The research conducted for this thesis has produced quantitative data on the biology and population genetic structure of the Mulloway Argyrosomus japonicus in Western Australia, where this sciaenid is recreationally and commercially fished. These data were used 1) to test various hypotheses regarding the relationship between key biological characteristics of A. japonicus and both latitude and environmental variables, 2) to investigate the population structure and genetic characteristics of populations of A. japonicus on the west and south coasts of Western Australia and to assess the relationships between these populations and those of A. japonicus in eastern Australia and South Africa, and 3) to consider the implications of the biological and genetic results for management.

The geelbek Atractoscion aeguidens is an important commercial and recreational linefish species along the South African eastern seaboard . Aspects of its biology and population dynamics were investigated using data collected from various sampling sites along the South African east coast and from catch statistics obtained from both the Sea Fisheries Research Institute (Cape Town), and dealer records. The biological aspects studied included age and growth, reproduction and feeding. It was established that A. aeguidens is a fast growing species with a relatively late age at sexual maturity and a 1:1 sex ratio. Feeding studies revealed that it has become specialized to feed on small pelagic fish. The South African geelbek stock consists of three distinct age related sub-populations, each representing a particular phase in the life cycle. The sub-adults (1-4 yrs) occur in the South West Cape and feed predominantly on anchovy, Engraulis capensis, which they follow, moving inshore in summer and offshore in winter. The adults (5-9 yrs) undergo a seasonal inshore migration to Natal where they spawn in spring. The dynamics of this migration are strongly influenced by the annual movement of their principal prey viz. , Sardinops ocellatus, to that region. As a result the geelbek first arrive in Natal during mid winter. Evidence is also presented to suggest that a significant number of "adolescent " fish (4-5 yrs) undergo limited gonad maturation and a partial migration to at least as far as the South East Cape. Spawning appears to occur offshore. It is postulated that eggs and larvae are transported southwards by the peripheral waters of the Agulhas Current. After spawning the adults probably remain offshore and use the current to aid their return to the South and South West Cape, where they spend summer feeding on the Agulhas Bank. Juveniles (<1 yr) first appear in the South East Cape between January and March. They apparently use this region as a nursery area for almost a year before moving southwards to join the sub-adults in the South West Cape. In the South East Cape, the juveniles feed initially on mysids whereafter they switch to anchovies and pilchards. A preliminary stock assessment using yield per recruit and spawner biomass per recruit models, indicated that despite the current legislation the South African geelbek population is already overexploited. This is largely attributed to high rates of fishing mortality of the migratory adult population. Further management recommendations are therefore proposed. These include a size limit (660 mm FL), derived from an investigation of the interrelationship between natural mortality and somatic growth in a theoretical unexploited cohort, as well as a uniform bag limit for all user groups (5 fish per person per day)

Made available in DSpace on 2016-06-02T19:30:05Z (GMT). No. of bitstreams: 1 6288.pdf: 1832069 bytes, checksum: 1b60b16b4da05304f9c4aadf5802ae6b (MD5) Previous issue date: 2014-06-04 / Trawling with network-of-doors practiced by the artisanal fleet directed to-bobshrimp Xiphopenaeus kroyeri in central and northern coast of Santa Catarina is an efficient way to capture the target species. However, it has low selectivity and incidentally capture large contingent of demersal and benthic fauna, grouped on the designation of bycatch species, part of this is compounded by the Sciaenidae comprising teleost fish with great commercial importance. Based on this finding, the aim of this work was to evaluate qualitative and quantitative fish species present in the Sciaenidae accompanying fauna in three traditional areas of fishing-bob-shrimp. Seasonally, during the day, from September 2009 to July 2010, drags on traditional shrimp fishing areas in the municipalities of Bal. Barra South and Porto Belo, Santa Catarina, and monthly hauls were performed during the period September 2011 to August 2012 at easel Itapocoroy Penha, Santa Catarina. It appears that the composition of the Sciaenidae of accompanying fauna is dominated by demersal fish, belonging to two genera and three species Stellifer rastrifer, and S. brasiliensis Paralonchurus brasiliensis characterized dominant. The populations show seasonal fluctuations in abundance, with the highest catch rates in summer and lowest in winter. In general, the populations of the three species showed similar results in the