Relative Condition Factor Research Articles

A Study on Water Quality in Relation to Length-weight Relationship and Relative Condition Factor of Two Fresh Water Fishes- Labeo Rohita and Oreochromis Niloticus in Krishna Raja Sagara Reservoir

Fish being the cheapest source of protein, the population explosion and economic pressure demands increase in fish yield. Since biotic and abiotic factors have influence on growth and well-being of fish, there is a need to continuously monitor the fish culture water bodies for physico-chemical water quality parameters and presence of pollutants. This work shows the allometric growth (cube rule) and well-being of two fresh water fishes Labeo rohita and Oreochromis niloticus and whether or not the deviation if any from cube rule is accompanied by altered water quality required for fish culture. This study reveals that majority of the physico-chemical water quality parameters namely temperature, pH, turbidity, conductivity, DO, BOD, TSS and phosphate were within the optimal range for fish culture, whereas nitrate levels were higher than the desired levels. These results indicate near normal growth and well-being in L. rohita as well as in O. niloticus in the prevailing environmental conditions in the KRS reservoir.

Reproductive biology of long-whiskered catfish (Mystus aor) relative to temperature and precipitation from the Kaptai Lake of Bangladesh.

Life-history information is necessary for effective conservation, aquaculture development and broodstock management of fishing populations, especially for fish with significant economic exploitation. Aiming to characterise the life-history traits in relation to the environmental parameters of the long-whiskered catfish, Mystus aor, a commercially important species from Kaptai Lake, Bangladesh, different life-history data were analysed. The monthly condition factor (K) ranged from 1.15 to 1.41, and the relative condition factor (Kn) ranged from 0.14 to 0.25. The estimated relative fecundity was 18474-55504 eggs/per fish, and the maximal oocyte diameter was found in May (0.83 ± 0.11μm). The lengths at first sexual maturity (Lm) for male and female M. aor were 49.5 cm and 54.1 cm, respectively. The GSI was peaked in May for both males and females, and histological analysis also revealed the presence of yolk granules and several mature spermatids in April and May in both sexes. Analysis of environmental data over 40 years in the Kaptai lake ecosystem indicate the significant increase in the precipitation rate in spawning month which is highly correlated with the spawning season. The findings of the current study will serve as a baseline for the conservation and broodstock management in the Kaptai Lake of Bangladesh.

Growth aspects of grey mullet Mugil cephalus Linnaeus, 1758 from Kilifi creek, Kenya

Mullets form a major component of pelagic fish landings in tropical areas. M. cephalus Linnaeus, 1758 were collected from Kilifi creek between October 2002 and September 2004 using gillnets and a cast net. The sampling sites were Nkoma, Mazioni, Kidundu and Kombeni sites in the southern arm while the northern arm had Sea Horse, Fumbini, Konjora and Rare sites chosen based on observed physical characteristics. The total length (mm), total weight (g) was recorded and the abdomen dissected for gonad identification. From 765 specimens obtained, length-weight relationship (Regression and test of isometry), relative condition factor (Kn), age and growth (Von Bertalanffy Growth Equation VBGE) were performed. In 537 males, length ranged between 57mm and 480mm, the weight between 3g and 1169g. The regression line fitted for length on weight was Log10 W = 1.7457 + 2.8658 Log10 L and the test of isometry (b=2.8658) was significantly different from 3 (t^ = 21.2138; P < 0.05). The length ranged between 61mm and 507mm, weight between 3.8g and 1385g in 228 females. The regression line fitted for length on weight being Log10 W = 1.7973 + 2.8955 Log10 L and the test of isometry (b=2.8955) was significantly different from 3 (t^ = 13.5536; P < 0.05). Low monthly variations in the relative condition factors between the sexes as well as during the different seasons was observed, however, the males had higher relative condition factors than females. Asymptotic length (VBGE) was calculated for M. cephalus at each site with largest fishes caught at Sea Horse, Nkoma, Fumbini and Mazioni while the smallest fishes were from Kombeni and Kidundu. In females, the asymptotic length L∞ (51.48 cm) was higher than in males (48.3 cm) and no notable difference was observed in K (growth coefficient) between females (0.83) and males (0.79) respectively. Kilifi creek needs conservation as source of juveniles for stocking in ponds for future culture

Length-weight relationships and condition factors of 24 mesopelagic fishes from the South China Sea

