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Climate change is altering the distribution and abundance of marine species, especially in Arctic and sub‐Arctic regions. In the eastern Bering Sea, home of the world's largest run of sockeye salmon (Oncorhynchus nerka), juvenile sockeye salmon abundance has increased and their migration path shifted north with warming, 2002–2018. The reasons for these changes are poorly understood. For these sockeye salmon, we quantify environmental and biological covariate effects within spatio‐temporal species distribution models. Spatio‐temporally, with respect to juvenile sockeye salmon densities: (1) sea surface temperature had a nonlinear effect, (2) large copepod, Calanus, a minor prey item, had no effect, (3) age‐0 pollock (Gadus chalcogrammus), a major prey item during warm years, had a positive linear effect, and (4) juvenile pink salmon (O. gorbuscha) had a positive linear effect. Temporally, annual biomass of juvenile sockeye salmon was nonlinearly related to sea temperature and positively related to age‐0 pollock and juvenile pink salmon abundance. Results indicate that sockeye salmon distributed with and increased in abundance with increases in prey, and reached a threshold for optimal temperatures in the eastern Bering Sea. Changes in population dynamics and distribution of sockeye salmon in response to environmental variability have potential implications for projecting specific future food securities and management of fisheries in Arctic waters. [ABSTRACT FROM AUTHOR]

How has parasitism changed for Alaskan salmon over the past several decades? Parasitological assessments of salmon are inconsistent across time, and though parasite data are sometimes noted when processing fillets for the market, those data are not retained for more than a few years. The landscape of parasite risk is changing for salmon, and long‐term data are needed to quantify this change. Parasitic nematodes of the family Anisakidae (anisakids) use salmonid fishes as intermediate or paratenic hosts in life cycles that terminate in marine mammal definitive hosts. Alaskan marine mammals have been protected since the 1970s, and as populations recover, the density of definitive hosts in this region has increased. To assess whether the anisakid burden has changed in salmonids over time, we used a novel data source: salmon that were caught, canned, and thermally processed for human consumption in Alaska, USA. We examined canned fillets of chum (Oncorhynchus keta, n = 42), coho (Oncorhynchus kisutch, n = 22), pink (Oncorhynchus gorbuscha, n = 62), and sockeye salmon (Oncorhynchus nerka, n = 52) processed between 1979 and 2019. We dissected each fillet and quantified the number of worms per gram of salmon tissue. Anisakid burden increased over time in chum and pink salmon, but there was no change in sockeye or coho salmon. This difference may be due to differences in the prey preferences of each species, or to differences in the parasite species detected across hosts. Canned fish serve as a window into the past, providing information that would otherwise be lost, including information on changes over time in the parasite burden of commercially, culturally, and ecologically important fish species. [ABSTRACT FROM AUTHOR]

This study compared collagens from cold-water and warm-water fish for their structural, rheological, and functional properties, and explored their potential applications, aiming to realize the high-value utilization of marine biological resources. To this end, chum salmon skin collagen (CSSC) and Nile tilapia skin collagen (NTSC) were both successfully extracted. Collagens from the two species had different primary and secondary structures, with NTSC having a higher molecular weight, imino acid content, and α-helices and β-turns content. The denaturation temperatures were 12.01 °C for CSSC and 31.31 °C for NTSC. CSSC was dominated by viscous behavior and its structure varied with temperature, while NTSC was dominated by elastic behavior and its structure remained stable with temperature. Both collagens had good oil holding capacity, foaming capacity, and emulsifying activity, but NTSC had better water holding capacity and foaming and emulsifying stability. Their different properties make CSSC more suitable for the preservation of frozen and chilled foods and the production of sparkling beverages, and give NTSC greater potential in biofunctional materials and solid food processing. [ABSTRACT FROM AUTHOR]

Depuration is a proven pre-harvest procedure that eliminates off-flavor from Atlantic salmon produced in recirculating aquaculture systems. However, applied research indicates that depurating salmon lose weight while fasting, which reduces farmgate revenue. Low-ration feeding was therefore evaluated as a method to mitigate weight loss while depurating 3–4 kg Atlantic salmon. Salmon implanted with passive-integrated-transponders were weighed, exposed to concentrated geosmin (GSM) and 2-methylisoborneol (MIB), and stocked in eight pre-disinfected partial reuse systems. Feed was either offered for 4 days or withheld entirely (n = 4) during a 6-day depuration period. Salmon from both treatments rapidly eliminated GSM and MIB, but slightly lower levels remained in fish that were fed (P <.05). Fed and fasted salmon lost 0.3 and 1.1% of their initial body weight, respectively (P <.05). Under the conditions of this study, feeding Atlantic salmon during depuration minimized weight loss without negatively impacting off-flavor elimination. [ABSTRACT FROM AUTHOR]

Steinkrauss and Slotnick (2024) reviewed neuroimaging studies linking the hippocampus with implicit memory. They conclude that there is no convincing evidence that the hippocampus is associated with implicit memory because prior studies are confounded by explicit memory (among other factors). Here, we ask a different yet equally important question: do reports of unconscious hippocampal activity reflect a Type-I error (i.e. a false positive)? We find that 39% of studies linking the hippocampus with implicit memory (7 of 18) do not report correcting for multiple comparisons. These results indicate that many unconscious hippocampal effects may reflect a Type-I error. [ABSTRACT FROM AUTHOR]

Male chum salmon display a courtship behaviour involving an actively "quivering" against female, which is essential for female orgasm. Because generally male prefer larger female, we determined whether the elements of quivering such as the number, the amplitude, and the distance are affected by female body size. Additionally, quivering changes towards oviposition; therefore, we also identified the essential time for the male to succeed in his courtship behaviour. We conducted two experiments to measure quivering parameters: (i) measuring the number and the amplitude of quivering by the acceleration data logger and (ii) measuring the distance between sexes during quivering by observation of recorded video. From the first experiment, there was no significant relationship between the ratio of female‐to‐male body lengths and the number and the amplitude of quivering, while an important relationship between the body length ratio and the distance between sexes from the second experiment. Therefore, we think the distance is more significant than the number or vigour of quivering for male choice, and males quiver more closely to a larger female to increase reproductive success. In addition, when the body length ratio of the sexes is 1.01, the distance during quivering is the shortest. So, there is a possibility that the reproduction of chum salmon is based on size‐assortative mating. And both experiments also showed that male quiver passively as spawning approaches. We suggest that males may not quiver actively for smooth mating as females spawning approaches. [ABSTRACT FROM AUTHOR]

