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During recent years, there has been a renewed interest in establishing farming of Atlantic cod (Gadus morhua) in Norway. However, a fatal abdominal disorder compromises animal welfare and causes economic losses. A similar problem was present during a previous attempt to establish Atlantic cod farming more than a decade ago. In this paper, we provide the first in‐depth description of this intestinal disorder, which is correctly denoted 'strangulating obstruction'. In affected fish, part of the intestine is permanently entrapped (incarcerated) under fibrous strands in the mesentery. The entrapment interferes with blood flow and physically blocks the intestine, causing a strangulating obstruction with severe venous congestion and ischemia of the intestinal wall. Furthermore, comparison of macroscopical and histological anatomy of farmed and wild Atlantic cod is presented and risk factors associated with the anatomical differences are discussed. [ABSTRACT FROM AUTHOR]

The International Union for Conservation of Nature (IUCN) Red List identifies threatened and endangered species and is a key instrument in global biodiversity conservation efforts. Our understanding of the structure and value of genetic biodiversity below the species level is rapidly increasing. Nonetheless, the IUCN assessment criteria overlook genetic variation within species. Here, we address this blind spot and discuss the principles of species conservation status classification relative to intraspecific biodiversity. We focus on coastal species, which thrive in heterogeneous environments known to drive genetic differentiation. The focal example species, Atlantic cod and sugar kelp, have contrasting life histories, are ecologically and economically important constituents of the coastal ecosystem, and are currently not classified as threatened in Norway and Canada. We expose important variation in population structure, the presence of ecotypes and genetic-environment covariation, as well as loss of ecotypes that threatens the conservation of these species. Because the genetic makeup of species directly influences their resilience, omitting this information from conservation status assessments can result in loss of adaptive capacity to future stressors, such as climate change. Consequently, recognizing and preserving intraspecific variation emerges as vital for species' abilities to adapt to and survive in future ocean conditions. [ABSTRACT FROM AUTHOR]

Aquaculture provides an important and expanding source of protein rich and healthy food to the world. However, to minimize environmental harm from aquaculture, interactions with wild fish communities need to be thoroughly assessed. Here, we characterize the existing knowledge pertaining to such interactions, exemplified with Atlantic salmon (Salmo salar) farming in open net pens along the Norwegian coast and potential consequences for wild Atlantic cod (Gadus morhua) populations. Importantly, the wild cod fishery also provides a protein rich, high quality food source with high economic value. We identify seven risk sources that may affect behaviour, physiology, and survival in wild cod. Of particular importance is the large amount of waste feed that causes wild fish to aggregate around farms, thereby altering a multitude of ecological interactions including predation and disease transmission. Moreover, altered food quality in pellets may alter physiological processes and cause mortality to vulnerable life‐stages in wild cod. More research is needed on mechanisms and thresholds for harm. As the most important cod fisheries are found in northern Norway, where climate change also is rapid, we expect stronger and potentially more harmful interactions between fish farming and wild cod fisheries as aquaculture continues to expand. We hope that our analysis will inspire further research, on farmed salmon and wild cod interactions, but also on aquaculture and wild fish interactions in general. Such research is fundamental for the development of management systems that can reduce the impact of aquaculture on fisheries and the environment. [ABSTRACT FROM AUTHOR]

Elucidating the effects of domesticated organisms escaping into the natural environment represents a topic of importance in both evolutionary and conservation biology. However, when excluding the abundant data on salmonids, there is a lack of knowledge on this topic for marine fish aquaculture, which continues to expand globally. In order to bridge this empirical gap, we investigated a suspected escape of sexually mature domesticated Atlantic cod from a commercial marine fish farm in northern Norway. This involved genotyping samples of fish from cages on the farm, putatively identified escapees and wild cod captured in the region and samples of recently spawned eggs collected in the sea. Genetic analyses confirmed a farmed ancestry of the suspected escapees, and significantly, 27% of the sampled cod eggs. Furthermore, statistical analyses revealed a strong reduction in genetic variation in all samples of the farmed cod, including low effective population size and high degree of siblingship. These results thus document the escape of sexually mature adult cod and the release of fertilized domesticated cod eggs into the natural environment. Although it is possible that some of the mature escapees spawned post‐escape, the fact that only a single egg of potential hybrid farmed × wild origin was identified, together with the high number of mature cod in the farm, points to within cage spawning as the primary source of these eggs. This suggestion is supported by oceanic particle‐drift modelling, verifying that transport of eggs between the farm and the egg sampling locations was plausible. This study represents a rare documentation of interaction between domesticated and wild populations for a marine fish, pointing towards potential impacts on the local wild population. [ABSTRACT FROM AUTHOR]

Predator–prey interactions in time and space determine stock productivity, making them an important consideration when managing marine resources, rebuilding stocks or considering reopening a fishery.We analysed fine‐scale diet data from surveys conducted in 2009–2010 and 2018–2019 in three fjords in northern Norway with geostatistical models investigating how predation varied in space, time and between predator species. Our focus prey species was northern shrimp (Pandalus borealis), valuable both as a commercial resource and a major food source for other important species like Atlantic cod (Gadus morhua).Diet composition of fish predators differed clearly between fjords. While predator species and size were good predictors of shrimp predation, the relationships with bathymetry, prey density and geospatial variables were complex.Our study indicates that predation of forage species, such as shrimp, varies spatially in heterogenous fjord ecosystems. Shrimp consumption was not highest in the fjord with highest predator density, indicating a higher dependency of cod on shrimp in specific areas.Realized predation is a complex combination of predator and prey densities and predator ecology that differed in each of the three fjords.Synthesis and applications. Ignoring spatial variations in predator–prey interactions may lead to an inaccurate perception of stock productivity, suboptimal management and possibly unsustainable management targets. We recommend spatially explicit assessment and management for fish stocks where predator–prey interactions vary substantially in space, such as fjords and reefs. [ABSTRACT FROM AUTHOR]

