Abstract Lophius gastrophysus is an exploited deep-sea demersal fishing resource in the Southeast-South region of Brazil, a capture target for the twin trawl multi-specific bottom trawling fleet. Considered a prized fish, it is commonly processed on board, retaining commercial cuts of the tail called colas. Thus it is difficult to recognize the original length of the specimens and, consequently, to assess the dynamics of sources and the impacts of catches. Individual length and weight data were used to generate body predictive models correlated to the monkfish cola. The parameters of growth, mortality and exploitation rate were also estimated from the size structure of Lophius gastrophysus captured by the industrial bottom trawling fleet in Southeast Brazil between May 2013 and April 2015, assessing monkfish stock based on indirect estimates of life history information. All predictive models of body size showed coefficients of determination above 0.9 (P <0.001), indicating good data adjustments. The growth parameters were determined by the minimum residual variance methodology, being: L∞ = 92.4 cm and k = 0.158/year. The size structure tended to increase with depth in the spring. Individuals under the age of sexual maturity contributed significantly to catches. The length of first sexual maturation was estimated at 48.6 cm and the recruitment age was between 6 and 7 years. The coefficients of total, natural, fishing and exploitation rates were estimated at: Z = 0.676; M = 0.241; F = 0.436 and E = 0.644. The fishing mortality rate was higher than the reference value (E > 0.50) indicating a state of overexploitation of the southeast most part of stock. A review of the current Brazilian legislation established for the species on the southeast coast is recommended.

Abstract The weakfishes, Cynoscion guatucupa and C. jamaicensis, are important demersal fishery resources and are targeted by multifleet operations in the Southwest Atlantic. This study describes the length-weight relationships between sagittae otoliths (length-OL, height-OH, thickness-OT, and weight-OWT) and the sizes of the fish (total length-LT, standard length-LS, and total weight-WT). The proportion between otolith length and height (aspect ratio-OAR) was also compared between species. The samples were obtained monthly from March 2017 to February 2018 from small-scale commercial fisheries from landings of bottom trawls and gillnets on the continental shelf in the Rio de Janeiro state, southeastern coast of Brazil. The ANCOVA did not indicate significant diferences in relative growth between sexes for both species (p > 0.05) while the length frequency was diferent (p < 0.001). Cynoscion guatucupa showed positive allometry, WT = 4E-06LT3.21 and C. jamaicensis negative allometry, WT = 2E-05LT2.90 (p < 0.05). Both species showed diferences in the condition factor between the sexes (p < 0.05). Significant diferences were observed in the measurements of the otoliths between the two species (p < 0.001). All regressions between fish measurements and otolith morphometry were highly significant (p < 0.001) for both species. The best estimates of fish size and weight were related to the otolith length: OL vs LT (r2 = 0.93; 0.96); OL vs LS (r2 = 0.92; 0.96); OL vs WT (r2 = 0.91; 0.93) for C. guatucupa and C. jamaicensis, respectively. This information adds useful biological data for multiple types of studies, e.g., food ecology (prey-predator), age and growth, reproduction, fisheries assessment and long-term landing monitoring. Our results confrmed the historical pattern of relative growth, supporting that otolith growth reflects the somatic growth of weakfishes in the study area, reinforcing the importance to determine these reference points.

ABSTRACT The bluefish, Pomatomus saltatrix (Linneus 1766) is captured by industrial, artisanal, and recreational fisheries throughout its distribution range. The reproductive biology of P. saltatrix in the southwestern Atlantic was studied using 1,102 specimens captured by the Brazilian commercial fleet between March 2014 and December 2015. The recruitment period was identified from records of juveniles in experimental beach seine hauls carried out on sandy beaches in the external sector of Guanabara Bay for four years (2012-2015). Based on the reproductive indices and on the macro- and microscopic analyses of the gonads, spawning peaks were identified in autumn and spring. The size at first maturity was estimated at 35.5, 38.3, and 37.4 cm for females, males, and general, respectively. Ovary analyses and measurements of the oocyte diameters indicated that bluefish are multiple spawners with asynchronous oocyte development. The batch fecundity estimate was 202,752.5 eggs and ranged from 9,800.9 to 426,787.0 eggs. The species reproduces throughout the entire study area, but it is more active in the south of Arraial do Cabo. The young-of-the-year were recorded on shallow water in all seasons, with modal peaks in the summer months. The parameters estimated in this study expand and update information on this species, providing important data for the evaluation and fisheries management of the stock of P. saltatrix in the southwestern Atlantic.

