Fulton's Condition Factor Research Articles

Biochemical composition of some catfishes from a coastal river of Bangladesh in relation to a biometric indicator

The proximate contents (protein, lipid, ash, and moisture) of three catfish species (Pangasius pangasius, Clupisoma garua, and Silonia silondia) were investigated from a coastal river of Bangladesh. The proximate composition was determined using the AOAC (1990) standard procedure. The average length and weight of the fish samples used in the experiment were 21.50 ± 1.61 cm and 65.55 ± 13.12 g; 19.67 ± 0.21 cm and 50.74 ± 3.13 g; 18.2 ± 1.21 cm and 43.40 ± 10.42 g for P. pangasius, C. garua, and S. silondia, respectively. The P. pangasius, C. garua, and S. silondia were rich protein sources, with 20.19%, 18.86%, and 15.24%, respectively. On the other hand, the lipid and ash contents were ranged between 2.11% to 3.07% and 0.52% to 2.28% respectively. The present study disclused water as the most abundant element in fish bodies ranging from 75.05% (P. pangasius) to 79.60% (S. silondia). In log-transformed data, the weight of the fish body had a very significant positive relationship with most of the studied body constituents. In all three fish species, total length in log-transformed data and Fulton's condition factor showed a highly significant positive relationship with most of the studied body constituents. These findings suggest that biological differences like length and weight across species can influence the fishes biochemical composition that should be established.

New distribution record of Varuna litterata from Caraga Region, Philippines: Analysis on morphometry, length/width-weight relationship, and condition factor

Abstract. Jumawan JH, Ruales JJJ, Avila MCA. 2022. New distribution record of Varuna litterata from Caraga Region, Philippines: Analysis on morphometry, length/width-weight relationship, and condition factor. Biodiversitas 23: 2935-2942. The study reported the occurrence of Varuna litterata in its habitat as a new record in Caraga Region, Philippines. The crab samples were collected using a hand-picked method and were of marketable sizes. There were 14 morphometric traits measured with the corresponding weight and sex of each specimen. Majority of the crab samples were medium-sized, with weight ranging from 11-20 grams, a carapace width range of 28-34 cm, and a carapace length range of 27-32 cm. Exploratory analysis of length /width-weight data fits the power regression model depicted into graphs. A strong relationship and highly significant was observed on pooled samples of WT-CW variables (R2: 0.9229: P<0.001) and WT-CL variables (R2: 0.9197); P<0.001). The derived log-transformed for WT-CW relationship was logWT: -2.7994+2.6456 logCW. Results suggest that carapace length and width tend to be smaller relative to the weight, which is an indication of a negative allometric growth pattern. The computed Fulton's condition factor was higher in males than females, as supported by Kruskal Wallis test (P<0.001). The data provides baseline information for comparing similar studies and in understanding the population dynamics of this crab species.

Responses of growth, blood health, pro-inflammatory cytokines genes, intestine and liver histology in Red Seabream (Pagrus major) to camelina meal

The current work assessed the inclusion impacts of oilseed camelina meal (CM) as a protein source in red sea bream (Pagrus major) diets. A 45 day assessment period with 180 juveniles (6.47 ± 0.17 g) were allocated in triplicates to 4 experimental groups and fed formulated diets in which fish meal (FM) was subrogated at graded series of 0% (T1), 20.5% soybean meal (T2), 20.5% camelina meal (T3), and 33% camelina meal (T4). No noticeable alterations were observed in specific growth rate, feed intake, survival rate, hepatosomatic index, and Fulton's condition factor among the experimental groups. Fish fed the T4 diet showed considerably reduced (P < 0.05) final weight and body protein content when compared to those fed T2, T3, and basal diets. Plasma biochemical parameters show no differences (P > 0.05) in glucose, total bilirubin, total protein, total cholesterol, triglyceride, glutamyl oxaloacetic transaminase, and glutamic pyruvate transaminase. Hematocrit levels decreased noticeably (P < 0.05) in fish groups fed camelina meal in comparison to the control group. Liver and intestinal histology showed a healthy status and an increase in villus length and goblet cell number in camelina groups. Fish fed the T4 diet displayed higher expression levels (P < 0.05) of relative mRNA interleukin 1 beta (IL-1b) and tumor necrosis factor-alpha (TNF-α) in comparison to other groups. The inclusion of camelina meal (up to 20%) in red sea bream diets produced similar outcomes to specimens fed fish meal and soybean meal.

