Fish Length Research Articles

Anatomical hooking location and bleeding occurrence in northern pike (Esox lucius) caught in recreational catch-and-release angling in a lake with reduced prey fish availability

Catch-and-release (C&R) is a common practice in recreational angling for northern pike (Esox lucius), whereby the angler releases the fish back into the water after capture with the expectation that it will survive with negligible stress and physical injuries. This may not always be the case, as hooking in critical anatomical locations, such as gills, esophagus, and stomach, increases the frequency of bleeding at the hook wound and has been recognized as a key determinant of post-release mortality in pike. Several factors (e.g. bait type and size, hook characteristics, and fish length) can influence the risk of hooking in critical locations, and the fish’s willingness to strike the fishing lure/bait may largely depend on previous feeding history and associated motivation to feed. In this respect, food deprivation and greater feeding motivation can be expected to result in an intensified response and more forceful attacks on fishing lures/baits, which could increase the risk of hooking injuries in sensitive tissues, as the fish may ingest the hook more deeply. Here, we assess the hooking location and bleeding occurrence in pike caught on soft plastic shads and baitfish in a shallow eutrophic lake. The prey fish density of this lake, primarily common roach (Rutilus rutilus), has been substantially reduced by seining as part of a lake restoration project. Experimental angling sessions took place at the end of 2020 and 2022, approximately 1–2 months and 25–26 months after the initial reduction in prey fish density, respectively. Removal of roach from the lake was also done regularly by seining after the angling sessions in 2020. Pike angled in 2022 had significantly lower body condition than individuals caught in 2020, indicating that mass removal of roach from the lake resulted in food shortage. The risk of hooking in critical locations (herein defined as hooking in gills and back of mouth) was not associated to angling year, body condition, or length of the pike. However, across the two angling years, the incidence of hooking in critical locations was higher for soft plastic shads compared to baitfish (24.2% versus 7.4%). Pike caught on soft plastic shads also bled more frequently than individuals caught on baitfish (19.7% versus 6.2%), most likely due to the fact that hooking in the gills almost exclusively occurred with soft plastic shads. Bleeding propensity was also not related to angling year, body condition, or fish length. Hence, the present study found no evidence that long-term reductions in food availability and resulting declines in body condition influence how pike strike and ingest fishing lures/baits, at least not in a manner that increases the risk of hooking injuries in sensitive locations. Instead, bait type seems to play the largest role for the observed bleeding patterns. We recommend that future studies investigate the potential effects of C&R angling on the post-release survival of pike with reduced body condition due to limited food availability.

Growth, Hematological Evaluation and Heavy Metal Bioaccumulation in Nile Tilapia (Oreochromis niloticus) from A Municipal Waste Landfill Reservoir

The aim of this study was to evaluate the growth performance, mortality rate, and blood profile of Cd-, Pb-and Cr-contaminated Nile tilapia from the Khon Kaen municipal waste landfill reservoir and compare the parameters with those of fish from unpolluted sites. Human bioaccumulation factor (BAF) determination was also performed. Thirty samples of Nile tilapia were taken from the Khon Kaen municipal waste landfill reservoir (CN) and from unpolluted (TN) ponds. Water and soil were collected from these sites, and tilapia muscle, gill, and liver were obtained for heavy metal evaluation. The Cd concentrations in the muscle, gill and liver were 0.003 ± 0.001, 0.006 ± 0.008, and 0.004 ± 0.003 mg/kg; the Pb concentrations were 0.078 ± 0.173, 0.880 ± 1.360 and 1.110 ± 1.862 mg/kg; and the Cr concentrations were 0.067 ± 0.135, 0.572 ± 1.098 and 0.636 ± 1.272 mg/kg, respectively. The total fish length, body weight and survival rate were significantly lower in the TN group (P <0.05), and alanine aminotransferase and creatinine were significantly (P <0.05) higher in the TN group. The hematocrit count of the TN group was also lower than that of the CN group but without a significant difference. The BAF ranged from 0.1-4.3, especially in the gills and liver, which are major heavy metal accumulation organs. Heavy metal contamination in landfill leachate negatively affects fish health and its production. Keywords: Aquaculture, Nile tilapia, Heavy metal, Pathology, Toxicity