ABSTRACT Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aL b . The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L ∞ ). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylor’s equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengula clupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinella brasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneus parvus showed the greatest total length, while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from K and L ∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated. Fishing was the primary source of mortality for Caranx crysos (Mitchill, 1815), Eucinostomus argenteus Baird & Girard, 1855, S. brasiliensis and U. parvus, and less important for Cynoscion jamaicensis (Vaillant & Bocourt, 1883), D. volitans, O. ruber, Selene setapinnis (Mitchill, 1815), T. lepturus and H. clupeola. The parameters generated may be used for the management and conservation of the species’ stocks.

RESUMO A sub-rotina simulação de habitat físico da metodologia incremental - IFIM usa variáveis hidráulicas e os índices de aptidão das espécies alvo para predizer como diferentes vazões afetam a ocupação de microhabitat por espécies de peixes. Esta abordagem de simulação de hábitat foi adotada para avaliar os efeitos ecológicos sobre três espécies de peixes tropicais de diferentes ordens (Bryconamericus ornaticeps , Ancistrus multispinis e Geophagus brasiliensis ) em dois trechos de um riacho de Mata Atlântica do sudeste do Brasil, durante a estação chuvosa de 2013 e a estação seca de 2014. Características topográficas e hidráulicas (profundidade, velocidade e tipo de substrato) foram mensuradas para implementação da simulação de habitat em uma dimensão; observações subaquáticas dos peixes foram realizadas para avaliação do uso do microhabitat. As curvas de aptidão de habitat de cada variável hidráulica foram utilizadas na simulação de habitat para obtenção das curvas de aptidão composta (HSI) e a área útil ponderada (WUA) versus fluxo, e propor vazões ambientais mínimas e ideais para as espécies de peixes-alvo. A amplitude de vazão de 0,65-0,85 m3/s foi registrada como o ótimo para satisfazer as necessidades das três espécies de peixes. Esta é uma informação objetiva para os gestores de recursos hídricos e que pode ser aplicada no planejamento de programas de gestão visando a conservação dos ecossistemas. Desse modo, pode ser considerado um estudo piloto bem sucedido na avaliação do fluxo ambiental em um riacho da Mata Atlântica do Brasil.

ABSTRACT The physical habitat simulation sub-routine of the Instream Flow Incremental Methodology (IFIM) uses hydraulic modeling and suitability indices of target fish species to predict how differences in-stream flows affect the microhabitat occupation by fish species. This habitat modelling approach was adopted to assess the ecological effects of running flows on three neotropical fish species of different orders (Bryconamericus ornaticeps , Ancistrus multispinis and Geophagus brasiliensis ).The study encompassed two reaches of an Atlantic Forest stream in Southeastern Brazil where topographic and hydraulic (depth, velocity and type of substrate) characteristics were measured to implement one-dimensional hydraulic simulation. Sub aquatic observation of fish was performed to collect data on microhabitat use and these data were used to develop habitat suitability curves that were used in the habitat simulation to obtain the habitat suitability index (HSI) and weighted usable area (WUA) versus flow curves. Upon these curves minimum and optimum environmental flows for the target fish species were proposed. Bryconamericus ornaticeps and A. multispinis selected microhabitats around 0.6 m depth, whereas G. brasiliensis showed a wider suitable range (0.35-0.9 m). All the three species were mainly observed in microhabitat with low flow velocity (0.1 m/s). Bryconamericus ornaticeps selected more frequently coarse substrate (e.g. boulders) but it appeared also over sandy substrate, whereas A. multispinis and G. brasiliensis selected preferably boulders. The range of 0.65-0.85 m3/s was found as the optimum to meet the needs of the three fish species. Our results agree with the necessary objective information to perform grounded management actions in the frame of a management program aiming at ecosystem conservation. Thereby it can be considered a successful pilot study in environmental flow assessment in an Atlantic Forest stream of Brazil.