Many Atlantic salmon (Salmo salar) populations have experienced significant declines for decades throughout North America and Europe. Mortality due to marine mammal predation during their early marine life could be an important factor contributing to these declines and limiting their population recoveries. However, quantifying predation events, and particularly the extent of marine mammal predation on Atlantic salmon, remains a challenge. In this study, we estimated the contribution of mesothermic and endothermic species predation to the mortality of Atlantic salmon post-smolts during their early marine life using acoustic telemetry. Predation events were inferred from changes in temperatures and depths experienced by acoustically tagged hatchery-reared Atlantic salmon smolts. No salmon were consumed by mesothermic predators, with most endothermic predation events being classified as marine mammals. Post-smolt mortality during the study period was low overall in both years (13.1%–16.7%), with endothermic predation accounting for 33.1%–42.9% of all marine mortality events (5.2%–5.6% mortality). Our results suggest that the current low return of adult Atlantic salmon observed in this area in recent years was not heavily influenced by endothermic predation on post-smolts in the first weeks at sea. [ABSTRACT FROM AUTHOR]

Ecotourism management can draw on theory and data related to non‐consumptive effects of risk on wildlife. The asset protection principle (APP) predicts that variable food supply and its associated risks will affect antipredator behavior; responses to predation risk should dominate when food reserves are high, while nutritional risk becomes more important when food reserves are limited. Additionally, the human shield hypothesis (HSH) describes how some individuals might seek human presence if it repels potential sources of risk. Using camera traps, we used generalized linear mixed effects and multinomial regression models to test components of the APP and HSH where ecotourism co‐occurs with grizzly bear (Ursus arctos) foraging during hyperphagia. When salmon abundance was high (+1 SD), bear activity (weekly detections) decreased by 13% with every 100 visitors/week. Under low salmon conditions, bear activity increased with visitor numbers, creating 'high bear‐high visitor' conditions. Consistent with HSH, detection data revealed an increased likelihood of detecting subordinate age‐sex classes compared with adult males when visitor numbers were high. Our findings suggest that when salmon are low, managers might consider limiting visitors to mitigate disturbance. More broadly, understanding how wildlife allocate anti‐predator behavior as a function of risk and food can inform conservation science and practice. [ABSTRACT FROM AUTHOR]

The feed legislation allows the use of fish protein hydrolysates in feed for the same species in which it came from, since enzymatic hydrolysis degrades the proteins and eliminates potential prions, which have caused disease in mammals, but not in fish. In this trial, we investigated the effects of partially replacing dietary fishmeal (FM) with salmon protein hydrolysate (FPH) on the intestinal gene expression and microbiota. Atlantic salmon post smolts were either fed a control diet containing 30% fishmeal (FM), a 20% FM diet with 9% salmon hydrolysate (FPH-09) or a 10% FM diet with 18% salmon hydrolysate (FPH-18), until doubling of weight. Gene expression analysis by RNA sequencing of pyloric caeca (PC), midgut (MG) and hindgut (HG) revealed a downregulation of immunological genes involved in inflammation in the intestine of FPH-18 fed salmon compared to salmon fed the FM control. The gene expression of paralogous peptide transporters (PepT) was analyzed by real time quantitative PCR in PC, anterior midgut (AMG), posterior midgut (PMG) and HG of salmon fed all the three diets. The PepT1b paralog had highest relative expression levels in PC and AMG, suggesting that PepT1b is most important for peptide uptake in the anterior intestine. PepT1a was also mainly expressed in the PC and AMG, but at lower levels than PepT1b and PepT2b in the AMG. The PepT2b paralog had high levels of expression in AMG, PMG and HG indicating that it contributed significantly to peptide uptake in the posterior part of the gastrointestinal tract. The gut microbiota in the mucosa and digesta of the MG and HG, were dominated by the phyla Cyanobacteria and Proteobacteria, but also Firmicutes were present. The only dietary effect on the microbiota was the higher prevalence of the phyla Spirochaetes in the mucosa of FPH-18 fed salmon compared to the FM fed salmon. In conclusion, replacing FM with salmon hydrolysate reduced the expression of inflammatory markers in the Atlantic salmon intestine suggesting improved health benefits. The reduced inflammation may be related to the reduced FM content, potentially bioactive peptides in the hydrolysate and/or the altered gut microbial composition. [ABSTRACT FROM AUTHOR]

Cooling-water intakes often entrain large numbers of larval and juvenile fish, leading to questions why a water intake on the Columbia River, USA, with axial flow, cylindrical screens on a T-screen structure entrained very few (four fish in 4,007 x 103 m3 of water sampled over four years). This is despite being downstream of spawning areas for Chinook salmon Oncorhynchus tshawytscha releasing up to 56 million pre-smolts and having screens consisting of porous plate with 9.5-mm-diameter pores capable of passing salmon fry and other small fish (poor physical exclusion). Multiple publications of experiments and observations in hydraulics and biology are used to help explain the low entrainment, concluding that effects of the screening structure rather than the actual screen are most important. Primary mechanisms appear to be: (1) bow-wave-like hydraulics at the structure's nose cone that deflect small fish away from the screen's pores, and (2) fish detection and avoidance of pressure and velocity changes upstream of the structure that aid deflection. These combined hydraulic and biological-behavior effects of the structure would cause salmon fry and other small fish to bypass the screened portion of the intake. At the screens, (3) high ratio of sweeping flow to approach and through-screen velocities likely further prevents entrainment. Although site- and design-dependent, this analysis may be useful for evaluating or planning other screen installations and focusing regulatory attention on hydraulics of the structure as well as the screen. [ABSTRACT FROM AUTHOR]

