Stellifer Rastrifer Research Articles

Early development of smallscale weakfish Cynoscion microlepidotus (Cuvier, 1830) (Sciaenidae: Teleostei).

Larval and transforming stages of smallscale weakfish Cynoscion microlepidotus (Sciaenidae) are described and illustrated based on samples obtained in three different sites along the Brazilian coast: São Marcos Bay (Maranhão state), Camamu Bay (Bahia state), and the Cananéia-Iguape Estuarine System (São Paulo state). Identification of early stages of C. microlepidotus was based on meristic counts, such as number of myomeres (22), number of fin spines and rays (dorsal XI, 24, anal II, 9 and pectoral 19), morphological features (presence of supraoccipital crest in larvae from flexion to transformation stages, branched anal fin spines) and pigmentation pattern. Early stages of this species are likely to be confused with Carangidae and Scorpaenidae due to the presence of a supraoccipital crest, and with the Sciaenidae species Stellifer rastrifer, Macrodon atricauda, M. ancylodon, and Isopistus parvipinnis due to branched anal fin elements. However, a distinction can be made when analyzing the set of characters (morphology, morphometry, pigmentation) in relation to the different stages of development.

Trophic dynamics in two South American estuaries encompassing industrial development and a biodiversity hotspot

Abstract Estuaries are critical to the life histories and development of many marine species, and support some of the most productive aquatic ecosystems. However, owing to their geographic accessibility, many estuaries face considerable anthropogenic threats, which can be exacerbated in developing nations. Understanding the ecological implications of anthropogenic activities as a precursor to dedicated conservation activities requires comprehensive assessments of baseline trophic relationships. This study addresses a shortfall in such information for two tropical, coastal ecosystems globally identified as priority areas for biodiversity conservation: the Paranaguá estuarine complex; and the Cananéia–Iguape estuarine lagoon system in southern Brazil. Ecological relationships were investigated through carbon and nitrogen stable isotope (δ13C and δ15N) determination in sediments, plant fragments and the muscle tissues of marine species occupying different trophic levels, including benthic invertebrates, ichthyofauna (Stellifer rastrifer, Paralonchurus brasiliensis, and Isopisthus parvipinnis), and delphinids (Sotalia guianensis and Pontoporia blainvillei). Isotope ratios facilitated distinguishing plant fragments, sediments (which were terrestrially influenced) and biota (predominantly marine influenced). However, despite variation among anthropogenic stressors, isotope ratios did not vary between the studied estuaries, implying similar impacts on trophic relationships which might reflect some inter‐estuary mixing. All ichthyofauna and the delphinids had similar generalist diets and shared the same trophic niche, which may reflect their consistent spatio‐temporal distributions and habitat patterns in the estuaries. The data illustrate the utility of isotopically characterizing biodiversity‐hotspot estuaries as a mechanism for rapidly assessing ecological relationships between key species and regional habitats. Such an approach can be used to evaluate ecological connectivity as a baseline for management and might be applied more broadly, embracing multiple regions as part of estuarine and coastal biome conservation efforts.

Assessment of metal contamination in fish from estuaries of southern and southeastern Brazil.

Historically, the Brazilian coast has been impacted by urban, industrial, and port activities that have increased the input of chemical contaminants, such as heavy metals, to the ecosystem. The Paranaguá estuarine complex (PEC), Cananéia-Iguape estuarine-lagoon complex (CIELC), and Santos-São Vicente estuarine complex (SSVEC) (S-SE Brazil) are surrounded by urbanized cities and port areas characterized by various anthropogenic discharges comprising several potential pollutants, including heavy metals. Concerns about such contamination are paramount because these estuaries are important for traditional fishing communities and are categorized as World Heritage sites and biodiversity hotspots by UNESCO. In this study, metals (Cu, Cr, Ni, Pb, Zn, and Hg) and metalloids (As and Se) known to affect the health of marine life were evaluated in regional fishes. Muscle and liver tissues from three demersal teleosts (Stellifer rastrifer, Paralonchurus brasiliensis, and Isopisthus parvipinnis) were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES), with a coupled vapor generated accessory (VGA). Irrespective of species, metal bioconcentration was significantly greater in fishes from the PEC and CIELC, which had higher As, Cu, and Zn concentrations, while Se levels were higher in fish from the PEC and SSVEC estuaries. Seasonality, fish species and maturation stage affected the accumulation of metals. Some metal levels, including As, Cr, Pb, and Se in all species across all estuaries, and Zn in the PEC, exceeded the maximum permitted level for seafood and might present a risk for daily human consumption. The results provide reference points for existing chemical contamination and should be used to guide monitoring programs and the sustainable development of these coastal regions, within a broader objective of maintaining public health.