High prevalence of Ichthyophonus sp. infections in Northeast Atlantic mackerel (Scomber scombrus).

High prevalence of Ichthyophonus sp. infections in Northeast Atlantic mackerel (Scomber scombrus).

The newly built Ribb Reservoir fisheries, Tana Sub‐basin, Ethiopia: New fishery establishment, diversity, production, challenges and management

AbstractIn the future, agriculture alone may not produce the food needed to feed the increasing world population. Hence, it can be augmented by developing irrigation and water resources, mainly fisheries resources. In Ethiopia, especially in the Tana Sub‐basin, the expanded irrigation practices by building dams and weirs along the tributaries of Lake Tana did not consider fisheries nor the development and management. The aim of this research was, therefore, to promote fisheries and integrate them into the irrigation systems of the Ribb Reservoir in Ethiopia. During the sampling time (from September 2020 to August 2021), primary and secondary data collection and discussions with experts and fishers were conducted. Although the dam prevented the upstream spawning migration of the Labeobarbus species, the reservoir created a new fisheries development. Water quality parameters, such as temperature (23.82 ± 1.38°C), pH (6.36 ± 0.64) and dissolved oxygen (8.84 ± 3.54 mgl‐1), were within the acceptable range for fish. Of the 11 identified fish species, L. nedgia and L. surkis were the most and the least common species, respectively. Riverine and cut spawner species were the sources of the population. However, Oreochromis niloticus (Nile tilapia) was restocked in 2017 to increase the livelihoods of fishers. The Fulton condition factor, K values of L. nedgia (1.63 ± 0.25), L. intermedius (1.70 ± 0.27), C. gariepinus (0.61 ± 0.13) and O. niloticus (1.65 ± 0.29), and their ‘b’ values were &lt;3. The newly established fishery in the reservoir is the source of income for fishers, and its annual production has been shown to increase from 148.5 to 1034.1 tons/year, indicating fish are adapting to the reservoir. However, the fishery has faced many challenges, such as illegal fishing, fisher engagement, and fishing gears. Limiting the number of fishers, restrictions on fishing gears and seasonality of fishing are some of the mitigations.

Mixed-sex Nile tilapia (Oreochromis niloticus) can perform competitively with mono-sex stocks in cage production

All-male tilapia stocks are widely used by farmers to supply both domestic and international markets with homogenous, large sized fish (500 g+). While a number of strategies are possible, hormonal treatment of fry with 17α-methyltestosterone (MT) is the most common method used by commercial farmers due to its low cost and ease of application. However, contrasting to its current widespread use, the implications of MT in tilapia farming have raised concerns especially from public and environmental perspectives. Therefore, in this study we tested the impact of stocking a mixed-sex fast growing strain of Nile tilapia (Oreochromis niloticus) fry at high density and then grading out females at 4 or 8 weeks intervals during grow-out and compared final production with a standard MT-treated mono-sex system. From a production perspective, the strategies to remove females at 4 or 8 weeks were successful as no differences in harvest weight, survival and feed conversion rate were observed when compared to the MT-treated group. Similarly, no differences at harvest were obtained in terms of external appearance, Fulton's condition factor, gonadosomatic index, fillet yield, fat-somatic index and visceral-somatic index (%) between MT-monosex group and the groups where females were removed (4 or 8 weeks). However, a financial analysis of this approach showed that the additional costs (fry, feed and labour) involved in the mixed-sex strategy resulted in lower profits. This could be mitigated if a proportion of the removed females could be sold at a premium price as potential broodstock. In the model presented, sales of 13% of the removed females for broodfish at current Thai prices, or a premium of at least 8% for non-sex-reversed final product would be sufficient for the mixed-sex system to return a higher profit than the mono-sex system. The latter strategy could also enable further social licence through use of small fish in nutritional and outgrower initiatives.

