Length-weight Relationship Research Articles

Assessment of River Ecological Health Status and Interbasin Water Transfer Potential: Case study of Luapula River Basin in Zambia

Water transfer is one mechanism for meeting increasing water demand in water-stressed areas. However, moving water from one area to another often disturbs the ecosystem including the fisheries biodiversity and growth patterns. Thus, when contemplating water transfer, baseline information on the status of the fisheries biodiversity and condition is cardinal for sustainable fisheries management during and after water transfer implementation. This work aimed at investigating the current fisheries condition (biodiversity, weight length relationship and condition factor) of the Luapula River Basin (LRB) to explore potential and implications for future interbasin water transfer on the basin fisheries. The fishes were sampled during the 2022/2023 dry and wet season at selected sites in LRB. Biodiversity indices, fish weight/length relationship and condition factor were used to describe the fish biodiversity, growth patterns and wellbeing which described the status of the aquatic condition of the donor basin. Species Richness, Shannon Diversity Index, Simpson Index and Evenness ranged between 0.8902 to 1.664, 0.9167 to 2.1437, 0.4416 to 0.8683 and 0.4172 to 0.8940 respectively. The growth coefficient (b) ranged from 1.223 to 3.755 indicating negative and positive allometric growth. The condition factor ranged between 0.692 and 2.218. Thus, it can be said that the LRB has good fish biodiversity albeit with some species showing dominance, normal growth pattern and wellbeing showing bias towards undisturbed habitats and physiological state. As such, this status quo of LRB needs to be maintained prior to, during and after IBWT implementation.

Sturgeon Biological Parameters in the Ural River (Zhaiyk) of the Republic Kazakhstan

The dynamics of capture of 4 Sturgeon species (family Acipenseridae): Russian sturgeon Acipenser gueldenstaedtii, Sterlet A. ruthenus, Stellate Sturgeon A. stellatus, Beluga Acipenser (Huso huso) in the IUU catches of the Ural (Zhaiyk) River within of the Republic of Kazakhstan borders is done. The annual number of Sturgeons estimated by arrested IUU catches in the period 2012–2018 which demonstrate the fluctuation of the Ural River Sturgeons number as well as male dominance is given. The biological indicators of Ural’s Sturgeons during the period of maximum catches in 2018: sex ratio, age, weight, length, length-weight relationship are given.

Using a length-weight relationship based on wild lumpfish (Cyclopterus lumpus L.) for estimation of body condition of lumpfish in salmon cages.

The use of lumpfish (Cyclopterus lumpus L.) as cleaner fish in Atlantic salmon aquaculture has emerged as a promising solution to combat the issue of sea lice infestation, as they have proven effective under the right conditions. The aquaculture industry, however, is facing challenges in ensuring the welfare and survival of lumpfish in salmon cages. Part of the welfare monitoring of lumpfish is the estimation of body condition. Previous research on standard length-weight relationships for lumpfish has primarily relied on the growth patterns of lumpfish in salmon cages, which might not align with the natural growth patterns of the fish. In this study, we argue for another perspective: using the standard weight of wild lumpfish to estimate the body condition of lumpfish in salmon cages. We assert that this approach aligns more closely with the natural growth pattern of the fish and may offer a more accurate representation of their condition. Our findings show significant differences in growth patterns between wild lumpfish, which show positive allometric growth, and those in salmon cages, which show slightly negative allometric growth. The findings underscore the importance of using appropriate length-weight relationships for lumpfish in aquaculture to ensure an accurate assessment of their body condition.

Length–weight relationships for 11 freshwater fish species (Actinopterygii) from four protected areas, northern Vietnam

The length–weight relationships (LWRs) of 11 fish species from one national park and three nature reserves, in northern Vietnam, totaling 737 individuals between October 2018 and November 2021, are described in this study. The following species, representing 11 genera and seven families, were studied: Aphyocypris normalis Nichols et Pope, 1927, Barbodes semifasciolatus (Günther, 1868), Beaufortia pingi (Fang, 1930), Carassius auratus (Linnaeus, 1758), Glyptothorax honghensis Li, 1984, Hemibarbus medius Yue, 1995, Macropodus opercularis (Linnaeus, 1758), Neolissochilus benasi (Pellegrin et Chevey, 1936), Onychostoma gerlachi (Peters, 1881), Opsariichthys minutus Nichols, 1926, Rhinogobius duospilus (Herre, 1935). All regressions were highly significant (P < 0.001). Positive allometric growth was seen in six species (b > 3, P < 0.01) and isometric growth in five species (b = 3, P > 0.05). This is the first report on the LWRs of six fish species, including Beaufortia pingi, Barbodes semifasciolatus, Neolissochilus benasi, Opsariichthys minutus, Glyptothorax honghensis, and Rhinogobius duospilus from four conservation areas. The presently reported study provides foundational data for future stock assessment works and management initiatives in protected areas, as well as facilities comparisons of LWRs from different habitats.

