ABSTRACT The aim of this study was to determine the composition of gastrointestinal content and protease and lipase activities in summer and winter as well as to evaluate the relationship between digestive enzyme activity and centesimal composition of gastrointestinal content and feeding habits of two omnivorous species, Rhamdia quelen (Quoy & Gaimard, 1824) and Pimelodus maculatus (LaCèpede, 1803), and of two detritivorous species, Loricariichthys anus (Valenciennes, 1835) and Hypostomus commersoni (Valenciennes, 1836). The activities of pepsin, trypsin, chymotrypsin, and lipase, and the levels of proteins and lipids in the gastrointestinal tract, were evaluated. The enzyme activities were not related to the centesimal composition of gastrointestinal content or feeding habits. This finding could be associated with the variations of nutrient availability over time in the environment, as was observed in the centesimal composition of food ingested by the fish in summer and winter. The analyzed enzymes exhibited a constitutive character in these species; that is, the digestive enzymes are always available in the gastrointestinal tract to digest any food that the fish may find as an adaptation to better utilize the nutrients available in the environment in winter and summer.

Brazilian mullet Mugil liza is a schooling fish that migrates in fall and winter, leaving estuaries and coastal lagoons to spawn in ocean waters. In order to understand the reproductive migration pattern of southern stock along Brazil's coast, we analyzed data collected through the Brazilian Satellite Vessel Tracking Program (Programa Nacional de Rastreamento das Embarcações Pesqueiras por Satélite-PREPS) from 2008 to 2012. The migration period overlaps with the fishing season (May-July) when the licensed purse seine fleet fishes along the southern and southeastern coast of Brazil, motivated to capture mullet by the high value of the roe. During the five fishing seasons the average effort was of 51 active vessels. The average time per season that each vessel navigated in the Speed Compatible with Fishing Operation (SCFO) was 349.3 h, which represented an average of 17% of the total time at sea. From May to July the highest frequency (54%) of SCFO transmissions occurred in June (P < 0.05), and in 95% of the SCFO transmissions the vessels were at depths less than 50 m. The temporal and spatial displacement of the fleet in a south-north direction follows the progression of sea surface temperature SST of 19-21°C (P < 0.05). Most (60%) SCFO signals occurred in areas with this range of temperature, independent of the month and latitude. The south-north displacement of the fleets through the season was similar among the different years (P > 0.05).

La lisa Mugil liza, es una especie que forma cardúmenes, migra en otoño e invierno, saliendo de los estuarios y lagunas costeras para desovar en el océano. Para comprender la migración reproductiva del stock del Sur a lo largo de la costa de Brasil, se analizó los datos obtenidos en el Programa Nacional de Seguimiento de Embarcaciones Pesqueras por Satélite de Brasil (PREPS en portugués). El período de la migración coincide con la temporada de pesca (mayo-julio), cuando los buques cerqueros autorizados pescan a lo largo de la costa sur y sudeste de Brasil, que buscan capturar las hembras de lisas por el alto valor de sus huevos. Durante las cinco temporadas de pesca (2008-2012), el esfuerzo promedio fue de 51 embarcaciones en operación. El tiempo promedio por temporada que cada embarcación navegó de acuerdo con la Velocidad Compatible con la Operación Pesquera (VCOP) fue 349,3 h, con un promedio de 17% del tiempo total en el mar. De mayo a julio la mayor frecuencia (54%) de las transmisiones VCOP ocurrió en junio (P <0,05), y en el 95% de las transmisiones las embarcaciones operaron a profundidades menores de 50 m. El desplazamiento temporal y espacial de la flota cerquera en dirección sur-norte sigue la progresión de la temperatura superficial del mar en el intervalo de 19-21°C (P <0,05). La mayoría de las señales (60%) VCOP ocurrieron en áreas con este rango de temperatura, independiente del mes y la latitud. El desplazamiento sur-norte de la flota durante la temporada fue similar entre los diferentes años analizados (P > 0,05).

The aim of this study was to compare the influence of different haul distances of a codend beach seine on the catchability of fish in a surf zone. Two different surf zone sites (A and B) at the Cassino Beach (Rio Grande do Sul, Brazil) were sampled at three different distances, parallel to the beach (30, 60, and 90 m). Starting 40 m from the beach line, diagonal distances of approximately 50, 70, and 100 m were swept. The total CPUE and CPUA haul distances are compatible with a declining trend in catch rates with increased haul distance at both sites. However, statistically significant differences were observed only for the short distance CPUA (50 m) in relation to the other haul distances at one of the sites sampled. Two fish size groups were observed (TL < 40 and > 40 mm), but only small individuals (< 40 mm) captured in the shorter haul distance at site B showed significant differences in CPUA. This result indicates that size structure for hauls at different distances was equal and that smaller individuals determined the pattern of fish abundance. The net performance indicates that a short haul (< 50 m) is the best strategy to reduce net avoidance and fish escape when using this type of sampling gear.