Seafood products are mainly provided through trade to international markets and Norway is the major international player for the export of salmon products. It is argued that fresh or chilled salmon, which are perishable products and Norway's main seafood export, need stable trade partners to safely and properly reach consumption markets. In this study, the firm-to-firm level trade transactional data for both exporters and importers for the 2005-2018 period was utilized for a trade duration analysis. The Kaplan-Meier survival estimators, Cox proportional hazard model, and frailty model were used to study the stability of trade relations between the partners through survival and hazard models. The study considers the heterogeneous firm trade model along with a theoretical framework. The results show that, on average, the trade duration for the salmon trade between firms is 2.39 years, which is relatively low for a perishable product such as salmon. It shows that the market entry and exit is relatively fast, and that the survival rate between the EU as a major demand market and non-EU countries is not very different. However, core and periphery markets can be defined by considering the survival rate, as major processing hubs in the EU, such as Poland and France as core markets, have higher survival rates compared with other countries that can be considered peripheries. Both extensive and intensive margins were found to reduce the hazard ratio. Different hazard ratios were also found between different types of exporter or ones utilizing different means of transport. We conclude that the trade duration between the partners can be increased if the competition in the market increases, which is probably possible in markets like the United States where other exporters such as Chile are available. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The colour of seafood flesh is often not homogenous, hence measurement of colour requires repeat measurements to obtain a representative average. The aim of this study was to determine the optimal number of repeat colour measurements required for three different devices [machine vision (digital image using camera, and computer processing); Nix Pro; Minolta CR400 colorimeter] when measuring three species of seafood (Atlantic salmon, Salmo salar, n = 8; rockling, Genypterus tigerinus, n = 8; banana prawns, Penaeus merguiensis, n = 105) for raw and cooked samples. Two methods of analysis for number of repeat measurements required were compared. Method 1 was based on minimising the standard error of the mean and Method 2 was based on minimising the difference in colour over repeat measurements. Across species, using Method 1, machine vision required an average of four repeat measurements, whereas Nix Pro and Minolta required 13 and 12, respectively. For Method 2, machine vision required an average of one repeat measurement compared to nine for Nix Pro and Minolta. Machine vision required fewer repeat measurements due to its lower residual variance: 0.51 compared to 3.2 and 2.5 for Nix Pro and Minolta, respectively. In conclusion, machine vision requires fewer repeat measurements than colorimeters to precisely measure the colour of salmon, prawns, and rockling. [ABSTRACT FROM AUTHOR]

The salmon lice-induced mortality of wild salmon stocks that result from aquaculture production can be considered a nonpoint pollution problem. In Norway, this externality is managed using a traffic light system (TLS), and the purpose of this system is to regulate the estimated aggregated salmon lice-induced mortality of wild salmon stocks in a number of production areas. This paper evaluates the TLS and in doing so, we depart from the literature on the regulation of nonpoint pollution problems. We argue that limited perceived influence of individual actions on the mortality of wild salmon stocks, difficulties in obtaining a reliable measure for the aggregated salmon lice-induced mortality and collective punishment of individual actions constitute the major problems of the TLS. As alternatives to the TLS, we discuss a subsidy to reduce the amount of salmon lice and a tax on salmon lice at farm site level. [ABSTRACT FROM AUTHOR]

Along the northeast Pacific coast, the salmon-eating southern resident killer whale population (SRKW, Orcinus orca) have been at very low levels since the 1970s. Previous research have suggested that reduction in food availability, especially of Chinook salmon (Oncorhynchus tshawytscha), could be the main limiting factor for the SRKW population. Using the ecosystem modelling platform Ecopath with Ecosim (EwE), this study evaluated if the decline of the Pacific salmon populations between 1979 and 2020 may have been impacted by a combination of factors, including marine mammal predation, fishing activities, and climatic patterns. We found that the total mortality of most Chinook salmon populations has been relatively stable for all mature returning fish despite strong reduction in fishing mortality since the 1990s. This mortality pattern was mainly driven by pinnipeds, with increases in predation between 1979 and 2020 mortality ranging by factors of 1.8 to 8.5 across the different Chinook salmon population groups. The predation mortality on fall-run Chinook salmon smolts originating from the Salish Sea increased 4.6 times from 1979 to 2020, whereas the predation mortality on coho salmon (Oncorhynchus kisutch) smolts increased by a factor of 7.3. The model also revealed that the north Pacific gyre oscillation (NPGO) was the most important large-scale climatic index affecting the stock productivity of Chinook salmon populations from California to northern British Columbia. Overall, the model provided evidence that multiple factors may have affected Chinook salmon populations between 1979 and 2020, and suggested that predation mortality by marine mammals could be an important driver of salmon population declines during that time. [ABSTRACT FROM AUTHOR]

Globally, salmon aquaculture promises to contribute to sustainable sources of animal protein for a growing human population. However, the growth of the industry also includes increased reports of mass mortality events—disaster events where large numbers of fish die in short periods of time. As salmon production increases in scale and more technology is used to grow salmon in contexts otherwise not suited for them, there is a possibility for more frequent and more severe mortality events. Despite investigations into specific cases of mass mortality events—no global study has been conducted to see if large scale mortality is increasing in frequency and scale. Using a global dataset of publicly available and government-collated data on salmon mortality events including nations responsible for the majority of salmon aquaculture, we document trends in mortality events, showing that in some of the major salmon producing nations of the world (in particular Norway, Canada, and the UK), mass mortality events have increased in frequency from 2012 to 2022. We also show that the scope of mass mortality events has increased over time—that is, the upper bound of how many fish were killed in a specific mortality event has increased over time. Finally, the expected maximum size of a mass mortality event differs from country to country, but is likely much larger than site and jurisdictional thresholds of concern for animal welfare, early warning thresholds, and capacity to respond to mortality events. The consequences of the increased scale and scope of mass mortality events extend past aquaculture production to include severe consequences to aquaculture companies and to coastal communities who depend on aquaculture. Our results agree with predictions of the concept of "manufactured risk", which suggests that risk emerges from the aggressive use of technology to optimize production in variable environments, and we argue that there is a need for more fine-scale and standard data collection on salmon mortality events, and that future investigations into salmon aquaculture should increase focus on disaster potential and realization. [ABSTRACT FROM AUTHOR]

