Key words: length-weight relationship, condition factor, Clarias gariepinus, Oreochromis niloticus, Wudil River. INTRODUCTION. Fish is any aquatic vertebrate. LENGTH-WEIGHT RELATIONSHIP AND CONDITION FACTOR OF experimental fish ranged from to cm and to g in length. Length-weight relationship (LWR) and condition factor of seven fish species from the Temengor Reservoir, Peninsular. Malaysia were analyzed. A total of
Many factors can influence sex ratio of adult crustaceans, such as migration, longevity, different growth rates and mortality between sexes Wenner, Nevertheless, Hayd and Anger mentioned the need for further studies on the relationships between variations in sex ratio, mating systems, ecological conditions and phylogenetic divergence to allow safe conclusions about the female biased sex ratio reported from natural populations of M.
With respect to body size, M. Therefore, the results found in this study are consistent with the patterns observed in populations of M. Distinct male morphotypes described by Moraes-Riodades and Valenti for the species have been recorded only for lotic environments Santos et al. The reproductive success of searching males depends on their ability to find and fertilize as many receptive females as possible without complex pre-copulatory behaviors Correa and Thiel, In this context, female-biased sex ratio as observed herein, and discussed above may also be advantageous for the pure search mating system, in which males could mate with different females increasing the reproductive output in population, as suggested by Leme and Negreiros-Fransozo for the crab Aratus pisonii H.
According Maciel and Valentiit is possible that populations in reservoirs suffer from degenerative genetic inbreeding, which could result in smaller individuals.
In the case of the M. Nevertheless, several authors have found negative allometry for this ratio for both sexes in coastal populations Flexa et al.
Therefore, it is possible that the type of environment lotic or lentic may also influence the relative growth pattern of M. According to Hartnollthe pattern of weight gain is ontogenetically determined, and may vary between males and females of the same species or even among different populations.
The most common pattern for M. The condition factor of M. In addition, although the monthly means of the allometric condition factor obtained for females were about 1. January-April showed that males achieved better conditions for weight gain than females, even though in both sexes the observed Kr was greater than 1. According to Molion and Bernardo the rainy season in the eastern part of Northeast Brazil occur from April to July, during the winter in the southern hemisphere.
During the period of the year when water temperature is higher and rainfall though increasing is below mm, the condition factor of M. On the other hand, when rainfall levels reached mm and water temperature dropped, the condition factor tends to be lower Fig. Furthermore, considering the monthly values of Kr, it is possible to conclude that in the months when temperatures are higher and precipitation levels are raising, the condition factor of the prawns is above the expected value Fig.
This corroborates the results found for the allometric condition factor and demonstrates the improved nutritional status of individuals in this period, compared to the period when temperature is lower and rainfall is dropping. According to Pinheiro and Fiscarellithe condition factor can be influenced by food availability in the environment. Macrobrachium amazonicum is omnivorous, feeding on filamentous algae, diatoms, aquatic insects and organic debris Maciel and Valenti, Stomach analysis of specimens collected in dams in Northeast Brazil revealed large amounts of microalgae Maciel and Valenti, Several studies indicate that phytoplankton productivity and biomass in reservoirs are influenced by many interdependent factors, for instance temperature, precipitation, light and nutrient input Talling and Rzoska, ; Kimmel et al.
On the other hand, rainfall, nutrient availability and residence time of water exerts an important influence on seasonal variations in primary productivity in tropical water bodies Calijuri et al. According to Calijuri et al.
At the same time, in the rainiest periods the availability of nutrients Henry et al. According to Chellappa et al. Thus, longer days when there is more sunlight incidence, less rainfall and higher temperatures could increase primary production in the Pedra do Cavalo Reservoir and hence food availability for prawns, leading to greater accumulation of energy i.
However, studies on the hydrological cycle and primary productivity of the Pedra do Cavalo Reservoir are needed to provide data that can be used to verify the influence of these aspects on the nutritional status of M.
Several authors have associated monthly or seasonal variations of the condition factor with the cycles of reproductive activity of fish and crustaceans; in general, lower condition factors are associated with investment of the accumulated reserves for reproduction e.
However, ovigerous females of M. In addition to reproductive factors, a decrease in the monthly means of the condition factor may be related to energy investment for somatic growth. Pinheiro and Taddei attributed a reduction in the values of the condition factor of Dilocarcinus pagei Stimpson, males to the molt cycle.
In the case of males and females of M. Therefore, it is possible that M. The study of weight gain and condition factor patterns through relative growth analyses proved to be an important tool to understand the biology of M.
Furthermore, the results presented here provide important information about the "well-being" of M. Gilson, local fisherman, for his help in sampling the specimens. Revista Brasileira de Zoologia, 20 3: Width-weight relationship and condition factor of Ucides cordatus Crustacea, Decapoda, Ucididae at a tropical mangroves of Northeast Brazil.