Dynamics of early life‐history stages of fish along an estuarine gradient

AbstractThis study aimed to identify the spatial and temporal patterns of composition and distribution of early life‐history stages of fish along an estuarine gradient. Samples were collected quarterly between April 2010 and January 2011 using conical‐cylindrical plankton nets in the Vaza Barris estuarine river system (NE Brazil). A total of 38,781 fish eggs and 3,526 larvae, representing 20 families and 42 taxa, were caught. The most abundant larval taxa were Microgobius meeki, Ctenogobius gr. smaragdus/boleosoma, Gobionellus oceanicus, Ctenogobius gr. stigmaticus/saepepallens/shufeldti, Bairdiella ronchus, Achirus sp., Trinectes sp., Stellifer rastrifer and S. stellifer, accounting together for 34.5% of the total catch. Ichthyoplankton distributions were characterized by high seasonal and spatial variability mainly attributed to the environmental characteristics of the estuary. Overall, lower estuarine region served as important accumulation areas for ichthyoplankton, concentrating the greatest diversity and abundance. Salinity gradient, water temperature, and inorganic nutrients were the main variables that affected the larval fish assemblages, presumably influencing spawning, development and survival of individuals or through their effect on food supply. Moreover, this study reinforced the concept that hydrological variations may have a strong influence on estuarine species retention and marine species immigration. Finally, this study highlights the importance of estuaries for the growth and maintenance of stocks of fish species, and the development of strategies to protect these habitats is of utmost relevance.

Influence of detached macroalgae on fish size and condition in nearshore habitats

Nearshore habitats are important for reproduction, feeding and growth of many fish species and are usually subject to seasonal influxes of adults from other habitats. Those areas consist mostly of small-scale sites whose environments are affected by meso- or large-scale and continental events, making it difficult to establish seasonality of habitat use. Understanding which drivers make these habitats suitable for fish species and, in particular, why this might vary seasonally is relevant to resource management. Detached macrophytes are likely to improve refuge and food for fishes and invertebrates, increasing abundance (especially juveniles) and diversity. On the southeastern Brazilian coast, detached macroalgae are carried by surface currents and swell and deposited along beaches in the winter (Dry period), but are largely absent in the summer, nutrient-enriched Rain period. This project aimed to investigate the potential importance of macroalgae to fish populations in the southeastern Brazilian coastal region. Four areas were surveyed on the southern Espírito Santo coast. The main diet of Larimus breviceps, Stellifer rastrifer and S. stellifer (Sciaenidae) was determined and some key food items were then sampled from macrophytes. Samples of fishes, food items, algae and higher plants were subject to carbon and nitrogen stable isotope analysis in order to define food chains from algae and higher plants to fish. Fish sizes were compared among Dry and Rain periods. Fish condition was addressed through linear regression models fitted with Log-transformed eviscerated weight as the response variable, and Log-transformed Standard Length, Period, Site, Species and Reproductive Class (and their first-order interactions) as the explanatory variables. Trophic positions of fish and their food items were estimated using stable isotopes signatures and macrophytes as the baseline. For most combinations of species and site, fish were shorter and lighter in the dry period than the rain period. However, fish of all three species were almost always predicted to be heavier for a given length in the Dry period, when macroalgae were present. The data suggest that detached macroalgae in the Dry period are a regional environmental driver of fish and crustacean distributions and that management of macroalgae may be important for biodiversity and fisheries conservation.