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

Life History Traits of Ambassidae Fish, Chanda nama (Hamilton, 1822) From the Old Brahmaputra River of Northeastern Bangladesh

ABSTRACTThe present study provides a comprehensive analysis of the population structure (length–frequency distributions), growth pattern (length–weight relationships [LWRs] and length–length relationships), physiological condition factors (allometric [KA], Fulton's [KF] and relative [KR]), relative weight (WR) and form factor (a3.0) of Chanda nama. A total of 1200 specimens were collected from the Old Brahmaputra River, northeastern Bangladesh, for 12 months by traditional fishing gear, including seine net and cast net. The total length (TL) of several individuals varied from 2.3 to 7.2 cm. The highest percentage contributed to the population's 4.0–4.5‐cm‐sized group. The LWRs indicated a positive allometric growth pattern (b > 3.0). Fulton's condition factor significantly correlated with TL and body weight (p < 0.0001). The calculated WR ranged from 67.38 to 137.64. No significant variations from 100 were found using the Wilcoxon rank test (p = 0.034), suggesting that C. nama might live there in a balanced predator–prey environment. Furthermore, the measured value for the form factor (a3.0) was 0.0105. In addition, fish with a TL of 7–8 cm should be caught since they are in good condition and have enough meat. The study's findings will greatly contribute to the efficient and enduring management of C. nama in the Old Brahmaputra River and its adjacent ecosystems.

Length-weight relationships and condition factor of 30 species from the Upper Syr Darya drainage, Uzbekistan

Length-weight relationships and condition factor of 30 species from the Upper Syr Darya drainage, Uzbekistan

Length-Weight and Otolith Morphometry Relationships of Hoplostethus mediterraneus Cuvier, 1829 from the Saros Bay, Northern Aegean Sea

Length-Weight and Otolith Morphometry Relationships of Hoplostethus mediterraneus Cuvier, 1829 from the Saros Bay, Northern Aegean Sea

Dentex maroccanus Valenciennes, 1830 Otolith Morphology, Age, and Growth in the Aegean Sea (E. Mediterranean).

Otoliths are important structures for balance and hearing of fish and constitute a useful tool in fisheries science. This study provides, for the first time in the Mediterranean, information on the otolith morphometrics of Dentex maroccanus, collected from the South Aegean Sea, and enriches the existing information on its age and growth by sex. The otolith shape variables examined showed a more circular to square otolith shape, related to the body size. Significant differences between sexes were detected for the otolith Area, Diameter, Perimeter, and Radius. Exponential regressions were used to examine the relationship of the otolith variables with total body length, from which five showed a strong correlation (Diameter, Width, Radius, Area, and Perimeter). The eviscerated weight-length relationship exhibited an isometric growth for both sexes, whereas when total weight was applied, a positive allometric growth was found for females. Sagittal otolith readings revealed four age groups for females and five for males. A Bhattacharya method was used for age validation. Von Bertalanffy growth parameters were as follows: L∞ = 23.08, k = 0.27, t0 = -1.93 for females and L∞ = 24.07, k = 0.24, t0 = -2.26 for males. This research offers valuable biological information for Dentex maroccanus useful in fisheries science.

Morphological characteristics of the species Gaidropsarus Mediterraneus (Linnaeus, 1758) population from the Romanian Black Sea coast in the year 2023

The aim of this study is to provide an overview of the Gaidropsarus mediterraneus (Linnaeus, 1758) species growth pattern from the Romanian Black Sea Coast, in the year 2023. This has been accomplished by studying the length-weight relationship, an important parameter, which helps to know the growth pattern of fish populations, Fulton’s condition factor (kc) (useful index for monitoring feeding intensity) from 180 shore rockling individuals caught by pots. Average lengths and weights were 24.4 ± 2.6 cm and 101.46 ± 38.11 g, respectively, the minimum and maximum values were 18.3 and 33.8 cm, 36 and 319 g in weight. The value of exponent b in the equation is 3.197, indicating that the increasing weight is allometrically positive and mean value of the Fulton was 0.68 ± 0.08, with the minimum and maximum values of 0.47 to 0.90. The obtained results can have useful effects on the stock management of this fish species.

