bimonthly using beach seine. A total of 5,475 individuals were analyzed, belonging to 78 species, of which 51.3% were of reef origin. Carangidae and Gerreidae had the highest diversity, whereas Clupeidae, Engraulidae and Gerreidae were the most abundant. Among the dominant species (89%), Rhinosardinia amazonica was particularly common (36%). Most of the species were predators (75%), including species with carnivorous feeding habits of the 2nd order (37.5%). The only statistically significant difference in diversity occurred between the lower and upper estuarine zones, being higher in the former. This is probably due to the higher morphological complexity, to the larger proportion of Rhizophora mangle (shelter and refuge for several fishes), and to the mud sediment that makes this a more productive area. The Trophic Contribution Factor (FCT) for the debris was higher in the upper estuarine zone, where there is a higher rate of silt and clay. This TCF for primary production was higher in the middle estuarine zone, where there is higher phytoplankton biomass. Most species were in the young ecophase, corroborating the importance of shallow waters in this tropical estuary as a natural nursery and shelter for several fish of ecological and economical importance.

O presente estudo foi realizado no litoral entre a divisa dos Estados do Paraná e Santa Catarina, em duas comunidades pesqueiras artesanais que integram os municípios de Guaratuba (PR) e Itapoá (SC). Foram acompanhadas as atividades pesqueiras das comunidades, entre julho de 2001 e março de 2003, com o objetivo de: listar as espécies de elasmobrânquios capturadas pelas comunidades em questão; avaliar o uso comercial das espécies; observar a ocorrência sazonal das espécies nos desembarques; estimar a freqüência relativa de captura por aparelho de pesca; e inferir sobre a biologia reprodutiva das espécies. Durante o período estudado foram capturados: Carcharhinus falciformis, Galeocerdo cuvier, Rhizoprionodon lalandii, R. porosus, Sphyrna lewini, S. zygaena, Squatina guggenheim, Narcine brasiliensis, Rhinobatos percellens, Zapteryx brevirostris, Rioraja agassizii, Dasyatis americana, D. guttata, D. hipostigma, Gymnura altavela, Myliobatis goodei, Rhinoptera bonasus e R. brasiliensis. Quanto à comercialização das espécies, foi observado que todos os tubarões capturados na área de estudo são comercializados, dentre as raias, apenas Rhinobatos percellens e Zapteryx brevirostris. Nos desembarques, a ocorrência de elasmobrânquios foi maior durante o inverno e a primavera. A maioria das capturas ocorreu com redes de emalhe, o arrasto camaroneiro pouco capturou. Os dados do presente trabalho indicaram a utilização da área estudada para o parto das espécies G. cuvier, R. lalandii, R. porosus, S. lewini, N. brasiliensis e R. agassizii; para o crescimento de todas as espécies amostradas; e para a gestação de R. percellens e Z. brevirostris. É sugerido que medidas que visem a proteger as espécies sejam tomadas, sem trazer prejuízos e conflitos para as comunidades de pescadores.

This study was done in the South coast of Parana State and North coast of Santa Catarina State, Brazil, in two artisanal fishermen communities. Between July, 2001 and March, 2003 the fishing activities were observed aiming to: report the elasmobranchs caught species; report which species are commercialized; observe the seasonal occurrence of the species in the landings; estimate the frequency of capture by different fishing gears; and infer about the reproductive biology of the species. During the studied period were captured: Carcharhinus falciformis, Galeocerdo cuvier, Rhizoprionodon lalandii, R. porosus, Sphyrna lewini, S. zygaena, Squatina guggenheim, Narcine brasiliensis, Rhinobatos percellens, Zapteryx brevirostris, Rioraja agassizii, Dasyatis americana, D. guttata, D. hipostigma, Gymnura altavela, Myliobatis goodei, Rhinoptera bonasus and R. brasiliensis. It was observed that all sharks and only two ray species (R. percellens and Z. brevirostris) are commercialized. In the landings, elasmobranchs were more frequent during winter and spring. Most catches were done by gillnets, while just a few captures were done by shrimp trawls. The data indicated that the studied area is used by G. cuvier, R. lalandii, R. porosus, S. lewini, N. brasiliensis and R. agassizii to give birth; by all species for growing; and during the gestation of R. percellens and Z. brevirostris. It is suggested that actions aiming to protect the species must be taken, without harming and conflicts for the fishermen communities.