The enigmatic occurrence, size distribution, and significance of a new macrourid species, Nezumia armentrouti, based on otoliths from the Lincoln Creek Formation (upper Oligocene Section), Washington State, USA

ABSTRACT Teleostean otoliths (112 sagittae) from the Lincoln Creek Formation (upper Oligocene), Washington State, U.S.A., were identified as Nezumia armentrouti n. sp. except for two specimens. The preponderance of one species (98.21%) is very unusual. Equally puzzling is the size of the otoliths that represents almost exclusively large, mature fishes (extant N. aequalis used as an analogue). Otoliths do not reflect various ages (sizes), and there appears to be an absence of larval, juvenile, or subadult representatives. The restricted range (97.32% of specimens 8.1–16.1 mm) of the otolith lengths (and corresponding fish length) is attributed to depth stratification, which is well-known in extant macrourids. Otoliths may be the result of piscivorous predators and subsequent excretion. However, the unusual occurrence of the otoliths (single, or at most, two specimens often associated with thin bone beds) may indicate a different process such as the death and decay of individual fish. This investigation is highly significant on many fronts including the first fossil occurrence of the benthopelagic deep-sea Nezumia in North America (excluding the Caribbean), possible evidence of depth stratification in the paleoenvironment based on otolith length, and otoliths from an outer shelf/shelf break to upper slope paleoenvironment (200–600 m), which are extremely rare in the published fossil record.

I spy: Factors influencing the observation of oxytetracycline in calcified structures of fishes viewed using standard light and fluorescence microscopy.

The antibiotic oxytetracycline (OTC) is a fluorochrome marker, and fluorescence microscopy is used to view OTC marks in fishes' calcified structures. However, OTC marks have been observed in calcified structures using standard light microscopy for multiple species. Therefore, we conducted an experiment to investigate potential factors (i.e., season, total length of fish, growth rate, and sex) influencing the observation of OTC in calcified structures (otoliths and fin rays or spines) from channel catfish Ictalurus punctatus, gray redhorse Moxostoma congestum, Guadalupe bass Mircopterus treculii, and redbreast sunfish Lepomis auritus viewed using standard light and fluorescence microscopy. OTC stains were not observed in any otoliths under standard light; however, OTC marks were commonly observed in I. punctatus spines using standard light microscopy (56.2%). Ninety-nine percent of otoliths and 88.9% of spines and fin rays had a visible fluorescent OTC mark when viewed using fluorescence microscopy. There was a negative relationship between the observed OTC mark and total length of fish for each season, but fish injected in the summer had the most structures with an observed OTC mark under either light condition. Understanding how OTC marking is affected by biological processes and environmental conditions will assist in future studies that rely on chemical marking of calcified structures by increasing efficacy of OTC marking and interpretation of marks.

Mean reef fish body size decreases towards warmer waters

AbstractAquatic ectotherms often attain smaller body sizes at higher temperatures. By analysing ~15,000 coastal‐reef fish surveys across a 15°C spatial sea surface temperature (SST) gradient, we found that the mean length of fish in communities decreased by ~5% for each 1°C temperature increase across space, or 50% decrease in mean length from 14 to 29°C mean annual SST. Community mean body size change was driven by differential temperature responses within trophic groups and temperature‐driven change in their relative abundance. Herbivores, invertivores and planktivores became smaller on average in warmer temperatures, but no trend was found in piscivores. Nearly 25% of the temperature‐related community mean size trend was attributable to trophic composition at the warmest sites, but at colder temperatures, this was <1% due to trophic groups being similarly sized. Our findings suggest that small changes in temperature are associated with large changes in fish community composition and body sizes, with important ecological implications.

