Evaluating mortality using length-frequency data when growth parameters are poorly known

A method is presented through which the total mortality undergone by several fish stocks of the same species can be compared when growth parameters are poorly known or unknown. Whereas the estimate of Z obtained via the length-converted catch curve is highly sensitive to the input parameters K and L sub( infinity ), the ratio of Z estimates obtained for different stocks with the same combination of parameters is almost independent of these inputs, at least when the fit of the linear regression is good. The method is tested on simulated data and an application is presented using real data from the Lesser Antilles. It provides the possibility of qualitatively comparing several stocks in situations of scarce biological knowledge.

Length-weight relationship of five serranids from Palawan Island, Philippines

The parameters a and b of the length-weight relationship (LWR) of the form W=aLb are presented for five species of serranids belonging to the genus Cephalopolis. The fish samples used for the study were caught by hook and line, fish corrals, and spearguns during August 1995 to December 1998 from the waters around Palawan Island, Philippines. Information on the LWR of six fishes from other studies conducted in Palawan is also provided.

Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico

Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000.

Length-weight relationship of marine fishes from southern Brazil

The relationship between length (L) and weight (W) was estimated for 80 species belonging to 50 families of marine fishes from the shelf and upper slope of southern Brazil (lat. 28°S - 34°S). Sample sizes (n) for different species ranged from 11 to 14 741 specimens collected from commercial landings and research surveys. The fit of the equations (W=aLb) with a and b parameters estimated from regular and functional regression (of log-transformed weight and length data) as well as from a non-linear iterative process using the quasi-Newton algorithm were compared. The non-linear method gave the most accurate estimates in terms of residual sum of squares. Differences were less than 2.3% for n>500 compared with predictive regressions and 1.5% compared with functional regressions. No difference was observed between both predictive and functional regressions. Determination coefficients (r2) increased with sample size, and the highest r2 were obtained for 50

Diet and feeding ecology of two sizes of Barbodes gonionotus (=Puntius gonionotus) and Oreochromis sp. in ricefields in Bangladesh

Fish culture experiments were conducted to compare and evaluate the feeding pattern and strategies, daily ration, gastric evacuation rates, dietary breadth, similarity and overlap of silver barb, Barbodes gonionotus, and tilapia, Oreochromis sp. (natural hybrid of O. mossambicus x O. niloticus) in a rice-fish system. B. gonionotus was found to be a macrophtophagous column feeder while Oreochromis sp. was a detrivorous benthophagic browser. Ontogenic shifts in diet were clearly observed in B. gonionotus while absent in Oreochromis sp. For both species, daily food ration for the small fish was twice as large as that for the large fish. Mean rates of gastric evacuation were 0.18 h super(1) for small and 0.05 h super(1) for large B. gonionotus and 0.09 h super(1) and 0.14h super(1) for small and large Oreochromis sp., respectively. In terms of intraspecific dietary width, the smaller sized individuals of both species had a wider dietary niche than the larger conspecifics. Larger fish increased their specialization and reliance on few food items with increasing size and competitive ability. When both species were reared together, B. gonionotus showed a wider niche width than tilapia. Wider interspecific niche width of B. gonionotus compared to that of tilapia and significant interspecific dietary overlap is likely to result in suppression of the growth of tilapia in mixed culture due to: 1) a high degree of specialization and reliance of tilapia on food of low-nutrient value, and 2) slower gastric evacuation rates as compared to B. gonionotus, which would allow B. gonionotus to outgrow similar sized tilapia.

Length-weight relationship of mudskippers (Gobiidae: Oxudercinae) in the coastal areas of Selangor, Malaysia

Parameters a and b of the length-weight relationship (LWR) were estimated for eleven species of mudskippers caught in the coastal areas of Selangor, Malaysia. The values of b ranged from 2.56 to 3.50 with the mean b equal to 2.95 (n=11; sd=0.302). A normal distribution of the calculated LWR exponent (b) was obtained.

Length weight relationships of Nigerian freshwater fishes

Length-weight relationships of 73 fish populations, covering 20 families, 28 genera and 40 species inhabiting freshwater ecosystems in Nigeria, were estimated (73 cases) or assembled from the literature (20 cases), and tested for difference between ecosystem types, There were no significant differences in the exponent of these relationships between lotic and lentic systems.