Este trabalho fornece dados sobre a biologia de C. bleekerianus do litoral do Estado do Paraná, reunindo dados sobre sua abundância, estrutura em tamanho, dieta e reprodução. Coletas mensais foram realizadas em 1999 e 2000 na plataforma continental interna, com rede de arrasto de fundo com portas. A captura por unidade de esforço não variou significativamente entre as estações do ano. No verão os indivíduos eram maiores, seguido do outono, primavera e inverno. C. bleekerianus é predominantemente planctívora, sendo copépodos seguidos de algas diatomáceas os itens alimentares mais freqüentes em sua dieta. As variações sazonais de valores da freqüência de estádios de maturação gonadal, do índice gonadossomático e do fator de condição gonadal indicam que o período reprodutivo compreende primavera e verão. O comprimento total médio de primeira maturação das fêmeas é estimado em 76 mm.

This study provides information on the biology of C. bleekerianus from Paraná State coast, Brazil, assembling data about its abundance, size structure, diet and reproduction. Monthly collections were accomplished in 1999 and 2000 in the internal continental shelf, with trawl net. The catch-per-unit-effort did not vary significantly among the seasons. In the summer, the individuals were larger, followed by autumn, spring and winter. C. bleekerianus was predominantly planktivorous and the most frequent items in its diet were copepods followed by diatomaceous algae. Seasonal variation in the frequency values of the gonad maturation stages, gonadossomatic index and gonadal condition factor indicated that the reproductive period encompassed spring and summer. The mean total length at first maturity of females was estimated to be 76 mm.

A survey performed in the Guaratuba Bay (25º52'S; 48º39'W) and the adjacent marine area has provided additional data about the habits of the croaker in the southern coast of Brazil. A dynamic pattern of movements along the marine and estuarine waters was observed, but it does not indicate spawning activity in the study area. During autumn/winter, pre-adults and adults use the marine waters. In spring/summer, following gonadal maturation,the individuals leave this area and probably move to deeper waters, where they spawn. Until the end of summer, the estuary is then occupied by juveniles coming from the marine spawning area. In autumn/winter, these juveniles and the new pre-adults move to the marine zone adjacent to the bay and begin gonadal maturation. It is suggested that the Guaratuba Bay and the adjacent marine area constitute an important site for growth and recruitment of the early lifestages of M. furnieri and initial stages of reproductive activity.

A survey performed in the Guaratuba Bay supports the hypothesis that the G. melanopterus individuals migrate to reproduce at the sea during summer. In autumn and winter, the adults return to the Bay, a pattern not yet described in the literature for this species. G. melanopterus explores the most internal areas of the Bay when the continental influence is lower. Differences in feeding habits were registered between individuals occupying the investigated area and those from a nearby mangrove previously studied.

No manguezal da Baía de Guaratuba, litoral sul do Brasil, os Gerreidae são representados por 3 gêneros e 5 espécies, compondo uma parcela numericamente importante da ictiofauna local. Este trabalho descreve a estrutura populacional e os hábitos reprodutivos de Eucinostomus argenteus, E. gula e E. melanopterus, reconhecendo as relações que mantêm com o manguezal. Os resultados indicam que o manguezal representa para elas um habitat transitório. Os subadultos crescem na área ao longo do ano, deixando-na na primavera ou no verão, quando completam a maturação e desovam, no mar ou em outra região da Baía. E. argenteus e E. gula não retornam ao manguezal após a desova, mas E. melanopterus provavelmente sim. As três espécies alimentam-se sobretudo de poliquetos, apresentando diferenças nos itens secundários da dieta.