evaluated parameters, experiencing a dominance of males in relation to females throughout the sampling period, with a predominance of males in the smaller length classes and the larger female. As the size of the first maturation of these species of approximately 9cm with the occurrence of two clutches per year. Trawling with network-of-doors practiced by the artisanal fleet operates intensely on juvenile population despite large share of the adult population. / A pesca de arrasto com rede-de-portas praticada pela frota artesanal dirigida ao camarão sete-barbas Xiphopenaeus kroyeri no litoral Centro-Norte catarinense é considerada eficiente na captura da espécie-alvo. Entretanto, apresenta baixa seletividade e incidentalmente captura grande contingente da fauna demersal e bentônica, agrupados sobre a denominação de fauna acompanhante, parte desta é composta pela família Sciaenidae que compreende peixes teleósteos com grande importância comercial. Tendo por base essa constatação, objetivou-se no presente trabalho avaliar qualiquantitativamente as espécies de peixes da família Sciaenidae presentes na fauna acompanhante em três áreas tradicionais de pesca de camarão setebarbas. Sazonalmente, durante o dia, de setembro de 2009 a julho de 2010, foram realizados arrastos em áreas tradicionais de pesca de camarões nos municípios de Bal. Barra do Sul e Porto Belo, em Santa Catarina, e arrastos mensais durante o período de setembro de 2011 a agosto de 2012 na Armação do Itapocoroy, Penha, Santa Catarina. Constata-se que a composição da família Sciaenidae da fauna acompanhante é dominada por peixes demersais, pertencentes a dois gêneros e a três espécies Stellifer rastrifer, S. brasiliensis e Paralonchurus brasiliensis que se caracterizam dominantes. As populações apresentam flutuações sazonais na abundância, com as maiores taxas de capturas no verão e as menores no inverno. De modo geral, as populações das três espécies apresentaram resultados semelhantes nos parâmetros avaliados, ocorrendo uma dominância dos machos em relação as fêmeas ao longo do período de amostragem, com o predomínio dos machos nas menores classes de comprimento e das fêmea nas maiores. Sendo o tamanho da primeira maturação dessas espécies de aproximadamente 9cm, com a ocorrência de duas desovas por ano. A pesca de arrasto com rede-de-portas praticada pela frota artesanal atua de forma intensa sobre a população juvenil apesar de grande participação da população adulta.

The effect of dietary protein, protein and energy ratios, fish meal replacement by Soya bean meal and feeding frequency was investigated on the growth, feed efficiency and body composition, of juvenile dusky kob, Argyrosomus japonicus. The effect of dietary protein levels was investigated by comparing isocaloric diets containing 35, 40, 45 and 55% protein. Dietary protein inclusion level significantly affected specific growth rates, feed efficiency and body composition (in terms of fat deposition) and results show that a minimum of 45% and maximum of 52.3% dietary protein is optimal. The protein and energy requirements were investigated by comparing three protein levels (35,40 and 45%) with three lipid levels (6, 9 and 12%) in a 3x3 factorial design. A diet 45% protein and 9% lipid, with a P: E ratio of29 mglkJ and DE of 15.5 kJ/g resulted in an optimal specific growth rate (1.6± 0.2), feed efficiency (FCR= 1.7±0.44; PER= 1.36) and body composition for A. japonicus. To investigate the effect of partial fish meal replacement by Soya bean meal (SBM) in the diet, 20-50% of the protein from fish meal was substituted by protein from SBM, and were compared with a control diet containing only fish meal. No significant differences in the specific growth rates, feed efficiencies and the body composition were recorded for the fish fed the control diet and for fish fed the 20 and 30% SBM treatments. Results show that up to 30% of the protein from fish meal can be replaced with protein from SBM in the diet of this species. The effect of feeding frequency and gut evacuation time was investigated by comparing four feeding frequencies. Fish were fed to satiation either once, twice, three or four times a day. Feed intake was significantly affected by feeding frequency and fish fed 2, 3 and 4 meals a day ate significantly more food (p< 0.05) than the fish fed one meal a day. No significant differences (p> 0.05) in the specific growth rates, feed efficiencies and body composition were recorded for fish fed 2, 3 and 4 times a day. Feed intake was used to calculate an optimal daily ration and feeding two meals a day resulted in an optimal daily ration of 4% BW/day. A gut evacuation time of 7.25 hours indicates that fish fed twice a day probably had sufficient time to digest their food and evacuate their guts, resulting in the same daily feed intake as fish given 3 and 4 meals a day. Results conclude that under the present experimental conditions, a minimum daily ration of 4% BW/day, fed twice a day (in the morning and evening) is required for optimal growth (SGR= 1.33± 0.1), feed efficiency (FCR= 1.96± 0.4; PER= 1.44± 0.2) and body composition in juvenile dusky kob.