Precision of four calcified structures for age estimation of Black Carp

AbstractObjectiveBlack Carp Mylopharyngodon piceus is an emerging invasive species in North America with an expanding population in the Mississippi River basin. Current aging methods use a suite of structures for age estimation, and a single structure is needed to minimize processing time, to maximize consistency of age and growth measurements, and to allow for back‐calculation of individual fish length at age.MethodsIn total, 236 Black Carp were collected throughout the year from 2017 to 2019 through incidental captures by commercial fishers and biologists. In a subsample, 119 Black Carp from 429 to 1268 mm total length were compared for the precision of annuli counts by two experienced readers for the two anterior pectoral fin rays, the anterior dorsal fin ray, sectioned vertebrae, and lapilli otoliths based on percent exact agreement (PA), percent agreement within 1 year (PA ± 1), coefficient of variation (CV), and bubble plots. Consensus annuli counts were compared by PA and CV between structures. We applied annuli counts, as opposed to age, as fish were collected during all seasons and structures were examined independently by readers without knowledge of capture date.ResultVertebrae and dorsal rays had the highest PA between readers. Dorsal ray had the lowest CV and higher PA ± 1. Pectoral rays and lapilli otoliths had the lowest PA. Between‐structure consensus annuli counts indicated that pectoral rays and the dorsal ray annuli counts were the most similar (PA >70% and CV <12) and lapilli otoliths were the most dissimilar (PA >35% and CV >24). Reader‐reported confidence was highest for vertebrae, then in decreasing order, dorsal ray, pectoral rays, and lapilli otoliths. Lumens were present in all fin rays with only minor effects observed on annuli counts, aside from the anterior‐most pectoral fin ray, in which lumens obscured the presence of one or more potential annuli in 61% of structures.ConclusionThe dorsal ray had the highest agreement between readers, with agreement with ±1 year at 98%; the structure can be efficiently extracted and processed, and the structure's morphology and growth pattern are conducive to aging older fish. Vertebrae had high agreement between readers, but a systematic pattern of double bands in vertebrae increased the between‐reader variation in older fish as the interannual growth pattern compressed the viewable area; this was identified by readers based on aging criteria and highlights the need for training novice readers. Validation of annual growth in the tested suite of structures is still needed.

Trace elements in the muscle and liver tissues of Garra shamal from the freshwater ecosystem of Oman: an exposure risk assessment

Anthropogenic activities lead to environmental contamination with foreign substances such as heavy metals. This work was aimed to monitor trace elements (total arsenic (As), cadmium (Cd), chrome (Cr), cobalt (Co), copper (Cu), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), and zinc (Zn)) contamination levels (dry weight base) in three natural freshwater reservoirs of Oman including Al Khawd and Al Amarat (Muscat Governorate) and Surur area (Ad Dakhiliyah Governorate as control area) using a native benthic inland fish (Garra shamal; Cyprinidae) for the first time. The muscle and liver of a hundred and twenty G. shamal were collected to assess the degree of metal contamination. Atomic absorption spectrometry was used as an analytical technique. From the spectrum of analyzed elements, we found Zn as a major element in monitored areas. The statistically significant (P < 0.05) highest concentrations of Zn liver (0.275 ± 0.065 µg/g) were in Al Amarat compared to the other areas. The concentrations of monitored elements in the fish muscle were lower than the liver samples. Furthermore, the fish length was significantly correlated with the accumulation of Hg and Co in both muscle and liver samples. In all analyzed fish from Oman inland water, the concentrations of elements were below the permissible limits; however, additional research is needed.

Accumulation of mercury in muscle of orange-spotted spinefoot(Siganus guttatus Bloch, 1787) by age and season in the coastal Quang Binh

Orange-spotted spinefoot (Siganus guttatus) is not only a fish with high economic value, rich in nutrients, but also popular with people for consumption. This research was carried out from November 2021 to May 2022, in the coastal and estuaries of Quang Binh province. A total of 60 samples of orange-spotted spinefoot were collected by age group, wet season, and dry season to analyse the accumulation of mercury (Hg) in their muscles. The Hg concentration was analysed by cold vapour atomic absorption spectroscopy. Research results showed a strong correlation between the length and weight of fish both in the wet and dry seasons. The age group has a strong influence on the accumulation of Hg in their muscles, the older fish group has a higher aggregation of Hg than the younger fish group. Although the average value of Hg concentration in the muscle of orange-spotted spinefoot in the dry season is higher than in the wet season, analysis results of “Tukey’s HSD test” showed that there was no significant difference.

