Search Results (66)

Over the past few decades, the population of cod in the Eastern Baltic has faced numerous challenges due to environmental changes, overfishing, and predation, as well as the effects of infection by third-stage larvae of the Anisakidae parasite in the liver. The aim of this study was to estimate the prevalence and infection level of Anisakidae nematodes in the Eastern Baltic cod stock over a five-year period and analyze the effect of infection on cod health condition. A total of 1946 samples of the Eastern Baltic cod (Gadus morhua) were collected and tested for the presence of Anisakidae nematode larvae. All nematodes found in livers were identified as Anisakidae with an overall prevalence of 30.9%, a mean infection density of 0.8 (median 0.4) nematodes per gram of liver tissue, and a range of 0.01–29.2 nematodes per gram. The prevalence of infection tended to increase with the age of the fish. In multivariate analysis, increasing infection intensity decreased the odds of cod having good Fulton’s and Clark’s condition scores and a hepatosomatic index (HSI) above the population average. While our study shows a clear Anisakidae effect on Fulton’s and Clark’s condition scores and the HSI, these indicators could also be influenced by other environmental, physiological, and pathological factors. Full article

Food gels were obtained using fish protein isolate recovered from Atlantic cod (Gadus morhua) by-products using the isoelectric solubilisation/precipitation method. The use of low temperatures (not exceeding 10 °C) at the alkaline solubilisation stage resulted in the production of a fish protein isolate with high-molecular mass (FPI-1), while the use of high temperatures (24 °C) resulted in the production of a fish protein isolate with low-molecular mass (FPI-2). The isolates demonstrated excellent gelling and nutritional properties based on their amino acid profiles. The denaturation temperatures of FPI-1 and FPI-2 determined by DSC were 163.0 and 158.5 °C. The secondary structure of FPI-1 demonstrated a high α-helix content and a low random coil content compared to FPI-2. The high-molecular isolate formed stronger gels than the low-molecular isolate, which is explained by the formation of a dense gel network with small pores of about 250 nm. The recovered cod protein isolates can be successfully used as food ingredients or food additives in the production of gel-like/enriched products. Full article

The rapidly developing food industry necessitates the efficient use of raw materials, which can be achieved through the production of functional ingredients with high nutritional value. Secondary fish raw materials generated during the filleting of Atlantic cod (Gadus morhua), including vertebral bones with residual muscle tissue, skin, tails, and fins, represent a promising source of both biologically active compounds and highly digestible protein substances. The aim of this study was to evaluate the properties of protein hydrolysates obtained from secondary Atlantic cod raw materials by conventional enzymatic hydrolysis and combined enzymatic-ultrasonic treatment. The best results were achieved at a power of 320 W and a treatment duration of 3.5 min prior to the addition of the enzyme preparation (Protozyme C). The application of ultrasound enhanced the degree of hydrolysis by 4–5% while simultaneously reducing the amount of enzyme used. Electrophoretic analysis demonstrated a predominance of smaller peptides in the 10–15 kDa range compared to the control sample (43–95 kDa). Infrared spectroscopy confirmed structural changes in the samples under study, manifested in an increase in the number of terminal groups and partial disaggregation of the peptide mixture. Particle size distribution analysis revealed a more uniform distribution and a decrease in the median particle size in samples with ultrasonic pretreatment. The safety and antioxidant activity assessment did not show any toxic effects, but manifested a significant increase in antioxidant indicators (2.5–3.2 times) compared to the control sample. The results obtained show the enzymatic-ultrasonic treatment to be promising for the integrated processing of fish raw materials and the production of functional food ingredients with improved properties. Full article

Early life nutrition is a critical factor influencing subsequent performance and quality, including skeletal development, in farmed Atlantic cod (Gadus morhua). This study investigated the effects of a novel start-feed protocol utilizing barnacle nauplii and plankton eggs and two experimental microdiets on larval survival, growth, skeletal anomalies, and organ ontogeny. Atlantic cod larvae were reared using three feeding protocols (COM, D1, and D2): COM used enriched rotifers and a commercial microdiet, while D1 and D2 protocols incorporated blue mussel eggs (Cryo-µ) and barnacle nauplii (Cryo-S, Cryo-L), followed by inert microdiets that differed in their phospholipid (PL) source (D1 richer in vegetable PL; D2 richer in marine PL). Larvae were sampled up to 66 days post hatching (dph) for morphometric, skeletal anomaly, and histological analyses. Survival averaged 21.3% and was unaffected by the diets. The control group had slightly higher standard length and dry weight at 66 dph compared to the experimental groups. However, larvae fed the D1 protocol exhibited a significantly lower overall prevalence of skeletal anomalies (52%) compared to the control group (91%). Moreover, D1 showed a lower occurrence of severe anomalies and a significantly reduced prevalence of scoliosis compared to both D2 and COM groups. Histology showed that group D1 achieved an overall accelerated organ ontogeny, with greater villi length and goblet cell abundance in the anterior intestine at 66 dph. In conclusion, the novel D1 feeding protocol, incorporating barnacle nauplii and a microdiet richer in vegetable phospholipids, enhanced larval quality by effectively reducing skeletal anomalies and accelerating internal organ development. Full article