Age and Growth Parameters of African Catfish (Clarias gariepinus Burchell, 1822) From Asi River, Turkey

This study aimed to determine the age and growth parameters of the African catfish Clarias gariepinus (Burchell, 1822) from the Asi River. A total of 185 fish samples have been collected from the Asi River, located in the Eastern Mediterranean region of Turkey, from December 2018 to March 2019. Samplings were carried out with fyke-nets. Lengths and weights of samples ranged from 20.47 to 62.46 cm and 74.4 to 1874.2 g, respectively. The sex ratio (1:1.06) was biased toward males (p>0.05). In terms of length-weight relationship, b-values were calculated as 2.98, 2.83, and 2.94 for female, male, and whole samples, respectively. Isometric growth was determined. The Fulton condition factor (CF) value for all samples was calculated as 0.7591±0.009. The ages of fish samples ranged from I to IV, and the dominant age and total length (TL) groups of the population were the I and II age groups. The von Bertalanffy growth parameters were estimated as =58.5 cm, K=0.41 , =-0.7, Φ’=3.15 for females; =68.3 cm, K=0.35 , =-0.6, Φ’=3.21 for males and =58.2 cm, K=0.39 , =-0.4, Φ’=3.12 for whole collected samples. As a result, climate change and its effects, especially the construction of dams in certain parts of the river for agricultural irrigation purposes and the resulting lack of management negatively affect the natural living stocks of the Asi River. Therefore, it can be said that the C. gariepinus stocks in these areas are overexploited. Legal arrangements should be made in this region to correct these conditions.

Enrichment in a Fish Polyculture: Does it Affect Fish Behaviour and Development of Only One Species or Both?

Physical enrichment of structures has been used for the last decades in aquaculture to improve fish production and welfare. Until now, this enrichment has been practiced in fish monoculture but not in fish polyculture. In this study, we developed a polyculture of two freshwater species (pikeperch and sterlet) in recirculated systems (tank of 2.4 m3) with or without physical structures for enrichment. Two types of structures were used: a cover plank on a part of the tank decreasing the light intensity and vertical pipes modifying the water flow. The experiment was conducted in triplicate for a three-month period with juvenile fishes (143 ± 41 g and 27.3 ± 2.2 cm for pikeperch and 133 ± 21 g and 32.8 ± 1.6 cm for sterlet). Behavioural (space occupation and abnormal behaviours) and morphological (total length, final weight, Fulton condition factor, coefficient of variation of the final weight, percentage of biomass gain and specific growth rate) traits were measured. The pikeperch changed their space occupation and showed a preference for low light areas. Sterlet also changed their space occupation: they did not use the cover and occurred mainly in the part of the tank without enrichment. There was no difference for the frequency of abnormal behaviours for pikeperch and sterlet between the two sets (with or without enrichment). There was no statistical difference between the two sets for all the morphological and growth parameters no matter the species and the rearing modality.

Morphometric Relationships, Growth and Condition Factors of Critically Endangered Chinese Pangolin (Manis pentadactyla).

Simple SummaryThe pangolin is the only scaly mammal in the world. Among the eight extant pangolin species, the Chinese pangolin (CP) is most threatened with extinction. Thus, this species is categorized as “Critically Endangered” by the International Union for Conservation of Nature (IUCN) and listed under “Appendix I” of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Taiwan is a single Formosa Island where the population of CP has been increasing for the last decade due to continuous conservation initiatives. The presence of sufficient samples of CP that are adapted to distinct environmental conditions could provide valid morphometric results. However, the morphometric relationships, growth type, and condition factors have not yet been enumerated for any pangolin species including Chinese pangolin. The study included 282 rescued and rehabilitated individuals from central and southern Taiwan. Adult male and female pangolins measure between 75.2–103 cm and 66–114.9 cm from the snout to the tip of the tail and weigh between 4–7.6 kg and 3–5.8 kg, respectively. Adults also showed negative allometric growth (b < 3) as their length increased. However, the average relative condition factor (KR) was 1.02 ± 0.16 and showed the majority of rescued adults in normal (59.7%) and good (39%) health conditions.Morphometric relationships and condition factors are crucial to quickly understanding the fitness and well-being of animals. Total length (cm) and bodyweight (g) of 282 (male = 167 and female = 115) pangolins were accounted for in this study which was received and rehabilitated in Pingtung Rescued Center, Pingtung and Endemic Species Research Institute, Nantou, Taiwan. The allometric equation; W = aLb was used to estimate the length-weight relationships where R2 = 0.70, a = 0.61, and b = 1.98. The ratio of total body length and tail length was between 1.1 and 2.7. Pangolins exhibited negative allometric growth (b < 3) as their length increased. The average relative condition factor (KR) was 1.04, indicating a state of good health for rescued individuals. However, Fulton condition factor (KF) and KR fluctuated in different months but was significantly heavier during the wet seasons. This study recommended to release healthy animals with KF of 0.8 or higher back into the wild in order to increase their survival rate. The study, thus will be helpful to promote standardized guidelines for conducting physical measurements and understanding health status. Additionally, it will support the recovery of this threatened species by husbandry and diet management in ex-situ and in-situ conservation.