Stock Assessment and Virtual Population Analysis of Carassius auratus (Linnaeus, 1758) in the Al-Diwaniya River, Middle of Iraq

A total of 1128 individuals of C. auratus were collected from the Diwaniyah River, Iraq. Samples were collected between November 2016 and October 2017 using different fishing gears aiming to assess the stock assessment and virtual population analysis. Fish length ranged from 8.0 to 33.0 cm, with a length-weight relationship exhibiting positive allometric growth. Asymptotic length (L∞) was estimated at 33.0 cm, the growth coefficient (K) was 0.16, and the growth performance index (Ǿ) was 2.241. The values of total (Z), natural (M) and fishing (F) mortality rates were 0.89, 0.47, and 0.42, respectively. The exploitation rate (E) was 0.48. Length with a 50% probability of capture (LC50) was estimated at 18.7 cm and was higher than the length at first maturity (Lm50). The recruitment consisted of one seasonal pulse from April to July. The exploitation rate (E) was below the biological target reference points (E0.1 and Emax), indicating the stock was under exploitation state. The result of the virtual population analysis revealed that most of the fishing mortality happened in mid-lengths (18-26 cm) with a maximum rate at a length of 25 cm. Natural losses were highest among individuals within the length range of 8.0 to 15 cm and then decreased gradually to the length group of 30. For management purposes, this study suggests that more yields can be obtained by increasing the fishing activities on this invasive species, such as increasing the number of fishing boats and decreasing the mesh size to decline its abundance in the long term.

Trophic Transfer of Cd, Cu, Pb, Zn, P and Se in Dutch Storage Water Reservoirs.

Heavy metals are naturally omnipresent in aquatic systems. Excess amounts of heavy metals can accumulate in organisms of pollution impacted systems and transfer across a food web. Analysing the food web structure and metal contents of the organisms can help unravel the pathways of biomagnification or biodilution and gain insight in trophic linkages. We measured heavy metals and other elements in mussel bank detritus and organisms of the Biesbosch reservoirs (the Netherlands) and linked those to stable isotopic signatures. The heavy metal contents (cadmium, copper, lead, and zinc) were often lowest in benthivorous, omnivorous and piscivorous species (mainly fish); whereas, phosphorus contents were lower in the autotrophs. Mussel bank detritus contained the highest amounts of heavy metals. The heavy metals were negatively correlated with δ15N values. For selenium no clear trend was observed. Furthermore, there was a negative correlation between fish length and some heavy metals. Based on all 20 analysed elemental contents, similarities between species became apparent, related to niche or habitat. This study confirms that elemental contents of species can differ between feeding guilds and/or species, which can be attributed to metabolic and physiological processes. The organisms in higher trophic levels have adaptations preventing metal accumulation, resulting in lower contents. Within the fish species biodilution occurs, as most metal contents were lowest in bigger fish. Overall, the metals did not seem to biomagnify, but biodilute in the food web. Metal analyses combined with isotopic signatures could thus provide insights in metal transfer and possible trophic linkages within a system.

Increasing mercury bioaccumulation and biomagnification rates of Nile perch (Lates niloticus L.) in Winam Gulf, Lake Victoria, Kenya

The Nile perch (Lates niloticus L.) commercial fishery for Lake Victoria in East Africa is an important source of revenue and employment. We focused on shifts in food web structure and total mercury (THg) bioaccumulation and biomagnification in Nile perch, and lower food web items collected from Winam Gulf (Kenya) sampled 24 years apart (1998 and 2022). Stable isotope carbon (δ13C) values were higher in all species from 2022 compared to 1998. Stable nitrogen isotope (δ15N) values in baseline organisms were lower in 2022 compared to 1998. In Nile perch, δ15N values were correlated with total length, but the δ15N-length regressions were steeper in 1998 compared to 2022 except for one large (158 cm) Nile perch from 1998 with an uncharacteristically low δ15N value. Total Hg concentrations were lower in lower trophic species from 2022 compared to 1998. However, the THg bioaccumulation rate (as a function of fish length) in Nile perch was greater in 2022 compared to 1998 resulting in 24.2 % to 42.4 % higher wet weight dorsal THg concentrations in 2022 Nile perch for market slot size (50 to 85 cm) fish. The contrasting observations of increased THg bioaccumulation with size in 2022 against decreases in the rate of trophic increase with size and lower THg concentrations of lower food web items imply reduced fish growth and potential bioenergetic stressors on Winam Gulf Nile perch. All samples except 1 large Nile perch (139 cm total length collected in 2022) had THg concentrations below the European Union trade limit (500 ng/g wet weight). However, for more vulnerable individuals (women, children and frequent fish eaters), we recommend a decrease in maximum monthly meal consumption for 55–75 cm Nile perch from 16 meals per month calculated for 1998 to a limit of 8 meals per month calculated for 2022.

