Allometric Research Articles

Derivation of allometric equations and carbon content estimation in mangrove forests of Malaysia

Derivation of allometric equations and carbon content estimation in mangrove forests of Malaysia

Biomass and Carbon Stock Estimation in Different Mangrove Areas in Mangunharjo Village, Semarang, Indonesia

Mangroves are one of the coastal ecosystems that play a crucial role in carbon storage. This study aims to determine the differences in biomass and carbon stock values across different mangrove areas, namely natural, mangroves near aquaculture ponds, and rehabilitated mangrove in Mangunharjo Subdistrict, Semarang. The method used in this study was a field survey intended to measure the diameter of mangrove tree trunks as the baseline data for calculating mangrove stand carbon stock. The research was conducted in three areas selected using purposive sampling: natural mangroves, mangroves near aquaculture ponds, and rehabilitated mangroves, with each area consisting of two sampling stations and three transect plots, each. The size of the transect plots used was 10 m × 10 m. Data collection employed a non-destructive method based on allometric equations to estimate mangrove stand biomass. Overall, the estimated carbon stock of mangrove stands in Mangunharjo Subdistrict was 7,257.708 tons of carbon (tonC), with an average carbon stock value across the three areas of 120.36 tons/ha. The results showed that the rehabilitated mangrove area had the highest average biomass and carbon stock values, with biomass of 290.47 ± 23.19 tons/ha and carbon stock of 127.60 ± 10.23 tons/ha, followed by the near aquaculture ponds mangrove area with biomass and carbon stock values of 268.39 ± 66.16 tons/ha and 117.63 ± 28.96 tons/ha, respectively. The lowest values were found in the natural mangrove area, with biomass and carbon stock values of 264.25 ± 57.23 tons/ha and 115.85 ± 25.30 tons/ha, respectively.

Combining long-term ICP Forests monitoring data with the Yasso carbon cycling model at the European scale

Forests form a major organic carbon reservoir, both above- and belowground. In the course of global change, predicting possible changes in these carbon reservoirs is essential. To this end, the Horizon Europe PathFinder project aims to develop an innovative forest monitoring system allowing consistent EU greenhouse gas reporting of LULUCF (Land Use, Land Use Change & Forestry) in combination with advanced policy pathway assessments. Greenhouse gas reporting of soil organic carbon (SOC) stock changes in forests commonly relies on simulations by soil carbon cycling models, such as Yasso (Y20), which uses only climate data and soil carbon inputs that can be derived by country-specific approaches from National Forest Inventories. However, the agreement between measured versus simulated carbon stocks and changes at the European scale has not yet been established. Within the framework of this project, this study aims to derive European-wide harmonised soil carbon inputs and stock estimates since the 1990s and further develop the current estimation methodology. After exploration of the available data sets, the ICP Forests Level II forest condition monitoring database was found the most suitable to set the initial modelling conditions. It is the only harmonised data set at the European scale that comprises above- and belowground compartments and contains repeated assessments on a subset of about 200 plots across Europe. The pre-processing of the observed data on soil carbon stock, growth and litterfall from the central ICP Forests database was very labour-intensive. As part of the ICP Forests monitoring programme, carbon concentrations and bulk densities are measured down to a depth of 80 cm. Using mass-preserving splines, soil carbon stocks were estimated down to a depth of 100 m to make them comparable with Y20. Regression models were developed to estimate litterfall inputs based on forest inventory data. We simulated SOC stocks by Y20 in ICP Forests Level II plots with available stand inventory data and soil characterization. Soil carbon inputs were obtained using two approaches: an inventory approach, with litterfall estimated by the above-mentioned regression models, and root and coarse-woody inputs by allometric functions, and a satellite approach, with net primary production (NPP) from MODIS at 500 m resolution. The Y20-simulated SOC stocks were compared with the SOC stocks to 100 cm depth based on the soil inventory data. an inventory approach, with litterfall estimated by the above-mentioned regression models, and root and coarse-woody inputs by allometric functions, and a satellite approach, with net primary production (NPP) from MODIS at 500 m resolution. The Y20-simulated SOC stocks were compared with the SOC stocks to 100 cm depth based on the soil inventory data. On average, the satellite approach estimated higher soil carbon inputs than the inventory approach (+20%). The SOC stocks simulated by Y20 were overall in line with observed SOC stocks. The simulations for broadleaf-dominated stands agreed well with SOC measurements, with average deviations below 1 kg C m-2 using the satellite approach. In coniferous stands, Y20-simulated SOC stocks were lower than observed by 3-5 kg C m-2. This is likely due to the intrinsic soil properties driving SOC storage and stabilization in highly acidic, coniferous forests (i.e. Podzols and Umbrisols), which are not accounted for in Y20.