Mesopelagic fishes are one of the most abundant marine organisms and have a wide distribution in the world’s oceans, thereby playing a central role in global marine ecology. We determined the length-weight relationships (LWRs) of 24 mesopelagic fish species, representing 11 families and 6 orders, inhabiting the South China Sea (SCS), and also assessed their growth types and various condition factors, using samples acquired from midwater trawls at depths of 70–750 m during eight cruises by a single fishing vessel in 2015–2018. Based on 894 specimens, the LWRs of the species were calculated for the first time. The values of the b coefficients in the LWRs ranged from 2.2669 (for Sigmops gracilis) to 3.5471 (for Ichthyococcus ovatus), except 2 species exhibited b values less than 2.5. The 95% confidence intervals of the a and b values were tested to identify the growth patterns: 10 species exhibited isometric growth, 7 species negative allometric growth, and 7 species positive allometric growth. The means of Fulton’s condition factor (Kc) ranged from 0.234 ± 0.046 (for S. gracilis) to 3.318 ± 0.781 (for Caristius macropus); the allometric condition factor (Ka) from 0.149 ± 0.014 (for Scopelosaurus hoedti) to 6.758 ± 1.162 (C. macropus); and the relative weight condition factor (Kn) from 1.000 ± 0.090 (for Scombrolabrax heterolepis) to 1.023 ± 0.208 (for Macropinna microstoma). The Kc values of fish in the families Opisthoproctidae and Myctophidae were mostly > 1, denoting species tending to have a relatively short, compressed, and deep body; conversely, fish with Kc values of < 1 tended to have an elongated body shape or a long, narrow tail. The Ka values were > 2 for 5 species, indicating the best condition compared with the other species; the values of 9 species ranged from 1.132 ± 0.135 to 1.938 ± 0.276, indicating a better condition; and the values of 10 species were < 1, indicating a poorer condition. The Kn values ranged from 0.983 ± 0.137 to 1.031 ± 0.249, whereby the results for 22 species reflected a good growth condition (Kn > 1), with the values of just two species being scarcely less than 1.000. In conclusion, these data will be helpful in future studies of mesopelagic fishes and provide basic biological data useful to fishery assessments and conservation of the mesopelagic fish resources in the SCS.

Influence of Longitudinal Fragmentation on Length–Weight Relationships of Fishes in the Someșul Cald River, Romania

Romania has a rich hydrographic network, which permitted the construction of over 80 large dams on its water courses, estimating a number between 545 and 674 hydropower plants that were either built or were in a different construction stage on the rivers of Romania in 2021. These hydropower plants were often built outside specific legislation regarding ecological impacts, especially before 1990. Longitudinal fragmentation of rivers causes severe ecological impacts on biodiversity, food chains, and nutrient cycles. Someșul Cald River is the main tributary of Someșul Mic River, the most important water source for the northwestern region of Transylvania. On its course, several dams and reservoirs were built from 1968 to 1980 for electricity production and population freshwater supply. The present study aimed to analyze the length–weight relationships (LWRs) and condition factors occurring in the longitudinally fragmented Someșul Cald River. The LWRs, relative condition factor Kn, and Fulton condition factor K were determined based on total length and wet body weight. Comparisons of LWRs, Kn, and K across river sections constrained by dams showed that some fish species exhibited similar growth patterns and physiological conditions, while others differed significantly. Freshwater fish physiology is altered by longitudinal fragmentation, both natural and artificial. Barriers such as dams influence the energy gradient, limiting feed availability and, consequently, the life history of fish species. Long-term management plans regarding conservation should take into consideration existing fish species population dynamics, along with their physiological and somatic status.

Life history of Mexican species of the genus &lt;i&gt;Tlaloc&lt;/i&gt; (Cyprinodontiformes, Profundulidae)

Fish of the genus Tlaloc are distributed from southern Mexico to Central America and are a distinctive example of the endemic fauna of the Mesoamerican highlands, which has been scarcely studied in Mexico. The present study provides basic life-history data for the species Tlaloc hildebrandi, T. candalarius, and T. labialis, which are native to the headwaters of the Grijalva-Usumacinta basin in southeastern Mexico. We collected 918 specimens to determine their Length-Weight Relationship (LWR), Relative Condition Factor (Kr), sex ratio, Gonadosomatic Index (GSI), fecundity, and size at first sexual maturity. Both sexes of all species had positive allometric growth, except for T. candalarius females (isometric). Mean Kr and sex ratio values differed significantly among species. Females’ GSI values differed significantly among species but were highest during the dry season in all three species. Absolute fecundity was positively correlated with standard length and weight. Sexual maturity was reached at different lengths among species. Based on these results, we suggest that all three species present an opportunistic life strategy, which is very common in fish of the order Cyprinodontiformes. These results represent a first contribution on the life-history of this group of fish and provide basic information that is fundamental to ensuring their conservation.