It is widely believed that a significant portion of the gut microbiota, which play crucial roles in overall health and disease, originates from the food we consume. Sashimi is a type of popular raw seafood cuisine. Its microbiome, however, remained to be thoroughly explored. The objective of this study is to explore the microbiome composition in sashimi at the time when it is served and ready to be eaten. Specifically, our tasks include investigating the diversity and characteristics of microbial profiles in sashimi with respect to the fish types. We utilized the Sanger-sequencing based DNA barcoding technology for fish species authentication and next-generation sequencing for sashimi microbiome profiling. We investigated the microbiome profiles of amberjack, cobia, salmon, tuna and tilapia sashimi, which were all identified using the MT-CO1 DNA sequences regardless of their menu offering names. Chao1 and Shannon indexes, as well as Bray–Curtis dissimilarity index were used to evaluate the alpha and beta diversities of sashimi microbiome. We successfully validated our previous observation that tilapia sashimi has a significantly higher proportions of Pseudomonas compared to other fish sashimi, using independent samples (P = 0.0010). Salmon sashimi exhibited a notably higher Chao1 index in its microbiome in contrast to other fish species (P = 0.0031), indicating a richer and more diverse microbial ecosystem. Non-Metric Multidimensional Scaling (NMDS) based on Bray–Curtis dissimilarity index revealed distinct clusters of microbiome profiles with respect to fish types. Microbiome similarity was notably observed between amberjack and tuna, as well as cobia and salmon. The relationship of microbiome similarity can be depicted as a tree which resembles partly the phylogenetic tree of host species, emphasizing the close relationship between host evolution and microbial composition. Moreover, salmon exhibited a pronounced relative abundance of the Photobacterium genus, significantly surpassing tuna (P = 0.0079), observed consistently across various restaurant sources. In conclusion, microbiome composition of Pseudomonas is significantly higher in tilapia sashimi than in other fish sashimi. Salmon sashimi has the highest diversity of microbiome among all fish sashimi that we analyzed. The level of Photobacterium is significantly higher in salmon than in tuna across all the restaurants we surveyed. These findings provide critical insights into the intricate relationship between the host evolution and the microbial composition. These discoveries deepen our understanding of sashimi microbiota, facilitating our decision in selecting raw seafood. [ABSTRACT FROM AUTHOR]

In summer, the survival zones of cold‐water species are predicted to narrow by both increasing water temperatures from the surface and by expanding hypoxic zones from the lake bottom. To examine how the abundance of cold‐water fishes changes along environmental gradients, we assessed the vertical environmental DNA (eDNA) distributions of three salmonid species which may have different water temperature tolerances during both stratification and turnover periods using quantitative PCR (qPCR). In addition, we examined on the vertical distribution of diverse fish fauna using an eDNA metabarcoding assay. The results suggested that the kokanee salmon (Oncorhynchus nerka) eDNA were abundant in deep, cold waters. On the other hand, rainbow trout (O. mykiss) eDNA were distributed uniformly throughout the water column, suggesting that they may have high water‐temperature tolerance compared with kokanee salmon. The eDNA concentrations of masu salmon (O. masou) were below the detection limit (i.e., <10 copies μL−1) at all stations and depths and hence could not be quantified during stratification. Together with the finding that the eDNA distributions of other prey fish species were also constrained vertically in species‐specific ways, our results suggest that climate change will result in substantial changes in the vertical distributions of lake fish species and thus affect their populations and interactions. [ABSTRACT FROM AUTHOR]

Wildlife must increasingly balance trade‐offs between the need to access important foods and the mortality risks associated with human‐dominated landscapes. Human disturbance can profoundly influence wildlife behavior, but managers know little about the relationship between disturbance–behavior dynamics and associated consequences for foraging. We address this gap by empirically investigating the consequences of human activity on a keystone predator–prey interaction in a region with limited but varied industrial disturbance. Using stable isotope data from 226 hair samples of grizzly bears (Ursus arctos horribilis) collected from 1995 to 2014 across 22 salmon‐bearing watersheds (88,000 km2) in British Columbia, Canada, we examined how human activity influenced their consumption of spawning salmon (Oncorhynchus spp.), a fitness‐related food. Accounting for the abundance of salmon and other foods, salmon consumption strongly decreased (up to 59% for females) with increasing human disturbance (as measured by the human footprint index) in riparian zones of salmon‐bearing rivers. Declines in salmon consumption occurred with disturbance even in watersheds with low footprints. In a region currently among the least influenced by industrial activity, intensification of disturbance in river valleys is predicted to increasingly decouple bears from salmon, possibly driving associated reductions in population productivity and provisioning of salmon nutrients to terrestrial ecosystems. Accordingly, we draw on our results to make landscape‐scale and access‐related management recommendations beyond current streamside protection buffers. This work illustrates the interaction between habitat modification and food security for wildlife, highlighting the potential for unacknowledged interactions and cumulative effects in increasingly modified landscapes. [ABSTRACT FROM AUTHOR]

Summary: Impacts of Maillard reaction on bitterness, physicochemical properties, antioxidant activities of salmon frame protein hydrolysates (PH) and its plastein (PT) using ribose or glucosamine (Glx) were investigated. PT showed higher bitterness than PH after Maillard reaction, regardless of sugars and concentrations used (P < 0.05). PH (10%) and 4% Glx heated at 120 °C for 120 min yielded Maillard reaction products (MRPs) with the least bitterness (score: 5.89) as compared to control sample (P < 0.05). Browning intensity and lightness of aforesaid sample were directly and inversely proportional to treatment time, respectively. MRPs (10% PH with 4% Glx) showed the increased DPPH and ABTS radical scavenging activities (37.06 and 45.65 μmol TE g−1, respectively) up to 60 min (P < 0.05). Moreover, bitterness score of MRPS heated for 60 min was reduced from 9.37 (PH) to 1.44 ascertained by decrease in hydrophobic amino acid contents (P < 0.05). Therefore, Maillard reaction could be used as a promising means to lower bitterness of salmon frame PH. [ABSTRACT FROM AUTHOR]