Length–mass relationships of Smicridea (Hydropsychidae, Trichoptera) larvae in a freshwater stream in Brazil

ABSTRACT Length–mass relationships for freshwater invertebrates are frequently used in ecological studies; however, few length–mass relationships are available for Brazilian tropical macrofauna. To avoid such problems, some studies suggest estimating proportional biomass using length–mass equations. The aim of this study is to evaluate which allometric measurements of the body of Smicridea larvae are most suitable for developing mathematical equations that describe biomass relationships for the population of this taxon in a tropical stream. To this end, we measured four body dimensions (body length, interocular distance, horizontal width of the head capsule, and vertical width of the head capsule) of Smicridea larvae. After measuring body dimensions and biomass, we used these values to develop mathematical equations for length–mass. Our results show that body length presented the best fit to estimate the biomass of Smicridea (R = 0.50). However, we observed a significant fit for interocular distance, vertical head height, and head width, presenting dimensions with biomass estimates above 38%. Thus, our results will be useful to provide the best measures and allometric equations to estimate the biomass of Smicridea larvae from tropical regions.

Effects of Stumping on Ecological Stoichiometry and Allometric Growth in Leaf, Absorptive Root, and Rhizosphere Soil of Hippophae rhamnoides.

To clarify the effects of stumping on the C, N, and P allocation strategy of Hippophae rhamnoides L. artificial forests at the decaying stage in feldspathic sandstone areas, we tested stumping heights of 0, 10, 15, and 20 cm from the ground (denoted H1, H2, H3, and H4, respectively) with non-stumped trees as a control (CK). The N (LN, RN), P (LP, RP), and N:P (LN:LP, RN:RP) in the leaves and absorptive roots and the C, N, C:N, C:P, and N:P in rhizosphere soils after different treatments all manifested in the order H3 > H2 > H1 > H4 > CK. Among them, the LN and RN of H3 presented the largest amplitudes of increase (31% and 263%, respectively) compared with those of CK. There were very significant allometric relationships between LC and RC (-0.57, trade-off relationship), between LN and RN, and between LP and RP (0.32, 2.01; synergistic relationship) in stumped H. rhamnoides, and the accumulation rates of LC and LN were slower than those of RC and RN. After the stumping, certain correlations were present between the characteristics, except that neither LC nor RC significantly differed across the different treatments. The growth of H. rhamnoides after the different treatments was mainly regulated by P. The stumped H. rhamnoides grew at a faster rate, and the optimal stumping height was 15 cm. These findings are valuable for revegetation and for the prevention and control of soil erosion in feldspathic sandstone areas.