Length–weight relationship and condition factor of thirteen fish species in the Tigris river before the construction of Ilisu and Cizre dams, Türkiye

The Ilısu Hydroelectric Power Plant (HEPP), situated on the Tigris river in Türkiye, began filling and forming a reservoir in 2021. In addition, there are plans for the construction of the upcoming Cizre HEPP. This situation has the potential to significantly impact the bio–ecology of fish species in the area. The research aimed to determine the length–weight relationships (LWR) and condition factors of thirteen fish species in the Tigris River: Arabibarbus grypus, Acanthobrama marmid, Alburnus sellal, Carassius gibelio, Cyprinion kais, Cyprinion macrostomus, Chondrostoma regium, Paracapoeta trutta, Capoeta umbla, Garra rufa, Squalius lepidus, Luciobarbus esocinus and Luciobarbus mystaceus, where Ilisu and Cizre dams reservoir will be formed. Length–weight relationships (LWRs) were determined using the formula W = aLb, where W represents weight and L represents length. Three types of lengths were considered: total length, fork length, and standard length. The exponent values (b) varied across the species, ranging from 2.7875 for Acanthobrama marmid to 3.2214 for Carassius gibelio. The relationships between length and weight were found to be highly significant, as indicated by the R2 values, which were all greater than 0.80, except for Alburnus sellal and Garra rufa, which had lower values below 0.80. The condition factors were calculated using Fulton’s condition factor (K) and relative condition factor (Kn). In all species, except for Arabibarbus grypus and Chondrostoma regium, the condition factors were greater than 1 (K&gt;1). However, for Capoeta umbla and Garra rufa, the relative condition factor (Kn) was less than 1 (Kn&lt;1).

Mystus vittatus (Hamilton, 1822)’un doğal ve kültür ortamındaki boy-ağırlık ilişkisi ve kondisyon faktörü

The Asian catfish Mystus vittatus is very popular food and ornamental fish in India. Length- weight relationships and condition factors of this fish are crucial component in fishery managements. The objective of this study is to investigate the relationships between the length, weight, condition factor (K), relative condition factor (Kn) and modified condition factor of Mystus vittatus (Hamilton, 1822). The study is particularly focus on analysing the sex wise variations in growth patterns, productivity, stocks, and conservation in two different habitats, natural habitat and biofloc system. The findings show that the species did not strictly follow the predicted cube law and showed allometric growth patterns in both habitats. The "b" value varies from 2.72 to 3.12, the condition factor (K) ranges from 0.587-1.50, modified condition factor ranges 0.54-2.26 and relative condition factor (Kn) ranges from 0.71-1.65. Natural habitats had the highest mean values for the regression parameter (b), condition factor (K), and relative condition factor (Kn). For male, female, and combined sexes in two different habitats, the R2 values show a statistically significant relationship between weight and length. The correlation analysis indicates some positive and negative significant relationships among sex, length, weight, condition factor, and relative condition factor. Therefore, there is significant relationship between condition factor, relative condition factor length, weight in two different habitats and it varies between male and female within same habitat. Thus, this finding will help to fishery managers for long term strategy development of Mystus vittatus in both natural as well as biofloc system.