Increased flood magnitude and frequency due to climate change can reduce the population productivity of organisms such as amphibian and fish species in river and stream systems; therefore, conserving habitats that maintain high productivity under such conditions is crucial. Here, we examined the relationship between the freshwater productivity of anadromous salmonids (measured as fry migrating to the ocean per spawner) and catchment hydrogeomorphology and identified the characteristics of rivers and streams that are prone to flood disturbance.We surveyed the spawner abundance and number of fry of pink salmon (Oncorhynchus gorbuscha) and measured environmental factors, including the average catchment slope and stream power, as characteristics of hydrogeomorphology, in 10 streams in the Shiretoko Peninsula, northern Japan. We then used generalised linear mixed models to predict the freshwater productivity of pink salmon populations in each catchment across the study region under current and future climatic conditions.The productivity of pink salmon in the study region differed among the sampled catchments and was negatively affected by the average catchment slope, stream power, and maximum daily precipitation averaged over the catchment. Namely, flood disturbance reduced the freshwater productivity of pink salmon, and salmon productivity in individual catchments was explained by catchment hydrogeomorphology. The predicted future productivity with increased precipitation was also lower than the current productivity.Our approach can be applied to other salmonids that have similar spawning behaviour to pink salmon. Highly productive catchments under the future climatic conditions predicted by the present study should be prioritised for conservation to ensure a sustainable salmonid population. [ABSTRACT FROM AUTHOR]

The value of estuaries as nursery habitat for juvenile anadromous salmon is likely variable across estuaries and species. Here, we compiled published empirical data on juvenile salmon estuarine growth and residency. We aimed to quantify the range and variability of these aspects for five species of Pacific salmon across estuaries, methodologies, and life histories. The majority of studies focused on Chinook and coho salmon, largely from their southern range. While there is some evidence of higher growth in wild-origin fish relative to hatchery-origin fish, the wide range of metrics employed made identification of trends among life histories challenging, and unification of reporting could strengthen future research. Different salmon life histories exhibited different residencies, with natural-origin subyearling coho exhibiting the longest mean residency (∼3 months) and 1+ sockeye salmon exhibiting the shortest (3.7 days). Across life histories, hatchery fish exhibited much shorter estuary residencies than wild fish. Collectively, our review highlights key patterns in salmon estuary ecology, identifies knowledge gaps, and lays the foundation for future studies to quantify the importance of estuaries for specific salmon. [ABSTRACT FROM AUTHOR]

Ecological models are used to understand where fishing vessels operate, improving fisheries management success. The ideal free distribution (IFD) predicts equalization of catch across locations in response to distributions of fish and competing vessels. We applied the IFD as a null model to investigate the movement and catch per vessel (CPUE) of the sockeye salmon drift gillnet fleet in Bristol Bay, AK, from 1980 to 2019. The IFD prediction of equal CPUE across areas was not supported, so we explored violations of two assumptions of the theory. We categorized each vessel according to its mobility, highlighting the "free to move" assumption, and found that when we removed nonmobile vessels, some districts had fewer vessels than predicted from their high CPUE. We examined the "equal competitive ability" assumption by calculating the average CPUE, relative to success of other vessels. The underutilization of profitable districts persisted. Overall, the fleet underused high CPUE areas when considering differences in mobility and relative fishing success, indicating that unmeasured safety concerns, travel costs, knowledge of fishing grounds, or other factors could be preventing an IFD. [ABSTRACT FROM AUTHOR]

Chinook salmon (Oncorhynchus tshawytscha) in the Columbia River basin are threatened by anthropogenic changes to migratory corridors, estuaries, and natal habitats. Streams provide spatially heterogeneous natal habitats essential for salmon spawning and rearing life stages. We fit a statistical state-space model to salmon populations in Idaho's Middle Fork Salmon River (MFSR) to assess spatial variation in natal productivity and population growth. Our model integrated multiple long-term data sets to estimate variation in per-capita smolt production and smolt-to-adult (SAR) survival. Smolt production varied across stream segments, averaging 104.48 female smolts per spawning female, while SARs averaged 0.74%. Chinook salmon population growth rates exceeded replacement in 17% of segments (4 of 23). By increasing SARs to 1.8% (near the lower bound of Columbia River basin recovery targets), we predict that all 23 MFSR segments will yield positive population growth rates at contemporary (very low) spawner densities. Our analysis suggests that for Snake River basin populations within high-quality natal habitats, SAR improvements will elevate salmon population growth rates and enhance restoration of at-risk wild Chinook salmon. [ABSTRACT FROM AUTHOR]

This study was conducted on salmon(Atlantic salmon)Salmo salar products imported to Iraq, which are a whole fish removed head and tail, fillets, rings, fingers and cubes evaluating of the sensory characteristics of these products and determining their suitability for human consumption. The products were obtained from King of Fish and Meat company ( K.F. M.), the exclusive agent in Iraq, and all products were within one meal and date, and the validity of each product was from 5/10/2021 to 4/7/2022. Results were as follows :The results of the sensory characteristics (color, flavor, freshness, juiciness, general acceptance) showed asignificant differences (p≤0.05) among salmon fish products, but they did not reach the limits of rejection. The results above of sensory tests of imported salmon fish products showed that they are suitable for human consumption and proved that they are within acceptable limits after comparing them with research and standard specifications. [ABSTRACT FROM AUTHOR]