Aquaculture is one of the fastest growing food production sectors in the world and further expansion is expected throughout the 21st century. However, climate change is threatening the development of the sector and action is needed to prepare the industry for the coming challenges. Using downscaled temperature projections based on the Intergovernmental Panel on Climate Change (IPCC) climate projection (Shared Socioeconomic Pathway, SSP2-4.5), we analysed potential future temperatures at a selected Atlantic cod (Gadus morhua L.) farm site in Northern Norway. Results showed that the farming area may experience increased temperatures the next 10-15 years, including more days with temperatures above 17°C. Based on the predicted future conditions, we designed a study with Atlantic cod (Gadus morhua L.) to evaluate effects from high temperature alone and in combination with Fransicella noatunensis infection. Fish were kept at 12°C and 17°C for eight weeks and samples of skin and spleen collected at different timepoints were analysed with transcriptomics, histology, scanning electron microscopy and immunohistochemistry. Results showed that high temperature had a stronger effect on the barrier functions of skin than the infection. Increased temperature induced gene expression changes in skin and spleen, heat shock protein 47 and cold inducible RNA binding protein were identified as potential gene markers for thermal stress. The effect of bacterial challenge was small at 12°C. At high temperature, the development of severe pathology in spleen coincided with a significant decrease of immunoglobulins transcripts, which contrasted with the activation of multiple immune genes. In addition, we used an in vitro model of skin biopsies and scale explants exposed to hydrogen peroxide (H2O2) to assess the effects of thermal and oxidative stress. High temperature and H2O2 reduced proliferation and migration of keratocytes, and increased expression of stress markers, and compounding effects were observed with combined stressors. Results suggest that the projected increased seawater temperature will pose a significant threat to Norwegian cod farming, affecting various biological processes and making fish more vulnerable to stressors and pathogens. Cod farming needs high attention to temperature changes, and special precautions should be taken if the temperature increases beyond cods' thermal optimum. [ABSTRACT FROM AUTHOR]

The Earth’s ecosystems are increasingly deprived of large animals. Global simulations suggest that this downsizing of nature has serious consequences for biosphere functioning. However, the historical loss of large animals means that it is now often impossible to secure empirical data revealing their true ecological importance. We tracked 465 mature Atlantic cod (Gadus morhua) during their winter spawning season and show that large females (up to 114 centimeters in length), which are still found in mid-Norway, were characterized by more complex movement networks compared with smaller females. Large males were sparse but displayed similar movement patterns. Our finding implies that management programs promoting large fish will have positive impacts on population resilience by facilitating the continued use of a diversity of spawning habitats and the connectivity between them. [ABSTRACT FROM AUTHOR]

Incidental capture of non-target species by fisheries, also referred to as bycatch, is a major concern for the management of marine megafauna species. In Norway, it has been estimated that 555 harbor seals (Phoca vitulina) get entangled and drown in gillnets every year. The majority of these bycatch events occur in large-mesh gillnet fisheries targeting cod (Gadus morhua) and monkfish (Lophius piscatorius). Young-ofthe-year individuals represent the largest proportion of bycaught harbor seals. To increase our understanding of harbor seal bycatch events along the Norwegian coast, times and areas of potential bycatch risk were identified. Seasonal variation in the at-sea distribution of harbor seals was simulated based on movement from their molting site to predicted at-sea locations. Relative age-specific bycatch abundances were used to weigh the different seasons (times of the year) based on harbor seal age. The overlap in the distribution of harbor seals and the documented distribution of fishing effort was then used to estimate the relative bycatch risks between harbor seals and fisheries in defined Statistical Sea Locations (SSLs) in each of the four seasons. The method used here provides a general framework for understanding temporal and spatial interaction between harbor seals and coastal gillnet fisheries. The times and areas of high interaction risk that were identified can be used in management practices to increase our understanding of bycatch events, and to ultimately reduce unwanted bycatch of harbor seals in coastal fisheries along the Norwegian coast. [ABSTRACT FROM AUTHOR]

This study investigates the impact of reservepriceson bidder participation in the main Norwegian auction market for frozen Atlantic cod. Theoretically, there is a negative relationship between reserve prices and bidder participation. However, our empirical findings show that the reserve price actually has no negative influence on bidder participation. A simulation exercise taking buyers' true valuations into account also shows a negligible effect of reserve prices on the probability of two or more participating bidders. Other factors are more important in attracting bidders to the auction. Most notably, cod caught by longline, which implies fish of high quality, enhances the probability of two or more bidders by 11.8%. Auctioneers should focus on information transparency regarding fish quality to attract participants and hence improve the efficiency of auction markets. [ABSTRACT FROM AUTHOR]