Several coastal fish use the estuarine habitat during a part of their life cycle. These sites are considered good for the reproductive activity, as well as for the growth of larvae and juveniles. Concerning the Gerreidae, however, many studies reveal that most species leave the estuaries to reproduce at sea. At Guaratuba Bay, southern Brazil, this family is represented by three genera and five species, which make an important fraction of the local assemblage. The present study investigated the populational structure and breeding habits of three Eucinostomus species, in order to know what relationship exists between them and the mangrove. It was found that the Guaratuba mangrove represents a transitory habitat for the life cycle of the Eucinostomus species. The sub-adults grow in the mangrove throughout the year and leave this milieu in spring or summer, when they complete the gonadal maturation and presumably spawn. E. argenteus and E. gula do not return to the mangrove after spawning. The three species feed mainly on polychaetes, but differences occur with respect to the secondary components of the diet.

A alimentação do cangulo ou canguá, Stellifer rastrifer, foi estudada no manguezal da Baía de Guaratuba entre fevereiro 1996 e fevereiro 1997. Constatou-se que a dieta está baseada em invertebrados, sobretudo Decapoda Brachyura e Polychaeta. Secundariamente, registram-se vegetais superiores, Copepoda, Gammaridea e Mollusca. O grau de participação dos itens varia com a estação e o tamanho dos indivíduos. Tal plasticidade no hábito alimentar, também conhecida em outras populações de peixes estuarinos, pode ser considerada como mais um indicador do grau de instabilidade encontrado nestes ambientes.

Feeding habits of Stellifer rastrifer (Perciformes, Sciaenidae) at Guaratuba mangrove, Parana, Brazil, were studied from February 1996 to February 1997. It was observed that its diet was based on invertebrates, mainly Decapoda non-Brachyura and Polychaeta. In a smaller proportion there were plants, Copepoda, Gammaridea and Mollusca. The level of contribution of each food item changed according to the season and the individual size. Such plasticity in feeding behaviour was similar to that described to some fish populations from other estuaries, and could be an indicator of the high level of instability presented by this kind of ecosystem.

Diapterus rhombeus (Cuvier, 1829) is one of the most common Gerreidae species in the estuarine region at the Guaratuba Bay, Southern Brazil. Based on studies developed between July, 1993 and January, 1997, it was observed that its presence in the mangrove area is not regular: the smallest individuais are more abundam during late summer and in autumn, and the largest ones during spring and early summer. Its diet comprises plant material and invertebrates, specially polychaets. The morphological aspects of the gonads, the monthly changes on the Condition Factor, and lhe monthly distribution of the individual size groups, suggest that this population spawns during the spring, out the estuarine region. The smaller individuais use the mangrove area of Guaratuba Bay to a growth phase, and the adulls to make somatic reserves to the spawning period.

The Guaratuba Bay (25o52'S, 48o39'W) is the second largest estuarine system of the State of Parana, Brazil. It extended inside of the continent for about 15 km and is surrounded by mangroves. Water depth can reach up to six meters. The fish faunal composition of this area was evaluated with a bottom trawl and, occasionally, casting and gill nets. One species of Chondrichthyes and 59 of the Actinopterygii (50 genera and 28 families) were reported from the Bay. The results were not significantly different from those of the Paranagua Bay, except by the lower number of species. These differences appear related to distinct collection efforts and the extension of surveyed areas. No species can be considered endemic to the region. Tipically freshwater species were not collected.

Reproductive and biometrical analyses were pertormed on 1629 individuals of P. corvinaeformis collected monthly from October 1993 to September 1996, at Guaratuba Bay, Southern Brazilian coast. The results indicate that the species is more abundant in the mangrove area during winter, when the largest individuais were collected, and spring, when the water temperature is lower and the salinity higher than summer or autumn. The relationship of body weight to body length, for grouped sexes, is "lnTW= -12,0456 + 3,1831 lnTL". The monthly Condition Factor is highest during summer and lowest during winter. It is suggested that P. corvinaeformis is present in the mangrove area during a specific etape of its life cycle and does not use this area to maturation and spawn.