Salmon, celebrated for its nutrition and flavor, suffers rapid degradation in freshness due to prolonged transportation and storage, offering a haven for microorganisms. Addressing the escalating need for safe, fresh fish consumption, we probed conventional chemical and physical indicators like total volatile basic nitrogen (TVB‐N), pH, texture profile analysis (TPA), and chromaticity across varying temperature intervals, linking these with gas sensors to identify sensitive sensor arrays. Importantly, an ensemble learning strategy for gas sensors, synthesizing the benefits of Linear, SVR, MLP, KNN, Gaussian Process, and decision tree algorithms, was employed for prompt and precise detection of salmon freshness and shelf‐life. Notably, the results demonstrated that gas sensors exhibited strong correlations, surpassing.8 for TVB‐N and.5 for shelf life, underscoring their aptitude for detecting salmon spoilage gas. Additionally, ensemble learning outperformed singular machine learning algorithms, with stacking emerging preeminent, achieving R2 values of.851 and.871, and MSEs of.120 and 1.573, for TVB‐N and shelf‐life detection, respectively. In summation, this study introduces an avant‐garde mechanism that amplifies the detection efficacy of gas sensors for salmon freshness, marrying them with stacking ensemble learning paradigms for cost‐effective and efficient determinations. In conclusion, we devised a novel method to augment the detection efficacy of gas sensors for salmon freshness. By integrating these sensors with stacking ensemble learning algorithms, we achieved a data‐driven, cost‐effective, and efficient approach, fulfilling the requirements of salmon freshness detection. Practical applications: Most existing gas sensors gas sensors predominantly employ singular machine learning methodologies, often limiting them to a sole freshness evaluation metric during assessments. This study introduces a pioneering approach using a stacking ensemble learning‐based gas sensor capable of concurrently assessing both TVB‐N and the shelf life of salmon. By discerning the correlations between freshness indices and gas sensor readings to pinpoint sensitive sensor arrays, we harnessed ensemble learning. This integrates the strengths of linear, SVR, MLP, KNN, Gaussian process, and decision tree models to enhance detection of freshness indicators. Notably, this advancement amplifies the sensor's efficacy in salmon detection solely through model optimization, bypassing the need to reconsider sensor materials and signal transmission pathways. Collectively, our findings present a cost‐effective and optimized strategy to elevate the performance of gas sensors in detecting salmon freshness. [ABSTRACT FROM AUTHOR]

Quorum sensing (QS) is a communication pattern between bacteria, hence the inhibition of bacterial QS system could be used as a new strategy to the control the spoilage caused by bacteria, and to some extent could avoid the bacteria drug resistance. In the study, dandelion water extract mediated biosynthesis Ag nanoparticles (D-AgNPs) was prepared with AgN03 as silver source and dandelion water extract as reducing agent. Its structure was characterized by ultraviolet visible absorption spectroscopy (UV-vis), dynamic light scattering (DLS), Zeta potential, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray energy spectrum (EDS). It was found that the synthesized D-AgNPs were spherical, with an average particle size of 13.9 nm and Zeta potential of (-14.07±0.25) mV. The effects of D-AgNPs on the growth of two Hafnia strains and quorum sensing regulated virulence factors such as biofilm, AHLs, proteases, exopolysaccharides, swimming and swarming motilities were determined. It was found that the minimum inhibitory concentration of D-AgNPs against Hafnia was 128 |g/mL, and could inhibit the formation of the biofilms of Hafnia at 1/16-1/2 MIC (8-64 |g/mL), whereas promoted its biofilm formation at 1/128-1/32 MIC (1-4 µg/mL). D-AgNPs showed different inhibition abilities on the AHLs and protease production, as well as swimming and swarming motilities; however, sub-MIC D-AgNPs promoted the production of exopolysaccharides. It is proved that D-AgNPs could be used as quorum sensing inhibitor. [ABSTRACT FROM AUTHOR]

This study identified the aroma profile of salmon by-product for high utilization of by-products, including hydrolysates of head, frame, and skin were treated with reducing sugars and thermal processing. Electronic nose (E-nose) and gas chromatography-mass spectrometry (GC–MS) coupled with gas chromatography–olfactometry (GC–O) were used to analyzed the aroma profile. A total of 140 and 90 volatile compounds were detected through E-nose and GC–MS respectively, and the main volatile compounds were aldehydes. A total of 23 odor active compounds were recognized using GC–O, and 3-methyl-butanal, heptanal, benzaldehyde, octanal, furfural, and methoxy-phenyl-oxime were identified as the aroma of salmon. Using multivariate analysis, the pattern between the pretreated samples and aroma profiles was confirmed, and there were clear separations among the samples. The results of this study provide the aroma profile of salmon by-products and are expected salmon by-products to be used as a potential food source. [ABSTRACT FROM AUTHOR]

Phenotypic diversity and abundance drive salmon resilience in the face of increasing environmental variability. But what happens when human activities fundamentally alter the habitat complexity that drives this diversity? And how can we restore habitats to recover both diversity and abundance to support salmon persistence in a warming climate? Here, we looked at the impact of a large watershed restoration effort on the abundance and climate resilience of the three remaining core natural spring‐run Chinook Salmon populations in the California Central Valley (Butte, Mill, and Deer Creek). Butte Creek fish, which have floodplain access, had higher overall productivity and faster juvenile growth compared with Mill and Deer Creek populations, and the proportion of floodplain inundation was positively correlated with Butte Creek adult abundance two years later. While Butte Creek exhibited significant increases in abundance post‐restoration (~2000%), it generally exhibited lower phenotypic diversity and only a marginal increase in population stability after restoration based on the coefficient of variation (CV). In particular, Butte Creek salmon tended to exhibit larger drops in escapement following dry years (e.g., return years 2010, 2017) compared with Mill and Deer Creek populations, presumably due to limited inundation of its downstream floodplain. The late‐migrating juvenile strategy (i.e., yearling), which disproportionately supported Mill and Deer Creek populations during droughts, was uncommon among Butte Creek adults (averaging 60% of returns for Mill and Deer Creek vs. 0.3% for Butte Creek). Increased spring‐run stock complex stability was found, post‐restoration, when combining the three spring‐run populations (i.e., lower aggregate CV). However, among‐river pairwise correlations also suggested increased synchronization in population abundances post‐restoration, potentially due to increasing frequency and severity of extreme climatic events (e.g., droughts and ocean warming). This study underscores the importance of restoring a connected mosaic of aquatic habitats across modified landscapes, such as cold water refugia and floodplains, to preserve multiple (across‐population) life history pathways for increasing salmon stock complex stability and abundance. These landscape‐scale process‐based habitat restoration efforts are likely to be crucial for the successful long‐term recovery of vulnerable species in a rapidly changing climate. [ABSTRACT FROM AUTHOR]

