Yasunobu Matsuura

A study of the life history of Brazilian sardines, Sardinella aurita: I. distribution and abundance of sardine eggs in the region of Ilha Grande, Rio de Janeiro

Distribution and abundance of sardine eggs in the Ilha Grande region, Rio de Janeiro, Brazil, were studied during five cruises for the 1969 1970 period. Using the shipboard fertilized eggs and the planktonic eggs, morphological descriptions of Brazilian sardine eggs are given. Spawning occurs during the summer from September to March in the coastal water off Ilha Grande to Ilha de Sao Sebastiao down to a depth of 100 meters. Spawning may take place a few hours prior to midnight. lt was noticed that spawning has a close relationship to an area of cold water up welling. Spawning groups are isolated and spawning is small in scale in this region. Temperature and salinity in the spawning area range between 18-24oC and 35.1-35.9‰ respectively.

Food and feeding ecology of Brazilian sardine (Sardinella brasiliensis) larvae from the southeastern Brazilian Bight

Plâncton amostrado na regiao sudeste do Brasil, em coletas integradas verticalmente e estratificadas, foi utilizado no estudo do comportamento alimentar das larvas de sardinha-verdadeira (Sardinella brasiliensis). As coletas de ictioplâncton foram realizadas com rede tipo Bongo de 60 cm de diâmetro durante os periodos de desova de 1991/92 e 1992/93. Microzooplâncton foi amostrado na regiao costeira ao largo de Ubatuba em dezembro de 1995, usando uma rede de fechamento. O estudo da alimentacao foi baseado em um total de 901 larvas capturadas. A analise do conteudo do trato digestorio das larvas de sardinha-verdadeira indicaram um padrao de alimentacao diurno. Os nauplios de copepode dominaram a dieta de larvas em preflexao e flexao e foram o segundo item em abundância em larvas em posflexao, que preferencialmente se alimentaram de copepoditos e adultos de Oncaea spp. Em media, a incidencia alimentar das 901 larvas foi de 37,6%, porem aumentou para 58,5% para larvas coletadas no periodo diurno. Setenta por cento das particulas ingeridas foram encontradas no trato medio e a digestao das particulas aumentou naturalmente desde o trato inicial ate o trato final. A distribuicao vertical do microzooplâncton revelou que os nauplios de copepode estiveram presentes em densidades de 10-20 ind. L-1, principalmente na camada superior de mistura (0-20 m da superficie), entretanto altas densidades de copepoditos e adultos de Oncaea, Oithona e Paracalanus foram encontradas dentro e atraves da termoclina. Os resultados obtidos indicaram que a larva de sardinha-verdadeira pode adaptar a sua dieta com sucesso, alimentando-se das particulas mais abundantes da camada de mistura na area estudada.

Distribution and abundance of carangid larvae in the southeastern Brazilian Bight during 1975-1981

Distribution and abundance of the carangid larvae collected during ten survey cruises in the southeastern Brazilian Bight were analyzed. Trachurus lathami was the most abundant species in the surveyed area with 58.54 % of total carangids taken, followed by Chloroscombrus chrysurus with 15.22 % and Decapteruspunctatus with 12.17 %. Larvae of T lathami and D. punctatus were found all over the continental shelf while the distribution of C. chrysurus larvae was limited to the coastal region. Most of the species occurred all year-around but remarkably during spring and summer. This intensive spawning period of most carangid species seems to be related to the seasonal variation of the hydrographie structure of the southeastern coast of Brazil.

The catfish, Rhinelepis aspera (Teleostei; Loricariidae), in the Guaíra region of the Paraná River: an example of population estimation from catch-effort and tagging data when emigration and immigration are high

Using the Leslie model, an estimate was made of the stock of the loricariid catfish, Rhinelepis aspera, in the fishing grounds in the Guaira region of the Parana River. The method was based on catch-effort and mark-recapture data collected over a 90 day period in 1986. The estimated initial population size, based on catch-effort, was 734 806 catfish with a biomass of 580 297 kg. During the experiment 2.372 million catfish entered the fishing area and 1.892 million catfish emigrated from it. A Petersen type estimate, based on the recapture ratio of tagged fish, was 812 359 catfish at the beginning of the experiment.

Distribuição sazonal de zooplâncton, ovos e larvas de peixes na região centro-sul do Brasil (1975-77)

Abundances of Zooplankton volumes, fish eggs and larvae were determined for 812 oceanographic stations on six survey cruises to the southern Brazilian continental shelf. Contour charts of Zooplankton volumes are presented. A marked seasonality on Zooplankton volumes and number of fish eggs and larvae was observed. The highest values were obtained during late spring and summer seasons and the lowest in the autumn. The mean values of Zooplankton volumes, eggs and larvae for different depth zones and subareas were presented. Major part of fish larvae were classified into 55 families. The most abundant group were those of family Engraulidae, Myctophidae and Gonostomatidae. The larvae of Clupeidae were abundant in the late-spring and summer cruises.

Osteological development of the lophiid anglerfish, Lophius gastrophysus.