Length-weight relationship and condition factor of Nile tilapia (Oreochromis niloticus) fed diets supplemented with guava and star gooseberry leaf extract

Background Nile tilapia (Oreochromis niloticus) is predominant cultured species in aquaculture. However, there is a scarcity of literature regarding relationship between guava and star gooseberry leaf extract and the condition factor. Thus, the present study aims to investigate the effect of guava and star gooseberry leaf extract-supplemented diets on the specific growth rate, length-weight relationship, and condition factor of Nile tilapia. Methods Six hundred and thirty Nile tilapia (8.7±0.4 g) were randomly distributed among twenty-one tanks (30 fish per tank) within a recirculation system. Over a 60-day period, the fish were fed diets supplemented with 5g/Kg and 10g/Kg of guava leaf extract (GLE-5, GLE-10), star gooseberry leaf extract (SGLE-5, SGLE-10), and a mixture of both (MxLE-5, MXLE-10). Subsequently, specific growth rate, length-weight relationship, and condition factor were determined. Results After 60 days, the specific growth rate was significantly higher in all the GLE, SGLE, and MxLE groups compared to the control group. The final lengths and weights differed significantly both in the control group and all the GLE, SGLE, and MxLE groups. The analysis of the regression equation indicated a positive correlation (r = 0.970, 0.977, 0.976, 0.974, 0.974, 0.974, and 0.969) between the length and weight of Nile tilapia in the control group and in all the GLE, SGLE, and MxLE groups. The regression exponent “b” values in all the GLE, SGLE, and MxLE groups were >3, indicating a positive allometric growth pattern in Nile tilapia compared to the control (b=2.866), which exhibited a negative allometry. The final condition factor values did not differ significantly in either the control group or any of the plant extract groups. Conclusions Nile tilapia exhibited positive allometric growth patterns and maintained good health when fed with GLE, SGLE, and MxLE groups. Therefore, these plant extracts demonstrate suitability for commercial Nile tilapia production.

Fishery characteristics, population dynamics and the impacts of the invasive red swamp crayfish (Procambarus clarkii) in the Nile River, Egypt

Alien intrusive species are one of the extreme pressures on biodiversity for their rapid reproduction and adaptation to new environments. Crayfish Procambarus clarkii entered Egyptian freshwater ecosystems at the beginning of 1980's. After many years of negative effects of its introduction onto the Egyptian waters, it became one of the commercially important species. Population parameters of P. clarkii are estimated based on 1355 specimens collected from the Nile off El-Minya during 2019–2020. The isometric growth of the species under the study is confirmed according to the obtained b-value of length–weight relationship (LWR). Annual sex ratio (female : male) was in favour of females with an annual sex ratio 1.44 : 1. The values of growth coefficient (K) and the asymptotic total length (L∞) were assessed for males, females and combined sexes. Using mortality estimates, the exploitation ratio was 0.64 year–1. Investigation of relative yield per recruit (Y'/R) and analysis of relative biomass per recruit (B'/R) for P. clarkii in the Nile off El-Minya provides the highest (Y'/R) at Emax = 0.81 and the E0.5 (utilisation level that preserves the spawner stock biomass at 50% of the virgin spawning biomass) was 0.38. From fisheries management point of view, the current exploitation level should be decreased to that maintain the spawning stock biomass (from 0.64 to 0.38).

Environmental effects on abundance and size of harvested bivalve populations in intertidal shellfish grounds

Clams, razor clams and cockle are intertidal bivalve species collected on foot in the shellfish grounds of the Rías Altas (NW Spain). Spatio-temporal distribution of these bivalves are typically at the expenses of the environmental conditions of the region; however, the responses to the abiotic conditions are poorly understood. Using data from 6 species (Ruditapes decussatus, Venerupis corrugata, Ruditapes philippinarum, Cerastoderam edule, Donax trunculus and Solen marginatus) sampled in 51 intertidal shellfish grounds during 2007 and 2008, we characterized the influence of the environment (temperature, salinity, nutrient salts, suspended organic matter, or sediment granulometry and composition) on the distribution and size of these species through a comparative statistical analysis. Shellfish grounds were grouped according to their sediment and water characteristics revealing a land-ocean gradient and the influence of the geological imprint that separates bivalve grounds from West to East. Statistical models showed that R. decussatus, V. corrugata and R. philippinarum together with C. edule were more abundant in sites combining a strong marine influence with organic-rich finer sediments. However, each of those species also had different environmental niches mostly related to their particular sediment affinities, the proximity to the river mouth, and their physiological tolerances to temperature and salinity. D. trunculus was only found in outer exposed shellfish grounds, while S. marginatus abundance increased in muddy sediments. River distance was a sound descriptor of individual shell length and length variability with contrasting effects on the different species. Furthermore, slopes of length-weight relationships were steeper in autumn than in spring, and this allometry tended to be more positive in sites located closer to the rivers’ mouth, which had a higher organic matter C/N ratio. Overall, harvested intertidal bivalves had identifiable environmental preferences that influence their spatial distribution in abundance, body size, and allometric growth.

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.

