This study contributes to the knowledge of traditional fishing gears and the weight-length relationship of fish species from the Bangkau Swamp, Indonesia. Although the use of fishing gears in Bangkau ...swamp complies with the local regulation but still, some weaknesses have been identified and the options for improvements are being proposed. The length-weight relationship of three dominant fish species, Channa striata, Trichogaster trichopterus, and T. pectoralis were analyzed. The b values ranged from 1.531 to 2.646, with R2 values ranged from 0.814 to 0.917 indicating negative allometric growth pattern; the species becomes leaner as the length increases. The food availability and temperature may have an effect on the growth pattern since the fishes were sampled in dry season. To the best our knowledge, this study is the first reference on WLR for swamp fish in the Bangkau village.
Weight-length relationships (WLRs) for 28 fish species were investigated in an enclosed basin in the Sea of Marmara. Due to low sample sizes ( 0.05). In this study, WLRs for Pomatoschistus marmoratus ...are presented for the first time in Turkish waters. Additionally, this study represents the first results for the entire Sea of Marmara and carries significant importance for the WLR database in light of previous studies, which only provided information for limited parts of this sea.
The flood pulse is a key factor that drives the biota of large rivers with adjacent floodplains, but the direction and intensity of its effects are not uniform for all trophic guilds of fish. In this ...study, we tested the existence of intra- and inter-annual changes in the relative condition factors (kn) of three Curimatidae: Potamorhina altamazonica, Potamorhina latior, and Psectrogaster rutiloides. We used weight and length data from fish that were caught in eight floodplain lakes of the Rio Solimões. These data were from experimental fisheries during each season of the hydrological cycle: flooding, flood, drying, and dry from 2004, 2005, and 2006. In general, there are similar patterns of intra-annual changes for these three species, with the highest estimates of kn during high water conditions. The lowest values were observed during the drying and dry seasons of 2005, when an extreme drought occurred in the Amazon basin. Higher values were observed during the same seasons in the year post-drought. We hypothesized that these patterns would be explained by the biological characteristics of these species and the effects of intra-annual hydrological changes, mainly the flood pulse effect, and by inter-annual climatic events, which are determined by global climate phenomena.
The Plata pompano, Trachinotus marginatus (Cuvier, 1832), is an endemic carangid of the Southwestern Atlantic Ocean, occurring from Rio de Janeiro to Uruguay. This study describes the reproductive ...period, spawning type, the size at first gonadal maturation and the length-weight relationship of individuals sampled from landings of the artisanal and commercial fishing fleets in Rio Grande that operate along the coast of Rio Grande do Sul state, southern Brazil (~ 32ºS) to the Uruguayan border (~ 34ºS). Monthly collections from September 2008 through January 2010 yielded 274 individuals ranging from 142 to 444 mm in total length (TL). The gonadal development stages were defined according to the histological examination of the ovaries and the testes. The relationship between TL (mm) and total weight TW (g) was statistically different between males (TW = 0.000463*TL2.7655) and females (TW = 0.000361*TL2.8131), showing negative allometric growth for both sexes. The sizes at first maturity were 187.2 mm and 254.9 mm for females and males, respectively. The presence of two modal groups of oocyte diameters suggested that total spawning occurred. The interpretation of the monthly variations of the condition factor and gonadosomatic index, which are associated with higher frequencies of the more advanced stages of gonadal development, identified the spring and summer months as the reproductive period, with a peak in the reproductive activity during November and January. These results suggested that the species has an opportunistic reproductive strategy.
Abstract The whitemouth croaker, Micropogonias furnieri, which is exploited off the state of Maranhão, Brazil, reinforces the need for maintenance programs of natural stocks of this species to assist ...in the management of this exploited resource. The aim of the present study was to describe aspects regarding its reproductive characteristics (gonadosomatic index and condition factor) and also the length distribution and weight-length relationships. The fish were caught in Lençóis Bay in the state of Maranhão (eastern Amazon) between June 2010 and July 2011. A total of 570 individuals were caught (318 males and 252 females). Differences in length were found between the sexes, with females larger than males. The sex ratio indicated a tendency for females to be more abundant in the rainy season (first semester), whereas males predominated in the dry season (second semester). The weight-length relationship indicated negative allometric growth for both sexes. The analysis of the variation in the condition factor suggests that lower values coincided with higher gonadosomatic index values and that this factor is a good reproductive indicator for M. furnieri in the region.