Variabilitas musiman terhadap hasil tangkapan Tuna Madidihang (Thunnus albacares)

Fishermen in North Buru often depend on seasonal changes in tuna madidihang abundance to plan their fishing operations. However, a more comprehensive understanding of how this seasonal variability affects catches and its implications for fisheries management is still an important research subject. The research was conducted in Wailihang Village, Waplau District, North Buru Regency, between October and December 2022. The observational method was used for this study, where available and precise time series data owned by the Indonesian Community and Fisheries Foundation (MDPI) was collected. The collected data is the number of catch productions (kg) and the total length of fish (cm) from each haul. Yellowfin tuna production tends to fluctuate, with the highest catch (CPUE) occurring in September (63.8%) and the lowest in June (34.2%). The west season and east seasons have a total catch of 556 fish (45.42%), with 382 fish (31.21%) caught during the east season and 174 fish (14.22%) caught during the west season. The distribution of fish length varies in the east season compared to the west season. The west season catches more fish, but they are generally small-sized, while during the east season, large fish dominate, with the highest presentation (38.67%).

PENGARUH KETINGGIAN AIR TERHADAP PERTUMBUHAN DAN KELANGSUNGAN HIDUP BENIH IKAN KOI (CYPRINUS CARPIO)

Koi fish (Cyprinus carpio) is one of the most popular ornamental fish with high economic value and can compete in local and international markets. One of the obstacles in koi fish farming is growth and survival caused by changes in temperature. One of the factors that affect temperature changes is water level. This study aims to determine the effect of water level on the growth and survival of koi fish seeds. This study used an experimental method with a completely randomized design (CRD). There were 4 (four) treatments tested, namely P1 (15 cm) as control, P2 (20 cm), P3 (25 cm), and P4 (30 cm). Each treatment was repeated 3 times, resulting in 12 experimental units. The variables taken were fish length and weight, and water quality (temperature, pH, DO, ammonia). The results showed that. The ideal container water level and can provide the best results to support the growth of koi fish fry is 25 cm. At a water level of 25 cm, weight growth of 0.034 grams/day, length growth of 0.018 cm/day, specific growth rate of 0.021%/day, and survival rate reached 100%. Meanwhile, water quality parameters during the study were in the optimal range, namely temperature 19 - 23 °C, pH 7, dissolved oxygen 5 - 8 mg/L, and ammonia 00.1 - 0.06 mg/L.

Diet of the European Shag Gulosus aristotelis during the non-breeding season at a roost within a tidal channel

ABSTRACT The diet of the European Shag Gulosus aristotelis was assessed at one of their most northerly roosts in the UK; Bluemull Sound, Shetland. One pellet and 40 faecal samples were collected during the non-breeding season. The most frequent prey was Velvet Swimming Crab Necora puber, while the highest number of otoliths were from Saithe Pollachius virens and estimated mean (±sd) fish length was 143.9 ± 66.9 mm (range 81.4–223.6 mm).

Implementation of YOLOv8-Pose Model for Identification and Estimation of the Length of Skipjack and Tuna Like Species on the Website

Skipjack and tuna species are crucial to Indonesia’s capture fisheries sector as they are the largest export commodities. These groups are diverse, and the identification and measurement of their length can be timeconsuming due to the abundance of caught fish and their morphological similarities. The objective of this study is to utilize an artificial intelligence algorithm to detect the species and estimate the length of four types of fish: bullet tuna (Auxis rochei), black skipjack (Euthynnus lineatus), mackerel tuna (Euthynnus affinis), and skipjack tuna (Katsuwonus pelamis). This algorithm will be implemented through a website. The YOLOv8-Pose deep learning model is employed to identify each fish species and estimate their length by determining keypoints. The dataset used consists of 148 images with rulers and 185 images of the four types of fish. Computer Vision Annotation Tool (CVAT) is used to assist in the labelling of the dataset, enabling the detection of boxes and keypoints. The labelled dataset is trained using Google Collaborator, resulting in the production of two model weights. Both models achieve an accuracy rate of 100%, as well as precision, recall, and an F1-score of 1. The coefficient value between the actual fish length and the detected fish length is 0.8649 or 86.5%, indicating a relationship between the two variables. To facilitate the identification, measurement, and storage of data in CSV format, a website is created using the Streamlit framework. In summary, the models accurately identify the limited number of datasets for Auxis rochei, Euthynnus lineatus, Euthynnus affinis, and Katsuwonus pelamis, and can provide estimates of fish length through the website.

Lernaeid parasites prevalence in commercial freshwater fish species at various fish farms in Pakistan.

Reports abound on Lernaea parasitizing the brood stock, fingerlings, and marketable-sized culturable freshwater fish species in various parts of the world. We investigated seven small-scale aquaculture farms and how the prevailing Lernaea is impacting them. Randomly seven fish farms were selected to determine the prevalence percentage of lernaeid ectoparasites. Relevant information of the fishponds to estimate the various aspects such as effects of water source and quality, feed, stocking density, treatment used, and weight and length of fish, concerned with Lernaea infestation and prevalence was gathered. The results indicated that Catla catla (F. Hamilton, 1822) showed highest prevalence (41.7%) among the seven fish species, whereas Oreochromis niloticus showed zero. Other five fish species Ctenopharyngodon idella, Cirrhinus cirrhosis, Cyprinus carpio, Labeo rohita and Hypophthalmichthys molitrix showed 13.2%, 8.1%, 7.7%, 7.4%, 0.9% prevalence, respectively. In Royal Fish Farm 84.3% lernaeid infestation was observed, while no parasite was observed in the Vicent's Chunnian fish farm. The water source, quality, feed, fertilizers, stocking density, water temperature, and potential treatment options displayed varying tendencies among fish farms and prevalence. Depending on the weight and length, the highest prevalence (56.7%, and 66.7%) was observed in 3501-4000 g and 81-90 cm groups. The infestation rate varied in various fish body parts with the dorsal fin the most vulnerable organ and showed 2.3% overall prevalence (while 18.4% contribution within total 12.6% infestation). Out of 147 infected fish samples, 45 were extensively contaminated by Lernaea spread. In conclusion, our findings confirm that Lernaea could pose a considerable threat to marketable fish, and various treatment options should be educated to the farmers to help mitigate the spread and potential losses. Furthermore, Catla catla is more vulnerable to Lernaea infestation (41.7%), so are the fish species being cultured at higher stocking densities.

Study of digestive enzymes in marine fish, Terapon jarbua, from Pakistan.

Current analysis were performed to investigate the activity of various digestive enzymes, such as lipases, proteases and amylases in gut and their relationship to the other morphometric variables in a wild marine fish, Terapon jarbua. The descriptive data of the studied traits included fish weight, fish total length, gut weight, gut length, relative gut length, relative gut mass, Fulton's condition factor, standard length and Zihler's index. Gut length showed positive correlation with fish total length and gut weight, relative gut length (RGL) showed positive correlation with gut length. Relative gut mass (RGM) also showed positive correlation with total length (TL), gut weight (GW) and gut length (GL). Fulton's condition factor showed positive correlation with fish weight, while negative correlation with fish total length and relative gut mass. Standard length displayed positive correlation with gut weight and gut length while, it showed negative correlation with Fulton's factor. Zihler's Index displayed positive correlation with gut length, RGL and Zihler's RGM while, while showed negative correlation with Fulton's factor and fish weight. Lipase showed negative correlation with gut weight. Amylase and protease activity have no correlation with other studied traits. Lipase activity displayed negative significant correlation with gut weight. Lipase activity showed significantly negative effect on gut-weight. Amylase activity on y-axis (PC2) contributed 13% in variation but not significantly correlated with first two principal components. It showed non-significant negative correlation with fish weight, fish length and Fulton's factor while positive but not-significant correlation with other traits. Protease has positive and non-significant correlation with fish weight, RGL, Fulton's factor, lipase and amylase while non-significant negative correlation with all other traits.