Seismic airgun surveys to map petroleum deposits in the seabed may impact behaviour of marine animals over large distances. Understanding whether fish spawning behaviour is affected by this anthropogenic noise source is important because reproductive success may be impacted. The fine-scale behavioural responses of Atlantic cod to airgun exposure over an extended period were investigated using an acoustic telemetry positioning system on a spawning ground in Norway. During 2019 to 2021, 135 spawning cod were equipped with telemetry sensor tags and were exposed to airgun shooting during the spawning periods of 2020 and 2021, with varying received sound levels comparable to a full-scale survey at distances of 5 to >40 km. Cod demonstrated only weak responses to the disturbance from repeated 3-h treatment periods over 5-d, swimming on average slightly deeper during seismic exposure compared to silent control periods. This response varied between individuals. Longer-term effects of seismic exposure on swimming depth were not detected. No changes in swimming acceleration, displacement, or area use occurred. These results suggest that relatively distant seismic surveys do not substantially alter cod behaviour during the spawning period at received sound exposure levels varying between 115 and 145 dB re 1 µPa2s over a 5-d period. [ABSTRACT FROM AUTHOR]

Cryptic population structure in exploited fishes poses a major challenge for fisheries management. In Atlantic cod, sympatric ecotypes are well-known, for instance off the coast of northern Norway. Recently, two sympatric cod ecotypes have also been documented in the Skagerrak and Kattegat, where adult cod has declined dramatically. One ecotype has an apparent offshore origin and displays a more migratory lifestyle than the other, which is generally resident at the coast throughout its life. To investigate their relative abundances along the Swedish west coast, juvenile cod were collected at high spatial resolution along the coast and genetically assigned to ecotypes. The results reveal large proportions of the coastal ecotype in the southern Kattegat, Öresund, and inshore Swedish Skagerrak, whereas the offshore ecotype dominates in offshore areas. A regression model comparison suggests that differences in bottom depth, rather than distance from the open sea, explain the heterogeneous spatial distribution of the two ecotypes. In addition, the two ecotypes display genetic differences suggesting adaptation to different environments. The results underline that successful fisheries management requires identification and consideration of locally adapted sympatric ecotypes. [ABSTRACT FROM AUTHOR]

Marine recreational fishing is popular in Norway, but current estimates of the catches by resident and tourist anglers are lacking due to several challenges, in particular Norway's long and intricate coastline with no defined access points and the large tourist fishery. To test methods for long-term monitoring of boat-based marine recreational anglers, estimate their catches, and characterize the fishery, we conducted a roving creel survey based on a novel spatial sampling frame and a survey of tourist fishing businesses in Troms and Hordaland County. These surveys showed that cod (Gadus morhua) and saithe (Pollachius virens) dominated the catches in Troms, while mackerel (Scomber scombrus) and saithe dominated the catches in Hordaland. The estimated total annual harvest of cod by all marine recreational anglers was 2 160 tonnes (relative standard error, or RSE 44%) in Troms and 73 tonnes (RSE 29%) in Hordaland, of which ∼40% (in weight) were landed in registered tourist fishing businesses, based on data from the tourist fishing survey. The results indicate that recreational anglers in Hordaland harvest more cod in coastal waters than commercial fishers. This study provides information for developing marine recreational fisheries monitoring in challenging survey situations to support science-based fisheries management. [ABSTRACT FROM AUTHOR]

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We compared stock origin, size- and age-distributions, and length growth rates derived from Atlantic cod otoliths from archaeological excavations at two sites in northern Norway: Vágar in Lofoten (68°12′N, ad 1156–1285) and the Værbukta site (70°57′N, ad 1450–1680). For comparison, modern otoliths were sampled during 1993–2001 from areas situated close to Vágar and Værbukta. Length-at-age from pre-20th century samples was back-calculated from otolith growth increments. The pre-20th century cod from Vágar was dominated by northeast Arctic cod (NEAC) of age 9–16 years and were much older and larger than the pre-20th century cod from Værbukta, which were dominated by coastal cod of age 2–6 years. Cod from Vágar had smaller increments and a shorter back-calculated length-at-age than modern cod from Lofoten. In contrast, the predominantly coastal cod from Værbukta had similar increments width and length-at-age as in modern samples. Age-distributions and mortality rates of the pre-20th century Vágar cod and NEAC from Lofoten in the 1930s were similar, indicating that both age at maturity and longevity were similar for these time periods. This contrasts with truncated and young age-distributions of spawning NEAC in the 1980s and 1990s following the strong increase in fishing and total mortality rate in the period 1955–2000. [ABSTRACT FROM AUTHOR]

The effects of marine reserves on the life history and demography of the protected populations are well‐established, typically increasing population density and body size. However, little is known about how marine reserves may alter the behavior of the populations that are the target of protection. In theory, marine reserves can relax selection on spatial behavioral phenotypes that were previously targeted by the fishery and also drive selection in favor of less mobile individuals. In this study, we used acoustic telemetry to monitor the individual spatial behavior of 566 Atlantic cod (Gadus morhua Linnaeus, 1758) moving within a marine reserve and a control site in southern Norway, starting 1 year before the implementation of the marine reserve and lasting up to 9 years after. Following a before‐after‐control‐impact approach, we investigated changes in (1) survival, (2) selection acting on behavioral traits, and (3) mean behavioral phenotypes, after the implementation of the marine reserve. We focused on three behavioral traits commonly used to describe the mobility of aquatic animals: home range size, depth position, and diel vertical migration range. Survival increased after reserve implementation, but contrary to our expectations, it subsequently decreased to preprotection levels after just 3 years. Further, we found no significance in selection patterns acting on any of the three behavioral traits after reserve implementation. Although some changes related to water column use (the tendency to occupy deeper waters) were observed in the marine reserve after 9 years, they cannot unequivocally be attributed to protection. Our results show that survival and behavioral responses to marine reserves in some cases may be more complex than previously anticipated and highlight the need for appropriately scaled management experiments and more integrated approaches to understand the effects of marine protected areas on harvested aquatic species. [ABSTRACT FROM AUTHOR]