Floodplains as a Suitable Habitat for Freshwater Fish: The Length–Weight Relationships and Condition Factors of Fish Inhabiting a Danube Floodplain in Croatia

When studying the well-being and fitness of ichthyofauna in a specific area, vital information comes from length–weight relationships (LWRs) and condition factor analyses and calculations. Data were collected from 2015 to 2019 in an area important for fish shelter, feeding, and spawning. Twenty four species belonging to 10 different families were identified from the total 16,895 of caught individuals, with the most abundant species being Blicca bjoerkna. The calculation of LWRs was possible for 19 species, (R2 = 0.7049–0.9998 (p &lt; 0.05)), with the values of the mean coefficient b ranging from 2.6831 to 3.5747, indicating an overall positive allometric growth in the fish population. The results of Fulton’s and the relative condition factors showed that a total of eight species were in a relatively good condition, although the species in question varied between the two condition factors. Fulton’s condition factor showed the highest average value for Lepomis gibbosus (1.4956), while Cobitis elongatoides had the lowest (0.4739). Contrarily, the relative condition factor showed the highest average value for Silurus glanis (1.0524), and the lowest for Gymnocephalus cernua (1.0023). The lower values of calculated condition factors in some species could be attributed to sampling being conducted during the colder months of autumn and winter. Future studies should include seasonal sampling in order to achieve a better understanding how various abiotic factors impact the condition factors of these fish species. Nevertheless, this research provided valuable data on the status of the fish population in the floodplain and could be used as a guideline for designing future ichthyofauna studies in this area.

Stock assessment of rosy barb, Pethia conchonius (Hamilton, 1822) in Dal Lake of Kashmir Himalayas

For management of fish stocks, assessing the various parameters of population dynamics are regarded as being extremely important. Under this backdrop the population dynamics parameters viz. growth, mortality and recruitment of Pethia conchonius, inhabiting the Dal Lake of Kashmir Himalayas were analysed using FiSAT II software. The analysed specimens were collected from five different sites within the lake and exhibited a total weight range of 0.3 to 6.4 g and a total length range of 3.1 to 7.8 cm. The relative condition factor for the fish was reported to be 1.11. The growth parameter i.e., asymptotic length, age at zero length, growth performance index and growth constant were reported to be 10.0 cm, –0.75 years, 1.48 and 0.30 year–1 respectively. The total mortality of 1.49 year–1, consisting of natural mortality of 0.88 year–1 and fishing mortality of 0.61 year–1 was reported. An exploitation rate of 0.41 is suggestive of a less exploited state of the fish. The length at first maturity was found to be higher than the length at first capture, a condition that can disturb the stock, as such the utility of a net with relatively larger mesh size is advisable. The current research on the population dynamics of P. conchonius can be used as the baseline data for its management practices.

Length-weight Relationship and Relative Condition Factor of Paratrypauchen microcephalus (Bleeker, 1860) along the Mumbai Coast

Length-weight Relationship and Relative Condition Factor of Paratrypauchen microcephalus (Bleeker, 1860) along the Mumbai Coast

Biometric Characteristic Study of Green Lipped Mussel, Perna viridis (Linnaeus, 1758) From Malad Creek, Mumbai, India

Biometric Studies are essential to understand the growth rate of the species which helps understand the growth patterns, reproduction rate and population distribution of the species. Growth patterns of molluscs help in evaluating their production potential and energy flows through populations and their distribution. Perna viridis (Linnaeus, 1758) commonly known as the green-lipped mussel or the Asian green mussel belongs to the family Mytilidae. It is distributed along the Indo-Pacific region. They are attached to the rocky substratum along the coast, in the intertidal region. The Biometric Analysis and Length-Weight Relationship study was carried out on Perna viridis (Linnaeus, 1758) to understand their growth rate and population distribution through the Coast of Mumbai. A total of 100 samples were used in this study. The correlation between the Total Weight of the Shell with the organism (WSO) to the Shell Length (SL), Shell Width (SW) and Shell Height (SH) and the correlation between the Soft Tissue Weight of the Organism (WO) to the Shell Length (SL), Shell Width (SW) and Shell Height (SH) gave an idea about the growth factors. The Relative Condition Factor was determined by equation W = aLb. The b values of each correlation showed negative allometric growth with p value to be p&lt;.001 with same significance in Pearson Correlation test. The Relative Condition Factor of WSO-SW and WSO-SL was observed to be above 1 indicating good growth conditions. Thus, biometric studies are a useful tool in study of Perna viridis (Linnaeus 1758) biology, physiology, ecology, growth potential, stock assessment, genetics and breeding of Perna viridis (Linnaeus, 1758).

Size-specific variations in the length-weight relationship and relative condition factor of Hilsa shad (Tenualosa ilisha) across its habitats in Bangladesh

The length-weight relationship (LWR) and relative condition factor are widely used as the most important biological parameters to infer the growth pattern and well-being of fishes. The aim of our study was to investigate the growth parameters of the LWR in different growth phases of Hilsa (Tenualosa ilisha), a flagship species of Bangladesh, and compare its relative condition factors across its major habitats. Fish from various rivers in Bangladesh and the Bay of Bengal were sampled, their length-weight growth parameters were measured and subjected to statistical analysis with pooled data from other studies. An isometric growth pattern in Hilsa was predominantly found in the size classes of 25 ≤ TL (total length) < 30, 30 ≤ TL < 35, and TL ≥ 40. However, the size class TL < 25 showed negative allometric growth with the value of the exponent (b, also known as growth coefficient) between 2.797 and 2.833. The highest weight-growth of Hilsa was within the size class of 35 ≤ TL < 40, with exponent values of 3.271–3.381 (positive allometric growth) across habitats. Our results revealed that the exponent value varied significantly (P < 0.05) between different size classes of Hilsa except between 30 ≤ TL < 35 and TL ≥ 40; however, no such significant differences in the exponent values were found across habitats. The Akaike Information Criterion value was lowest for the size-specific length-weight regression model of Hilsa, indicating it was the best-fit model compared to the habitat-specific and pooled sample models. The relative condition factor of Hilsa by habitat was found in the order of Meghna > Bay of Bengal > Andharmanik > Biskhali > Tetulia > Padma. Additionally, the relative physiological well-being of Hilsa from the river Padma and Tetulia was poor compared to that of other habitats. A more in-depth analysis is required to determine the factors that can influence Hilsa's growth and well-being in relation to habitat quality. The present findings have significant relevance for fisheries biologists and managers in understanding and interpreting Hilsa's ecology, relative well-being of populations of same or contrasting habitats, demographic assessment, and for better management of Hilsa in the future.

Growth Patterns, Status of Well-Being and Trend Analysis of Three Commercially Important Clupeid Species from Selangor Landing Port

Length-weight relationships (LWRs) and condition factors are vital to quickly understanding the fitness and well-being of fish. There is currently no available evidence on LWRs, condition factors and landing trend for these three species and an absence of this information will result in improper management and monitoring of fish species. In this study, the growth patterns, status of well-being and trend analysis of commercially important clupeid species from the west coast of Peninsular Malaysia were studied. Sardinella lemuru, Amblygaster sirm and Nematalosa japonica were selected due to high commercial value and conservation status. S. lemuru was specifically categorized as near threatened by the IUCN with decreasing global populations. Total length (cm) and body weight (g) of S. lemuru, A. sirm and N. japonica were accounted for in this study, which was obtained from the wet market in the west coast of Peninsular Malaysia. The relationships between length and, weight and, condition factors (Fulton’s, KF; relative condition factor, Kn; Allometric) were assessed. The allometric equation; W = aLb was used to evaluate the length-weight relationships while KF = 100W/Lb and Kn = W/aLb were used to estimate fish condition factor. ARIMA (1,1,1) and ARIMA (0,1,0) models were utilised to forecast the fish landing pattern until 2030. The results showed that the coefficient of determination R2 values varied between 0.263 (Sardinella lemuru), 0.5187 (Amblygaster sirm) and 0.8443 (Nematalosa japonica) and b values ranged from 0.0959 to 2.1005. From this, all three fish species have shown a negative allometric growth pattern b&lt;3, reflecting a relatively slow growth rate and size of fish. No positive allometry was detected for any of the sampled fish species. A low value of relative condition factor (Kn &lt; 1) suggests that all the fish species in this study have poor physical characteristics due to inadequate food resources, and unsuitable habitats for expansion of the fish population. Prediction based on Autoregressive Integrated Moving Average (ARIMA) model showed that N. japonica would increase gradually in the coming years, while S. lemuru would remain constant. This study contributes to the knowledge base for S. lemuru, A. sirm and N. japonica in the west coast of Peninsular Malaysia, and is crucial in terms of understanding the ecology of the habitat for supporting conservation strategies, and the restoration and management of these species in future.

Study of Parasitary Fauna in Tilapia of Fish Cultures in the Distrito Federal

Objective: This article discusses the parasitic fauna found in tilapia, the most produced in the DF, collected in fish farms and presents an analysis of water quality, a relative condition factor and the influence of seasonality on the average abundance of parasites. Methodology: For each acquisition campaign, ten fish were collected from each visited fish farm, totaling 180 sampled fish. The fish were collected by fishing nets with mesh 14 and transported in thermal boxes, with each specimen properly packed in a plastic bag, to ensure protection during transport to the Aquaculture Laboratory of the University of Brasília (AcquaUnB). Results and Conclusion: In the two acquisition campaigns, parasitism by Trichodina sp., Monogenoids, Ichthyophthirius multifiliis and Apiosoma sp. Infestations by Trichodina sp. presented higher prevalence and average intensity than other parasites in general, followed by infections by Monogenoides, Ichthyophthirius multifiliis and Apiosoma sp, respectively. The average abundance of Trichodina sp., monogenenoids, Ichthyophthirius multifiliis and Apiosoma sp. showed a positive correlation with temperature and the concentration of ammonium and phosphate in fish farm water. On the other hand, the average abundance of parasites showed a negative correlation with the levels of dissolved oxygen and nitrate concentration. The ectoparasites found do not directly affect human health. There was a significant difference between the average abundance of parasites found in fish collected in the months of February and August, so that the highest parasitic rates were observed in February, when there is greater rainfall in the Federal District and when the values of water parameters were findings. less suitable.

Defining the role of Sabellaria alveolata reefs as nursery areas for juvenile fish: first evidence from drone-based imagery and underwater visual census data

The biogenic reefs built by the honeycomb worm Sabellaria alveolata constitute priority habitats along Atlanto-Mediterranean coastal areas. Despite their wide extent and important ecological role, the nursery value of S. alveolata reefs remains unclear, and more information is needed to define how such structured habitats affect juvenile fish assemblages. In this study, habitat use by juveniles of 7 fish species was investigated by underwater visual census (UVC) at 3 study sites representing a gradient of complexity of Sabellaria reef habitats, spanning from a large and uniform reef to patchy and isolated small reef formations. Sabellaria reef metrics derived by drone-based cartography and GIS analysis were used to quantitatively monitor the seasonal structural changes occurring due to the natural dynamics of the reefs. We also tested the potential effect of Sabellaria habitats on the growth and relative condition factor (Kn) of white seabream Diplodus sargus juveniles. Five of the 7 surveyed species, especially sparid fishes, showed a clear preferential association with Sabellaria formations. Generalized additive modelling revealed a significant effect of the compactness ratio on estimated fish densities at high and low index values. The juvenile fish sampled on Sabellaria reefs exhibited higher values of Kn than those sampled on rocky habitats, supporting the hypothesis that structural complexity positively affected their condition. We provide evidence on habitat use by juveniles, suggesting that the presence of the Sabellaria reef may act as a nursery and affect local fish density in Mediterranean coastal waters.

RELATIONSHIP BETWEEN LENGTH AND WEIGHT AND CONDITION FACTORS OF SCAD FISH (Decapterus Russelli) CATCH OF PURSE SEINE IN LAMPUNG BAY AT KM.GUNUNG JATI

The rate of exploitation of scads fish has increased, giving rise to concerns that the recruitment process is overfished. Relationship between length and weight in fisheries is one of the complementary information that needs to be known in relation to fisheries resource management. The purpose of this practice are to know the composition of yield, growth pattern catch of fly fish (Decapterus russeli) in the Lampung Bay. Sampling by simple random method were conducted in December until mid-March 2020. Samples consisted of catches from Lampung bay ships landed at the Lempasing fishing port. Data analysis by Linear Allometric Models (LAM), relative condition factors and fultons. The results showed the fly fish (Decapterus russeli) had a negative allometric growth pattern in December with a value of b = 2,7244, January with a value of b = 2,7153, February with a value of b = 2,8918, and in March with a value of b = 2,7067 value of 100,82-101,16 from relatively high relative condition factor and value of 2,85-2,91 from fulton condition factor which supports abundant feed which supports the life of Deccapterus russeli fish in good condition.