Determinamos neste estudo a preferência de habitat de sete espécies de peixes abundantes em um rio regulado do Sudeste do Brasil. Testamos a hipótese de que peixes diferem na preferência de habitat e usam trechos do rio com diferentes características hidráulicas e tipos de substratos. Realizamos amostragens de peixes, utilizando redes de espera e tarrafas em quatro trechos do rio de 1 km de extensão, compreendendo diferentes características do habitat, onde também obtivemos medidas de profundidade, velocidade da água e tipo de substrato. Quatro Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus e Trachelyopterus striatulus) e três Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus e Hoplias malabaricus) que juntos compreenderam aproximadamente 70% do número total e 64% do peso total de peixes foram estudados. Classificamos os peixes em quatro guildas: (1) peixes que ocorrem em trechos com baixa velocidade de fluxo e substrato constituído predominantemente de lama e areia, compreendendo dois Siluriformes, um de áreas rasas (< 4 m, i.e., H. littorale) e outro de áreas profundas (> 8 m, i.e., L. castaneus); (2) peixes que utilizam rápidos de áreas laterais mais profundas com substrato lamoso, representados pelos pequenos Characiformes, A. aff. bimaculatus e O. hepsetus; (3) peixes que utilizam rápidos que ocorrem em áreas rasas e substrato arenoso, representado por T. striatulus; e (4) peixes de corredeiras que utilizam as margens rasas com fundo lamoso, representados por H. malabaricus e P. maculatus. As espécies estudadas apresentam diferenciação na preferência por variáveis do hábitat, corroborando a hipótese investigada.

We determined in this study the habitat preferences of seven native fish species in a regulated river in Southeastern Brazil. We tested the hypothesis that fishes differ in habitat preference and that they use stretches of the river differing in hydraulic characteristics and substrate type. We surveyed fishes in four 1-km long river stretches encompassing different habitat traits, where we also measured water depth, velocity, and substrate type. We investigated preference patterns of four Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus, and Trachelyopterus striatulus) and three Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus, and Hoplias malabaricus), representing approximately 70% of the total number of fishes and 64% of the total biomass. We classified fishes into four habitat guilds: (1) a slow-flowing water guild that occupied mud-sand substrate, composed of two Siluriformes in either shallow (< 4 m, i.e., H. littorale) or deep (> 8 m, L. castaneus) waters; (2) a run-dwelling guild that occurs in deep backwaters with clay-mud substrate, composed of the Characiformes A. aff. bimaculatus and O. hepsetus; (3) a run-dwelling guild that occurs in sandy and shallow substrate, composed of T. striatulus; and (4) a fast-flowing guild that occurs primarily along shorelines with shallow mud bottoms, composed of H. malabaricus and P. maculatus. Our hypothesis was confirmed, as different habitat preferences by fishes appear to occur in this regulated river.