Spatiotemporal variation among demersal ichthyofauna in a subtropical estuary bordering World Heritage-listed and marine protected areas: implications for resource management

Benthic trawl surveys were performed to quantify the spatiotemporal distributions of teleosts and key abiotic associations throughout an ecologically important estuary within Brazil’s Atlantic Forest biosphere. Approximately 52000 fish (51% juveniles) representing 75 species were sampled, with residents accounting for 36 and 61% of total species and individuals respectively. Five artisanally important species comprised 77 and 81% of individuals and biomass respectively. Cathorops spixii was most abundant (>40% of total), whereas Stellifer rastrifer, Aspistor luniscutis, Sphoeroides greeleyi and S. testudineus collectively contributed towards 37 and 34% of individuals and biomass respectively. The abundance of A. luniscutis, C. spixii and S. rastrifer was negatively associated with salinity, whereas the presence of the latter two species was also positively associated with temperature, and S. greeleyi and S. testudineus (mostly adults) were more abundant in deeper areas. These relationships seemed to be affected by species-specific reproductive (S. rastrifer, C. spixii and A. luniscutis), habitat (S. greeleyi and S. testudineus) and prey preferences (juvenile C. spixii and A. luniscutis). Protection for these various species may be achieved via immediate fishing effort regulations, but more research is required to manage other anthropogenic effects. Such work should be a priority to ultimately preserve what is one of the most important South American biodiversity areas.

Closely Related Fishes Inhabiting Different Ecosystems Exhibit the Same Oocyte Production and Recruitment Pattern.

Information on oocyte production and recruitment in phylogenetically related species can help in understanding the evolution of reproductive life-history traits in fish of indeterminate fecundity. The present study compared, for the first time, oocyte production and recruitment patterns between two closely related species: Stellifer brasiliensis and Stellifer rastrifer (Perciformes, Sciaenidae), in the southwestern Atlantic, Brazil. Specimens of S. brasiliensis were sampled from the coastal waters of Ubatuba, and samples of S. rastrifer were taken from the Cananéia Lagoon Estuarine System. Ovaries were investigated using histology and model-based stereology. The total number of oocytes per individual (N) and stage-specific oocyte packing density did not differ significantly between S. brasiliensis and S. rastrifer The number of pre-vitellogenic and vitellogenic oocytes were positively correlated with female total weight and length, and ovary weight in both species. Analysis of oocyte recruitment across their development stages revealed that approximately 5.9% of the standing stock oocytes larger than 50 μm in S. brasiliensis and 5.0% in S. rastrifer were recruited to form the next batches. Females of S. brasiliensis and S. rastrifer, in spawning-capable phase, exhibit the same oocyte production and recruitment patterns, showing no influences of the ecosystems on primary and secondary oocyte production.

Gradiente Latitudinal da Beta Diversidade da Fauna Acompanhante das Pescarias Industriais de Camarões Marinhos da Costa Norte do Brasil

Industrial shrimp fisheries in northern Brazil use vessels equipped with trawls of low selectivity that capture considerable amounts of non-target bycatch species, and consequently, generate fauna biomass. In this study, we aimed to examine the composition and distribution of ichthyofaunal bycatches associated with pink shrimp industrial fishery between May 2010 and June 2011. Seven vessels were monitored for a period of151 travel days, during which trawls were towed 461 times. The northern coast was subdivided into the Para Continental Platform, Amazonas River Estuary (ARE), and Amapa Continental Platform (ACP). Perciformes was the most abundant order (68.91%); Sciaenidae, the most abundant family (55.89%); and Macrodon ancylodon , the most abundant species (23,48%). ARE and ACP are regions with high biological diversity and density of species and similar ichthyofauna. The similarities between ARE and ACP regions can be attributed to the Guiana Current, which carries most of the water drained from the rivers of the Amazon Basin along the coast of Amapa; it promotes the high productivity of these regions. Monitoring of shrimp trawl fishing in the northern coast of Brazil can contribute to the preservation of populations of endemic animal species such as Macrodon ancylodon and Stellifer rastrifer , which are frequently associated with shrimp bycatch and therefore, particularly affected by this type of fishing. Keywords: Farfantepenaeus subtilis ; fish; Sciaenidae; industrial fishing.