Influence of the social status of male Aulonocara nyassae on behavior, growth, hematology, biochemical parameters, reproduction and larviculture

The aim of the present study was to evaluate the influence of social status of Aulonocara nyassae males on behavior, growth and reproductive performance, hematological parameters and male and female biochemicals and the success of offspring larviculture. For the pre-experimental phase, four aquariums with three males each were observed for 48 h and videos of 10 min, twice a day, were recorded and an ethogram was generated on the definition of social status, classified according to aggressive behavior, territorialism and coloration as dominant, subdominant and submissive. The experimental phase lasted 66 days. One male was stocked per aquarium, from each of the three social statuses, with three females and four replicates. The animals were filmed for 10 min, twice a day, for 5 days, every 30 days. An ethogram on the reproductive behavior of males and females was generated. Locomotion was more frequent in subdominant and submissive males and in females with dominant and subdominant males (P < 0.05). Courtship behavior was more frequent in dominant and subdominant males and in females from aquariums with dominant males (P < 0.05). The survival of females with subdominant males was lower (P < 0.05). Final weight (FW), average weight gain (AWG), glucose (GLU), triglycerides (TG), viscerosomatic (VSI) and hepatosomatic (HSI) indices for males; final mean total length (FTL), mean length gain (MLG), hemoglobin (Hb), specific growth rate (SGR), Fulton condition factor (K), total cholesterol (TC), FW, AWG, GLU and for females and for progeny, average of egg production, hatching rate, average of larvae produced, mean final larvae weight and mean final larvae length were higher for dominants. In males, SGR and FTL, in females, total plasma protein (TPP), gonadosomatic index (GSI), intraperitoneal fat index (IPFI), TG, HSI and VSI were higher for submissive (P < 0.05). However, the mean length gain (MLG), GSI and IPFI, Hb and TPP were higher for subdominant and submissive males (P < 0.05). K was higher for dominant and submissive males (P < 0.05). Therefore, the social status of males influences growth performance, hematological, biochemical parameters and reproductive capacity of males and females of A. nyassae.

The body condition of invasive crayfish Faxonius limosus (Raf., 1817) (Decapoda: Cambaridae) is better in small rivers than in dam reservoirs in Central Europe.

The impact of dam reservoirs on river ecosystems is one of the current major issues in hydrobiology. In addition to the impact on native biodiversity, impoundments may facilitate biological invasions. A successful invasion is presumably related to the individual life history and resource allocation strategy in expanding populations. We tested whether reservoirs affect the body condition of invasive Faxonius limosus in upland streams. We found positive allometry of growth in females but more frequent isometric growth in males, and the form factor a3.0 was significantly higher in males than in females within populations. Fulton's condition factor (K) was calculated for standard carapace lengths of 20mm (juvenile) and 40mm (adult). Both mean KCL 20 and KCL 40 were higher in males than in females. Positive allometry of growth in females resulted in a larger mean KCL 40 than KCL 20. The majority of the mean K obtained in reservoirs was similar or lower than the respective condition in streams. The condition of adult females was higher in streams in comparison to reservoirs. The obtained results are in contrast to the hypothesis that reservoirs positively affect individual body conditions and show that these man-made lakes do not provide more favourable habitat conditions for F. limosus than those in the natural aquatic environments of an upland landscape. An advantageous effect of the presence of reservoirs on invasion spread may be possible in more ecologically harsh landscapes, especially in colder climatic zones. Our study is the first to investigate the relationship of the body condition of F. limosus in two contrasting habitats.