Three male sperm whales (Physeter macrocepha-lus) stranded on the island of Andøya in northern Norway in 2020. This created an opportunity to do gross necropsies with a focus on stomach contents as the diet of sperm whales in Norwegian waters is poorly understood and also to study potential presence of marine debris. Four new prey types for sperm whales in Norwegian waters were identified: (1) angler fish, (2) Atlantic cod, (3) cartilaginous fish, and (4) cock-eyed squid. In general, the results support earlier studies of male sperm whale diet in high latitude foraging grounds in the North Atlantic consisting of a mixture of cephalopods and meso and bathypelagic fish. The only type of marine debris found was part of a fishing line. Based on estimates from teeth, the whales were 25, 45, and 49 years old. The size of all individuals was smaller than the median length based on whaling data for these age classes caught in Iceland in the 1970s. [ABSTRACT FROM AUTHOR]

Identifying how physical and biotic factors shape genetic connectivity among populations in time and space is essential to our understanding of the evolutionary trajectory as well as the management of marine species. Atlantic cod is a widespread and commercially important marine species displaying several ecotypes with different life history strategies. Using three sets of SNPs: neutral, informative, and genome‐inversion linked, we studied population genetic structure of ~2500 coastal Atlantic cod (CC) from 40 locations along Norway's 2500 km coastline, including nine fjords. We observed: (1) a genetic cline, suggesting a mechanism of isolation by distance, characterized by a declining FST between CC and North East Arctic Cod (NEAC—genetically distinct migratory ecotype) with increasing latitude, (2) that in the north, samples of CC from outer‐fjord areas were genetically more similar to NEAC than were samples of CC from their corresponding inner‐fjord areas, (3) greater population genetic differentiation among CC sampled from outer‐fjord areas along the coast, than among CC sampled from their corresponding inner‐fjord areas, (4) genetic differentiation among samples of CC from both within and among fjords. Collectively, these results permit us to draw two main conclusions. First, that differences in the relative presence of the genetically highly distinct, migratory ecotype NEAC, declining from north to south and from outer to inner fjord, plays the major role in driving population genetic structure of the Norwegian CC. Second, that there is limited connectivity between CC from different fjords. These results suggest that the current management units implemented for this species in Norway should be divided into smaller entities. Furthermore, the situation where introgression from one ecotype drives population genetic structure of another, as is the case here, may exist in other species and geographical regions, thus creating additional challenges for sustainable fisheries management. [ABSTRACT FROM AUTHOR]

Atlantic cod is a historically abundant species in the North Atlantic region and has contributed to the prosperity of many nations. But a decline in stocks in the last century has prompted to initiate commercial farming of cod in captive conditions. Several approaches have been employed ranging from stock enhancement, capture‐based aquaculture and intensive cod farming. However, except for the enhancement efforts which were carried out for almost a century, efforts on other methods were intermittent coinciding with lower quotas. Intensive farming was attempted in Norway, Scotland, Ireland, Canada, Iceland and Faroe Islands in the 2000s. But it was carried out hastily to cash in the demand for cod in the market even though there were many biological knowledge gaps that are required for a successful aquaculture venture. The reasons for the failure of commercial farming in Norway during the 2000s were not only because of limited knowledge of the biology of cod but also the economic meltdown in Europe in 2008. Cod farming came to a halt; however, the Norwegian National Cod Breeding Program (NCBP) initiated in 2003 continued to operate and produced a fifth generation of a domesticated cod in 2019. Efforts to fill the gaps and the selective breeding for better growth and disease resistance within NCBP have improved the quality of the juveniles produced. We will discuss the past efforts and reasons for failure in farming of cod, how the current situation looks and the future direction in terms of cod biology, political atmosphere and market. [ABSTRACT FROM AUTHOR]

Specific changes identified in the otolith macrostructure of Northeast Arctic cod as "spawning zones" are presumed to represent spawning events, but recent experimental studies have challenged this relationship. Because these zones are not routinely recorded outside of Norway, otoliths from multiple Atlantic cod populations with different life history and environmental traits were first examined to see if spawning zones could be identified as a general characteristic of cod. Then, a large archival collection of cod otoliths was used to investigate temporal changes in the occurrence of spawning zones and test for correlations between maturity at age derived from otolith spawning zones and gonad maturity stages. This study shows that spawning zones likely are a universal trait of Atlantic cod and not limited to certain environments or migratory behaviors as previously proposed. Maturity at age derived from spawning zone data showed trends consistent with those from gonad examinations. However, spawning zones appear to form with a one- or two-year lag with sexual maturity, which is suspected to reflect a stabilizing of energy partitioning after the first spawning events. Our results illustrate the potential for use of spawning zones, for example in species or populations with limited available maturity data, and highlights the need for addressing the physiological processes behind their formation. [ABSTRACT FROM AUTHOR]