Novel therapeutic approaches for wound healing have included biomaterials from the Atlantic cod (Gadus morhua L.), with promising results in wound management. The use of extracellular vesicles (EVs), which can be isolated from cod biofluids, remains to be studied. EVs play key roles in cellular communication, and their use both as biomarkers and as therapeutic agents is widely reported in human pathologies, particularly with respect to mesenchymal stem cells. This pilot study characterized the total proteomic cargo content of EVs from cod serum and mucus and assessed the EVs’ potential for regenerative activity in wound-healing processes, using human and mouse fibroblast and keratinocyte in vitro scratch injury models. The pro-regenerative potential of both cod serum EVs and mucus EVs was identified, with differing capacities for accelerating wound closure in fibroblast and keratinocyte cells. This was further supported by varying effects of the cod serum EVs and mucus EVs on cellular vimentin and FGF-2 levels. The serum EV and mucus EV protein cargoes differed with respect to abundance of protein hits and associated enriched functional GO and KEGG pathways, but both were associated with immune, stress and wound-healing processes. Cod EVs may present as innovative therapeutic options for regenerative medicine applications, and our reported findings provide valuable insights for future in-depth studies. Full article

This study investigates the effects of warming water on growth in seven demersal fish species including Atlantic cod (Gadus morhua), American plaice (Hippoglossoides platessoides), Greenland halibut (Reinhardtius hippoglossoides), roughhead grenadier (Macrourus berglax) and three species of redfish (Sebastes spp.) in the Northwest Atlantic and compares the changes in growth across species. Length-at-age data were collected from EU bottom trawl surveys from 1993 to 2018, and bottom temperature data were obtained from the Copernicus Marine Service. Generalised additive mixed models (GAMMs) were used to describe the temperature effects on growth. The analysis was carried out separately for males and females. Both sexes of all species except American plaice showed significant temperature effects on growth. To obtain the growth parameters, von Bertalanffy growth functions (VBGFs) were fitted to the predictions from best-fit GAMMs for all species and both sexes under five different bottom temperature scenarios (3, 3.5, 4, 4.5 and 5 °C). The predictions from all best-fit GAMMs were broadly similar in form to the fitted von Bertalanffy growth functions (R² > 90%). Increased bottom temperature generally resulted in a decrease in the asymptotic length (L_∞) and an increase in the growth rate (k). The species with the most dramatic increase in k over the temperature range of 3 °C to 5 °C was Atlantic cod, for which k increased from 0.05 to 0.13 year⁻¹ in females and from 0.08 to 0.14 year⁻¹ in males. The maximum length (L_max), predicted by the VBGF at maximum age generally declined from 3 °C to 5 °C. The species with the most pronounced decline in L_max was beaked redfish (S. mentella). An increase in the proportion of smaller individuals could impact population productivity and result in lower biomass available to fisheries. Uneven changes in fish growth in the warming ocean could also have wider ecological implications and alter the trophic landscape. Full article

The visual underwater monitoring of fish size, position, and swimming speed is experiencing increasing interest in aquaculture and marine research. Despite the long-standing use of video monitoring, there is no methodological consensus, but numerous researchers and developers advocate for 3D video capture techniques to facilitate biometric estimations. Most of the previous systems, however, use partially synchronized cameras (within one frame), which causes an inherent error if observing moving fish in relation to the camera. This study proposes the use of a completely synchronized 3D camera system for underwater video capture, which can be calibrated, and which allows analyses to be performed using open-source software(s). We present data on the maximum theoretical error in the size estimation of swimming fish. This article presents a guide on how to build and set up the camera hardware and run the system, including a formal study investigating pre-measured lengths, and an informal study investigating the lengths of Atlantic cod (Gadus morhua). Full article