Distribution patterns of the demersal fish fauna on the inner continental shelf of Suriname

This study aimed to characterise the spatio-temporal patterns of the demersal fish community in the shallow (<40 m) inner shelf waters of Suriname, based on (bi)monthly data for the period February 2012–April 2013. From 148 demersal trawl samples, distributed over 15 locations, 98 fish species were identified. Stellifer rastrifer, Amphiarius rugispinis and Cynoscion jamaicensis represented 50 % of the catches. Cluster analysis revealed three species assemblages, occurring in a nearshore–offshore depth gradient. A coastal fish assemblage occurred in the shallow turbid waters, characterised by muddy sediments with relatively high organic carbon content. A transition assemblage around 27 m water depth marked the shift towards a very different offshore fish assemblage on the deepest sampling locations (34 m), which were characterised by coarser sediments, with clear overlying waters. The coastal assemblage represented the ‘sciaenid community’ of tropical shelves, dominated by Sciaenidae and Ariidae. The offshore assemblage had a significantly lower fish density and diversity, and contained representatives of fish families typical for deeper tropical shelves, such as Paralichthyidae, Triglidae and Lutjanidae. The shift between the coastal and offshore fish assemblage was the most important feature of the demersal fish community, and coincided with a transition between two principal ecosystems: a coastal, river influenced system fuelled by detritus versus an open shelf system based on primary production. Whereas pelagic fishes are known to gain in importance on the open shelf, demersal fishes thrived in the coastal ecosystem, together with a potentially important epibenthic food source, the Atlantic seabob shrimp Xiphopenaeus kroyeri. In Suriname, large demersal (mainly sciaenid) fishes are the main fisheries resource for the artisanal fleet in the nearshore waters below 20 m depth. Because juveniles of commercially important fishes were abundant in our coastal trawl catches, we suggest the shallow nearshore waters have a main nursery function.

Feeding habits of the congeneric species Stellifer rastrifer and Stellifer brasiliensis (Acanthopterygii: Sciaenidae) co-occurring in the coast of the state of Santa Catarina, Brazil.

The objective of the present study was to investigate the feeding habits allowing the occurrence of the congeneric species Stellifer rastrifer and Stellifer brasiensis, collected on a seasonal basis, in the operating area of the artisanal seabob-shrimp trawl fishery in Porto Belo, an important fishing area on the southern Brazilian coast. Fish were collected seasonally from November 2009 to August 2010, in isobaths of 10, 20 and 30 m. Of the 450 stomachs analyzed, 194 belonged to Stellifer rastrifer and 242 to Stellifer brasiliensis. From the totality of analyzed stomachs 33.49% were empty and 66.52% had some content. Crustacea were the predominant food category in the diet of S. rastrifer and S. brasiliensis, and the shrimp Acetes americanus was the most frequent crustacean in stomachs of both studied species. The overlapping in the diet of the species was high, however when analyzing the overlap in each season it was found that it occurred only during spring and winter. Although the most important items in the diet of these species are the same, the intake of each alternates in time, suggesting a difference in predation pressure, which leads to less direct competition in a given time.

Variação e Abundância do Ictioplâncton em Canais de Maré no Extremo Norte do Brasil

The aim of this study was to describe the spatial and temporal variation of the composition and abundance of the ichthyoplankton in the tidal channels of the Maraca-Jipioca island, at the Amapa coast. The surface water temperature and salinity presented mean values of 28.5 o C and 11 respectively. The lowest rainfall (124 mm) was recorded in November, and the largest was recorded in May (679 mm). A total of 18,191 fish larvae were captured andclassified into 36 taxa (18 species). The families Eleotridae and Gobiidae were dominant contributing with 90% of the total larvae captured. Among the species of economic interest, we captured larvae of Sciaenidae ( Cynoscion acoupa , C. leiarchus , Micropogonias furnieri and Stellifer rastrifer ) and others, as Elops sp., Caranx sp., Centropomus sp., Lutjanus sp., Mugil sp. and Arius sp. The highest density of larvae occurred in the inner areas of the channels, where the highest temperatures and lower salinities were recorded. The temporal distribution is probably associated with the seasonal rainfall regime and the local hydrodynamics. The spatial distribution of larvae indicated high faunal similarity between the sites. However, we emphasize the importance of these environments as breeding areas for fish species with ecological and economic importance, emphasizing the value of protection areas for the maintenance of fish stocks. Further studies in the region are recommended to increase the information on the ecology of early life stages of fish. Keywords: fish larvae; spatial and temporal distribution; coastal environment; northern region.