Length–Weight Relationship and Sexual Maturity Stages of Bluefish: Pomatomus saltatrix (L, 1766) in Tripoli Coast, Libya

Pomatomus saltatrix (L, 1766) is an important commercial fish in several countries, and that suffer from overfishing problems. In this study, 50 individuals of P. saltatrix were conducted during the fall, (October-November, 2022), on the Tripoli coast. Their total lengths and total weights were measured. The sex of the fish was determined, and the stages of sexual maturity were identified. The results showed that their lengths ranged 23.5-35cm, total weights 139-408g. The relationship between length and weight was negatively allometric, the number of males was higher than that of females, and all stages of sexual maturity were present.

Life history of Mexican species of the genus <i>Tlaloc</i> (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.

Estimation of Growth and Mortality Parameters for the Annular Seabream Diplodus annularis (Linnaeus, 1978) in the Southern Aegean Sea

The growth and mortality parameters were examined for the annular seabream Diplodus annularis collected from the Didim coast, Southern Aegean Sea. A total of 654 annular seabream individuals, 263 female (40.21%) and 391 male (59.79%), were sampled by commercial trawlers and gillnets from September 2022 to January 2024. The total length varied between 9.0 and 24.3 cm for females, 8.6 and 24.0 cm for males, and the weight varied between 8.60 and 146.57 g for females, 7.00 and 128.96 g for males. The length-weight relationships were calculated for females, males, and all individuals as W = 0.0115 x L2.9641, W = 0.0131 x L2.8995, and W = 0.0118 x L2.9440, respectively. The growth pattern was determined as negative allometric. The maximum age class was V for both females and males. The von Bertalanffy growth parameters were L∞ = 25.27 cm, k = 0.424 year-1, t0 = -0.308 years for females; L∞ = 25.63 cm, k = 0.338 year-1, t0 = -0.935 years for males; L∞ = 27.43 cm, k = 0.283 year-1, t0 = -1.121 years for all individuals. The growth performance index (Φ´) for females, males, and all individuals were 2.432, 2.347, and 2.329, respectively. This study provides the first information on the growth and mortality parameters of D. annularis along the Didim coast, southern Aegean Sea.

Real‐time estimation of olive flounder growth in indoor aquaculture using cameras combined with a grid

AbstractEstimating fish growth in real time has many benefits for indoor aquaculture farms, such as saving labor time and costs, reducing water pollution during feeding, improving feeding activity and determining when to harvest. Hence, this study proposed a visual‐information‐based method for measuring olive flounder (Paralichthys olivaceus) length, using accurate growth tracking for efficient aquaculture management. Using two cameras, an light‐emitting‐diode (LED) grid was placed at the bottom of the water tank to measure fish length. The pixels unit from the fish length in the captured image was converted to centimeters based on the relationship of a pre‐built dataset. A total of 180 lengths were calculated using images captured by the cameras. The average length of each fish acquired from the cameras was calculated separately, and Lagrange's interpolating polynomial algorithm was implemented to calculate the overall length of each fish. This method reduced the computational complexity, and results were obtained more rapidly and in a user‐friendly environment. The power model generated the length–weight relationship, which allowed us to estimate the body weight of each olive flounder based on the length. The proposed approach enabled us to calculate the length of olive flounders with a highly accurate R2 of 0.995.

Evaluation of post-stocking re-encounters of an endangered fish using a large, multi-agency database to inform recovery

Managers frequently rely on conservation hatcheries to maintain declining fish populations in the wild, which is the case for bonytail Gila elegans, an endangered species endemic to the Colorado River basin, USA. We used a multi-agency database of stocking, capture, and PIT-tag detections during 2013-2021 across the upper Colorado River basin to assess if re-encounter probability of bonytail varied among seasons, stocking habitats (mainstem, tributary, and off-channel), and with length-at-stocking. Because of previous observations of recaptured bonytail in poor body condition, we tested for differences in condition among stocking habitats. Of 325054 stocked bonytail examined, 90% were never re-encountered. Most re-encounters (93%) were PIT-tag detections near stocking locations. Re-encounter probability was low regardless of stocking habitat, and 95% of fish were at large for <195 d. The effect of length-at-stocking on re-encounter probability varied among habitats and was positive in mainstem and tributary and negative in off-channel habitats. Slopes of length-weight relationships of recaptured fish differed among stocking habitats. Given consistently low re-encounters of stocked bonytail in all habitats regardless of length-at-stocking or stocking season, we recommend managers consider refining the stocking program to better identify specific factors that affect survival, including stocking fish into intensively managed off-channel habitats which afford greater control of abiotic and biotic conditions than riverine habitats. If stocking continues among multiple habitat types, at a minimum we suggest stocking fish at consistent locations over time to better allow for quantitative assessment and to ensure fish are stocked into water temperatures that align with optimums for growth, recovery-from-handling, and survival.

Seasonal Length-weight Relationship of Puntius terio (Hamilton, 1822) in West Bengal, India

Seasonal Length-weight Relationship of Puntius terio (Hamilton, 1822) in West Bengal, India