A new dataset on the diet of Atlantic cod in the Barents Sea from the 1930s to the present day has been compiled to produce one of the largest fish diet datasets available globally. Atlantic cod is one of the most ecologically and commercially important fish species in the North Atlantic. The stock in the Barents Sea is by far the largest, as a result of both successful management and favourable environmental conditions since the early 2000s. As a top predator, cod plays a key role in the Barents Sea ecosystem. The species has a broad diet consisting mainly of crustaceans and teleost fish, and both the amount and type of prey vary in space and time. The data – from Russia, Norway and the United Kingdom – represent quantitative stomach content records from more than 400 000 fish and qualitative data from 2.5 million fish. Many of the data are from joint collaborative surveys between Norway and Russia. The sampling was conducted throughout each year, allowing for seasonal, annual and decadal comparisons to be made. Visual analysis shows cod diets have changed considerably from the start of the dataset in the 1930s to the present day. There was a large proportion of herring in the diets in the 1930s, whereas in more recent decades capelin, invertebrates and other fish dominate. There are also significant interannual asynchronous fluctuations in prey, particularly capelin and euphausiids. Combining these datasets can help us understand how the environment and ecosystems are responding to climatic changes, and what influences the diet and prey switching of cod. Trends in temperature and variability indices can be tested against the occurrence of different prey items, and the effects of fishing pressure on cod and prey stocks on diet composition could be investigated. The dataset will also enable us to improve parametrization of food web models and to forecast how Barents Sea fisheries may respond in the future to management and to climate change. The Russian data are available through joint projects with the Polar Branch of the Russian Federal Research Institute of Fisheries and Oceanography (VNIRO). The UK and Norwegian data (Townhill et al., 2020) are being released with this paper at 10.21335/NMDC-2139169383. [ABSTRACT FROM AUTHOR]

The commercialization of a new species through aquaculture is much more complex than the mastery of the production process, or closing the loop, as it is sometimes referred to. Commercial aquaculture is a layer within the global seafood industry, much as wild capture is; however, it places human control at a much earlier phase in the life cycle of the harvested product. As an important species on both sides of the Atlantic, the commercialization efforts for the culture of Atlantic cod are described for four locations, Norway, United Kingdom, New England, and Atlantic Canada that highlight many similar technical challenges and the progress made from the late 1980s through 2012. We also describe some of the marketing challenges faced and how they differ. Technically, the species has been commercialized. Hatcheries and farms in all four countries were successfully established. However, there are clear differences in access to capital for research and industrial expansion from both the private and public sector, social acceptance of farmed fish, as well as the impacts on sales when marketing farmed cod in the context of a global seafood supply. Lower cost species substitution, from either the farmed or wild catch, is also a factor that can have a significant impact on long‐term successful commercialization. [ABSTRACT FROM AUTHOR]

The mode and extent of rapid evolution and genomic change in response to human harvesting are key conservation issues. Although experiments and models have shown a high potential for both genetic and phenotypic change in response to fishing, empirical examples of genetic responses in wild populations are rare. Here, we compare whole-genome sequence data of Atlantic cod (Gadus morhua) that were collected before (early 20th century) and after (early 21st century) periods of intensive exploitation and rapid decline in the age of maturation from two geographically distinct populations in Newfoundland, Canada, and the northeast Arctic, Norway. Our temporal, genome-wide analyses of 346,290 loci show no substantial loss of genetic diversity and high effective population sizes. Moreover, we do not find distinct signals of strong selective sweeps anywhere in the genome, although we cannot rule out the possibility of highly polygenic evolution. Our observations suggest that phenotypic change in these populations is not constrained by irreversible loss of genomic variation and thus imply that former traits could be reestablished with demographic recovery. [ABSTRACT FROM AUTHOR]

The relationship between physiology and temperature has a large influence on population‐level responses to climate change. In natural settings, direct thermal effects on metabolism may be exaggerated or offset by behavioural responses influencing individual energy balance. Drawing on a newly developed proxy, we provide the first estimates of the thermal performance curve of field metabolism in a wild fish. We investigate the thermal sensitivity of field metabolic rate in two sympatric, genetically distinct ecotypes of Atlantic cod from the Skagerrak coast of southern Norway. The combined ecotype median of field metabolic rate increased with increasing temperature until around 16°C, coincident with the thermal optimum for growth for juvenile Atlantic cod. Individual cod experienced temperatures in excess of the thermal optimum for field metabolic rate, indicating some degree of thermal limitation of field metabolism in a complex natural environment with the potential for thermal refugia. The two cod ecotypes showed different thermal performance curves for field metabolic rate, revealing that genetic components to temperature sensitivity persist beyond acclimation effects. The cold‐adapted fjord ecotype maintained higher field metabolic rates at cooler temperatures than the warm‐adapted North Sea ecotype, which showed clear preference for warmer waters around the thermal optimum. Field metabolic rates of the two ecotypes were strongly influenced by year and location of sampling, implying more complex behavioural responses to environmental conditions. We emphasise that the energy uses reflecting physiological conditions in the field should be considered in the evaluation of the effect of climatic variables on fish population dynamics and demonstrate that otolith isotopes provide an analytical framework to answer this question. [ABSTRACT FROM AUTHOR]

In high latitude coastal regions, benthic scavenger communities are largely composed of invertebrates that play a key role in the cycling of organic matter. Factors including temperature and depth can structure Arctic and Subarctic fjord benthic communities, but the response of scavenging communities to these factors is poorly known. To address this, we compared scavenging fauna in eight fjords with different physical characteristics in Svalbard and northern Norway using time-lapse imagery of scavengers consuming Atlantic herring (Clupea harengus) bait. Fjords influenced by relatively warm Atlantic waters, both in Norway and Svalbard, had high scavenger richness. However, Svalbard fjords with negative bottom temperatures had the lowest species richness and were dominated by lysianassoid amphipods and ophiuroids. In these cold Svalbard fjords, the mean carrion removal rates were almost 20 times higher than mean values noted elsewhere, except in the warm Norwegian fjord Kaldfjorden. Amphipods and ophiuroids quickly reduced the bait to bones (207.6–304.7 g removed per hour (g h−1); mean 290.6 ± 7.3 g h−1, n = 4) in cold Svalbard fjords. In the warmer Svalbard fjords, carrion removal rates were low (0–51.5 g h−1; mean 14.6 ± 9.0 g h−1, n = 5). Carrion removal rates in Kaldfjorden were higher than other Atlantic Water influenced fjords (132.1 and 372.5 g h−1, n = 2) owing to the scavenging activity of Atlantic cod (Gadus morhua). The results demonstrate potential ecosystem responses to warming in Arctic and Subarctic fjords, particularly effects related to range expansion of boreal species. [ABSTRACT FROM AUTHOR]