Mercury (Hg) concentration in fish commercialized in the São Luís fish market (MA) and potential exposure of consumers.

Fish consumption is the main path of human exposure to Hg and may represent a risk to public health, even with low Hg concentrations in fish, if consumption rates are high. This study quantifies, for the first time, the Hg concentrations in nine most commercialized species in the São Luís (MA) fish market, where fish consumption is high, and estimates human exposure. Average Hg concentrations were highest in carnivorous species, yellow hake (Cynoscion acoupa) (0.296 mg kg-1), the Atlantic croaker (Micropogonias undulatus) (0.263 mg kg-1), whereas lowest concentrations were recorded in iliophagous Mullets (Mugil curema) (0.021 mg kg-1) and the Shorthead drum Larimus breviceps (0.025 mg kg-1). Significant correlations were observed between Hg concentrations and fish length in two species: the Coco-Sea catfish (Bagre bagre) and the Atlantic bumper (Chloroscombrus crysurus), but not in the other species, since they presented relatively uniform size of individuals and/or a small number of samples. Risk coefficients, despite the relatively low Hg concentrations, suggest that consumers should limit their consumption of Yellow hake and Atlantic croaker, as they can present some risk to human health (EDI > RfD and THQ > 1), depending on the frequency of their consumption and the consumer's body weight.

Determination of metals in different tissues of Trachurus trachurus from the Marmara Sea and evaluation of their health risks

The present study aimed to determine the differences in metal levels of Aluminum (Al), Cadmium (Cd), Chromium (Cr), Copper (Cu), İron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb) and Zinc (Zn) between muscle and liver tissues of Trachurus trachurus, the correlation of metal accumulation in tissues with fish length and weight was examined. Health risks and nutritional adequacy were evaluated based on metal levels accumulated in fish muscle. The results demonstrated that fish liver accumulated higher metal levels than muscle. The investigation revealed that the majority of metals present in the tissues of the fish did not exhibit a significant correlation with their size (p&gt;0.05). It can be concluded that fish are not an adequate source of these nutrients because their nutrient levels are below reference values. The fish were found to be nutrient deficient, as the levels of nutrients were below reference values. The estimated daily intakes of all metals accumulated in muscle were below reference doses. The target hazard coefficient and target hazard index values were less than 1. Lifetime carcinogenic risk values were below 10-4, and total carcinogenic risk values were within the acceptable range. Pb and Cd concentrations in muscle exceeded the tolerable limit. The daily amount of fish that could be consumed without non-carcinogenic health risk was 181 grams for Cd and 295 grams for Pb. The daily amount of fish that could be consumed without carcinogenic health risk was 1.21 grams for Cd and 231 grams for Pb.

The Effect of a Combination of Tofu Drugs and Maggot Flour (Hermetia Illucens L) as an Alternative Feed on the Growth of Sangkuriang Catfish (Clarias Gariepinus Var)

Feed is a crucial thing to support the production and growth of catfish. Most catfish farmers still rely on commercial feed or factory feed. Meanwhile, factory feed prices are currently still relatively high. Maggots can be an alternative feed that meets the requirements as a protein source. Apart from Maggot, fish also need a source of vegetable protein such as tofu dregs which has the advantage of having chemical properties that are dominated by protein so that it can be used as an alternative feed ingredient. The aim of this research is to determine the effect of the combination of tofu dregs and maggot flour ( Hermetia illucens L) as an alternative on the growth of Sangkuriang catfish ( C. gariepinus var ) and to determine the percentage of the combination of tofu dregs and maggot flour ( Hermetia illucens L) that can provide the best growth influence on the growth of Sangkuriang catfish ( C. gariepinus var ). This research used an experimental method using a Completely Randomized Design (CRD) consisting of 5 treatments with 4 replications. The frequency of feeding is 2 times a day, namely morning and evening. Measurement of length, weight, viability and water quality, once every 15 days. The results of the research showed that there was a combination effect between maggot pellets and tofu dregs. The best combination percentage was in treatment D (25% tofu dregs + 75% maggot flour) with an average length and weight of fish of 3.86 cm and 6.24 kg with a survival rate of 100%.