Feeding ecology and resource sharing patterns betweenStellifer rastrifer(Jordan, 1889) andS. brasiliensis(Schultz, 1945) (Perciformes: Sciaenidae) along the coasts of Paraná and Santa Catarina, Brazil

In this study the diet of Stellifer rastrifer and S. brasiliensis were analysed in order to assess the role of resource partitioning between these congeneric, sympatric and abundant species along the coasts of Paraná (25 °55′28″S; 48 °33′35″W) and Santa Catarina (26 °25′55″S; 48 °34′46″W), in southern Brazil. The stomach contents of 240 S. rastrifer specimens (52–195 mm total length) and 167 S. brasiliensis (60–182 mm total length) collected by trawl boat in March of 2006, were analysed to assess the influence of sites, day and night periods as well as the size class in their diet composition. Although crustaceans have been the main resources of both species, S. rastrifer consumed pelagic and epibenthic items, whereas S. brasiliensis also used benthic resources. Results of permanova analysis provided significant evidence for food resource partitioning and confirm the role of feeding changes in the function of morphology (species, P = 0.001), behaviour (day and night, P = 0.024), and ontogeny (size classes, P = 0.001), strategies to reduce competition and to maintain the coexistence of these syntopic species.

Multi-species generalist predation on the stochastic harvested clam Tivela mactroides (Mollusca, Bivalvia)

Top-down control is an important force modulating the abundance of prey and structuring marine communities. The harvested trigonal clam Tivela mactroides is hypothesized to be part of the diet of a variety of marine organisms, with its stock influencing predator abundance and being influenced by them. Here we analyzed the diet of potential predators of T. mactroides in Caraguatatuba Bay, northern coast of São Paulo State, Brazil, to identify the main consumers of this marine resource, and also to address the importance of this clam in the diet of each predator. Samples were taken year-round by trawls; all specimens collected were identified and measured and the food items identified and quantified. Twenty-one species consumed T. mactroides, whose importance in the diet varied greatly in both the volume ingested and the frequency of occurrence (pompano Trachinotus carolinus > blue crab Callinectes danae > starfish Astropecten marginatus). Top-down influence on T. mactroides was also dependent on the abundance of consumers (yellow catfish Cathorops spixii > rake stardrum Stellifer rastrifer > barred grunt Conodon nobilis > A. marginatus). Considering the mean volume ingested, the frequency of occurrence of T. mactroides in the diet, and the relative abundance of consumers, the predators that most influenced T. mactroides were T. carolinus, A. marginatus, and C. danae, in decreasing order. Large numbers of small-sized individuals of T. mactroides (<10 mm) were generally preyed upon by A. marginatus, which may have a stronger effect on clam abundance in comparison to C. danae and T. carolinus, which preyed upon larger clams. In conclusion, the results of this study indicate that predators' consumption of T. mactroides in Caraguatatuba Bay can influence its stocks, mainly due to the type and/or abundance of predator species, the volume and number of individuals of T. mactroides preyed upon, and the temporal variations in the abundance of predators.

Influence of the artificial reef size configuration on transient ichthyofauna – Southeastern Brazil

To investigate how variations in the volume of artificial reefs affect the structure and composition of the transient ichthyofauna, reefball-type concrete modules were arranged at 9 m of depth along the northern coast of the state of Rio de Janeiro. The modules were arranged in three configurations, each in triplicate: (1) solitary modules (1 m3), (2) side-by-side modules (2 m3) and (3) modules forming a triangle (3 m3). The surrounding ichthyofauna were sampled in two periods of the year (dry: September 2009 and October 2010; rainy: April 2010 and April 2011) with gillnets to record the richness, species diversity, number of individuals and biomass per volume unit. The total mean values of richness, diversity, number of individuals and biomass did not differ significantly among the reef volumes. However, when these variables were analyzed per standardized volume unit, there was an increase in these variables with the increase in reef volume, considering all the transient ichthyofauna as well as the most representative families, Ariidae and Sciaenidae. A non-metric multidimensional scaling ordination analysis revealed differences in the composition of the ichthyofauna between the sampling periods, dominated by Sciaenidae (Stellifer rastrifer, Paralonchurus brasiliensis, Larimus breviceps and Cynoscion virescens) in the dry period and by Ariidae (Aspistor luniscutis) and Carcharinidae (Rhizoprionodon porosus) in the rainy period. The results suggest that the increase in module size from 1 to 3 m3 may result in slight alterations in the community descriptors, with a decrease in the relative values of richness, diversity and density per standardized volume unit. Furthermore, the effects of the seasonal flow of the Paraíba do Sul River may overlap the effects of reef configuration, mainly in the rainy period with higher flow. The implementation of several dispersed 1 m3 modules seems to be the most favorable configuration to attract transient ichthyofauna, especially Ariidae and Sciaenidae, on the northern coast of the state of Rio de Janeiro.