Carbon Stock and Potential for Carbon Absorption by Mangrove Forests on Maspari Island: The Outermost Small Island in South Sumatra

Maspari Island is the only small outermost island located in the southern part of Bangka Strait, included in the coastal area of Ogan Komering Ilir Regency, South Sumatra. The island harbors a mangrove ecosystem that is believed to play a significant role in climate change mitigation through carbon storage. This study aims to identify mangrove species and measure carbon stock estimates in upper-stand biomass, lower-stand/root biomass, and sediment. Identification of mangrove species using a vegetation analysis approach. Transect plots measuring 10 m × 10 m were parallel to the coastline at 6 observation station points. The diameter of vegetation at the tree and sapling levels was measured at a height of 1.3 m from the ground surface. Carbon stock estimates were calculated using allometric equations and sediment carbon analysis methods. The results identified seven mangrove species: Avicennia marina, Bruguiera sexangula, Ceriops tagal, Excoecaria agallocha, Rhizophora apiculata, Rhizophora stylosa, and Sonneratia alba. Estimated carbon stocks of mangrove stands at all stations reached 3,443.42 tC/ha, with an average of 573.90 tC/ha, while carbon stocks in roots amounted to 862.96 tC/ha, with an average of 143.83 tC/ha. The total estimated carbon stock of mangrove sediment at all stations was 240.71 tC/ha, with an average of 40.12 MgC/ha. Sonneratia alba provided the highest carbon absorption, reaching 3,059 tC/ha for the upper stand and 697.80 tC/ha for the lower stand. Considering the contribution of the carbon storage potential in Maspari Island, this study suggests extending the investigation of the mangrove carbon fixation in other small islands in Indonesia, especially for the S. alba species. Keywords: carbon stock, mangrove, Maspari Island, sediment, carbon stock, Sonneratia alba

Pharmacokinetics and pharmacodynamics of remimazolam for procedural sedation in children and adolescents.

Remimazolam is not approved for use in pediatric patients. The pharmacokinetics of remimazolam have been reported to be similar to those of adult patients after scaling for body size. This manuscript reports on the pharmacokinetics and pharmacodynamics of pediatric patients aged ≥6 to ≤18 years and a subsequent model-based optimization of the used dosing regimen. 31 patients were included in the trial and stratified across four treatment arms: bolus administration, infusion, bolus + fentanyl or infusion + fentanyl. The University of Michigan Sedation Scale (UMSS) was used to assess the depth of sedation. Blood samples were drawn to measure the concentrations of remimazolam and its metabolite CNS7054. Population pharmacokinetic pharmacodynamic modelling was performed in NONMEM ®. A population pharmacokinetic model was developed for remimazolam and CNS7054. The elimination clearance of remimazolam was 0.70 L.min -1.70kg -1. A proportional odds model combined with a simplified Minto model described the observed UMSS well. The EC50 of remimazolam for UMSS ≥3 was 777 ng.ml -1 in the absence of fentanyl, and decreased to 655, 533, and 287 ng/ml for concomitant fentanyl steady-state concentrations of 1, 2, or 4 ng.ml -1, respectively. Simulations confirmed that the studied dosing regimen resulted in 9.2 to 22.0% of patients not reaching UMSS ≥3 at the end of the induction. Model-based optimization resulted in higher per kg dosages and the removal of the maximum allowable dose. Simulations indicated that the percentage of patients achieving UMSS ≥3 can be expected to be high (88% to 97%). This study has shown that the pharmacokinetics of remimazolam are likely different between children ≥6 years old and adults (after correcting for size). In addition, the exposure-response relationship shows that to effectively use remimazolam for procedural sedation in children ≥6 years, the dosing regimen should be modified to allow for higher remimazolam exposures.

Systematic Literature Review: Comparison between Different Forest Biomass Estimation Methods