The dusky grouper Epinephelus marginatus is a marine species historically exploited showing slow growth, late maturation and protogynous hermaphroditism. Currently, it is considered as endangered by the IUCN. Therefore, it is essential to increase the knowledge about its biology and ecology to help conservation of this species. The present study reports the first record of a dusky grouper individual undergoing sexual transition, from female to male, in the Atlantic Ocean based on histological analyses of gonads. The specimen with total length: 770 mm; total weight: 8.1 kg and age: 21 years was captured in a rocky bottom along the coastline of the southernmost in state Brazil.

El mero Epinephelus marginatus es una especie marina que presenta crecimiento lento, madurez sexual tardía y hermafroditismo protogínico. Actualmente está clasificada por la IUCN como amenazada, razón por la cual es esencial aumentar el conocimiento sobre su biología y ecología, para ayudar en su conservación. Se presenta el primer caso documentado de transición sexual gonadal de un mero, de hembra a macho, en el Océano Atlántico sudoccidental basado en análisis histológicos de las gónadas. El espécimen con largo total de 700 mm, peso total de 8.1 kg y edad de 21 años fue capturado en un fondo rocoso en la costa del extremo sur de Brasil.

The present study compares fish species composition, dominance, and size-structure patterns at an open sand beach area (32°15'S, 52°46'W) in Mirim Lake, RS, Brazil, estimated from samples collected with two distinct beach seine nets. The BS-9m net is 9 m long and 1.5 m high, and is made with a 5 mm multifilament mesh on its central portion and 12 mm on the side wings. The BS-30m net is 30 m long and 1.8 m high, with a 12 mm monofilament nylon mesh all over the net, except for a 30 cm strip made with a 12 mm multifilament mesh on the lower portion. Thirty hauls were performed with both nets resulting in a total of 849 fish captured, comprising 34 species. BS-9m was selective for individuals smaller than 60 mm TL and BS-30m for individuals larger than 60 mm TL. Low values of the faunal similarity (JI = 0.41, ANOSIM R = 0.2309, p < 0.0001) and numeric dominance (PSI = 0.46) indexes were revealed. We suggest that the concurrent use of both samplers provide a better description of the fish fauna of shallow areas. However, due to their robustness, rusticity, and ease of use and maintenance, small multifilament seines are indicated for regular work in environments without obstacles and with little open sand area available for sampling.

Neste trabalho é apresentada uma compilação do conhecimento atual de Lycengraulis grossidens, uma espécie de peixe amplamente distribuído pela costa oeste do Atlântico Sul, ocorrendo de Belize a Argentina. Esta espécie é abundante nos estuários e tem importância na pesca recreacional além de sofrer impacto da pesca do camarão. São revisados dados publicados sobre a taxonomia, filogenia, ecologia, pesca e ciclo de vida da espécie. Nossa revisão mostrou que, ao longo de sua distribuição, a espécie tem sido classificada de várias formas na tentativa de descrever seu uso do habitat, desde residentes de água doce, anádromos, marinhos migrantes, estuarinos residentes, catádromo e semi-catádromo. Conclui-se que a espécie é capaz de se reproduzir em água doce ou salgada, com uma alta plasticidade no uso do habitat e na sua história de vida, com componentes migrantes e residentes no mesmo local. Além disso, parece haver uma mudança no comportamento migratório da espécie em diferentes latitudes, mostrando um padrão anádromo ou semi-anádromo nas maiores latitudes e marinhos migrantes ao longo da costa tropical do Brasil.

In this paper, we present a summary of the current knowledge of Lycengraulis grossidens, a widely distributed coastal fish that occurs from Belize to Argentina. This species is abundant in estuaries along the Southwest Atlantic Coast and is important for recreational fishing, and as bycatch of shrimp fisheries. We compiled data available on taxonomy, phylogeny, ecology, fisheries and organized conceptually the life cycle of the species according to modern estuarine-use classification. Our review showed that along its geographic distribution and inside some particular environments (i.e., estuaries and costal lagoons) the species have been classified in a variety of ways in order to describe the remarkable complexity of habitat use that varies from freshwater resident, anadromous, marine migrant, estuarine resident, marine stragglers, catadromous to semi-catadromous. We conclude that L. grossidens is able to reproduce either in freshwater or estuarine water and postulate that it has a high plasticity in habitat use and life history, with migratory and resident contingents in the same local population. There seems to be a latitudinal change in migratory behavior of this species along the South America Coast, prevailing anadromous or semi-anadromous pattern at higher latitudes and marine migrants at the tropical northeast coast of Brazil.