The lack of locally manufactured marine finfish diets motivated the current project, which aimed to develop a practical diet specifically formulated for dusky kob. The first growth trial investigated the effect of pellet texture (i.e. hard versus soft pellets) and the inclusion of an additional binder, test treatments were compared to two reference diets. There was no significant difference in weight gain between fish fed the hard or soft pellets (p=0.17), over nine weeks. The fish fed the local trout feed weighed significantly less than those fed the test diets (p=0.003). There was no significant difference in leaching rate amongst treatments (p=0.45). A hard pelleted diet without gelatin is recommended in the commercial culture of dusky kob. Pellets with different physical shapes were tested to determine the effect of shape on settling speeds. A square shaped pellet had a slower sinking rate compared to a round shaped pellet (p<0.0001). Juvenile dusky kob, held in cages, fed the square pellets grew significantly faster than the fish fed the round pellet, with a mean weight gain of 16.81 ± 0.45 g (p=0.018). A growth trial was used to optimize the protein to energy (PE) ratio by adjusting dietary protein and lipid levels. Fish fed the diets with high levels of protein (46 % protein) achieved the better growth rates (125 % weight gain) compared to the lower protein diets (92 % weight gain) (p<0.0001). There was no significant difference in total ammonia production (TAN) level for the 46 and 42 % protein diets (p=0.68). The overall performance of the prototype diet was investigated in a closed recirculating system. Growth and FCR of the fish fed the prototype diet was on a par to those fed the commercially available diet currently used in the local farming industry. There was no significant difference in the blood chemistry for fish held at increased stocking densities. The prototype diet is suitable for use in recirculating systems, as there were no negative effects on water quality parameters. This study has laid a foundation for the manufacture of a practical commercial dusky kob diet in South Africa.

Recordings of fish sound production were made in Charlotte Harbor, Florida using Long Term Acoustic Recording Systems (LARS) programmed to record 10 seconds of sound every 10 minutes. Results demonstrated a strong circadian pattern in fish sound production that occurred within a few hours of dusk each evening. Sound production lasted on average 8.7 hrs each evening during the peak spawning season. LARS were deployed when Hurricane Charley crossed Charlotte Harbor in August, 2004. The hurricane did not inhibit nightly chorusing events of spawning fish. Rather, sound levels produced by spawning fish on the night of and 3 days after the hurricane were higher and lasted longer than any of the 9 days recorded prior to the hurricane. Acoustic time series data recorded at multiple sites in Charlotte Harbor during 2005 revealed changes in the spatial distribution of fish sound production in response to increased freshwater inflow and consequent decreased bottom dissolved oxygen concentrations in early June. Fish sound production decreased rapidly over several days at study sites in the northern portion of the harbor most immediately affected by changes in environmental conditions. Meanwhile, fish sound production increased at the study site furthest seaward where normoxic levels were sustained. By August levels of fresh water inflow decreased substantially, bottom dissolved oxygen levels increased and sound production resumed at sites previously affected by these conditions. Fish sound production began intermittently in February and ended in November. Peak levels were reached by mid-late April / early May and continued throughout the summer time. Seasonal patterns of sound production match the reported spawning periods of estuarine sciaenid species recorded. Black drum sound production was measured in the canal systems of Cape Coral and Punta Gorda, Florida during the 2004-2006 spawning seasons. The circadian pattern of sound production was similar to other sciaenids documented in Charlotte Harbor. Seasonal patterns of black drum sound production occurred during October through April and peaked in February. This seasonal period of sound production also matched patterns of black drum reproductive readiness and spawning reported in the literature for the Gulf of Mexico. A hydrophone array was used in the Cape Coral canal system to localize calling black drum and measure source levels and propagation of calls. Source level estimates averaged 165 dBRMS re: 1muPa SPL (SD=1.0) (n = 1,025). Call energy was concentrated in the fundamental frequency (94 Hz) and first two harmonics (188 Hz and 282 Hz). A square root model best described propagation of the fundamental frequency and first harmonic and a log 10 model best described the second harmonic. Based on the mean RMS source level, signal propagation, background levels, and hearing sensitivity, the communication range of black drum at the study site was estimated at between 33 and 108 meters and was limited by background levels, not auditory sensitivity. The timing and levels of sound production and egg production were compared in black drum. Eggs were collected hourly from 1800 - 0400 by surface plankton tows on two consecutive evenings while black drum sound production was continuously recorded. This sampling effort was conducted five separate times from January through April, 2006. Evidence of the time of spawning was indicated by the collection of blastodiscs (fertilized single cell eggs) or back calculated early cleavage stage eggs. Neither the timing nor the quantity of sound production was positively correlated with egg production on a nightly basis and the greatest densities of eggs were collected on evenings which had the lowest levels of sound production. This may have been due to differences in the fecundity of individual females spawning on the evenings when sampling was conducted.