Land use, land use change and forestry sector (LULUCF) is important in terms of carbon sequestration; it plays a crucial role in achieving Green Deal goal by making the EU climate neutral by 2050. This goal can be achieved by increasing carbon sequestration in LULUCF. Living biomass during its growth sequestrates CO2, therefore, if knowing the amount of biomass in forest, it is possible to calculate total carbon stock and annual carbon sink. Therefore, it is important to accurately estimate forest biomass. This systematic literature review (SR) follows PRISMA methodology (Preferred Reporting Items for Systematic reviews and Meta-Analyses method), which provides an overview of different methods used to estimate biomass from the forest. Several approaches to estimate biomass exist, like traditional methods, where measurements and information collections are done in field and allometric equations are applied; this method can be precise but needs large amount of labor and can be spatial limited, other method includes advanced technology, where remote and optical sensing data are used to determine variables, this method spatial efficient, but requires calibration with field data. Comparative analysis indicates advantages, limitations and accuracy of each method, showing the importance of compromise between scalability and accuracy. It is concluded that LiDAR can provide accurate information on higher cost, where SAR or ORS use can be cost effective but can be limited by complex data processing or cloud cover, field – based methods can have high biomass estimation accuracy, but can be time consuming. Future research should be aimed at hybrid methods, to achieve more precise biomass estimation, with lower costs.

Aboveground Forest Biomass Generally Increases with Elevation Gradients in China’s Qinling–Daba Mountains

The complexity of forest ecosystems leads to differences in the distribution patterns of different vegetation types along elevation gradients. This study aimed to explore the characteristics of AGB variations along elevation gradients for different forest types and tree species components in the Qinling–Daba Mountains. Based on 329 field vegetation survey plots, including four sampling transects and four representative mountains, individual tree AGB was calculated using allometric biomass equations. Further, generalized additive models (GAMs) were used to investigate the relationships between AGB and elevation for four forest types (broadleaf forests, coniferous forests, mixed coniferousbroadleaf forests, and shrublands) and three AGB components (total AGB (tAGB), broadleaf species AGB (bAGB), and coniferous species AGB (cAGB)) across eight vegetation survey regions. The results showed that the AGB of different forest types is significantly related to elevation (p < 0.05), with broadleaf forest AGB showing a unimodal pattern with elevation, coniferous forest and mixed forest AGB increasing with elevation, and shrubland AGB exhibiting a noticeable rise at higher elevations. The AGB components across different vegetation survey regions also showed significant relationships with elevation (p < 0.05), with broadleaf species AGB displaying a monotonically increasing trend in regions with a small elevation range and exhibiting a unimodal or bimodal distribution in regions with a large elevation range, while coniferous species AGB generally increased with elevation. Although elevation significantly influenced forest AGB, the variation in R2 values indicated that elevation is not the sole determinant of AGB variation. This study improves the understanding of spatial patterns of forest biomass along elevation gradients.

Ecological Restoration in Semi‐Arid Landscapes: Comparing Exclosures and Pasture for Vegetation, Soil Nutrients, and Carbon Stocks

ABSTRACTLand degradation in semi‐arid regions poses a major threat to Sustainable Development Goal 15 (SDG 15) by undermining ecosystem services and biodiversity. Although restoration strategies like exclosures are gaining attention, there remains a critical gap in quantifying their long‐term ecological and carbon sequestration benefits, particularly in severely degraded landscapes such as Ethiopia's Tigray region. This study addresses that gap by comparing 15‐year‐old exclosures with adjacent open pasture using a mixed‐methods approach. We assessed 62 plots (31 per land use type) for species diversity (Shannon‐Wiener and Simpson indices), biomass (via allometric equations), soil properties (at 0–15 cm and 15–30 cm depths), and carbon stocks, employing Principal Component Analysis (PCA) and Pearson correlation. Results showed that exclosures significantly outperformed pasture, supporting 174 plant species versus 69, higher soil organic carbon (18.71 g/100 g vs. 15.91 g/100 g at 0–15 cm, p < 0.001), and greater above‐ground biomass (40.72 t/ha vs. 14.24 t/ha, p < 0.001). These findings underscore the potential of exclosures as a scalable and cost‐effective strategy for restoring degraded semi‐arid ecosystems, offering robust empirical evidence to inform national policy integration, advance SDG 15, and support climate change mitigation across similar regions globally.