Length‐weight relationships and condition factors of 14 Oxynoemacheilus species (Cypriniformes: Nemachelidae) from Turkey

Length-weight relationships (L-WRs) and Fulton's, relative and mean condition factors were estimated for 14 Oxynoemacheilus species from Turkish river basins. Specimens were caught by electrofishing (SAMUS 725MP) in spring, summer, and autumn in the years of 2014, 2017, 2018, and 2019. The water depth at which the samples were collected varies depending on the station, but usually varies between 2 and 40 cm. Sampling was carried out using an electroshoker as standard at each station in the 100 m stream section. In the laboratory, total length (L) and total weight (W) were measured to the nearest 0.1 cm and 0.01 g, respectively. The lowest and highest values of b were estimated to be 2.727 for O. mediterraneus and 3.233 for O. cilicicus, respectively. The LWRs are not presented to FishBase for all species and are given in this study for the first time. In addition, the maximum length of all species studied is not available in any database. This is the first time it has been shown.

Length Weight Relationships and Condition Factor of Sicydium sp. (Gobiidae) from the Yallahs River and Swift River, Jamaica

Sicydium sp., commonly known as gobies, are migratory freshwater fish that spend most of their life cycle in rivers, but when the larvae emerge they drift downstream to the sea where further development of juveniles occurs. Although Sicydium sp. are abundant in Jamaican rivers, little is known about the ecology of these species on the island and throughout the Caribbean. This study examines aspects of the ecology and biology of Sicydium populations in Jamaica. Fish sampling was carried out using dip nets and bottom kick nets at sites along the south coast in the Yallahs River, and along the north coast in the Swift River. A total of 850 gobies were captured, measured, and weighed. The values of the allometry coefficient or growth pattern (b) in the length weight relationships (LWR) were significantly different among males, females, and juveniles (p < 0.05). The growth pattern derived from LWR's was positive for females, males, and juveniles in the Yallahs River, and positive for females and juveniles but negative for males in the Swift River. The mean Fulton's condition factor (K) indicates that fish populations in both rivers are healthy and in good condition. These results augment the body of knowledge on Sicydium gobies in Jamaica.

Length-Weight Relationships and Condition Factors of Three Epinephelus Grouper (Epinephelidae) Harvested in the Northern Coast of Aceh, Indonesia

The current research reports the length-weight relationships (LWRs) and Fulton’s condition factor (K) of three grouper species, namely: areolate grouper (Epinephelus areolatus), blacktip grouper (Epinephelus fasciatus), and honeycomb grouper (Epinephelus merra) harvested in the northern coast of Aceh, Indonesia. The fish samples were gathered from Pelabuhan Perikanan Samudera (PPS) Lampulo, Kuta Alam District, Banda Aceh, Aceh from June - December 2020. In total, 571 grouper specimens were collected during the study period (186 of E. areolatus, 205 specimens of E. fasciatus, and 180 E. merra). The total length (TL) of each fish species ranged from: 125.9-302.5 mm (mean 222.5 ± 30.3) (E. areolatus), 113.3-268.6 mm (mean 196.6 ± 26.9) (E. fasciatus) and 111.1-215.4 mm (mean 162.9 ± 21.7) (E. merra) with weight (W): 25.5-367.6 g (mean 145.8 ± 64.6) (E. areolatus), 24.0-290.9 g (mean 130.3 ± 56.2) (E. fasciatus) and 24.0-290.9 g (mean 130.3 ± 56.2) (E. fasciatus). In addition, the observed Fulton (K) condition factor and Ws values for all the three species were above 100 and 1. Furthermore, the LWRs analysis results revealed that all three fish species showed the b value of 3.0548 (r2=0.97), 3.0466 (r2=0.94) and 3.1681 (r2=0.97) for E. areolatus, E. fasciatus and E. merra, respectively, indicating that the three observed fish species had a positive allometric growth pattern and had a solid relationship between body weight and total length. This study delivers a reference point of several biological characteristics of the observed grouper species that will benefit and improve the fisheries management in the region.