Length-weight relationships of Nigerian coastal water fishes

Length-weight relationships (LWR) of 76 fish populations, distributed among 11 families, 18 genera and 22 species, inhabiting coastal (marine/brackish water ) ecosystems in Nigeria were estimated (39 cases) or assembled from the literature (37 cases). The mean exponent (b = 2.912) is significantly less than 3. While the frequency distribution of a was positively skewed, that of b was approximately normal. The mean a and b data are also presented by fish genera and families.

Length-fecundity relationships of Nigerian fish populations

Parameters of the exponential body length (L)-fecundity (F) relationship of the form F=a.L super(b) are presented for 47 populations and 26 species of Nigerian fishes. Estimates of b varied between 1.563 (Ilisha africana) and 5.771 (Barbus callipterus) with a mean of 3.054 (s.d. = 1.024). The maximum sizes of fish populations examined did not significantly influence the relative magnitudes of b. The parameters Alpha and Beta of the linear length-fecundity relationships of the form F = Alpha + BetaL are also presented for five fish populations. Estimates of Beta ranged from 243.5 (Chrysichthys walkeri) to 1,334,895 (Tilapia mariae).

Length-weight relationships of freshwater fishes in Greece

Length-weight relationships were calculated for nine fish species from Lake Volvi (Macedonia, Hellas), caught with gillnets of five different mesh sizes between October 1995 and October 1996. In addition, length-weight relationships for 24 Greek freshwater fish species and one hybrid were also obtained from the literature. The values of the exponent of the length-weight relationships for all fish species examined ranged between 2.14 and 3.70 (mean = 3.12; SE=0.0321), and the median value was 3.19.

Length-weight relationship of fishes from a seagrass meadow in Negros Oriental, Philippines

The parameters a and b of the length-weight relationship of the form W=aL super(b) were estimated for 13 fish species sampled in a seagrass meadow in Negros Oriental, Philippines. Also, to facilitate conversions, the relationship between total length and standard length for the 13 species is given.

Growth, mortality, maturity and length-weight parameters of fishes in Lake Kariba, Africa

This preliminary compilation presents vital parameters for 22 species of freshwater fish from Lake Kariba. The majority of the growth parameters are derived from tables in Balon and Coche's "Lake Kariba: a man-made tropical ecosystem in central Africa". The rest of the parameters are compiled from more recent sources and unpublished data.

Memórias e Histórias do Curso de Psicologia da Faculdade Salesiana de Lorena/SP: Uma contribuição para a historiografia da Psicologia no Brasil

O presente estudo objetivou construir uma história do Curso de Psicologia da Faculdade Salesiana de Filosofia, Ciência e Letras de Lorena, com a perspectiva de compreender as relações sociais, culturais, as práticas cotidianas e os modos de fazer que caracterizaram a constituição do curso, tendo como recorte histórico o período de 1952 a 1974. A meta final foi contribuir para a historiografia da Psicologia no Brasil. Apresentamos, inicialmente, de forma concisa, a história dos salesianos, desde sua criação e de sua inserção no Brasil. Detemo-nos mais em sua chegada à Lorena, com a fundação do Colégio São Joaquim e, muito mais especialmente, do Laboratório de Psicologia Experimental. Exploramos seu significado para os salesianos e sua missão educativa, bem como para a emergência do curso de Psicologia. Foram utilizados, como fontes documentais, documentos escritos e iconográficos, além disso, foram realizadas Entrevistas Narrativas, que nos possibilitaram apontar algumas características do começo do curso, como, por exemplo, as questões de gênero. Assinalamos como a abordagem experimental, dominante no primeiro momento do curso, em que os principais professores eram oriundos da USP e da PUC-SP, muda aos poucos para a abordagem humanista, ruptura causada pela presença de um professor, Franz Victor Rudio. Concluímos que o curso de Psicologia de Lorena emergiu não por um documento ou por uma ação intencional e isolada de um sujeito individual, mas por ação de muitos personagens que, durante um longo período, construíram práticas ligadas à Psicologia que levaram à constituição do curso. No entanto, pode-se afirmar que estas práticas foram fundamentadas na missão salesiana de formar educadores qualificados para o exercício do magistério, apoiada no tripé razão, religião e amorevolezza.