In China, the brown trout is a second-level key aquatic wildlife protection animal in the Tibet Autonomous Region. In order to protect the brown trout germplasm resources in the Tibet Autonomous Region, the Institute of Aquatic Sciences of the Academy of Agricultural and Animal Husbandry Sciences of the Tibet Autonomous Region and the Heilongjiang Institute of the Chinese Academy of Aquatic Sciences collaborated on research on the key technologies of brown trout family construction. A fast in silico simulation method was employed in this study to discover numerous polymorphic SSRs. A total of 1,115,563 SSR loci with two to six nucleotide repeat motifs were mined from 40 chromosomes of the brown trout reference genome by GMATA. The whole genome sequences (30×) of 30 brown trout samples were compared to the reference genome's chromosome sequence. Then, the HipSTR program was employed to carry out in silico genotyping through comparisons and enumerations of repeat count variants on the motifs of the SSR loci among the samples. The loci with monomorphism and high deletion in the SSR genotype data were removed, and the loci with more than one non-reference allele were retained. The final set of polymorphic SSR loci screened was 106,194. Forty-three SSR markers were randomly selected for characteristic analysis. The range of alleles per locus was 3 to 9 (mean = 5). Observed heterozygosity was in the ranged from 0.167 to 1.000. Expected heterozygosity was in the ranged from 0.155 to 0.823. Twenty-three loci significantly deviated from Hardy-Weinberg equilibrium. These SSR markers will provide valuable information for assessing the genetic diversity of constructed brown trout families and for the genetic improvement of brown trout. [ABSTRACT FROM AUTHOR]

Rising temperatures due to anthropogenic climate change pose a threat to wild Atlantic salmon (Salmo salar) populations in their natural habitat and to farmed populations during their major growth phase in coastal (seawater) net pens. Given that tremendous gains have been made in farmed salmon production through artificial selection programs for traits such as growth rate and disease resistance, we therefore examined variation among 105 families in post-smolt seawater thermal tolerance to assess whether this trait warrants inclusion in a selective breeding program. We used two established thermal challenge protocols for this: a rapid temperature increase using loss of equilibrium as the endpoint (critical thermal maximum; CTmax [1506 fish]) and a slower increase with mortality or morbidity as the endpoint (incremental thermal maximum; ITmax [936 fish]). High estimated heritability values were obtained for both (h² = 0.47 and 0.40, respectively), suggesting that improved acute and/or chronic high-temperature tolerance may be attainable for farmed salmon through artificial selection. Furthermore, given that farmed salmon are not many generations removed from wild, wild populations may also have some capacity to adapt to increasing temperatures brought about by climate change. However, we found no genetic correlation between CTmax and ITmax. Genetic correlations between these indices and other traits that might influence thermal tolerance (body size, condition factor, ventricle size, and hematocrit) were absent or, at most, weak.

Salmon backbones make up about 10 % of the total fish weight and contain valuable proteins, collagen and lipids that can be used for marine ingredients production. Gelatine is derived from the collagen fraction and this study evaluated how different fractionation and extraction procedures can affect the yield and composition of extracted gelatine. Fractionation by mild thermal treatment of backbones (10 min in 40–42 °C) leads to structural changes of muscle, which improves separation of meat from bones and gives better yield of de-muscled backbone fractionation compared to mechanical meat removal. The highest yield of the gelatine (9.3 ± 0.3g dry gelatine from 100g de-muscled backbone dry material) was obtained from mechanically de-muscled backbones. De-muscled backbones were pre-treated with alkaline (0.04 N NaOH) followed by EDTA and 10 % ethanol for de-calcification and lipid extraction, respectively. Gelatine from pretreated backbones was extracted with 60 °C water. The amount of gelatine amino acids (sum of hydroxyproline, proline and glycine) was 43.4 ± 0.2 % of all amino acids in the gelatine. Extracted backbone gelatines showed film-forming ability. Gelatine films were obtained by casting procedure. Resulted salmon backbone 6 % gelatine and 30 % sorbitol films showed properties (e.g. water vapour permeability, colour difference, transparency value) similar to films obtained with commercial gelatine, indicating the capability of the extracted gelatines for its valorisation as edible coatings or bio-based film layers in packaging.

Large dam removal is being used to restore river systems, but questions remain regarding their outcomes. We examine how the removal of two large dams in the Elwha River, coupled with hatchery production and fishing closures, affected population attributes of Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss). Initial responses by returning adult Chinook salmon and steelhead was an increase in the number and spatial extent of natural and hatchery origin fish. Although few naturally produced juvenile Chinook salmon and steelhead outmigrants were observed prior to and during dam removal, abundances increased three years after adult fish passage was restored, suggesting that impacts due to downstream sedimentation after dam removal were reduced. The Chinook salmon population demographics remain dominated by hatchery production, while increases in winter steelhead abundance included both hatchery and natural-origin spawners. The spatial expansion of winter steelhead upstream of former dam sites was predominantly by natural-origin spawners. We also observed a natural “reawakening” of summer steelhead that were in part derived from an up-river resident population that returned to the Upper Elwha. Our results showed that a combination of habitat, hatchery, and harvest actions can result in positive responses for salmonid populations.

This paper explores the three cooking methods (frying, grilling, and steaming) related to fish most commonly utilized by consumers, with a focus on their implications for both food quality and safety. The mean contents of water and fat were found to be 12.63% and 66.22%, respectively. The fat content of the raw fish samples was significantly lower than that of heat-treated samples, and the percentage fat content did not differ significantly between treatment types. In trout, the greatest water loss was observed during grilling and steaming; in the case of salmon, during frying and steaming. In raw trout and salmon, 5.56 log cfu/g of psychrotrophic bacteria and 5.20 log cfu/g of psychrotrophic bacteria were found, respectively. The steaming method proved the least efficient at eliminating psychrotrophic bacteria. In the present study, the grilling method was found to be the best for quality, safety and better health.