Acellular tissue matrices of fish skin origin are highly promising materials for tissue engineering due to their low biological risks and few religious restrictions. The main component of acellular fish skin matrices (AFSMs) is collagen, but collagen properties significantly differ between marine and freshwater fish. Although the characteristics of acellular matrices may vary, relevant reports about them are few. In this study, we used cod and tilapia fish skin as raw materials to prepare acellular matrices with low DNA content (≤50 ng/mg) and low endotoxin. They were denoted as C-AFSM (cod) and T-AFSM (tilapia) and had endotoxin removal rates of 92.47% and 96.73%, respectively. Their physicochemical properties, cytotoxicity, and wound healing effects were evaluated and compared. Scanning electron microscopy images showed that C-AFSM and T-AFSM had collagenous meshwork and high porosity. They also did not induce skin irritations. Their proliferation rates on mouse fibroblasts at 36 h were 192.21% ± 33.25% and 162.89% ± 36.47%, respectively. The wound healing effect of C-AFSM was faster than that of T-AFSM group (7 and 14 days: 45.3% ± 5.99% and 93.77% ± 1.58% for C-AFSM and 39.7% ± 2.84% and 93.35% ± 1.1% for T-AFSM, respectively). Therefore, the two acellular fish skin matrices can be used as tissue-engineering materials for wound repair, with C-AFSM being more effective than T-AFSM. Full article

Managing fishery resources is crucial to ensure the marine environment continues to provide diverse goods and services. To overcome difficulties of classical methods used for fish stock management, molecular tools have shown potential to address this issue assessing both targeted and non-targeted species. This study aims to evaluate the spatiotemporal diversity of fish using 12S rRNA gene eDNA metabarcoding sequencing in the Berlengas archipelago and compare two seawater eDNA sampling sources: samples collected by fishermen during their activities and those collected by our research team. The results indicated that autumn presented the highest diversity and that the area around Berlenga Island was the richest area, increasing biodiversity across the region. Fisher-collected samples were generally less diverse than those by the research team but detected species typical of deeper and open-ocean habitats, validating this sampling method. Our study also highlighted eDNA’s role in monitoring fish species by detecting unexpected species for the region, such as Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua), while cautioning against false positives like orange clownfish (Amphiprion percula) and blue tilapia (Oreochromis aureus). Future optimisation of our eDNA sampling methodology could better refine marine ecosystem dynamics around the UNESCO Biosphere Reserve of the Berlengas Archipelago, Portugal. Full article

Alcohol dehydrogenases (ADHs) are critical enzymes involved in the oxidation of alcohols, contributing to various metabolic pathways across organisms. This study investigates type I functional divergence within three ADH1 families: Saccharomyces cerevisiae (PDB ID: 4W6Z), Gadus morhua (PDB ID: 1CDO), and Homo sapiens (PDB ID: 1HDX). Understanding the molecular evolution and mechanisms underlying functional divergence of ADHs is essential for comprehending their adaptive significance. For this purpose, we performed a computational analysis that included structural characterization of ADHs through three-dimensional modeling, site-specific analysis to evaluate selective pressures and evolutionary constraints, and network analysis to elucidate relationships between structural features and functional divergence. Our findings indicate substantial variations in evolutionary and structural adaptations among the ADH families. Full article

Animals form functional units with their microbial communities, termed metaorganisms. Despite extensive research on some model animals, microbial diversity in many species remains unexplored. Here, we describe the taxonomic profile of the microbes from the outer gut mucus layer from the Northeast Arctic cod using a shotgun DNA sequencing approach. We focused on the mucus to determine if its microbial composition differs from that of the fecal microbiota, which could reveal unique microbial interactions and functions. Metagenomes from six individuals were analyzed, revealing three different taxonomic profiles: Type I is dominated in numbers by Pseudomonadaceae (44%) and Xanthomonadaceae (13%), Type II by Vibrionaceae (65%), and Type III by Enterobacteriaceae (76%). This stands in sharp contrast to the bacterial diversity of the transient gut content (i.e., feces). Additionally, binning of assembled reads followed by phylogenomic analyses place a high-completeness bin of Type I within the Pseudomonas fluorescens group, Type II within the Photobacterium phosphoreum clade, and Type III within the Escherichia/Shigella group. In conclusion, we describe the adherent bacterial diversity in the Northeast Arctic cod’s intestine using shotgun sequencing, revealing different taxonomic profiles compared to the more homogenous transient microbiota. This suggests that the intestine contains two separate and distinct microbial populations. Full article