Condition factor and carapace width versus wet weight relationship in the swimming crab Callinectes danae Smith Decapoda, Portunidae at the Santa Cruz Channel, Pernambuco State, Brazil. Boletim do Instituto de Pesca, 26 1: Oecologia Brasiliensis, 12 1: The selection of suitable indices for the measurement and analysis of fish condition.
Journal of Fish Biology, 34 2: Revista Brasileira de Biologia, 46 2: Revista Nordestina de Biologia, 10 2: Arquivos de Biologia e Tecnologia, 36 3: Temporal changes in the phytoplankton community structure in a tropical and eutrophic reservoir Barra Bonita, SP - Brazil. Journal of Plankton Research, 24 7: Phytoplankton community and physical-chemical characteristics of water in the public reservoir of Cruzeta, RN, Brazil.
Brazilian Journal of Biology, 68 3: Mating system in caridean shrimp Decapoda: Caridea and their evolutionary consequences for sexual dimorphism and reproductive biology. Revista Chilena de Historia Natural, 76 2: Flood pulse influence and anthropic impact on the chemical composition and energy content of Oryza glumaepatula in an Amazonian lake.
Population structure and reproductive biology of Macrobrachium amazonicum Heller, Decapoda: Brazilian Journal of Aquatic Science and Technology, 16 2: On monthly basis it depart from three, except for November and April when they showed values closed to three.
This overall value 2. The parameter b represents growth alometric rate, and depends on genetically determined effects. If it stay constant and tending to assume values close to 3.
The regression coefficient and the constant regression present a remarkable inverse relation. BRAGA found an inverse variation between the regression coefficient and constant of regression for Paralonchurus brasiliensis due to seasonal variation in the physiologic state of the fish, expressed by the condition factor.
ATKINSON analyzed the length-weight relationship for Coryphaenoides rupestris for different fishing areas in the Atlantic and found different values for the regression coefficients and constant of regression. This relationship can be explained by differences in environments and ontogeny of fish. Youngs-of-the-year tend to allocate a large amount of energy in growth, while adults put a considerable part of their energy in reproduction process or increasing weight.
Smaller sized individuals present high growth rate and it was observed on the monthly variation in the regression coefficient which were correlated to constant regression, that is inversely related to condition factor BRAGA As the variation in the regression constant corresponds to the condition factor, that is, subject to seasonal oscillations, its variation can interfere in the variation of the regression coefficient.
BRAGA suggests that the regression coefficient is not a good support indicator for characterization of different populations, because it can vary seasonally in the same population. The condition factor presented higher values in the inner zone, due probably the largest input of organic matter from continental drainage, favoring organic enrichment of the local substratum muddywhere predominate youngs-of-the-year and juvenile.
In the outer zone, where larger sized fishes predominated, relatively high values were also detected. Differences in the condition factor have been interpreted as a measure of several biological events, such as fat reservations, adaptation to the environment and gonadal development LE CREN Mean values for condition factor varied among zones and size, indicating that youngs-of-the-year and adults can present higher condition independent of the time and distribution area.
The lowest values occurred in June, November and February, coinciding with higher frequency of emptied ovaries. In the present study also have been found three peaks October-November, April and August with the lowest values recorded from January to March, July and September.
Other important point to be raised is that M.
Falkland currents penetrate through west Bay side, probably transport can bring into the bay eggs and larvae from M. Juveniles and adults also presented high condition factor values in the outer zone, and this can be associated to the fact of these fish reach sexual maturity and allocate energy to reproductive process. Isometric growth for M.
This species seems to have developed adaptative processes for using this Bay area and supporting adverse conditions. The alometric coefficient change inversely with constant regression, shifting values among the months and indicating changes in population structure.
The best fish condition was recorded during the winter and spring. The best fish condition in the innermost area of the Bay coincided with dominance of the smallest sized individuals. We also thank all colleague of Laboratory of Fish Ecology for help in field work. Length, weight and associated structural indices, p. Bethesda, American Fisheries Society, p.
Revista Brasileira de Biologia, Rio de Janeiro, 58 3: Weight-length relationship of roundnose grenadier Coryphaenoides rupestris Gunnerus, in different areas of the North Atlantic. Fisheries Research, Amsterdam, 7: Computing the mean weight of the fish of a given lenght class. Selection of suitable indices for the measurement and analysis of fish condition.
Journal of Fish Biology, Dumfries, Revista Brasileira de Biologia, Rio de Janeiro, 46 2: Revista Brasileira de Biologia, Rio de Janeiro, 57 3: Biologia reprodutiva de Micropogonias furnieri desmarest, Teleostei, Sciaenidae. Fisheries biology, assessment and management. Oxford, Fishing News Books, p. The lenght-weight relationship and seasonal cycle in gonad weight and conditions in the perch Perca fluviatilis.
Journal of Animal Ecology, London, 20 2: