Small Fish Research Articles

Population parameters of golden ponyfish, Photopectoralis aureus and goldstripe ponyfish, Karalla daura from Saint Martin Island, Bay of Bengal

Golden ponyfish Photopectoralis aureus and Goldstripe ponyfish Karalla daura are small fish with less economic value. Many marine fish population parameters were not investigated because of their low commercial value. Therefore, the primary goals of this study were to determine the size frequency, length-weight relationship (LWR), length-length relationship (LLR), and Fulton’s condition factor (Kn) of two tropical ponyfishes from Saint Martin’s Island. From March to April 2022, specimens were caught using fixed purse nets. A total of 409 specimens of P. aureus and K. daura were measured to determine size frequency, LWRs, LLRs, and Fulton's condition factor. For P. aureus, the maximum total length (TL) of 12.9 cm sets a new record. The LWRs for P. aureus and K. daura were highly significant (p<0.001), where the coefficient of determination (r2) was 0.985 and 0.869 for P. aureus and K. daura, respectively. The estimated slope (b) for P. aureus and K. daura were 3.147 and 2.986, respectively. The LLR equations were TL = 1.1089 SL + 0.2689 for P. aureus and TL = 0.6792 SL + 3.3309 for K. daura. The Kn value had no significant difference between the species of different length classes for P. aureus (0.97-1.40) and K. daura (1.19-1.26). There has never been any prior reporting of LWRs or length-length relationships (LLRs) for P. aureus in literature or FishBase. The study's findings may benefit the management and conservation of these ponyfishes. Res. Agric. Livest. Fish. Vol. 11, No. 1, April 2024: 105-114

Asian swamp eels (Synbranchidae, Monopterus) in Florida: distribution, spread, and range of hydrologic tolerance over twenty-seven years (1997–2023)

Asian swamp eels (Monopterus albus/javanensis) were first reported as introduced to Florida waterbodies in 1997 near Tampa and Miami; a third population was recorded by 1999 in Homestead. Initial assessments, published soon after swamp eels in southern Florida were first recorded in wetlands beyond canals and ponds (in 2007), concluded there was little threat to Florida’s aquatic ecosystems. Long-term data now suggest they precipitated population crashes of crayfishes and small fishes in the eastern Everglades. We used records from continuous long-term monitoring programs, sporadic monitoring studies, and online databases to reconstruct swamp eel presence across Florida. Monitoring studies provided wetland hydrologic variables to assess limits for swamp eels. From 1997–2007, populations in southern Florida remained restricted to canals; initial spread from 2007–2017 across southern Everglades National Park proceeded slowly and the two populations covered ~1500 km2 of southern Florida. From 2017–2022, the rate of spread increased as they spread west and north (~5800 km2 range). Through 2014, the Tampa population occurred only along southern/eastern Tampa Bay (~60 km2) but has since spread south along the Gulf Coast, east into central Florida, and south along the Lake Wales Ridge (~11,000 km2). We found evidence of two potentially new introductions, in Palm Beach County and Orlando. There was no clear evidence of limitation of wetland drying on swamp eel occurrence in the Everglades; they were captured in marshes that dried for 1–5 months during the previous dry season, but short-hydroperiod wetlands may have slowed spread. In the Everglades, evidence suggests swamp eels may have been inadvertently spread into marshes from canals used to deliver water for flood control and hydrologic restoration. Swamp eels are currently spreading unchecked across Florida, and there should be great concern about continued spread in this region and their establishment and spread elsewhere.

Accelerometer-based swimming metabolism of smallmouth bass (Micropterus dolomieu).

Bioenergetics is informative for a range of fundamental and applied resource management questions, but findings are often constrained by a lack of ecological realism due to the challenges of remotely estimating key parameters such as metabolic rate. To enable field applications, we conducted a calibration study with smallmouth bass (Micropterus dolomieu, 0.7-2 kg) surgically implanted with accelerometer transmitters and exposed to a ramp-Ucrit swimming protocol in a swim tunnel respirometer across a range of water temperatures (6, 12, 18, and 24°C). There was an exponential increase in fish acceleration with swimming speed, and acceleration per speed was higher in smaller fish and female fish, and at colder temperatures. Mass-specific fish metabolic rate (MO2; mg O2 kg-1 h-1) increased with swimming speed, acceleration, and temperature, and decreased with fish mass, which when combined were strong predictors of MO2. Maximum metabolic rate (MMR) was estimated to peak at 22°C, but maximum sustained swimming speed (Ucrit) remained high at c. 90-100 m s-1 above 20°C, based on second-order polynomial functions. Aerobic scope (AS) estimates peaked at 20°C (>90% AS at 17-24°C; >50% AS at 11-28°C). Males exhibited marginally higher MMR, AS, and Ucrit than females at higher temperatures. Larger fish generally exhibited higher Ucrit, but smaller fish had a marginally broader performance range (AS, Ucrit) among temperatures, benefiting from higher MMR despite a steeper increase in resting metabolic rate with temperature. These findings enable field studies to estimate metabolic metrics of smallmouth bass in situ to characterize their ecological energetics and inform bioenergetics models.

An integrative approach highlights the discrepancy in the genetic, phenotypic, and presumptive taxonomic structure of Phoxinus (Actinopterygii, Leuciscidae, Phoxininae) in Bulgaria.

The present drainage network of Bulgaria is the result of a complex Neogene and Quaternary evolution. Karst, which has developed on 23% of the territory, further complicates the hydrological pattern. Fresh waters of Bulgaria drain into the Black Sea and the Aegean Sea basins and can be roughly divided into the Danube (Middle and Lower Danube), non-Danube Black Sea, East Aegean, and West Aegean hydrological regions. Phoxinus, a small leuciscid fish, has a mosaic distribution in all four of these regions, inhabiting small mountainous and semi-mountainous streams. Based on morphology, it was identified as three species, Phoxinus phoxinus in the Danube, Phoxinus strandjae in the non-Danube, and Phoxinus strymonicus in West Aegean region. Later, molecular data revealed Phoxinus csikii and Phoxinus lumaireul in the Middle Danube and P. csikii in the Lower Danube. Phoxinus has been the focus of many studies, showing a high molecular and morphological diversity, which is not entirely consistent with previous morphology-only-based taxonomic concepts. In this study, molecular (a mitochondrial marker and a nuclear marker) and morphological data from both historical and recently sampled collections were analysed to assess the applicability of the integrative approach in Phoxinus. The results showed a significant influence of the complex paleo- and recent hydrology on the currently observed genetic structure of the considered populations and species. Furthermore, the study also demonstrated a strong influence of phenotypic plasticity on the morphological analysis of Phoxinus and the lack of a clear differentiation between P. csikii and P. strandjae. A barcoded specimen was designated as neotype to fix the species named P. strandjae in the current taxonomic concept. Finally, a significant discordance between genetically delimited clades and phenotypic groups did not allow a proper delineation of the species distributed in Bulgaria, demonstrating that more molecular markers are needed for further taxonomic study of the Phoxinus complex.

Combining mesocosms with models reveals effects of global warming and ocean acidification on a temperate marine ecosystem.

Ocean warming and species exploitation have already caused large-scale reorganization of biological communities across the world. Accurate projections of future biodiversity change require a comprehensive understanding of how entire communities respond to global change. We combined a time-dynamic integrated food web modeling approach (Ecosim) with previous data from community-level mesocosm experiments to determine the independent and combined effects of ocean warming, ocean acidification and fisheries exploitation on a well-managed temperate coastal ecosystem. The mesocosm parameters enabled important physiological and behavioral responses to climate stressors to be projected for trophic levels ranging from primary producers to top predators, including sharks. Through model simulations, we show that under sustainable rates of fisheries exploitation, near-future warming or ocean acidification in isolation could benefit species biomass at higher trophic levels (e.g., mammals, birds, and demersal finfish) in their current climate ranges, with the exception of small pelagic fishes. However, under warming and acidification combined, biomass increases at higher trophic levels will be lower or absent, while in the longer term reduced productivity of prey species is unlikely to support the increased biomass at the top of the food web. We also show that increases in exploitation will suppress any positive effects of human-driven climate change, causing individual species biomass to decrease at higher trophic levels. Nevertheless, total future potential biomass of some fisheries species in temperate areas might remain high, particularly under acidification, because unharvested opportunistic species will likely benefit from decreased competition and show an increase in biomass. Ecological indicators of species composition such as the Shannon diversity index decline under all climate change scenarios, suggesting a trade-off between biomass gain and functional diversity. By coupling parameters from multilevel mesocosm food web experiments with dynamic food web models, we were able to simulate the generative mechanisms that drive complex responses of temperate marine ecosystems to global change. This approach, which blends theory with experimental data, provides new prospects for forecasting climate-driven biodiversity change and its effects on ecosystem processes.

Association between consumption of small fish and all-cause mortality among Japanese: the Japan Multi-Institutional Collaborative Cohort Study.

Although small fish are an important source of micronutrients, the relationship between their intake and mortality remains unclear. This study aimed to clarify the association between intake of small fish and all-cause and cause-specific mortality. We used the data from a cohort study in Japan. The frequency of the intake of small fish was assessed using a validated food frequency questionnaire. The hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality according to the frequency of the intake of small fish by sex were estimated using a Cox proportional hazard model with adjustments for covariates. The Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. A total of 80,802 participants (34,555 males and 46,247 females), aged 35-69 years. During a mean follow-up of 9.0 years, we identified 2,482 deaths including 1,495 cancer-related deaths. The intake of small fish was statistically significantly and inversely associated with the risk of all-cause and cancer mortality in females. The multivariable-adjusted HRs (95% CIs) in females for all-cause mortality according to the intake were 0.68 (0.55-0.85) for intakes 1-3 times/month, 0.72 (0.57-0.90) for 1-2 times/week, and 0.69 (0.54-0.88) for ≥3 times/week, compared with the rare intake. The corresponding HRs (95% CIs) in females for cancer mortality were 0.72 (0.54-0.96), 0.71 (0.53-0.96), and 0.64 (0.46-0.89), respectively. No statistically significant association was observed in males. Intake of small fish may reduce the risk of all-cause and cancer mortality in Japanese females.

Trophic interactions between common minke whales (Balaenoptera acutorostrata) and their prey during summer in the northern Barents Sea

Global warming is causing rapid change in marine food webs, particularly at northern latitudes where temperatures are increasing most rapidly. In this study, the diet of common minke whales Balaenoptera acutorostrata was assessed both in terms of short-term (morphological analyses of digestive tract contents) and longer-term (tissue chemical markers: fatty acids and stable isotopes) prey use in the northern Barents Sea to see if they are prey shifting. Samples (blubber cores, muscle, and stomach contents) were obtained from 158 common minke whales taken during Norwegian commercial whaling operations during summer over the period 2016–2020. Two prey items, capelin Mallotus villosus and krill (primarily Thysanoessa sp.), dominated the stomach contents in the entire period of investigation, which included sampling both in June and in August, similar to findings from earlier studies. A few gadoids were also observed in the whale stomachs. Lower blubber fatty acid (FA) contents in 2016/2017 as compared with 2018/2019 were observed. This is most likely explained by differences in sampling time (June in 2016/2017 vs August in 2018/2019, i.e., after a longer feeding period during the summer in the latter case). This explanation also fits with the fact that FA profiles of the 2018/2019 whales were more similar to the FA profiles of the potential prey, presumably reflecting the two months longer assimilation time for these whales. Multidimensional mixing models based on carbon and nitrogen isotope composition of the most likely prey groups suggested that the whales ate mostly krill in four of the five sampling years. In 2018 there were indications of a higher proportion of gadoid fish, showing some dietary flexibility. The trophic level of the whales’ feeding, as interpreted from the nitrogen isotope values, was positively correlated with blubber thickness suggesting that fish-eaters tended to assimilate more energy than whales that focused more exclusively on lower trophic prey. The variation suggested by different dietary analyses methods − stomach contents, fatty acids, and stable isotopes – most likely reflects different turnover times, with muscle stable isotopes likely representing several months of dietary integration, while lipid stores are more dynamic and may represent weeks, and stomach contents represent feeding events during the last few hours. The change in diet of minke whales from small pelagic fishes (in the past) to a greater quantity of krill and demersal fish (seen in this study) suggests that the whales are responding to the ongoing borealization of the Barents Sea ecosystem.

Consistent and informed choice of drug and route of administration is key to increasing adherence to osteoarthritis treatment

The need to follow an integrated approach when prescribing treatment for patients suffering from osteoarthritis (OA) is beyond doubt. It is clear that success depends on the implementation of recommendations for both lifestyle modification and the introduction of pharmacological agents with different compositions and mechanisms of action aimed at reducing pain, stiffness, inflammation, normalizing joint function, and preventing cartilage destruction. The arsenal of such drugs is increasing, and the evidence base of effectiveness and safety is being enriched. Considering the heterogeneity of OA patients seeking help in terms of gender, age, body mass index, financial wealth, comorbidity, clinical manifestations of the disease, radiological stage of the disease and its duration, experience of previous treatment, a reasonable and agreed upon choice with the patient not only of the drug is relevant, but also the method of administration. The article provides a clinical example of a justified and coordinated choice of treatment for a patient with a generalized form of OA, synovitis of the knee joint, suffering from obesity, depression, low adherence to treatment using the example of prescribing a chondroprotector, the active component of which is a bioactive extract from small sea fish. The treatment effect was confirmed by clinical and instrumental assessment methods over time.

Catch composition, catch per unit effort (CPUE) and species selectivity of fishing gears on multi-species Kaptai Lake in Bangladesh

Kaptai Lake, the largest artificial reservoir in Southeast Asia, is home to a diverse fish fauna that supports thousands of livelihoods and is distinguished by multi-species and multi-gear fisheries. In Kaptai Lake, the gear-based catch composition, catch rate and distribution pattern are little known. From August 2020 to April 2021, a nine-month study was conducted in five upazilas using direct catch assessment surveys and fishing effort surveys from four fishing gears, namely seine nets, gill nets, lift nets, and push nets. A total of 49 morpho-species from 22 families were found, with three species from the Clupeidae accounting for 93.63 % of the catch in all gear combined. The total catch composition and CPUE were higher in seine nets (75.07 %, 13.86 ± 1.8 kg/gear/trip respectively) and lower in lift nets (4.97 %, 1.01 ± 0.21 kg/gear/trip) and showed significant differences among gears, except sampling sites whereas CPUE was higher in Naniarchar for seine nets (17.29 ± 8.89 kg/gear/trip) and lower in Langadu for lift nets (0.62 ± 0.25 kg/gear/trip). Seine nets captured more species, and the number of species increased significantly as CPUE increased. Our study assessed four gears that targeted different fish species with little overlap in leading species; seine nets and gill nets primarily targeted Clupeidae (96.53 % and 41.69 %, respectively), whereas lift nets and push nets primarily targeted Cyprinidae and Palaemonidae (38.93 % and 99.37 % respectively). The observed abundance and variety of fish species captured in gill nets suggest a significant overlap in the selectivity of this fishing method with that of lift nets. Due to the varying contributions of sites and gears, the nMDS ordination pattern reveals a weak spatial variation in catch composition. According to the SIMPER results, Bagridae, Gobiidae, and Ambassidae were the most significant contributors to site grouping patterns across all gears. Furthermore, the findings indicate that the catch composition does not follow the typical pattern of spatial variation. By implementing measures to eliminate or decrease the usage of small mesh nets, there is expected to be a corresponding decrease in the capture of small fish. Additionally, this action will help mitigate the issue of overlapping selectivity among the current fishing gears. Our findings provide baseline data on the potential efficacy of gear limitation and suggest a gear-based management strategy.

No evidence of an association between size and levels of four per- and polyfluorinated substances (PFAS) in perch (Perca fluviatilis)

It was assessed how the size of perch (Perca fluviatilis) is related to levels of four per- and polyfluorinated substances (PFAS) in its muscle tissue. These were PFOS, PFNA, PFOA, and PFHxS, for which the sum, denoted as ΣPFAS4, has a tolerable intake derived by the European Food Safety Authority. The results indicate that, in contrast to, e.g., mercury levels, ΣPFAS4 levels in perch muscle do not increase with increasing weight of the fish, which implies that consuming larger perch does not increase the risk of exceeding the TWI of ΣPFAS4, in relation to consuming smaller perch. Therefore, for risk assessment, analyzing samples of smaller perch is sufficient, demanding less effort to catch. The credibility of the results was strengthened by applying the same statistical model to mercury levels in the same samples. As expected, larger fish had generally higher levels than small fish for mercury.

Infection with Clonorchis sinensis (Cobbold, 1875) Metacercariae in Fish from the East Lake of Wuhan: Freshwater Fish in Urban Lakes May Act as Infection Sources of Liver Fluke

The liver fluke disease caused by Clonorchis sinensis is one of the most serious food-borne parasitic diseases in China. Many freshwater fish and shrimps can be infected with C. sinensis metacercariae as the second intermediate hosts in endemic regions. Owing to the lack of infected humans and the good administration of pet dogs and cats in cities of non-endemic regions, few fish are expected to be infected with C. sinensis metacercariae in urban lakes. To determine the infection of C. sinensis metacercariae in freshwater fish and shrimps in urban lakes, a total of 18 fish species and one shrimp species were investigated in the East Lake of Wuhan City. Metacercariae were isolated by artificial digestive juice and identified using morphology and rDNA-ITS2 sequences. Five species of fish, Pseudorasbora parva, Ctenogobius giurinus, Squalidus argentatus, Hemiculter leuciclus, and Rhodeus spp., were infected with C. sinensis metacercariae. The overall prevalence of C. sinensis was 32.5%. The highest prevalence was found in P. parva with 57.9%, while S. argentatus exhibited the highest mean abundance (13.9). Apart from the C. sinensis metacercariae, four species of other trematode metacercariae were also identified across twelve fish species in total. Owing to the consumption of undercooked fish and feeding cats with small fish caught by anglers, there is a potential risk that the small fish infected with C. sinensis metacercariae may act as an infection source to spread liver fluke. Given the complete life cycle of C. sinensis, stray cats and rats were inferred to act as the important final hosts of C. sinensis in urban lakes in non-endemic areas.

Effectiveness of Bacillus genus application in the treatment of osteoarthritis by bioactive fish concentrate

Background. Understanding the impact of gut microbiota on the development of osteoarthritis (OA) and investigating the potential of probiotics as a treatment remain crucial areas of research. The study aimed to evaluate the efficacy of a Bacillus-based probiotic in combination with a bioactive marine fish concentrate for the OA treatment. Materials and methods. This study included 38 patients diagnosed with grade II knee OA. A structural-modifying drug containing 0.2 ml of bioactive concentrate derived from small marine fish, was administered every other day in a dose of 2.0 ml (10 intramuscular injections in total) for 21 days. Twenty patients (main group) additionally received a probiotic containing bacteria of the genus Bacillus (B.subtilis, B.licheniformis, B.amyloliquefaciens, B.megaterium, B.pumilus) in the dosage form of oral suspension daily for the entire treatment period of 21 days. Clinical efficacy was assessed by the Western Ontario McMaster Osteoarthritis Index (WOMAC), the questionnaire was comple­ted by all patients before the study and after 3, 7, 14 and 21 days of the therapy. Results. The findings showed a significant reduction in pain by 40.6 % (p < 0.001), stiffness by 36.8 % (p < 0.001), and improvement in knee function by 26.6 % (p < 0.05) in the main group (undergoing combined therapy with bioactive fish concentrate and the probiotic) on the 7th day of treatment. In the comparison group, a decrease in pain by 27.4 % (p < 0.05), stiffness by 25.0 % (p < 0.05), and improvement in joint function by 28.9 % (p < 0.05) were observed only on the 14th day of therapy. Conclusions. It was demonstrated that administering a probiotic composition containing bacteria from the genus Bacillus enhances the efficacy of bioactive sea fish concentrate in treating OA. Reduction in pain, stiffness, and improvement in joint function can be observed as early as the 7th day after initiating their combined use. In contrast, when using the bioactive concentrate of marine fish alone, the clinical effect is typically observed by the 14th day of treatment.

Post‐Harvest Travels of Marine Fish: How Small Fish Food Systems Variously Support Food Security and Nutrition in Coastal and Inland Cities in Ghana

AbstractThis paper enquires into the travels of low‐cost varieties of marine fish in the context of Ghana, distinguishing flows that move toward coastal cities versus those destined for distant, inland cities. It derives data from field research on the Ghanaian small fish food system through surveys, FGDs and interviews conducted in Accra and Tamale. It is argued that although both coastal and inland cities partake in small fish food systems, they experience different flow patterns and FSN outcomes. These are partly related to the fact that Ghana relies on the confluence of local and imported sources for the delivery of low‐cost fish varieties to the population, especially in urban regions where such demand is high. We recommend that policies should focus on investing in infrastructure, especially transport and distribution systems linking cities to fishing communities, to enhance low‐cost fish distribution and improve FSN outcomes for low‐income urban consumers in Ghana.