La corvina es una especie carnívora que se ha incorporado a la producción de la acuicultura en el Mar Mediterráneo, por sus altos índices de crecimiento y calidad de la carne. Por la poca información nutricional existente para esta especie, se ha introducido en su producción la experiencia que ya se tiene en la dorada y la lubina. Los objetivos de esta tesis doctoral fue determinar las necesidades nutritivas de la corvina y estudiar la inclusión del turtó de soja como una fuente proteica vegetal alternativa de la harina de pescado. Para determinar las necesidades de proteína y energía se trabajó con un pienso comercial, se experimentó con dos grupos de peces (53 y 200 g), en donde se aplicó un modelo factorial, obteniendo que las necesidades de mantenimiento para la proteína fue de 0,0617 g PD 100 g pez-1 día-1 y para la energía de 2.74 kJ ED 100 g pez-1 día-1. Las necesidades para el máximo crecimiento de la proteína fue de 0,64 g PD 100 g pez-1 día-1 y de energía 38.5 kJ ED 100 g pez-1 día-1. Con peces de 52 g, se realizó el estudio del efecto de los niveles de la proteína digestible (35%, 43%, 49% y 53%), los peces alimentados con piensos con niveles de 43%, 49% y 53% de proteína digestible, obtuvieron los mejores crecimientos (Coeficiente térmico de crecimiento = 2,47, 2,57 y 2.69 x 10-3, respectivamente). El nivel óptimo de proteína digestible ingerida para juveniles de corvina fue de 0,8 g PD 100 g pez-1 día-1. Para determinar la relación Proteína/Energía se experimentaron con peces de 147 g en jaulas marinas y fueron alimentados con piensos de 47/20, 51/28 y 55/17, obteniendo los mejores crecimientos e índices de conversión con el pienso 47/20. Para estudiar la inclusión del turtó de soja en la corvina se realizaron dos fases de investigación. En una primera fase se utilizaron 800 peces de 165 g, durante 107 días fueron alimentados con cuatro piensos isoproteíco (50% de proteína bruta) e isolípidico (17% de grasa bruta), con niveles de inclusión del 0, 15, 30 y 45% de turtó de soja. En los piensos del 15 y 30% de turtó de soja se obtuvieron los mejores resultados y de acuerdo a la regresión cuadrática el nivel óptimo de inclusión de turtó de soja fue del 27.6%. La relación entre el porcentaje de aminoácidos esenciales de la dieta y el porcentaje de aminoácidos esenciales a nivel corporal de los peces presentó deficiencias en arginina, lisina, treonina y principalmente de metionina. En la segunda fase se utilizó la misma metodología que en el primer experimento, pero utilizando 300 peces de 346 g de media durante 26 días. Los resultados muestran que la corvina presentó un alto crecimiento (Coeficiente térmico de crecimiento = 4,00 x 10-3) y se recomienda una inclusión de turtó de soja de entre un 30 ¿ 45%. En base a los resultados obtenidos, se propone un pienso para Argyrosomus regius de 47% de proteína bruta, 17% de grasa bruta y un 30% de inclusión de turtó de soja, suplementado con metionina y lisina, con el fin de obtener altos crecimientos, disminuir el uso de la harina de pescado y hacer más rentable la producción acuícola de esta especie en el Mar Mediterráneo / Velazco Vargas, JL. (2014). Contribución al estudio de las necesidades nutritivas de la corvina (Argyrosomus regius, Asso 1801) [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35446

Fisheries management regulations for dusky kob Argyrosomus japonicus, an important commercial and recreational fisheries species, have failed and the stock is considered collapsed. It is important to take an ecosystems approach to management which includes understanding the effect of environmental factors on recruitment, abundance and distribution. The distribution of early juveniles (20-150 mm TL) in the wild appears to be restricted to the upper reaches of estuaries at salinities below 5 psu. Food availability could not explain the distribution of early juveniles. The aim of this study was to investigate the role of salinity on the distribution of early juvenile dusky kob (<150 mm TL) by examining physiological responses of juveniles exposed to a range of salinities under laboratory conditions. The hypothesis was that the physiological functioning of early juveniles would be optimised at the reduced salinities which they naturally occur at. The objectives of this study were to investigate the effect of salinity on: i) plasma osmolality; ii) growth, food conversion ratio and condition factor; and iii) gill histology with emphasis