The sabre-toothed cat Smilodon fatalis Leidy, 1868 (Felidae, Machairodontinae) in the late Pleistocene-early Holocene of South America (Dolores Formation, Uruguay): New insights about its paleodistribution, taxonomy and status of the genus

The sabre-toothed cat Smilodon fatalis was an iconic predator in the Americas during the Ice Age. While its distribution in North America is abundant, its record in South America is very scarce and is restricted to only a few locations. In the present contribution a new skull assigned to Smilodon fatalis is described. The specimen comes from the Dolores Formation (late Pleistocene-early Holocene, Lujanian Stage/Age) in southern Uruguay. This skull is elongated and narrow in its general shape; its nasals are not markedly high and, in the posterior part, the large lambdoid crest is anteroventrally straight, converging in the same plane with the mastoid process, characteristics observed in S. fatalis that clearly differentiate it from S. populator. Body mass estimations, according to allometric equations for extant felids, and the quantitative analyses (bivariate graphs) provide results consistent with the aforementioned taxonomic assignment. Based on this finding, which turns out to be, to date, the southernmost record for this species in the Americas, some paleobiogeographic and taxonomic implications in a regional context are discussed.

Investigation of Biomass and Carbon Storage of Tree Species in Zhengzhou, a Megacity in China

Urban trees play a dual role in enhancing landscape aesthetics and contributing to carbon sequestration. This study evaluated the biomass and carbon storage of eight common urban tree species in Zhengzhou, China, using organ-specific measurements and allometric growth models. The results revealed that biomass and carbon were primarily allocated to the trunk, followed by the roots, branches, and leaves; these results are consistent with previous findings. Acer buergerianum Miq. and Magnolia grandiflora L. demonstrated the highest per-tree carbon storage, while Styphnolobium japonicum (L.) Schott and Salix babylonica L. performed better in carbon storage per unit area. These patterns are linked to variations in species morphology, growth performance, and planting density. The study provides evidence-based recommendations for optimizing urban tree species selection to enhance carbon sink capacity. Future applications include integrating these results into urban planning strategies and long-term carbon monitoring systems, thereby contributing to low-carbon city development.

Allometric equations for estimating biomass and carbon stocks of on-farm bamboo species in the agricultural landscapes of Kenya

Allometric equations for estimating biomass and carbon stocks of on-farm bamboo species in the agricultural landscapes of Kenya

Allometric equations quantify accelerated growth and carbon fixation in trees of northeastern North America

Allometric equations quantify accelerated growth and carbon fixation in trees of northeastern North America

Quantifying Mangrove Forest Attributes Using Terrestrial Laser Scanning

Mangroves are increasingly recognised for their ecosystem services, including their capacity to store carbon and adapt to climate pressures by stabilising shorelines and acting as storm barriers. To quantify these services, relevant parameters such as mangrove biomass and drag coefficients have been calculated using allometric equations fitted to field measurements of physical mangrove attributes. However, previous research to quantify mangrove attributes has involved time-consuming hand measurements and long processing times associated with terrestrial laser scanning (TLS). To more efficiently capture and process mangrove attributes, such as the density, diameter, height, and projected area of stems and roots, a novel method for collecting mangrove field data using TLS was developed. Recorded TLS data were compared to field measurements conducted in 12 Avicennia marina forests across 10 estuaries and 4 unique estuary typologies. The results demonstrated the reliable estimation of mangrove attributes using TLS and revealed a link between these attributes and estuarine geomorphology. Mangrove stems were accurately identified in all estuary typologies, with attribute estimations more accurate for forests in Drowned River Valleys (DRVs). A sensitivity analysis revealed that 10–20 trees for DRVs and 35–45 trees for barrier estuaries require point cloud processing to characterise a forest area of 400–1300 m2 and to achieve convergent stem diameter and tree height results. The method presented herein offers an efficient way to quantify aboveground stem and root attributes and the surface area of mangrove trees. This data can be used to characterise mangrove forests worldwide and provide fundamental attributes for quantifying ecosystem services.