The osteological development of the head skeleton and dorsal, pectoral, and anal fin supports, are described from cleared and stained specimens ofLophius gastrophysus larvae, ranging from 4.6 to 21.8 mm NL; the results are compared with those of juvenile (79.8 mm SL) and adult (398 mm SL) specimens. Tiny conical teeth are present on the premaxillary, dentary, palatine and vomer since early stage. The first three dorsal fin spines are initially positioned on the midline of body posterior to the supraoccipital, but they migrate forward with growth and become cephalic in juveniles. The forward movement of the dorsal spines is produced by the forward extension of the cartilaginous basal inside the subepidermal space. During the planktonic larval stage the pectoral fins are on the sides of body as in ordinary fishes, but they move ventrad and become leg-like in bottom living juveniles and adults. Ossification of the caudal complex ofL. gastrophysus larvae proceeds very slowly and only the 21.8 mm NL larva has an almost completely ossified caudal complex. Eight principal caudal rays are loosely attached on the posterior edge of the hypurals and no procurrent rays are present. Larvae have well developed parhypurapophysis at the mid-portion of the urostyle which transforms into keel-like structure in juveniles and adults.

A study of the life history of Brazilian sardine, Sardinella brasiliensis: III. development of sardine larvae

O presente trabalho e parte do projeto SOL e tem por objetivo descrever a morfologia das larvas da sardinha verdadeira, Sardinella brasiliensis (=S. aurita), com o intuito de determinar um padrao que possibilite a identificacao das mesmas. Sao feitas consideracoes sobre a morfologia das larvas de outros clupeideos existentes na regiao e ressaltadas as diferencas com relacao as larvas de S. brasiliensis. Os resultados, posteriormente, serao usados como base para o estudo quantitativo da abundância de larvas de sardinha. O material foi coletado na costa sul do Brasil de 1969 a 1971, com uma rede de plâncton do tipo conico-cilindrico. Durante o desenvolvimento das larvas, foi observado um consideravel deslocamento das bases das nadadeiras dorsal e anal, para uma posicao mais anterior. Com o tamanho de 19 mm (comprimento padrao), ocorre uma mudanca geral, consideravel, nas proporcoes corporais. A ossificacao de todos os raios das nadadeiras completa-se quando a larva atinge 20 mm, mas a ossificacao dos escudos ventrais so se completa quando ela atinge 30 mm de comprimento. A ossificacao das vertebras completa-se a 16 mm de comprimento. O tamanho de 19 mm foi considerado como o fim do estagio larval, e, apos este comprimento, consideramos a larva no estagio prejuvenil (=transformal).

Distribution and abundance of skipjack (Katsuwonus pelamis) larvae in eastern Brazilian waters

Based on data from two ichthyoplankton surveys carried out off the eastern Brazilian coast in June and November-December 1978, the larval distribution of skipjack is discussed. Skipjack larvae were more abundant in the November-December cruise (southern hemisphere spring). They occurred mainly at stations near the margin of the continental shelf or over seamounts. Out of 240 specimens of scombrid larvae collected in this area, skipjack larvae comprised only 10.4% (25 specimens), whereas the most abundant larvae were Thunnus spp. with 68.8% (165 specimens).

Estudo do ciclo de vida do peixe-espada Trichiurus lepturus

Eggs and larvae of the cutlassfish, Trichiurus lepturus, were collected during the survey cruises of the project FINEP to determinate spawning areas and season. Six cruises were made from 1975 to 1977 in southern Brazil (23o S -29o S). Spawning occurred throughout the year, but intensively in the cruise, May 1976 (autumn). The heavy spawning area was offshore region of Ilha Grande and of Ilha de Sta. Catarina. Mean temperature of the spawning area was 24.09 oC, ranging from 21.15 to 26.29 oC and mean salinity was 35.31 ‰, ranging from 35.04 to 35.52 ‰. Catch data of cutlassfish fishery showed a gradual increase last several years in the two states: Sao Paulo and Santa Catarina.

A study of the life history of Brazilian sardine, Sardinella brasiliensis: IV. Distribution and abundance of sardine larvae

O presente trabalho apresenta a distribuicao e abundância de larvas de sardinha-verdadeira, Sardinella brasiliensis, coletadas nas aguas do sul do Brasil no periodo de 1969 a 1971. A abundância relativa de larvas para tres epocas de desova foi calculada usando o metodo apresentado por Smith (1972). De um modo geral, a abundância de larvas de cada subarea coincidiu com a dos ovos, mas sua distribuicao abrangeu uma area um pouco maior do que a dos ovos. A abundância relativa de larvas na epoca de desova de 1970-71 foi mais fraca do que as de 1969-70 e de 1971-72. Tal resultado confirma o obtido para a abundância de ovos, e, a razao deste fracasso, podera ser atribuida ao fato de que massas de agua mais quentes cobriram a area de desova na epoca de 1970-71. A temperatura media nas estacoes oceanograficas onde as larvas foram coletadas, foi de 23,4oC, variando de 14,6 a 27,4oC. A salinidade media foi de 35,6o /oo, variando de 35,0 a 36,7o /oo. A razao de captura noite/dia de larvas foi de 3.93. Foi calculada curva de sobrevivencia. Foram analisadas a distribuicao da frequencia de comprimentos das larvas e sua distribuicao nas diferentes profundidades e subareas. O resultado mostrou que nao ha deslocamento de larvas em uma direcao unica, mas sim uma dispersao da area de desova para toda plataforma continental. Sao discutidos alguns problemas sobre a distribuicao e migracao de larvas e jovens de sardinha-verdadeira.