Coastal aquaculture and local fisheries interact in shared marine environments, influencing each other synergistically and/or antagonistically. Salmon farming, notably with open-net sea cages along the Norwegian coast, attracts wild fish due to increased food availability from uneaten feed, but it also exposes wild fish to farm emissions like waste and toxic chemicals (de-lice treatments, antifouling and medical agents). The attraction behaviour of wild fish can impact fatty acid composition in fish tissues, influenced by the high terrestrial fat content in salmon aquafeed. We study how the Atlantic cod, aggregating around salmon farms in a subarctic fjord in Northern Norway, can be affected, potentially altering their natural diet and fatty acid profiles. Our study compares the muscle-tissue fatty acid compositions of cod caught near aquaculture facilities (impact) versus fish caught in neighbouring fjords (control), and we hypothesise decreased omega-3 fatty acids near farms. The analysis revealed no significant differences in the fatty acid concentrations or categories between the impacted and control fish, challenging our initial expectations. However, differences were found for C18:1(n9)t (elaidic acid), with a higher value in the impacted fish. These findings suggest that salmon farming’s influence on cod’s fatty acid profiles in the flesh (i.e., relevant for the nutritional quality of the fillets that consumers eat) may be limited or minimal despite their aggregative behaviours around farms. The threshold levels of salmon feed consumed by wild cod before it affects the quality and survival of, e.g., sperm or other life stages, are not known and require new investigations. This study underscores the complexity of interactions between aquaculture and wild fisheries, impacting both ecological dynamics and consumer perspectives on seafood quality and health benefits. Full article

The results of our preliminary studies indicated that the diets of predatory fishes can be bioindicators of faunistic changes in ecosystems and indirectly of changes taking place in aquatic environments in the Pomeranian Bay. We examined the diet composition of top predators Gadus morhua, Sander lucioperca, Perca fluviatilis, and the mesopredator Neogobius melanostomus. The diet composition of the perch, pikeperch, and round goby in the Pomeranian Bay was analyzed for the first time. Our findings indicated that perch, an euryphagous species, is the best potential bioindicator because it is present in the area studied most of the year and has a low to moderate feeding index (FI). Baltic cod, also an euryphagous species, could be a good bioindicator in the areas where it is abundant and occurs frequently, but not in the Pomeranian Bay, where it is caught mainly in the fall. Round goby, which is present in the area studied and had a low FI, is a stenophagous species that preys mainly on benthic species, while pikeperch had a very high FI and the least number of prey species in its diet. The results of trophic interaction analysis among the predators analyzed and their non-native/invasive prey are also provided. Full article

During the desalting of salted cod, significant textural, histological, and biochemical changes occur. Understanding these changes is crucial for enhancing the preservation and extending the shelf life of desalted cod. This study aimed to investigate the physicochemical quality parameters and enzymatic activities during the desalting process of cod (16 h at 4 and 20 °C) and to extend the shelf life of desalted cod through high-pressure processing (HPP) at 400 and 550 MPa for 5 min. During desalting, a correlation was noted between the pH and trimethylamine content in samples desalted at 20 °C, with both parameters increasing in the initial 4 h and stabilizing thereafter. The soluble protein in cod muscle decreased over desalting time, as it dissolved into the desalting water. Enzymatic activity showed a decline in cathepsins (B and D) and acid phosphatase throughout desalting, whereas lipase activity increased, particularly at 20 °C. HPP effectively extended the shelf life of desalted cod by controlling endogenous microbial growth, enabling an extension to 14–21 days compared to the 7 days observed in untreated control samples. This study highlights quality changes during desalting, with lesser effects at lower temperatures. Subsequent HPP improved the microbiological quality of desalted cod during refrigerated storage. Full article

There is a need to find novel sources of fertilizers to meet the increasing food demands of a growing human population and alternatives to mined and synthetic fertilizers for the certified organic sector. Composting is a common method for processing and stabilizing organic residues for use in horticulture. To that end, a small-scale composting experiment with six combinations of dried and ground rockweed (Ascophyllum nodosum), algae fiber from chemically processed rockweed, ground bones and fishmeal from cod (Gadus morhua), and ground blue mussels (Mytilus edulis) was conducted in Dewar flasks to assess whether these residues are suitable for composting and have potential for use as fertilizers. Expanded clay aggregates were used as a bulking material. Physicochemical analyses were performed on the residues and their mixtures before and after composting, and the temperature in the flasks was monitored for 92 days. Suitability was determined by evaluating the temperature dynamics, changes in physiochemical parameters, and nutrient profiles. All treatments generated heat, with reductions in C/N ratio, weight, and volume, demonstrating suitability for composting. The treatments with algae fiber had a higher mean temperature (34.5 vs. 29.0 °C) and more degree days above the thermophilic range (mean = 176- vs. 19-degree days), the greatest reduction in volume (mean = 35% vs. 27%), and the lowest C/N ratios at the end of active composting (18 vs. 24) compared to the treatments with dried and ground seaweed. In terms of fertilizer value, none of the finished composts were balanced for use as fertilizers alone and, in some cases, contained too much Na, but contained sufficient concentrations of K, S, Mg, and Ca and could be a valuable source of these nutrients and organic matter in combination with other N- and P-rich sources. Full article