on chloride cell size and number. A preliminary study was undertaken to determine whether the use of 2-phenoxyethanol had an effect on plasma osmolality. Juveniles pithed prior to blood sampling were used as the control. Plasma osmolality was not affected by exposure or duration of exposure (2, 4, 6, 8, 10 min) to 2-phenoxyethanol. The ability of teleosts to regulate plasma osmolality over a wide range of salinities indicates their degree of ‘physiological euryhalinity’. Plasma osmolality of juveniles exposed to 5, 12 and 35 psu was measured every two weeks over a total of six weeks. Although juveniles were able to regulate plasma osmolality over the duration of the experiment, plasma osmolality at 5 and 12 psu was significantly lower than in fish maintained at 35 psu. Growth is used as an indicator of the relative energy used for osmoregulation at different salinities, as the energy used for osmoregulation becomes unavailable for growth. A nineweek growth experiment was conducted on juveniles exposed to 5, 12 and 35 psu. Juveniles grew and survived at all three salinities. However, growth of juveniles at 5 psu was significantly lower than at 12 and 35 psu. Other than a significantly greater weight gain at 35 psu relative to 12 psu, there was no significant difference in specific growth and length gain between juveniles at 12 and 35 psu. Food conversion ratio and condition factor at 12 and 35 psu were not significantly different, but food conversion ratio and condition factor at 5 psu was significantly greater and lower than at 35 psu respectively. In fish, gills are considered the major organ involved in osmoregulation. Within the gills, chloride cells are the predominant site of ion exchange which is driven by the Na⁺, K⁺- ATPase enzyme. Gill samples of juveniles exposed to 5, 12 and 35 psu for six weeks were examined histologically using light microscopy. Chloride cells of juveniles maintained at 5 psu were significantly more abundant than in juveniles at 12 and 35 psu. Chloride cells of juveniles at 5 psu were significantly larger than in juveniles kept at 12 psu, but not significantly different to those of juveniles kept at 35 psu. The ability of the juvenile fish to regulate plasma osmolality indicates that they are 'physiologically euryhaline', but the reduced growth and proliferation of chloride cells at 5 psu suggests that energy expenditure for osmoregulation is increased at hypoosmotic salinities. Salinity induced physiological responses could therefore not explain the natural distribution of early juvenile dusky kob and it is proposed that other environmental factors (e.g. temperature) are also important. It is also hypothesised that the high conductivity of an estuary in South Africa, to which our understanding is limited, may negate the effect of reduced salinity. Although freshwater input into estuaries is an important factor, further investigations to explain the distribution and abundance of early juveniles is required to make management recommendations. Dusky kob is also becoming an increasingly popular aquaculture species in South Africa. In this regard, early juvenile dusky kob can be grown at salinities as low as 12 psu without negatively affecting growth and production.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-02-20T19:05:55Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvalicaoBiologiaReprodutiva.pdf: 5895607 bytes, checksum: d83a42e53047542bb5d0096df736676f (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-02-25T16:41:53Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvalicaoBiologiaReprodutiva.pdf: 5895607 bytes, checksum: d83a42e53047542bb5d0096df736676f (MD5) / Made available in DSpace on 2013-02-25T16:41:53Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvalicaoBiologiaReprodutiva.pdf: 5895607 bytes, checksum: d83a42e53047542bb5d0096df736676f (MD5) Previous issue date: 2009-04-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Projeto PIATAM Mar II / O Porto de Vila do Conde, situado no município de Barcarena/PA, vêm sofrendo diversos desastres ambientais nos últimos anos o que pode eventualmente acarretar no desequilíbrio do uso que os recursos aquáticos fazem do ambiente e no ecossistema como um todo. A pesca artesanal nesta região é bastante relevante, destacando Plagioscion squamosissimus e P. surinamensis que são importantes como fontes de renda e de alimento para a população. O objetivo deste estudo foi descrever as áreas