Life history traits of Mystus vittatus in the Ganges River, Bangladesh: recommendation for its sustainable management considering climate change.

Freshwater catfishes are regarded primarily as a source of food and sport, so they are highly valuable economically. We comprehensively studied life history features of Mystus vittatus, including sex ratio (SR), population structure, growth pattern, condition, form factor (a3.0), sexual maturity (Lm), spawning season, fecundity, mortality (i.e., total mortality (Z), natural-mortality (MW), and fishing mortality (F)), optimum catchable length (Lopt), length at first capture (Lc), and environmental factors (temperature and rainfall) with management policies from the Ganges River during July 2017 to June 2018. SR (1:1.48) differed noticeably from the expected 1:1 ratio (p < 0.05). Total length (TL) ranged from 6.80-16.00cm for males and 6.53-18.80cm for females. The growth was negative allometric for both sexes. Fulton's condition factor was the best one and mean relative weight showed no significant difference from 100 for both sexes that indicates balanced population. Lm was 9.60, 9.70, and 8.80cm based on the gonadosomatic index (GSI), logistic, and maximum length (Lmax), respectively. Spawning season was April to September and the peak was May to July. Fecundity varied from 5942 to 49,852 (mean ± SD, 11,898 ± 5028) and a positively correlated with TL and BW. Z was 1.80year-1, Mw was 0.97year-1, and F was 0.83year-1. Lopt was 11.14cm (TL) and Lc was ~ 8.47cm (TL). Temperature and rainfall both were significantly related with GSI and suitable range of temperature and rainfall for spawning of M. vittatus was 28-34°C and 200-390mm, respectively. Long data series pointed that average air temperature was increasing and rainfall was decreasing. By considering all of the above parameters, we can take the proper management actions for M. vittatus and other freshwater catfishes on the Indian sub-continent, to ensure long-term self-sustainability and sustainable harvest for the benefit of fishers and communities.

Predicted strong genetic gains from the application of genomic selection to improve growth related traits in barramundi (Lates calcarifer)

Barramundi (Lates calcarifer) is a tropical species of increasing aquaculture interest. In efforts to accumulate genetic gains through selection, the species is now subject to several pedigree-based breeding programs globally; however, these breeding programs would further benefit from the implementation of genomic selection methodologies. Here we make genomic predictions for polygenic growth and body shape traits and compare expected genetic gains from genomic selection across several breeding strategies to those expected from pedigree-based on-farm selective breeding programs.A commercial scale cohort of barramundi (24 half-sib families) was grow-out at two farm locations, a brackish-water pond-based system in Queensland, and a freshwater recirculating aquaculture system (RAS) in Victoria. A total of 2139 fish were genotyped using a custom 70 k Axiom™ myDesign™ SNP array (ThermoFisher Scientific™) and phenotyped at harvest for whole fish weight (WFW), standard fish length (SL), body depth (BD), Fulton's condition factor (K) and body shape index (BS). Fillet weight (FW) was also recorded on a subset of Victorian fish. Heritabilities based on genomic relationships were estimated across barramundi from both farm sites for WFW (0.33 ± 0.06 to 0.35 ± 0.04), SL (0.27 ± 0.05 to 0.35 ± 0.04), BD (0.29 ± 0.06 to 0.30 ± 0.04), and K (0.14 ± 0.04 to 0.21 ± 0.04), and for FW (0.35 ± 0.16) in the Victorian site only. Genotype-by-environment interactions were also detected for all traits (GBLUP rg between locations ranging from 0.41 for K to 0.61 for SL).To optomise the design of a breeding program using genomic information, three possible genomic selection strategies were explored: MULTIPLE, separate breeding programs at each farm site; GENERAL, a single breeding program using the general effects from an interaction model; and SINGLE, a single breeding program based on the performance of individuals within one main farm site. The accuracy of GBLUP breeding value prediction for the WFW, SL and BD traits was higher than PBLUP for all scenarios (10–33% and 15–49% improved prediction accuracy in the Victoria and Queensland environments, respectively). Estimates of genetic gain were also consistently higher when GBLUP was applied (19–31% for WFW in VIC) compared to PBLUP (14–23% for WFW in VIC).Under the SINGLE scenario, genetic gains for the target farm site were the same as for MULTIPLE, but only 48–66% of the MULTIPLE gains were predicted for the non-target farm site. In comparison, GENERAL, which operates at half the cost of MULTIPLE, achieved 72–97% of the expected gains of MULTIPLE across farm sites, suggesting that it would be the most appropriate scenario for genomic selection in the production environments evaluated.