Simplifying drone-based aboveground carbon density measurements to support community forestry.

Community-based forest restoration has the potential to sequester large amounts of atmospheric carbon, avoid forest degradation, and support sustainable development. However, if partnered with international funders, such projects often require robust and transparent aboveground carbon measurements to secure payments, and current monitoring approaches are not necessarily appropriate due to costs, scale, and complexity. The use of consumer-grade drones in combination with open source structure-from-motion photogrammetry may provide a solution. In this study, we tested the suitability of a simplified drone-based method for measuring aboveground carbon density in heavily degraded tropical forests at a 2 ha restoration site in Sabah, Malaysia, comparing our results against established field-based methods. We used structure-from-motion photogrammetry to generate canopy height models from drone imagery, and applied multiple pre-published plot-aggregate allometric equations to examine the importance of utilising regionally calibrated allometric equations. Our results suggest that this simplified method can produce aboveground carbon density measurements of a similar magnitude to field-based methods, quickly and only with a single input metric. However, there are greater levels of uncertainty in carbon density measurements due to errors associated with canopy height measurements from drones. Our findings also highlight the importance of selecting regionally calibrated allometric equations for this approach. At scales between 1 and 100 ha, drone-based methods provide an appealing option for data acquisition and carbon measurement, balancing trade-offs between accuracy, simplicity, and cost effectiveness and coinciding well with the needs of community-scale aboveground carbon measurement. Of importance, we also discuss considerations relating to the accessibility of this method for community use, beyond purchasing a drone, that must not be overlooked. Nevertheless, the method presented here lays the foundations for a simple workflow for measuring aboveground carbon density at a community scale that can be refined in future studies.

Allometric equations to predict aboveground biomass and carbon stock of Faidherbia albida in parkland agroforestry

Maintaining trees on farmland improves the carbon sequestration potential of agricultural lands and contributes to global carbon balance. Samples of 35 trees were harvested for aboveground biomass (AGB) and carbon stock measurements in parkland agroforestry fields of Tigray, Ethiopia. Allometric equations were developed using the regression models that related the total AGB with a diameter at stump height (DSH), diameter at breast height (DBH), and a combination of DSH, DBH, height (H), and crown diameter (CD). The allometric model related to diameter at breast height, Ln (AGB) = -2.85 + 2.4 ln (DBH), was considered the best fit, with the highest adjusted coefficient of determination (0.88) and lowest prediction residuals sum of squares (3.51 kg), bias (-2 kg), root mean square error (0.3 kg), and Akaike information criterion (P < 0.01). The best-fitting model for aboveground biomass estimation was validated using cross-validation. When assessed with the aboveground biomass of F. albida data sets from this work, the species-specific and multi-species previously published models were substantially overestimated by 60% and underestimated by 50%, respectively. F. albida total aboveground biomass was 3372.25 kg ha−1 and 1584.96 kg ha−1 of carbon for a density of 47 trees ha−1 in the parklands. The results showed that the statistical fits of our model were generally good, enabling confidence in its use to predict the aboveground biomass of F. albida stands. Our study identified patterns of carbon distribution in different F. albida tree sizes that may serve as a guide for programs that measure, report, and verify carbon stock and promote a climate-resilient farming system.

Length-Weight Relationship and Condition Factor of Labeo rohita (Hamilton, 1822) in Aquaponics System