Spatial And Temporal Distribution Patterns Of Larval Sciaenids In The Estuarine System And Adjacent Continental Shelf Off Santos, Southeastern Brazil

Based on data collected during the project "The influence of the Santos-São Vicente estuarine system on the ecosystem of the adjacent continental shelf" (ECOSAN), from Nov/2004 to Mar/2006, the space-temporal distribution pattern of Sciaenidae larvae in relation to biotic and abiotic factors was investigated. Bongo net was used for sampling, aboard the R/V "Prof. W. Besnard" on the shelf, and the boats "Veliger II" and "Albacora" in the estuarine region. Twelve taxa were identified: Bairdiella ronchus, Ctenosciaena gracilicirrhus, Cynoscion spp., Isopisthus parvipinnis, Macrodon atricauda, Micropogonias furnieri, Menticirrhus spp., Nebris microps, Ophioscion punctatissimus, Paralonchurus brasiliensis, Stellifer rastrifer and Stellifer spp. Sciaenidae larvae were widespread on the continental shelf in both campaigns (frequency of occurrence &gt;80%). They were most abundant in Mar/2006 (mean = 6.47 larvae.m-2; sd = 8.36) and least abundant in Sep/2005 (mean = 2.37 larvae.m-2; sd = 3.33). The average abundance in the estuarine region ranged from 0.12 larvae.m-2 (sd = 0.11) in Jun/2005 to 4.28 larvae.m-2 (sd = 1.99) in Nov/2004. Frequency of occurrence minimum occurred in Aug/2005 (50%) and the maximum in Nov/2004 (100%). The presence of Sciaenidae larvae in most locations and periods suggests that the reproductive process of this family in the region is continuous, spawning being more intense in the warmer months.

A new approach to marine fish otoliths study: electron paramagnetic resonance

The biocrystallization process and the prescence of manganese in sagitta otoliths is described for the first time via electron paramagnetic spectroscopy. Spectra of Mn2+ are applied to verify inter-species differences in 12 Sciaenidae species and geographic variations among three stocks of banded croaker Paralonchurus brasiliensis and rake stardrum Stellifer rastrifer. Similar spectra shape and zero-field splitting D (22.4 mT) indicated that the biocrystallization process is the same for all fish species, at any stage of development and under different environmental conditions, corresponding to Mn2+ in the aragonite (CaCO3). Inter-species differences in Mn2+ concentration were detected regarding the otolith shape. Elongated otoliths have higher manganese concentrations compared to rounded otoliths. Geographic variations among stocks of P. brasiliensis and S. rastrifer could be detected. Fish stocks under riverine influence have less Mn2+ concentration than ones under marine influence. Manganese detection via electron paramagnetic spectroscopy is a non-destructive approach that can be useful in fish stocks studies.

Body growth and reproduction of individuals of the sciaenid fish Stellifer rastrifer in a shallow tropical bight: A cautionary tale for assumptions regarding population parameters

Knowledge of population parameters and the ability to predict their responses to environmental changes are useful tools to aid in the appropriate management and conservation of natural resources. Samples of the sciaenid fish Stellifer rastrifer were taken from August 2003 through October 2004 in shallow areas of Caraguatatuba Bight, southeastern Brazil. The results showed a consistent presence of length-frequency classes throughout the year and low values of the gonadosomatic index of this species, indicating that the area is not used for spawning or residence of adults, but rather shelters individuals in late stages of development. The results may serve as a caveat for assessments of transitional areas such as the present one, the nursery function of which is neglected compared to estuaries and mangroves. The danger of mismanaging these areas by not considering their peculiarities is emphasized by using these data as a study case for the development of some broadly used population-parameter analyses. The individuals' body growth parameters from the von Bertalanffy model were estimated based on the most common approaches, and the best values obtained from traditional quantification methods of selection were very prone to bias. The low gonadosomatic index (GSI) estimated during the period was an important factor in stimulating us to select more reliable parameters of body growth (L∞ = 20.9, K = 0.37 and Z = 2.81), which were estimated based on assuming the existence of spatial segregation by size. The data obtained suggest that the estimated mortality rate included a high rate of migration of older individuals to deeper areas, where we assume that they completed their development.