Challenging long‐held perceptions of fish management units can help to protect vulnerable stocks. When a fishery consisting of multiple genetic stocks is managed as a single unit, overexploitation and depletion of minor genetic units can occur. Atlantic cod (Gadus morhua) is an economically and ecologically important marine species across the North Atlantic. The application of new genomic resources, including SNP arrays, allows us to detect and explore novel structure within specific cod management units. In Norwegian waters, coastal cod (i.e. those not undertaking extensive migrations) are divided into two arbitrary management units defined by ICES: one between 62° and 70°N (Norwegian coastal cod; NCC) and one between 58° and 62°N (Norwegian coastal south; NCS). Together, these capture a fishery area of >25,000 km2 containing many spawning grounds. To assess whether these geographic units correctly represent genetic stocks, we analysed spawning cod of NCC and NCS for more than 8,000 SNPs along with samples of Russian White Sea cod, north‐east Arctic cod (NEAC: the largest Atlantic stock), and outgroup samples representing the Irish and Faroe Sea's. Our analyses revealed large differences in spatial patterns of genetic differentiation across the genome and revealed a complex biological structure within NCC and NCS. Haplotype maps from four chromosome sets show regional specific SNP indicating a complex genetic structure. The current management plan dividing the coastal cod into only two management units does not accurately reflect the genetic units and needs to be revised. Coastal cod in Norway, while highly heterogenous, is also genetically distinct from neighbouring stocks in the north (NEAC), west (Faroe Island) and the south. The White Sea cod are highly divergent from other cod, possibly yielding support to the earlier notion of subspecies rank. [ABSTRACT FROM AUTHOR]

Gillnets made of the biodegradable resin polybutylene succinate co-adipate-co-terephthalate were tested under commercial fishing conditions to compare their fishing performance with that of conventional nylon polyamide (PA) gillnets. Both types of gillnets were made of 0.55 mm Ø monofilaments. However, since the biodegradable nets are weaker than nylon PA nets when using the same monofilament diameter, we also used biodegradable nets made of 0.60 mm Ø monofilament that had a similar tensile strength to the 0.55 mm Ø nylon PA nets. The relative catch efficiency of the different gillnet types was evaluated over the 2018 autumn fishing season for saithe and cod in northern Norway. For cod, both biodegradable gillnets (0.55 and 0.60 mm) had a significantly lower catch efficiency compared to the traditional nylon PA net (0.55 mm) with estimated catch efficiencies of 62.38% (CI: 50.55–74.04) and 54.96% (CI: 35.42–73.52) compared with the nylon PA net, respectively. Similarly for saithe, both biodegradable gillnets (0.55 and 0.60 mm) had a lower estimated catch efficiency compared to the traditional nylon PA net (0.55 mm) with estimated catch efficiencies of 83.40% (71.34–94.86) and 83.87% (66.36–104.92), compared with the nylon PA net, respectively. Tensile strength does not explain the differences in catch efficiency between the two gillnet types, since increasing the twine diameter of the biodegradable gillnets (to match the strength of nylon PA gillnets) did not yield similar catch efficiencies. However, the elasticity and stiffness of the materials may be responsible for the differences in catch efficiency between the nylon PA and biodegradable gillnets. [ABSTRACT FROM AUTHOR]

A new dataset on the diet of Atlantic cod in the Barents Sea from the 1930s to the present day has been compiled, to produce one of the largest fish diet datasets available globally. Atlantic cod is one of the most ecologically and commercially important fish species in the North Atlantic. The stock in the Barents Sea is by far the largest, as a result of both successful management and favourable environmental conditions since the early 2000s. As a top predator, cod plays a key role in the Barents Sea ecosystem. The species has a broad diet consisting mainly of crustaceans and teleost fish, and both the amount and type of prey vary in space and time. The data, from Russia, Norway and the United Kingdom, represents quantitative stomach contents records from more than 400,000 fish, and qualitative data from 2.5 million fish. Much of the data is from joint collaborative surveys between Norway and Russia. The sampling was done throughout each year allowing for seasonal, annual and decadal comparisons to be made. Visual analysis shows cod diets have changed considerably from the start of the dataset in the 1930s to the present day. There was a large proportion of herring in the diets in the 1930s, whereas in more recent decades, capelin, invertebrates and other fish dominate. There are also significant interannual asynchronous fluctuations in prey, particularly capelin and euphausiids. Combining these datasets can help us understand how the environment and ecosystems are responding to climatic changes, and what influences the diet and prey switching of cod. Trends in temperature and variability indices can be tested against the occurrence of different prey items, and the effects of fishing pressure on cod and prey stocks on diet composition could be investigated. The dataset will also enable us to improve parametrisation of food web models, and to forecast how Barents Sea fisheries may respond in the future, to management and to climate change. The Russian data is available through joint projects with Polar branch of VNIRO. The UK and Norwegian data (Townhill et al., 2020) is being released with this paper at https://doi.org/10.21335/NMDC-2139169383. [ABSTRACT FROM AUTHOR]