A proposta deste estudo foi investigar os níveis de Na+, Cl-, K+, Ca2+, and Mg2+ no plasma de teleósteos de água doce e marinhos/estuarinos coletados em diferentes salinidades (0 a 34) nas porções de água doce e estuarinas do Canal São Gonçalo, sul do Brasil. Uma possível relação entre os níveis iônicos plasmáticos e a salinidade também foi investigada bem como a capacidade de regulação iônica dos teleósteos coletados em três ou mais salinidades (Genidens barbus e Micropogonias furnieri). Os resultados mostraram que não houve relação entre os níveis iônicos no plasma com a salinidade quando considerando todas as espécies juntas, mas as duas espécies coletadas em três ou mais salinidades mostraram uma relação significativamente positiva entre níveis iônicos no plasma e salinidade, mostrando que G. barbus e M. furnieri apresentaram uma grande capacidade para regular os íons do plasma em baixas e altas salinidades.

The purpose of this study was to investigate Na+, Cl-, K+, Ca2+, and Mg2+ levels in the plasma of freshwater and marine/estuarine teleosts collected at different salinities (0 to 34) from the estuarine and freshwater portions of the São Gonçalo channel in Southern Brazil. Any relationship between plasma ion levels and salinity and the capacity of ionic regulation of teleosts found at three or more different salinities (Genidens barbus and Micropogonias furnieri) was also investigated. Results showed no relationship between plasma ion levels and salinity when considering all species together, but the two species collected from three or more different salinities showed a significant positive relationship between plasma ion levels and salinity, indicating that G. barbus and M. furnieri have a high capacity to regulate plasma ion levels at both low and high salinities.

This study analyzes the spatiotemporal variation of the ichthyofauna of the surf zone of Praia do Cassino, municipality of Rio Grande (state of Rio Grande do Sul, Brazil) from October 2005 to September 2006. Fishes were collected monthly and during daytime using a large beach seine net (30 m x 1.8 m, with 12 mm uniform mesh manufactured with monofilament nylon wire). Five hauls were conducted on each of three sampling sites: one near the jetties of Patos Lagoon and two located 5 km and 10 km south from the jetties, respectively. We caught 10,066 fishes, weighting 128,486 g, distributed in 37 species belonging to 18 families that are similar in species composition to the dominant fish fauna - Trachinotus marginatus (Cuvier, 1832), Atherinella brasiliensis (Quoy & Gaimard, 1825), Brevoortia pectinata (Jenyns, 1842), Mugil platanus (Gunther, 1880), Menticirrhus americanus (Linnaeus, 1758), Menticirrhus littoralis (Holbrook, 1847), and Oncopterus darwinii (Steindachner, 1874) - usually collected in the beaches of Rio Grande do Sul with a smaller net. The dominant size classes were between 50 and 100 mm TL and represent 43% of total catch. Based on CCA analysis we suggested that the ichthyofauna is primarily structured by seasonal variation in the physicochemical and environmental parameters and secondarily by the spatial difference between areas nearer (< approximately 10 km) or more distant (> approximately 10 km) from the Patos Lagoon's jetties. The composition and dominance of the fish community of the surf zone of Cassino Beach changed little in the latest 20 years, indicating a possible stability of the system.

Episódios El Niño ocorrem na região tropical do Oceano Pacífico e estão associados com o aumento da descarga continental de água na Lagoa dos Patos (10.360 km²) e sua região estuarina (971 km²). A partir de um banco de dados meteorológicos e biológicos de longo prazo (1979-1983 e 1996-2000), este trabalho investiga as variações no recrutamento de juvenis e no desembarque da pesca artesanal da tainha (Mugil platanus) no estuário da Lagoa dos Patos e suas relações com anomalias regionais de chuva e anomalias locais de salinidade durante dois fortes episódios El Niño (1982-1983 e 1997-1998). Tanto os juvenis quanto a captura dos adultos na pesca artesanal diminuíram em abundância durante as chuvas excessivas e salinidades próximas a zero que prevaleceram no estuário durante ambos eventos climáticos. Duas hipóteses são sugeridas para explicar os efeitos ocasionados pelo El Niño sobre as fases juvenis e adultas da tainha no estuário da Lagoa dos Patos. Primeiro, a elevada descarga continental durante forte eventos El Niño poderia afetar negativamente o transporte passivo de juvenis de tainha para o interior do estuário, o que levaria ao declínio de juvenis na região nesse período. Segundo, as salinidades próximas a zero durante vários meses no estuário durante forte eventos El Niño poderia acarretar maior dispersão dos cardumes de tainhas adultas durante a sua migração reprodutiva para o mar, resultando em menores capturas pelos pescadores artesanais da região.