Life-history traits of ten commercially important small indigenous fish species (SIFS) in the Oxbow lake (Southwestern Bangladesh): key for sound management

For the first time, we revealed the life-history traits including growth pattern (length-weight relationships, LWRs), condition factors, form factor (a3.0), first sexual maturity (Lm), age at first sexual maturity (tm), life span (tmax), natural mortality (Mw), asymptotic length (L∞), and optimum catchable length (Lopt) of ten commercially important small indigenous fish species (SIFS) in the Oxbow lake (Baor), southwestern regions of Bangladesh. A total of 1651 specimens were sampled during January to December 2020 with traditional fishing gears including seine nets, gill nets, and lift nets. Individual total length (TL) and body weight (BW) were measured by digital slide calipers and digital balance, respectively. To calculate the Lm, empirical maximum length-based model was considered, and Lopt was calculated based on L∞. The TL vs. BW relationship indicated positive allometric growth for Chanda nama (Hamilton 1822), Channa punctata (Bloch 1793), Channa striata (Bloch 1793), Lepidocephalichthys guntea (Hamilton 1822), Macrognathus pancalus (Hamilton 1822), and Puntius sophore (Hamilton 1822), but negative allometric growth for Badis badis (Hamilton 1822), Gudusia chapra (Hamilton 1822), Glossogobius giuris (Hamilton 1822), and Hyporhamphus limbatus (Valenciennes, 1847). All r2 values exceed 0.910 that indicated all LWRs were highly significant (P < 0.001). According to Spearman correlation test, Fulton's condition factor (KF) vs. BW was highly correlated (P < 0.001), indicating better well-being for these species. Moreover, a3.0 indicates B. badis, C. punctata, C. striata, G. giuris, H. limbatus, L. guntea were elongated; C. nama, P. sophore, were short and deep; G. chapra was fusiform, and M. pancalus was eel-like body shape respectively. The minimum tm and tmax were obtained as 0.74year and 2.66year for C. striata and maximum were 0.93year and 3.31year for B. badis, respectively. This study provided information on tm and tmax for ten SIFS that is globally absent. From empirical models, the smallest mean value of Lm was found for B. badis (3.98cm), and the greatest was found for C. striata (16.96cm). The minimum Lopt was obtained as 3.78cm TL for B. badis and maximum was 14.09cm TL for C. punctata. The minimum Mw was documented as 1.39 for B. badis and maximum was 1.73 for C. striata. The output of this research will be helpful for developing sustainable management policies and protection of SIFS through the application of mesh size based on Lm and Lopt in the Oxbow lakes, Bangladesh and neighboring countries.

A novel morphological index applied to genetic improvement of body shape in grass carp Ctenopharyngodon idella

Body shape is an economically important trait in grass carp (Ctenopharyngodon idella) that directly influences consumer acceptance and farmer profitability. It is essential to incorporate shape traits into the ongoing breeding program, as this would be expected to achieve rapid growth and maintain a slender shape for cultured populations. Thus, the aim of this study was to explore a suitable morphological index for genetic improvement of shape traits in grass carp. The viscerosomatic index (VSI) was introduced as a quantitative indicator of individual slenderness for the evaluation of various morphological ratios. Then, based on correlation and path analysis among body measurements (BMs) and weights of 290 recorded individuals, nine representative ratios that can reflect body slenderness from different angles were employed in this study, including Fulton's condition factor (K), Richter's condition factor (B), and other length ratios of different BMs (S1–S7). The results showed that each of these ratios exhibited a favorable relationship with VSI, confirming that more slender individuals always have a lower VSI. Of these ratios, S1 (body height-to-body length ratio, BH/BL), S2 (body height-to-caudal peduncle height ratio, BH/CPH), and S3, calculated as (BH-CPH)/BL, had the top three correlation coefficients with VSI (r = 0.501, 0.558, and 0.591, respectively). Furthermore, the S3 index reached the highest correlation (r = 0.732) in the sample group (n = 50) of mean body weight of 1560.8 g, suggesting that a quantitative comparison of individual slenderness would be more accurate within this fish size range. In addition, 636 pedigreed fish from 21 full-sib families were used for estimates of genetic parameters via an animal model. In comparison with the low heritability of K, the three ratios showed moderate to high heritability (h2 = 0.47 ± 0.14, 0.20 ± 0.08, and 0.31 ± 0.11, respectively), indicating significant potential for their genetic improvement. However, there were weak but undesired phenotypic and genetic correlations between body weight and the three ratios (0.13 < rp < 0.19; 0.23 < rg < 0.50), predicting that selection for rapid growth may slowly lead to the development of a rotund shape. In conclusion, the novel S3 index was suggested as the preferred candidate of shape traits for selective breeding in grass carp, especially because its expected relative genetic gain (4.07% at 10% selection intensity) was higher than those of the others (1.44%–3.99%).