Diapterus rhombeus é uma das espécies de peixes mais abundantes na Baia de Sepetiba, ambiente costeiro de 520 km² de área semifechada no sudoeste do Brasil. O tamanho e distribuição dos indivíduos desta espécie foram descritos com o objetivo de determinar o uso das áreas de criação numa dimensão espacial e temporal (sazonal). Um programa de amostragem de arrasto de fundo foi conduzido mensalmente entre outubro 1998 a setembro 1999, em três zonas da baía (externa, central, interna), definidas através de gradientes de profundidade e salinidade. Diferenças altamente significativas foram encontradas para CPUEs (número e biomassa) entre estações do ano e zonas. O comprimento variou de 50 a 230 mm CT. Três grupos de tamanhos foram definidos de acordo com uma escala de maturação gonadal (n = 1435): 1 - imaturo (< 80 mm Comprimento Total - CT); 2- indivíduos em primeira maturação (L50) (80-90 mm CT); e 3 - adultos (L100) (> 100 mm CT). Imaturos e indivíduos L50 foram abundantes (número e biomassa) durante o outono na zona interna, enquanto adultos (L100) predominaram durante o verão na zona externa. Evidências de movimento de indivíduos jovens (50-90 mm CT) da zona interna para zona externa foram detectadas conforme os animais foram atingindo maiores tamanhos (180 mm CT), no segundo ano de vida. A condição (k) aumentou em indivíduos maiores na zona externa durante a primavera, quando estes se tornam aptos a iniciar o processo reprodutivo. Duas coortes foram detectadas de acordo com a progressão modal: a primeira (menores tamanhos) mostrando crescimento mais rápido do que a segunda, evidenciando uma taxa menor de crescimento a medida que atingem maiores tamanhos. Diferentes classes de comprimento ocupando diferentes zonas da baía sugerem que grupos de idades otimizam sua coexistência compartilhando os recursos disponíveis e evitando competição intra-especifica.

Diapterus rhombeus is one of the most abundant fish species in the Sepetiba bay, which is a 520 km² semi-closed coastal area in Southeastern Brazil. The size and distribution of this species have been described in order to assess the use of the area as a rearing ground in both spatial and temporal (seasonal) dimensions. A fish sampling program was conducted monthly by using an otter trawl between October 1998 and September 1999, in three bay zones (outer, middle and inner), defined according to depth and salinity gradient. Highly significant differences were found for CPUEs (number and biomass) among seasons and zones. Size ranged from 50 to 230 mm TL, and three size-groups were defined according to a maturation scale (n = 1435): 1 - immature (< 80 mm Total Length - TL); 2- individuals at the first maturation (L50) (80-90 mm TL), and 3 - adults (L100) (> 100 mm TL). Immature and L50 individuals were more abundant (number and biomass) during Autumn in the inner zone, while adults (L100) predominated during Summer in the outer zone. Evidences of movements of young-of-the-year (50-90 mm TL) individuals from the inner to the outer zone were detected as they reach larger sizes (180 mm TL) in the second year of life. Condition (k) was higher in larger sized individuals in the outer zone during Spring, when they are apt to start the reproductive process. Two cohorts were detected according to modal progression: the first (smaller size) showing faster growth than the second, evidencing a slower growth rate as they reach larger size. Distinct size classes occupying different bay zones suggest that the age-groups optimize their coexistence by partitioning the available resources, avoiding intra-specific competition.

The length-weight relationship and spatial, temporal and ontogenetic changes in the condition factor of Micropogonias furnieri (Desmarest, 1823) were analyzed, from samples collected between October 1998 and September 1999, in the Sepetiba Bay, a coastal area with a wide communication with the sea (22º54'-23º04'S, 43º34'-44º10'W) at Southeast Brazil. The aim was to supply basic information on the form of growth of the population of M. furnieri that uses the bay, as well as to assess changes in the fish condition. Most fish were young and subadults. The length-weight equation, based on 2499 unsexed individuals, was Wt = 0.009095 * Lt2.99, where Wt is the total weight (g) and Lt is the total length (cm). The regression constant and the regression coefficient presented significant inverse relationship (p < 0.01), indicating that the regression coefficient from the length-weight relationship is not a good parameter for characterizing different populations, because its strong association between one another. The best condition was recorded in October/November and April, and the worst, between January and March. Spatially, the best condition was observed in the inner bay zone, where most fish were young-of-the-year, and in the outer zone where predominate larger sized fish, indicating that individuals of intermediary size could be allocating large amount of energy for growth, presenting, consequently, lowest condition. Isometry was detected for M. furnieri populations at Sepetiba Bay, and variations in physiologic condition could be associated to feeding availability, mainly in the inner zone, where the harsh water quality would not be constrained for development of this species.