Stable isotope and elemental analyses of the Atlantic cod (Gadus morhua) and harp seal (Phoca groenlandica) bone component of the marine food that dominated the Younger Stone Age (c. 6.1–3.5 ka BP) diet in Varanger, Arctic northern Norway, indicate, at times, climate change induced highly elevated levels of the heavy metals cadmium (Cd) and lead (Pb), and elevated levels of mercury (Hg). On average, the levels of cadmium and lead contamination in cod were up to 22 and 3–4 times, respectively, higher than today's recommended limits in soft tissue. The corresponding figures for seal were 15 and 3–4 times, respectively. The levels of Hg were generally below today's recommended limit in soft tissue, but still of considerable magnitude, almost similar to the measured values in modern fish in the Arctic. This shows that marine food in the Younger Stone Age was unhealthy, if not unsafe. We discuss this unexpected knock-on effect in terms of sea surface temperatures and sea level change. The elevated values may have been detrimental for humans, if not for society; a balancing factor may have been a larger component of terrestrial resources than previously assumed. Concomitantly, this contribution to the paleo base-line record of toxicity may lead to predictions for seafood contamination in the future. [ABSTRACT FROM AUTHOR]

To explore ecosystem dynamics and functions it is vital to obtain knowledge on predator–prey relations. Harbour seals are piscivorous predators that can come into conflict with fisheries. Recently, as the Skagerrak and Kattegat population of harbour seals has increased, claims have emerged that seals are depleting coastal cod populations. The diet of harbour seals in Norwegian Skagerrak was investigated based on otolith identification from scats. The overall seal diet included 20 different fish species/groups. The most important prey (combined index Qi) were haddock/pollack/saithe (32.7%), genus Trisopterus (Norway pout/poor cod/bib, 12.5%), plaice (12.4%) and herring (10.0%). Plaice also had the largest biomass (24.1%). Gadoids and pleuronectids comprised 88.6% of the diet (combined index Qi) and 87.1% in terms of biomass. Cod constituted 0.7% (combined index Qi) of the overall diet and 2.3% in terms of biomass. Fish length estimates showed that seals generally prefer small fish below minimum allowed landing size. Estimated total amount of fish consumed was 315 tons per year and was dominated by non-commercial species. Annual cod consumption was an estimated 7.1 tons, representing 5% of annual cod landings, suggesting that competition between local fisheries and harbour seals is limited. [ABSTRACT FROM AUTHOR]

The relative importance of host-specific selection or environmental factors in determining the composition of the intestinal microbiome in wild vertebrates remains poorly understood. Here, we used metagenomic shotgun sequencing of individual specimens to compare the levels of intra- and interspecific variation of intestinal microbiome communities in two ecotypes (NEAC and NCC) of Atlantic cod (Gadus morhua) that have distinct behavior and habitats and three Gadidae species that occupy a range of ecological niches. Interestingly, we found significantly diverged microbiomes among the two Atlantic cod ecotypes. Interspecific patterns of variation are more variable, with significantly diverged communities for most species' comparisons, apart from the comparison between coastal cod (NCC) and Norway pout (Trisopterus esmarkii), whose community compositions are not significantly diverged. The absence of consistent species-specific microbiomes suggests that external environmental factors, such as temperature, diet, or a combination thereof, comprise major drivers of the intestinal community composition of codfishes. [ABSTRACT FROM AUTHOR]

While many in-laboratory ecotoxicological studies have shown the adverse impact of pollutants to the fitness of an individual, direct evidence from the field on the population dynamics of wildlife animals has been lacking. Here, we provide empirical support for a negative effect of pollution on Atlantic cod (Gadus morhua) population dynamics in coastal waters of Norway by combining unique time series of juvenile cod abundance, body size, environmental concentration of toxic contaminants and a spatially structured population dynamics model. The study shows that mercury concentration might have decreased the reproductive potential of cod in the region despite the general decline in the environmental concentration of mercury, cadmium and hexachlorobenzene since the implementation of national environmental laws. However, some cod populations appeared to be more resistant to mercury pollution than others, and the strength and shape of mercury effect on cod reproductive potential was fjord-specific. Additionally, cod growth rate changed at scales smaller than fjords with a gradient related to the exposure to the open ocean and offshore cod. These spatial differences in life-history traits emphasize the importance of local adaptation in shaping the dynamics of local wildlife populations. Finally, this study highlights the possibility to mitigate pollution effects on natural populations by reducing the overall pollution level, but also reveals that pollution reduction alone is not enough to rebuild local cod populations. Cod population recovery probably requires complementary efforts on fishing regulation and habitat restoration. [ABSTRACT FROM AUTHOR]