Short-term heat waves have long-term consequences for parents and offspring in stickleback

Abstract Extreme temperature events, such as heat waves, can have lasting effects on the behavior, physiology, and reproductive success of organisms. Here we examine the impact of short-term exposure to a simulated heat wave on condition, parental care, and reproductive success in a population of threespine stickleback (Gasterosteus aculeatus), a small fish with exclusive paternal care, currently experiencing regular heat waves. Males were either exposed to a simulated heat wave (23°C) for five days or held at ideal temperature (18°C). Following this five-day treatment, all males were transferred to 18°C where they completed a full parenting cycle. Offspring were raised at 18°C. We found that while mass and body condition were unaffected in males exposed to a heat wave, cortisol responses were dampened across the nesting cycle compared to control males. In addition, heat wave males had longer latency for eggs to hatch, lower hatching success, and showed lower levels of parental care behavior compared to control males. Offspring of heat wave males had lower body condition, affecting swimming performance. Altogether, our results highlight the long-term impact that even short-term events can have on reproductive success, parental behavior, and subsequent generations, providing insight into population responses to rapid environmental change.

Mass capture fishing in the Marquesas Islands

ABSTRACTMass capture of small fishes with a variety of nets, traps, and weirs was widely practiced and economically important across East Polynesia at western contact. Archaeological research, however, has suggested these technologies were less important during the early settlement period and gained prominence over time. Several explanations have been proposed, including resource depression, changes in marine environments, and/or social and economic reorientations. In the Marquesas Islands, pelagic and offshore fishes were historically well represented in early assemblages relative to most Polynesian islands. Here we report on fishbone assemblages from Nuku Hiva Island that were recovered with fine mesh screens, identified using a wide range of skeletal elements, and analysed with morphometric methods. The Hakaea Beach results demonstrate that mass capture of small fishes was especially important at this locality and sustained over three early, successive occupations. These patterns may reflect the nature of the local fisheries, preferential use of high‐return capture strategies in this reef‐limited setting, and/or purposeful avoidance of ciguatera‐prone fishes and a preference for less vulnerable fishes. Overall, our findings highlight geographic variation in early Marquesan fisheries and provide archaeological evidence that mass capture technologies had an important place in the maritime toolkits of the earliest East Polynesian fishers.

Whole-Genome Sequencing Analyses Reveal the Evolution Mechanisms of Typical Biological Features of Decapterus maruadsi.

Decapterus maruadsi is a typical representative of small pelagic fish characterized by fast growth rate, small body size, and high fecundity. It is a high-quality marine commercial fish with high nutritional value. However, the underlying genetics and genomics research focused on D. maruadsi is not comprehensive. Herein, a high-quality chromosome-level genome of a male D. maruadsi was assembled. The assembled genome length was 716.13 Mb with contig N50 of 19.70 Mb. Notably, we successfully anchored 95.73% contig sequences into 23 chromosomes with a total length of 685.54 Mb and a scaffold N50 of 30.77 Mb. A total of 22,716 protein-coding genes, 274.90 Mb repeat sequences, and 10,060 ncRNAs were predicted, among which 22,037 (97%) genes were successfully functionally annotated. The comparative genome analysis identified 459 unique, 73 expanded, and 52 contracted gene families. Moreover, 2804 genes were identified as candidates for positive selection, of which some that were related to the growth and development of bone, muscle, cardioid, and ovaries, such as some members of the TGF-β superfamily, were likely involved in the evolution of typical biological features in D. maruadsi. The study provides an accurate and complete chromosome-level reference genome for further genetic conservation, genomic-assisted breeding, and adaptive evolution research for D. maruadsi.

A rapid and simple procedure for the whole-mount bone staining of small fish

ABSTRACT The cartilage and bone structure has provided insightful knowledge about evolution and ecology of fish, which is an important component of biological oceanography. However, the whole-body bone staining is a lengthy and complicated process that typically takes five days to several months, and the improvement of the conventional method has been one of the important issues in this field. Here we report a quick and easy whole-mount bone staining method for small fish, in which a newly designed fixative is applied. Compared to conventional methods, this novel protocol is a straightforward process that could be adopted for small estuarine fish and other small vertebrates.