Age and Growth of Japanese Anchovy (Engraulis japonicus, Temminck &amp; Schlegel, 1846) in Coastal Waters around Shandong Peninsula, China

Japanese anchovy (Engraulis japonicus) is a small pelagic fish with commercial and ecological importance. In spite of its importance, in recent years, specific research on anchovy in the Shandong Peninsula area has been relatively scarce and outdated. This study aims to estimate the age and growth characteristics of anchovy through year-round seasonal sampling from 2016 to 2017, utilizing length–frequency and otolith microstructure analysis. The higher coastal abundance and larger size observed in the spring and summer suggest a potential peak spawning period for anchovies dominated by larger-sized individuals. Based on otolith analysis, anchovies range in age from 0 to 4 years, with a limited presence at age 0 and dominance in the age-1 group. The length–weight relationship (LWR) equation shows hyper-allometric growth for each season, with a mean relative condition factor (Kn) of 1.025 ± 0.005, indicating good health. Additionally, the von Bertalanffy growth equation of can be expressed as Lt = 154.40 [1 − e−0.604 (t + 0.965)], suggesting a medium growth rate (K = 0.604). These findings contribute to the understanding of anchovy age and growth patterns, emphasizing the continuous need for research and monitoring to support rational and sustainable fisheries management and conservation efforts.

Length-Weight Relationship and Condition Factors of Sea Cucumber on Mare and Moti Islands Conservation Areas in North Maluku

This work aimed at determining the growth patterns and condition factors of three sea cucumber species, namely Holothuria atra, Bohadschia marmomata, and B. vitiensis in seagrass beds of Mare and Moti Islands. Samples were collected in March 2023 using a roaming survey method in a block area with an area of 5000 m2. As amount of 54 sea cucumbers were analysed from Mare Island and 58 individuals from Moti Island. The results of this study indicate that the correlation (r) length-weight relationship for the three sea cucumber species is stronger (r &gt; 0.6) on Moti Island than Mare Island. H. atra and B. marmorata have a negative allometric growth pattern, while B. vitiensis has a positive allometric growth pattern on both islands. The Fulton condition factors for the sea cucumbers assessed on Mare Island were recorded for H. atra of 2.84 ± 2.01, B. marmorata of 3.13 ± 2.47 and B. vitiensis of 9.24 ± 5.73. Meanwhile, at Moti Island were found for H. atra of 12.49 ± 11.66, B. marmorata of 9.58 ± 7.38, and B. vitiensis of 8.87 ± 3.68. This is indicated that all sea cucumber species are in good physical condition. Meanwhile, the relative weight condition factor (Wr) of the three species of sea cucumbers on both islands were in the range above 100, which indicated a food surplus in their habitat. The results of this research can be important as the preliminary data in terms of sustainable management of sea cucumber stocks in North Maluku.

The trophic state of the reservoir influences the allometric coefficient and condition factor of Giant Freshwater Prawn (Macrobrachium rosenbergii) cultured in perennial reservoirs of Sri Lanka

Giant Freshwater Prawn (Macrobrachium rosenbergii) is an essential crustacean species in culture-based fisheries of Sri Lanka. Studying the morphometric characteristics and empirical models in fishing and aquaculture is highly beneficial; thus, it is the most accurate way of analyzing growth patterns. The present study aimed to establish the length-weight relationship and compute the relative condition factor for the M. rosenbergii cultured in trophically different perennial reservoirs in Sri Lanka, considering the trophic status of the reservoirs. The allometric coefficient and condition factor of M. rosenbergii concerning the trophic state of the reservoir were empirically ascertained from the samples collected from twenty-five dry-zone perennial reservoirs of Sri Lanka. Carlson's Trophic State Index (TSI) was calculated based on the chlorophyll-a content. The allometric coefficient and relative condition factor were computed using the total length and weight of the M. rosenbergii. The TSI ranging between 44.09±0.47 and 65.15±0.24 differed significantly (p&lt;0.05). Sexual dimorphism in the growth of males over the female M. rosenbergii was ascertained with the aid of allometric coefficient (b value) 3.2306 (positive allometric growth) and 2.9534 (negative allometric growth), respectively. In eutrophic perennial reservoirs, Giant Freshwater Prawns showed the highest allometric coefficient in both sexes. There was a positive correlation between the allometric coefficient and TSI among males, r(23)=0.7210, p&lt;0.001, and combined sexes, r(23)=0.7900, p&lt;0.001, respectively. The results of the present study revealed that the trophic state of the reservoir influences the allometric coefficient and condition factor of M. rosenbergii cultured in perennial reservoirs of Sri Lanka.&#x0D;