A ictiofauna do Canal de Bertioga, São Paulo, Brasil

O Canal de Bertioga, localizado no litoral do estado de São Paulo, é delimitado pelo continente e pela ilha de Santo Amaro, constituindo a unidade natural que conecta os municípios de Santos, Guarujá e Bertioga, representando uma segunda conexão do complexo estuarino de Santos-São Vicente com o oceano. No presente estudo foram realizadas coletas, entre dezembro de 2009 a novembro de 2010, no trecho norte do Canal de Bertioga (23° 51' 23,83" S e 46° 07' 58,87" O e 23° 53' 31,72" S e 46° 11' 17,74" O), com o objetivo de inventariar a ictiofauna da região. Foram coletados 1.429 exemplares, pertencentes a 78 espécies, incluídas em 14 ordens, 39 famílias e 67 gêneros. As famílias mais especiosas foram Sciaenidae (nove spp.), Carangidae (nove spp.), Haemulidae (sete spp.), e Ariidae (cinco spp.), e as espécies mais abundantes foram Stellifer rastrifer (n = 243), Harengula clupeola (n = 182), Cathorops spixii (n = 144), Oligoplites palometa (n = 109) e Mugil curema (n = 102), sendo que Achirus lineatus, Atherinella brasiliensis, Cathorops spixii, Chaetodipterus faber, Citharichthys spilopterus, Genidens genidens, Micropogonias furnieri e Stellifer rastrifer, ocorreram em todas estações do ano. Das espécies encontradas, seis foram reconhecidas constantes, 19 acessórias e 53 ocasionais. Em relação aos seus hábitos, 40 espécies são marinho-estuarinas, 26 marinhas, 11 estuarinas e uma de água doce, sendo 52 espécies demersais e 26 pelágicas. Onze espécies são relacionadas em listas de espécies ameaçadas. Adicionalmente, é apresentada uma chave de identificação para as espécies do trecho norte do Canal de Bertioga.

Seasonality, dietary overlap and the role of taxonomic resolution in the study of the diet of three congeneric fishes from a tropical bay.

Not only seasonality but also taxonomic resolution of prey categories has been shown to affect diet studies. We analyzed the stomach contents of three sympatric species, Stellifer rastrifer, S. brasiliensis and S. stellifer, sampled monthly from August 2003 to October 2004 in Caraguatatuba Bay, southeastern Brazil. General characteristics and similarities among their diets were evaluated by considering high taxonomic ranks of all prey groups, and also the lower taxonomic ranks of the main prey groups. Dietary similarity was relatively high among species and low between seasons, and both evaluation criteria gave the equivalent results. The rare items, however, provided information about resource partition, and the species compositions of the most important groups were apparently good indicators of food availability.

Sustainability of capture of fish bycatch in the prawn trawling in northeastern Brazil

The prawn fishery produces more discards than any other type of catch and captures a large quantity of immature individuals. This research aimed to assess the sustainability of capture of fish bycatch in prawn trawling. Each species was assessed according to two groups of criteria: (1) their relative vulnerability to capture by trawl and mortality due to this fishery (2) recovery capacity of the specie after a possible collapse of the population. Within each group, each species was ranked (1-3), being 1 the highest value, meaning the species is highly susceptible to capture or has a low resilience. A total of 8,894 individuals were caught, belonging to 28 families. The species with capture least sustainable were Stellifer rastrifer and Isopisthus parvipinnis. These latter species are highly susceptible since they are either benthic or demersal, and their diet may include benthic organism. Chirocentrodon bleekerianus and Anchoa tricolor were the most likely fishes to be sustainable since they are pelagic, they are least susceptible to capture by trawls, and also have a greater capacity to recover, as most individuals have bred before capture. Due to the fishery's multi-specific nature, it is difficult to implement mitigation measures for specific species. Thus, the creation of fishing exclusion zones should be considered as the most appropriate management measure.