The present experiment was conducted in circular FRP tanks kept indoor under polycarbonate house to provides information on the length-weight relationship and condition factors of Labeo rohita in aquaponics system. Aquaponics, an integrated system of aquaculture and hydroponics, has gained significant attention due to its sustainable and efficient nature. Understanding the growth dynamics and condition of fish within such systems is crucial for optimizing production and maintaining fish health. The length weight relationship were estimated by linear regression equation. The species exhibits positive allometric growth (b&gt;3) with the values of condition factor (K) being greater than one, indicating the well-being of the species in its natural habitat. The water quality parameters were within the acceptable range for fish production. A fine mesh net is used to scoop fishes. The fish total length was measured from the anterior tip of the snout to the distal end of the caudal fin, and its weight was assessed using a precision single-pan electronic balance. Result shown that, the length-weight relationship of 900 experimental fish in aquaponics system with different stocking density shows that the treatment T2 performed better than T1 and T3. L. rohita juveniles reared in experimental tanks exhibited positive allometric growth and in good condition of health. This growth pattern favours fish farming as it enhances its profitability. The values of ‘K’ ranged from 0.97-1.00 which depicted good condition of fish in these water bodies. These observed parameters were useful to evaluate the well-being of L. rohita population in the aquaponics system and provided useful information on fish biology for scientific management of fisheries.

Foliar gas exchange, morphology, and cannabinoid contents of three hemp varieties in southwest Texas

AbstractIn the United States, a high level (≥0.3%) of the intoxicating Δ‐9‐tetrahydrocannabinol (THC) threatens farm‐scale production of hemp (Cannabis sativa L. ssp. sativa), but the linkage between THC and major physio‐morphological traits of hemp is not well known. This study aims to characterize the variations in physiological and/or morphological parameters and cannabinoid contents of three hemp varieties, that is, Berry Blossom, Painted Lady, and Skipper. Diurnal foliar gas exchange, chlorophyll fluorescence, water potential, and canopy temperature were measured on five clear days in the 2022 growing season, and cannabinoids were measured at peak flowering using high‐performance liquid chromatography. Allometric equations were developed to use easily measured biomass or morphological variables to predict variables that are more difficult to measure. The diurnal foliar gas exchange of the three hemp varieties was largely unaffected by the high temperatures of southwest Texas, with Berry Blossom and Skipper showing the highest and lowest photosynthesis, respectively, and Painted Lady having the most efficient stomatal control of gas exchange. Although the rooting depth of Berry Blossom was shallower than that of the two other varieties, there was no evidence showing the effect of rooting habit on the physiology of the studied hemp varieties, which was presumably due to the lack of water stress in our experiment. Nor were there significant differences in the cannabinoid contents in relation to environmental and varietal responses, as the measured THC contents of all three varieties were under 0.3%. Overall, the three hemp varieties showed different behavior strategies in southwest Texas.

Length-Weight Relationships and Reproductive Biology of Rita rita (Hamilton, 1822) for Conservation from the Brahmaputra River

The freshwater bagrid catfish, Rita rita (Hamilton, 1822), commonly known as ‘Rita’, constitutes a commercially significant food fish species throughout the Brahmaputra River basin and its associated tributaries. In the present study, data on length-weight relationship and reproductive biology containing sex ratio, condition factor, fecundity, hepatosomatic index and gonado-somatic index (GSI) of Rita rita were assessed. Samples were collected from the landings centre located on the bank of river Brahmaputra at Tezpur, river Jamuna at Jamunamukh and river Kopili at Dharamtul from August,2022 to July, 2023. The slope (b) in length-weight relationship equation was 1.87, 1.25, and 1.12 for female, male and pooled suggesting a negative allometric growth pattern. An overall sex ratio (M/F) of 1: 2.70 observed was statistically non-significant. The gonadosomatic index ranged from 0.22-3.81 in males and 0.65-11.45 in females, both showing peaks in the month of July. The hepatosomatic index (HSI) varied from 0.88-1.35 in male, 1.34-2.14 in females and 1.09-1.59 for the pooled sample, the value of HSI index gradually decreases with increase of GSI in both male and female. The fish was highly fecund and the fecundity ranged from 10445.88 to 26262.52 eggs with an average of 16,865.89 ±73.8. The fecundity was found to increase with the increase of total length, body weight and the ovary weight and the relationship was linear and significant among them However, the relative condition factor &gt;1 suggested the species to be in good condition throughout the year in both the males and females.