Nutrient composition of dried marine small fish in Bangladesh and their potential to address hidden hunger

This study investigates the nutrient composition of fish powder intended for direct consumption, sourced from seven small fish species indigenous to the Bay of Bengal, Bangladesh. Locally known as chapila, chewa, faissa, ichre, loittya, mola, and olua, these fish were collected, dried to a moisture content consistent with local practices, pulverized, and subjected to analysis for proximate composition, mineral content, vitamin levels, heavy metal presence, and fatty acid profile. While the dried fish samples exhibited high nutritional quality, significant variations were observed among species for each nutrient analyzed. Consequently, no single species emerged as superior when considering all nutritional factors collectively. However, consuming 10 g of dried small fish powder sourced from the analyzed species could potentially fulfill 100% of the recommended nutrient intake (RNI) for protein, calcium, selenium, and vitamin B12 among children aged 6–23 months. Moreover, its serves as a significant source of these nutrients for pregnant or lactating women. Importantly, this intake level does not pose any risk associated with mercury or cadmium content. These findings hold promise as a valuable addition to the national food composition table, offering insights into the utilization of dried small fish from marine sources as a potent tool in the fight against malnutrition.

Fatty acid composition of two small fish in the Gyda River (Kara Sea Basin, Northwestern Siberia, Russia)

The fatty acid composition of the flesh of rainbow smelt (RS, Osmerus mordax) and ruffe (RF, Gymnocephalus cernuus), two small fish species inhabiting the Gyda River (Siberia, Russia), was assayed using a gas-liquid chromatographic method with an ionization detection system and high efficiency capillary columns. RS was found to be richer in the total fatty acid content than RF (21.5 vs. 7.07 mg g–1). The proportion of saturated fatty acids (SFA) was similar in the fish studied (29.2 % in RS and 29.6 % in RF) whereas the flesh of RS contained a higher proportion of monounsaturated fatty acids, MUFA (42.2 vs. 13.9 %), and a lower proportion of polyunsaturated fatty acids, PUFA (28.6 vs. 56.5 %) than RF. RS is rich in essential n-3 PUFAs (2610 and 2390 μg g–1 for docosahexaenoic and eicosapentaenoic acids, respectively). In RF, the atherogenic index (0.39) and thrombogenic (0.20) index were lower than in RS (0.59 and 0.27, respectively). The fatty acid profile of RS in the study area differed from that reported for the flesh of this species from a Canadian estuary probably due to substantial differences in the diet of RS in these habitats. A comparison among fish species from the Gyda River indicated that in terms of nutrition indices, RS has the highest similarity with the muksun Coregonus muksun while RF is closely related to the northern pike Esox lucius. Based on the results from this study, both RF and RS can be recommended for human consumption. In particular, RS may be used as a replacement for muksun, an overfished species, in the traditional diet of indigenous peoples in northwestern Siberia.

Efficiency of clustering methods and self-organizing maps of Adriatic sardines and anchovies regarding organochlorine and fatty acid burden.

The Adriatic Sea plays a crucial role as both a significant fishing ground and a thriving trading market for small pelagic edible fish. Recognized for their nutritional value, these fish are esteemed for their high protein content and abundance of polyunsaturated omega-3 and omega-6 fatty acids, making them a sought-after and healthful food choice. Nevertheless, pelagic species can also serve as a reservoir for lipophilic organochlorine pollutants, posing potential risks to human health. In this study, we compared traditional classification methods traditional principal component analysis (PCA) and Ward's clustering with an advanced self-organizing map (SOM) algorithm in determining distribution patterns of 24 organochlorines and 19 fatty acids in sardine and anchovy samples taken from the eastern Adriatic. The outcomes reveal the strengths and weaknesses of the three approaches (PCA, Ward's clustering, and SOM). However, it is evident that SOM has proven to be the most effective in offering detailed information and data visualization. Although sardines and anchovies exhibit similar distribution patterns for p,p'-DDE, PCB-28, PCB-138, PCB-153, PCB-118, and PCB-170, they differ in the concentrations of fatty acids such as stearic, palmitic, myristic, oleic, docosapentaenoic, and docosahexaenoic acid. Our findings supply valuable insights for environmental authorities and fish consumers concerning the potential risks associated with organochlorines in these two types of fish.