Abstract Intraspecific diversity plays a critical role in the resilience of Chinook salmon populations. California's Central Valley (CV) historically hosted one of the most diverse population complexes of Chinook salmon in the world. However, anthropogenic factors have dramatically decreased this diversity, with severe consequences for population resilience. Here we use next generation sequencing and an archive of thousands of tissue samples collected across two decades during the juvenile outmigration to evaluate phenotypic diversity between and within populations of CV Chinook salmon. To account for highly heterogeneous sample qualities in the archive dataset, we develop and test an approach for population and subpopulation assignments of CV Chinook salmon that allows inclusion of relatively low‐quality samples while controlling error rates. We find significantly distinct outmigration timing and body size distributions for each population and subpopulation. Within the archive dataset, spring run individuals that assigned to the Mill and Deer Creeks subpopulation exhibited an earlier and broader outmigration distribution as well as larger body sizes than individuals that assigned to the Butte Creek subpopulation. Within the fall run population, individuals that assigned to the late‐fall run subpopulation also exhibited an earlier and broader outmigration distribution and larger body sizes than other fall run fish in our dataset. These results highlight the importance of distinct subpopulations for maintaining remaining diversity in CV Chinook salmon, and demonstrates the power of genomics‐based population assignments to aid the study and management of intraspecific diversity.

Many ecological data sets are proportional, representing mixtures of constituent elements such as species, populations, or strains. Analyses of proportional data are challenged by categories with zero observations (zeros), all observations (ones), and overdispersion. In lieu of ad hoc data adjustments, we describe and evaluate a zero-and-one inflated Dirichlet regression model, with its corresponding R package (zoid), capable of handling observed data x $$ x $$ consisting of three possible categories: zeros, proportions, or ones. Instead of fitting the model to observations of single biological units (e.g., individual organisms) within a sample, we sum proportional contributions across units and estimate mixture proportions using one aggregated observation per sample. Optional estimation of overdispersion and covariate influences expand model applications. We evaluate model performance, as implemented in Stan, using simulations and two ecological case studies. We show that zoid successfully estimates mixture proportions using simulated data with varying sample sizes and is robust to overdispersion and covariate structure. In empirical case studies, we estimate the composition of a mixed-stock Chinook salmon (Oncorhynchus tshawytscha) fishery and analyze the stomach contents of Atlantic cod (Gadus morhua). Our implementation of the model as an R package facilitates its application to varied ecological data sets composed of proportional observations.

Dams, once considered catalysts for economic development in the Western US, are now being targeted for removal due to their adverse ecological and social outcomes. However, dam removal often remains controversial. In the Pacific Northwest, four dams on the Lower Snake River have long been criticized for their negative impacts on salmon. In 2021, the Columbia Basin Initiative was proposed, seeking to dismantle the dams in order to simultaneously improve salmon health, redesign Idaho’s energy landscape, change transportation pathways, and protect other dams. Response to the initiative has been polarized. In this paper, we build upon political ecology and ‘unlikely alliance’ scholarship by examining the reactions to and points of tension around the initiative. We specifically focus on the viewpoints of key stakeholders who have shifted from their historically rooted alliances and views. We found that being in favour of dam removal in general was not necessarily enough to cause someone to support the Columbia Basin Initiative (and vice versa). In particular, stakeholders were split on views around legal provisions in the initiative that would limit the future utility of current environmental law. We contribute to political ecology and unlikely alliance scholarship by demonstrating that dam removal is a complex issue that can bring actors together in unanticipated ways.

Aquatic animals are an important source of food for humans, yet little is known about their potential to transfer zoonotic viruses. Multiple recent cases of SARS-CoV-2 from cold-chain aquatic food and environmental samples has evoked worldwide concerns, and even though these cases pale in comparison to poultry and livestock. To investigate the potential threat of food from aquatic animals, we map their transcriptomes to the genomes of human respiratory- and intestine-related viruses. Analyses only find an influenza virus sequence in a salmon (Salmo salar) skin transcriptome. BLAST and phylogenetic analyses identify this sequence as influenza A, and this likely owes to contamination from a worker. Thus, when prepared properly, aquatic animals can provide great nutritional benefits to humans while posing minimal health risks.

Over the years, human impacts have resulted in great losses in riverine biodiversity. Ecosystem restoration could contribute to reversing this trend. Ecosystem restoration, however, involves many actors and perspectives and is, therefore, a complex governance challenge. So far, this governance challenge has been understudied, and it is not clear which governance conditions may contribute to a successful restoration of riverine ecosystems. This paper addresses this knowledge gap by developing an assessment framework that is applied in a critical case study. We first reviewed scientific papers and compiled governance conditions found in an assessment framework. The framework is tested and refined by conducting a case study on the ecosystem restoration process coordinated by the International Commission for the Protection of the Rhine. This process aims to bring back the Atlantic salmon and other species in the basin. Our analysis revealed that despite efforts to reintroduce Atlantic salmon, a self-sustaining population is not present in the basin. Moreover, the governance structure in the basin only meets 13 out of 23 governance conditions. Challenges identified include slow decision-making, ambiguity in responsibilities, and limited financial incentives. Based on our case study, we have refined the framework to tailor it more for future research and policy development.

Variations in species distribution, population structure, and behavior can provide a portfolio effect that buffers populations against rapid environmental change. Although diversity has been identified as a goal for effective resource management and genetic and demographic tools have been developed, life history remains challenging to quantify. In this study, we demonstrate a novel metric of life history diversity using telemetry data from migratory fish. Here, we examined diversity in the outmigration behavior of juvenile Chinook salmon (Oncorhynchus tshawytscha) released in the Sacramento River, California, between 2007 and 2017. In this synthesis, we examined a wide variety of landscape and demographic drivers at high resolution by incorporating many individual telemetry studies, with variability in release location by year, environmental conditions, and all runs of salmon that are present in the watershed. When years were grouped by shared hydrologic conditions, variation in travel time was significantly higher in wet years. Further, our model showed a negative effect of warm temperatures at low flows on the variation in migration movements. This suggests that enhanced hydrologic connectivity increases the variation in migration time, a representation of habitat complexity and biocomplexity, despite the degraded state of this watershed and the weakened state of these populations. Variation in migration behavior could buffer species from current and future environmental changes, such as climate effects on precipitation and temperature. Hence, behavioral metrics generated from telemetry studies can be used to understand life history diversity and the potential effects of environmental fluctuations.