In the southeastern coast of Brazil, catches of the Brazilian sardine (Sardinella brasiliensis) have been decreasing from more than 200 thousand tons/year in the early '70s to about 32 thousand tons in 1990. From 1994 to 1997, catches recovered slightly (118 thousand tons), dropping then to about 20 thousand tons in 1999-2000. Extensive investigations on biology and stock assessment of Brazilian sardine have been developed in the '80s, providing stock biomass and recruitment estimates based on commercial fishing data obtained from 1977-1992. The present paper aims to update biological and stock assessment parameters from sardine data obtained during two acoustic surveys carried out in 1995 and commercial catches from the 1993-1997 period. Results from both cruises showed the weight-length relationship Wt=0.0000019. Lt3,26 (90-240 mm total length) and four age classes (mostly class II+). In the commercial catches, sardines belonged to ages 0+ and 3+ years old (mostly older than 1-year old) with 90-250 mm total length. Annual growth parameters were: Li=275 mm, K= 0.55 (1996), and Li=273 mm, K=0.50 (1997). Total mortality (Z) and natural mortality (M) coefficients were: Z= 3.8; M= 0.7 -1.2 (1996), and Z= 3.6; M= 0.6 - 1.1 (1997). The variation amplitude of M is due to the application of several different methods. Considering the historical series of 21 years of data (1977-1997), results showed that the stock went through two favorable periods (1980-84, 1989-94) and one unfavorable period (1985-89). 1997 seems to have been the beginning of a new unfavorable period, revealing recruitment cycles likewise other stocks from California and Japan.
In the southeastern coast of Brazil, catches of the Brazilian sardine (Sardinella brasiliensis) have been decreasing from more than 200 thousand tons/year in the early '70s to about 32 thousand tons in 1990. From 1994 to 1997, catches recovered slightly (118 thousand tons), dropping then to about 20 thousand tons in 1999-2000. Extensive investigations on biology and stock assessment of Brazilian sardine have been developed in the '80s, providing stock biomass and recruitment estimates based on commercial fishing data obtained from 1977-1992. The present paper aims to update biological and stock assessment parameters from sardine data obtained during two acoustic surveys carried out in 1995 and commercial catches from the 1993-1997 period. Results from both cruises showed the weight-length relationship Wt=0.0000019. Lt3,26 (90-240 mm total length) and four age classes (mostly class II+). In the commercial catches, sardines belonged to ages 0+ and 3+ years old (mostly older than 1-year old) with 90-250 mm total length. Annual growth parameters were: Li=275 mm, K= 0.55 (1996), and Li=273 mm, K=0.50 (1997). Total mortality (Z) and natural mortality (M) coefficients were: Z= 3.8; M= 0.7 -1.2 (1996), and Z= 3.6; M= 0.6 - 1.1 (1997). The variation amplitude of M is due to the application of several different methods. Considering the historical series of 21 years of data (1977-1997), results showed that the stock went through two favorable periods (1980-84, 1989-94) and one unfavorable period (1985-89). 1997 seems to have been the beginning of a new unfavorable period, revealing recruitment cycles likewise other stocks from California and Japan.
Na costa sudeste do Brasil, as capturas da sardinha-verdadeira {Sardinella brasliensis) decresceram de mais de 200 mil t/ano no início dos anos 70 para cerca de 32 mil t em 1990. De 1994 a 1997, as capturas se recuperaram alcançando 118 mil t, caindo então para cerca de 20 mil t em 1999-2000. Estudos abrangentes sobre a biologia e avaliação do estoque da espécie foram desenvolvidos nos anos 80, permitindo a estimativa da biomassa e recrutamento do estoque com base em dados da pesca comercial durante 1977-1992. Os objetivos do presente trabalho foram atualizar as estimativas dos parâmetros biológicos e avaliação do estoque através de dados obtidos durante dois cruzeiros de prospecção acústica realizados em 1995 e de dados da captura comercial no período 1993-1997. Como resultados de ambos os cruzeiros, a relação peso/comprimento estimada foi: Wt=0,0000019.Lt'~6 (amplitude de comprimento total de 90-250mm) e quatro classes etárias (maior freqüência para a classe II+) estiveram presentes. Nas capturas da pesca comercial ocorreram indivíduos de idades 0+ a Ill+ anos, principalmente adultos com mais de 1 ano de idade e comprimentos entre 90-250mm. Os valores dos parâmetros de crescimento estimados foram Li = 275 mm e K = 0,55 (1996), e Li = 273 mm e K = 0,50 (1997). As taxas de mortalidade total (Z) e natural (M) foram: Z = 3,8 e M = 0,7 - 1,2 (1996), e Z = 3,6 e M = 0,6 - 1,1 (199...
M orphologiaal drlta of horse-maakerel (TMeh~ latham~)
Brazilian sardine datawere collected between September 1981 and August 1982 from the southeastern Brazilian waters. Otoliths were read using reflected ligth on the surface of the whole structure. Three methods were used to determine the time of ring formation, being the mean length per ring the best one. There are two annual rings clearly visible, one laid down in November/December, and the other one laid down in March/April. A method of age determination is described, being the maximum age 3 years.
Brazilian sardine datawere collected between September 1981 and August 1982 from the southeastern Brazilian waters. Otoliths were read using reflected ligth on the surface of the whole structure. Three methods were used to determine the time of ring formation, being the mean length per ring the best one. There are two annual rings clearly visible, one laid down in November/December, and the other one laid down in March/April. A method of age determination is described, being the maximum age 3 years.
A idade da sardinha Sardinella brasiliensis foi determinada pelo exame de otólitos de exemplares provenientes de desembarques da pesca comercial e artesanal, na área compreendida entre 22ºS (Cabo Frio, RJ) e 28ºS (Cabo de Santa Marta, Grande, SC), durante o período 1981-83. Este estudo e parte de um programa mais amplo de nominado "Programa Integrado de Estu dos Biológicos sobre Sardinha", desenvolvido na região sudeste do Brasil desde 1981, objetivando conhecer as variações dos parâmetros biológicos da espécie, e fornecer subsídios a avaliação pesqueira do recurso. Foram contados os anéis translúcidos dos otolitos, colocados inteiros em recipientes de fundo preto, imersos em álcool 70% e iluminados com luz incidente sob estereomicroscópio binocular. Além das contagens, foram efetuadas medidas das distancias do núcleo do otolito ao bordo, e do núcleo a cada anél translúcido, bem como observações da natureza do bordo. Foram utilizados três métodos para determinar a época e periodicidade de formação dos anéis. Os parâmetros de crescimento L, K e t0 foram estimados, e as curvas ajustadas usando-se a equação de von Bertalanffy. Os resultados mostraram que os otolitos possuem de 0 a 7 anéis, sendo formados dois anéis por ano: um entre novembro-dezembro, e outro entre março-abril. Estas épocas estão intimamente ligadas ao período de reprodução. Descreveu-se um método para a determinação da idade de sardinha, tendo sido identificadas clas ses etárias de 0 a 3 anos. Verificou-se também a ocorrência de dois grupos de peixes dentro de um dado período de de sova (outubro e março), que representa riam individuos que nascem no início da estação de desova, e aqueles que nas cem posteriormente; ambos grupos formam uma classe anual. Os parâmetros de crescimento obtidos foram: classe anual 1982: Lt = 230,99 [1-e-0,7225(t+0,2496)] classe anual 1983: Lt = 226,09 [1-e-0,7194(t+0,3432)]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.