Resumo A corvina, Micropogonias furnieri, é explotada no Maranhão, Brasil, ressaltando a necessidade de programas de manutenção de estoques naturais desta espécie para auxiliar na gestão deste recurso explorado. O objetivo do presente estudo foi o de adquirir informações sobre as características reprodutivas (índice gonadossomático e fator de condição) e também sobre a distribuição de comprimento e relação peso-comprimento da espécie. Os peixes foram capturados na Baía dos Lençóis, no estado do Maranhão (Amazônia Oriental) entre junho de 2010 e julho de 2011. Um total de 570 indivíduos foram capturados (318 machos e 252 fêmeas). Os valores de comprimento apresentaram diferença entre os sexos, com fêmeas sendo maiores que os machos. A proporção entre os sexos indicaram uma tendência para as fêmeas serem mais abundantes na estação chuvosa (primeiro semestre), enquanto os machos predominaram na estação seca (segundo semestre). A relação peso-comprimento indicou crescimento alométrico negativo para ambos os sexos. A análise da variação do fator de condição sugere valores mais baixos coincidindo com os resultados mais elevados para a relação gonadossomática, apresentando-se como um bom indicador reprodutivo de M. furnieri na região.
The Burbot (Lota lota L, 1758) is a holarctic distributed freshwater fish in the Gadidae family. In northwestern Canada, it has an important value for local and traditional fisheries. We describe the ...morphology and ecology of Burbot from four populations in the Mackenzie River Delta. Two subspecies come into contact in this area, which is the western edge of Lota lota maculosa distribution (one population in our study) and the eastern edge of Lota lota lota distribution (three populations in our study). We found the combined length–weight relationship in these four populations to be log10 (weight) = −3.986 + 2.617 * log10 (length). There was no difference in mean body length (overall mean and standard deviation 73.4 ± 8.7 cm), although the L. l. lota populations were heavier than the L. l. maculosa population. All populations differed in their carbon and nitrogen stable isotope signatures (δ15N overall mean 12.1 ± 1.59; δ13C overall mean −25.54 ± 1.11). Main prey items were four fish species: Ninespine Stickleback (Pungitius pungitius L, 1758), Broad Whitefish (Coregonus nasus Pallas, 1776), Burbot, and Northern Pike (Esox lucius L, 1758). Ecological and morphological differences may be due to local conditions and population variability or to the different Lota lota subspecies. More ecological and morphological information from this region is needed to resolve possible phenotypic differences between the subspecies.
Length and weight data are often analyzed in fisheries science to derive a parametric weight–length relationship for estimating biomass and to develop indices of condition for comparing the ...‘wellness’ of different populations of fish. However, analysis of such data often ignores the inherent spatial and temporal grouping of the observations, and hence, the data hierarchy. This paper proposes the use of linear mixed-effects models as an effective means of analyzing and comparing weight–length relationships and indices of condition when there are many groups. The use of simple linear regression (where grouping is ignored), ANCOVA (where group effects are incorporated as fixed-effects), and linear mixed-effects models (where group effects are random-effects) are compared using data for Atlantic sea scallops (
Placopecten magellanicus). The group means of residuals is proposed as a measure of relative weight or index of population condition. Linear mixed-effects models should be used to analyze grouped data because the variability among groups is ignored in simple linear regression and ANCOVA. Also, it is important that explanatory variables be incorporated in analyses of grouped data because their influence may mask the true differences among groups.
The skipjack tuna is the main tuna species caught in Brazil with pole and live-bait. Samples taken during 1984-1986 and the 2004-2009 periods provided length, weight and age data. A comparison of the ...population structure was made showing a decrease in the median and means of fork length in the 80's (median: 55 cm) and recent years (median: 51 cm), an increased participation of smaller individuals (40 cm) in recent catches, a high variability of lengths in each year class and a decrease of the condition factor K. These results indicate alterations in the population structure and dynamics. The von Bertalanffy growth parameters calculated for the recent years were L∞= 669 mm; k = 0.24 yr-1; t o = -3.8. CPUE data for the studied period seems to be stable (mean annual catch of 20,000 ton). However, the unit of effort used in Brazil (fishing days) does not reflect changes in fishing power and technology properly as occurred during 30 years of exploitation. It is concluded that the present situation requires a close monitoring of the fishery.
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