Based on biological and meteorological long-term database (1979-1983 and 1996-2000), we analyzed the variation in the juvenile recruitment and artisanal fishery landings of the mullet (Mugil platanus) in the Patos Lagoon estuary and its relationships with the regional rainfall and estuarine salinity anomalies during two strong El Niño events (1982-83 and 1997-98). Juvenile and adult mullets declined in abundance under the high rainfall and near-zero salinity that prevailed in the estuary during both El Niño events. We proposed two different hypotheses to explain the El Niño-induced effects on the juvenile and adult stages of the mullet in the estuary. First, high freshwater outflow during a very strong El Niño might render ineffective the mechanism of passive immigration of juvenile mullets into the estuary, which can lead to their decline in the estuary during El Niño events. Second, near-zero salinity at the estuarine area along several months during strong El Niño events could lead to higher spatial dispersion of the maturing mullet during their migration to the ocean , resulting in smaller shoals of individuals and, consequently, lower catches by artisanal fishermen.

Este trabalho avaliou do impacto da pesca do camarão-rosa Farfantepenaeus paulensis (Perez-Farfante, 1967) sobre a assembléia de peixes e crustáceos do Parque Nacional da Lagoa do Peixe. Constatou-se que, em média, a composição nas capturas da pesca do camarão-rosa, com a arte de pesca aviãozinho, é semelhantes àquelas descrita em para outros estuários do Rio Grande do Sul, quando considerada apenas a proporção das grandes categorias analisadas (espécie alvo - camarão-rosa 53%: captura acessória 24%: rejeito 23%). A composição da fauna acompanhante (captura acessória + rejeito) apresente diferenças pronunciadas ao longo do gradiente salino da laguna. No geral, ao nível específico, as espécies de peixes capturadas com maior intensidade - Brevoortia pectinata (Jenyns, 1842), Micropogonias furnieri (Desmarest, 1823) e Jenynsia multidentata (Jenyns, 1842) - diferem daquelas capturadas em outros estuários do Rio Grande do Sul, onde, além de M. furnieri, os bagres Genidens barbus (Lacepède, 1803) e Genidens genidens (Cuvier, 1829) dominam nas capturas. As estimativas do potencial de impacto das capturas acessório e do rejeito apresentaram valores, do ponto de vista pesqueiro, bastantes satisfatórios, quando comparados com outras artes de pesca do camarão, o que sugere que a decisão de proibir a pesca no Parque Nacional da Lagoa do Peixe não deve ser baseada no impacto da pesca do camarão-rosa sobre a fauna acompanhante, mas sim na atividade pesqueira em si, uma vez que a legislação Brasileira vigente proíbe a pesca dentro de Parques Nacionais.

This work evaluates the impact of the pink shrimp Farfantepenaeus paulensis (Perez-Farfante, 1967) fishery on fish and crab assemblages of Lagoa do Peixe National Park, Brazil. We observed that composition of catches is similar to shrimp fisheries using fyke-net at others estuaries of Rio Grande do Sul State: pink shrimp (53%), accessory catches (24%) and bycatch (23%). However, fishery composition showed distinct differences along the saline gradient of the main park's lagoon. Regarding only fish species, the most impacted species in this fishery were Brevoortia pectinata (Jenyns, 1842), Micropogonias furnieri (Desmarest, 1823), and Jenynsia multidentata (Jenyns, 1842). In others estuaries from Rio Grande do Sul, in contrast, the most impacted species were M. furnieri, Genidens barbus (Lacepède, 1803) and Genidens genidens (Cuvier, 1829). The potential impact of the pink shrimp fishery at Lagoa do Peixe National Park seemed to be weaker when compared to shrimp fisheries elsewhere. We believe that the decision to prohibit this fishery at the Lagoa do Peixe National Park should not be based on its potential damage to the fish and crab assemblages but based on the simple fact that Brazilian laws do not allow fisheries inside National Parks.