de concentração e a biologia reprodutiva de P. squamosissimus e P. surinamensis na área adjacente ao Porto de Vila do Conde, destacando a importância da utilização destes ambientes para reprodução. Para identificar a época e os pesqueiros de maior abundância foram realizados cálculos de CPUE (Kg/viagem) por meio de dados obtidos no período de junho de 2007 a maio de 2008. A determinação do uso da área para reprodução e a descrição da biologia reprodutiva foi efetuada através da coleta de 40 a 53 indivíduos de cada espécie por bimestre, obtidos pela pesca comercial. Em laboratório, foram obtidos valores de peso e comprimento e as gônadas foram retiradas para a determinação do estágio de maturidade. A abundância de P. squamosissimus é máxima entre setembro a fevereiro e P. surinamensis ocorreu principalmente entre março a maio. A relação peso-comprimento mostrou isometria para as fêmeas de P. squamosissimus e ambos os sexos de P. surinamensis. Apenas os machos da espécie P. squamosissimus apresentaram alometria positiva. A proporção sexual foi favorável aos machos de P. surinamensis (1,05macho: 1fêmea) e favorável às fêmeas (1,11fêmea: 1macho) para P. squamosissimus. O valor de L50 (Tamanho de primeira maturidade) para P. squamosissimus foi 16,14 cm para fêmeas e 21,43 cm para machos. P. surinamensis apresentou valor de L50 de 27,65 cm para fêmeas e 27,13 cm para os machos. O percentual de indivíduos em reprodução da P. squamisissimus é relevante. O pico da reprodução desta espécie (outubro/novembro e fevereiro/março) coincide com o pico de abundância, indicando que esta espécie está na área para reprodução. P. surinamensis apresentou maior porcentagem de indivíduos nos estádios imaturo e em maturação, indicando que a mesma utiliza esta área principalmente como área de criadouro. Os indivíduos que estavam reproduzindo foram mais numerosos entre agosto/setembro e outubro/novembro. / The Port of Vila do Conde, situated in the city of Barcarena/PA, have been exposed to a number of environmental disasters in recent years which can eventually cause the disequilibrium of the use that the aquatic resources make of the environment and consequently to the ecosystem as a whole. Artisanal fishery in this region is relevant, detaching Plagioscion squamosissimus and P.surinamensis as the mains sources of income and food for the population. The objective of this study was to describe the areas of concentration and the reproductive biology of P. squamosissimus and P. surinamensis in the adjacent area of Vila do Conde, mainly identifying the importance of the use of these environments for reproduction. Aiming to identify to the period and fishing sites of greater species abundance, it was obtained the index of abundance CPUE (Kg/viagem) based on data collected from June 2007 to May 2008. The determination of the use of the area for reproduction and the description of reproductive biology was based on 40 to 53 individuals of each species collected from the commercial fishery in a bimensal basis. In laboratory, total length and total weight was registered and gonads were removed for the identification of sexual maturity. The abundance of P. squamosissimus is maximum between September and February and for P. surinamensis it is registered between March the May. The weight-length relationship showed isometry for the females of P. squamosissimus and for both sexes of P. surinamensis. For males of P. squamosissimus positive alometry was registered. The sexual ratio was favorable to the males for P. surinamensis (1,05male: 1female) and favorable to the females (1,11female: 1male) for P. squamosissimus. The value of L50 (length at first maturity) for P. squamosissimus was 16,14 cm for females and 21,43 cm for males. The length at first maturity for P. surinamensis was 27,65 cm for females and 27,13 cm for the males. The percentage of individuals in reproduction of the P. squamisissimus is considerable. The peak of the reproduction of this species (October/November and February/March) coincides with the peak of abundance, indicating that this species is in the area for reproduction. P.surinamensis presented greater percentage of immature and maturing individuals, indicating that this species uses this area mainly as a nursery. For P. surimamensis, reproductive individuals was mainly reported in August/September and October/November.

published_or_final_version / Biological Sciences / Master / Master of Philosophy