A complete check-up of European eel after eight years of restocking in an upland river: Trends in growth, lipid content, sex ratio and health status

By combining field research and careful laboratory analysis of samples over the course of an eight-year study, we met the challenge of assessing the life history traits and health status of eels restocked in freshwater ecosystems. We found that restocked eels exhibited good growth performance; moreover, the stocks were female-dominated, showed a good Fulton's condition factor (K) and lipid stores and had high survival probability estimated using the best model of Jolly-Seber stock assessment method for open populations. A necropsy revealed the absence of internal lesions. A swim bladder examination revealed the absence of the parasite Anguillicola crassus. Polymerase chain reaction (PCR) analyses revealed an increase of Anguillid herpesvirus-1 (AngHV-1) prevalence throughout the study. Most positive subjects expressed viral loads compatible with a latent infection and correlated positively with K. All restocked eels were contaminated by at least one of the organic pollutant congeners studied, but the pollution loads corresponded to the lowest range of pollutant concentrations reported in the available literature for European eels and did not exceed the maximum residue and contaminant limits in food and feed of several national and international regulations. Pollutant loads were negatively correlated with K, lipid content and eel density for polychlorinated biphenyls PCB 138, 153 and 180 and K for pesticides p.p’-DDE, p.p’-DDD, p.p’-DDT and PBDE47. This study highlights the potential role played by upland aquatic ecosystems in enhancing riverine silver eel production from the perspective of species conservation. To be successful, restocking must be accompanied by improved ecosystem quality and migration routes for eels in inland freshwaters. We also provide some recommendations for future research to improve the management of restocking programmes.

Assessing integrated biomarkers of triplefin fish Forsterygion capito inhabiting contaminated marine water - A multivariate approach

The presence of multiple chemicals in aquatic ecosystems makes evaluation of their real impact on the biota difficult. Integrated biomarkers are therefore needed to evaluate how these chemicals contribute to environmental degradation. The aims of the present study were to evaluate responses to and effects of marine pollution using a series of biomarkers through multivariate analyses. Transcriptional responses of cyp1a (cytochrome P450), mt (metallothionein), vtg (vitellogenin) and cyp19b (cytochrome P450 aromatase); branchial and hepatic histological alterations; and Fulton condition factors (CF) were evaluated, as well as the metals and polycyclic aromatic hydrocarbons present in Forsterygion capito in Auckland, New Zealand. Sites were selected along a contamination gradient: four highly contaminated sites and four less contaminated. Molecular responses with a higher relative expression of the mt and cyp1a genes were detected at a highly contaminated site (Panmure). Several histological lesion types were found in the livers of fish inhabiting both types of sites, but gill lesions were present primarily at highly contaminated sites. In terms of general health status, the lowest CF values were overwhelmingly found in fish from the same site (Panmure). The multivariate approach revealed that telangiectasia and hyperplasia were associated with the presence of chemicals, and these showed negative associations with the CF values, with fish from three highly contaminated sites being most affected. In conclusion, the multivariate approach helped to integrate these biological markers in this blennioid fish, thus providing a more holistic view of the complex chemical mixtures involved. Future studies should implement these analyses.