In Norway, mine tailings waste can be deposited by coastal submarine dispersal. Mine tailings slurry includes fine particles <10 µm with elevated levels of metals (e.g., copper, iron) from residual mineral ore. Prolonged suspension of small particles in the water column may bring them into contact with locally spawned pelagic fish eggs, including Atlantic cod, Gadus morhua. Newly fertilized cod embryos were exposed to suspended mine tailings particles up to 3.2 mg/L in flow‐through aquaria for a total of 21 d. Significantly more particles adhered to the surface of the chorion from the high treatment after 11‐d exposure, and dissolved Cu concentrations increased in the water (up to 0.36 ± 0.06 µg/L). There was no adverse effect on embryo mortality but an 8% elevation in larval mortality. There were no differences with treatment on timing of hatching, embryo and larva morphometrics, abnormalities, or cardiac activity. There was a treatment‐dependent up‐regulation of stress marker genes (hspa8, cyp1c1) but no indication of metal‐induced activation of metallothionien (mt gene transcription). Transcription markers for DNA and histone methyltransferases did show treatment‐related up‐regulation, indicative of altered methylation in larvae when developmental methylation patterns are determined, indicating some level of chronic toxicity that may have longer‐term effects. Environ Toxicol Chem 2019;38:1446–1454. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Summary: Atlantic cod (Gadus morhua) is an ecologically important species with a wide‐spread distribution in the North Atlantic Ocean, yet little is known about the diversity of its intestinal microbiome in its natural habitat. No geographical differentiation in this microbiome was observed based on 16S rRNA amplicon analyses, yet such finding may result from an inherent lack of power of this method to resolve fine‐scaled biological complexity. Here, we use metagenomic shotgun sequencing to investigate the intestinal microbiome of 19 adult Atlantic cod individuals from two coastal populations in Norway–located 470 km apart. Resolving the species community to unprecedented resolution, we identify two abundant species, Photobacterium iliopiscarium and Photobacterium kishitanii, which comprise over 50% of the classified reads. Interestingly, the intestinal P. kishitanii strains have functionally intact lux genes, and its high abundance suggests that fish intestines form an important part of its ecological niche. These observations support a hypothesis that bioluminescence plays an ecological role in the marine food web. Despite our improved taxonomical resolution, we identify no geographical differences in bacterial community structure, indicating that the intestinal microbiome of these coastal cod is colonized by a limited number of closely related bacterial species with a broad geographical distribution. [ABSTRACT FROM AUTHOR]

Abstract Catch-based aquaculture (CBA) is an important production system in many parts of the world, especially in developing countries. In Norway CBA is based on capture and storage/farming of mature, North-east Atlantic (NEA) cod (Gadus morhua). The objective is to reduce seasonal variations and add value, by storing/farming fish to take advantage of higher prices in low seasons. Despite numerous development programs and economic incentives, the development of the CBA business has been slow. Few actors are storing fish long enough to take advantage of high price in low season. A reason for this is that CBA is caught in between two sectors: the fisheries and aquaculture, with radically different institutional frameworks, creating entry barriers and a complex regulatory framework. Moreover, the legitimacy of the CBA is in question, as CBA intervene into the resource allocation mechanism in traditional fisheries. Still, it is too early to conclude that CBA has failed, as we are dealing with an industry in the making. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to assess whether fish in Kollevåg, a sheltered bay on the western coast of Norway, previously utilized as a waste disposal site, could be affected by environmental contaminants leaking from the waste. Farmed, juvenile Atlantic cod (Gadus morhua) were caged for six weeks at three different locations in Kollevåg bay and at one reference location. Sediments and cod samples (bile and liver) were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), per-and polyfluoroalkyl substances (PFASs) and polycyclic aromatic hydrocarbon (PAH) metabolites, revealing a contamination gradient at the four stations. Furthermore, hepatosomatic index (HSI) and Fulton's condition factor (CF) were significantly lower in cod caged closest to the disposal site. Levels and activities of biomarker proteins, such as vitellogenin (Vtg), metallothionein (Mt), and biotransformation and oxidative stress enzymes, including cytochrome P450 1a and 3a (Cyp1a, Cyp3a), glutathione s-transferase (Gst) and catalase (Cat), were quantified in blood plasma and liver tissue. Hepatic Cat and Gst activities were significantly reduced in cod caged at the innermost stations in Kollevåg, indicating modulation of oxidative stress responses. However, these results contrasted with reduced hepatic lipid peroxidation. Significant increases in transcript levels were observed for genes involved in lipid metabolism (fasn and acly) in cod liver, while transcript levels of ovarian steroidogenic enzyme genes such as p4 50scc, cyp19 , 3β-hsd and 20β-hsd showed significant station-dependent increases. Cyp1a and Vtg protein levels were however not significantly altered in cod caged in Kollevåg. Plasma levels of estradiol (E2) and testosterone (T) were determined by enzyme immunoassay (EIA) and showed elevated E2 levels, but only at the innermost station. We conclude that the bay of Kollevåg did not fullfill adequate environmental condition based on environmental quality standards (EQSs) for chemicals in coastal waters. Following a six weeks caging period, environmental contaminants accumulated in cod tissues and effects were observed on biomarker responses, especially those involved in reproductive processes in cod ovary. Highlights • Compared to the reference site, the following differences were observed in Kollevåg: - Increased contaminant levels in sediments. - Accumulation of environmental contaminants in caged cod. - Significant alterations of several biological responses in caged cod. - Biomarkers affected included those involved in reproductive processes in cod ovaries. • The capped waste disposal site does not fullfill environmental quality standards. [ABSTRACT FROM AUTHOR]

The Northeast Arctic cod (Gadus morhua) is the world's northernmost stock of Atlantic cod and is of considerable ecological and economic importance. Northeast Arctic cod are widely distributed in the Barents Sea, an environment that supports a high degree of ecosystem resiliency and food web complexity. Here using 121 years of ocean temperature data (1900–2020), 41 years of sea ice extent information (1979–2020) and 27 years of total mercury (Hg) fillet concentration data (1994–2021, n = 1999, ≥71% Methyl Hg, n = 20) from the Barents Sea ecosystem, we evaluate the effects of climate change dynamics on Hg temporal trends in Northeast Arctic cod. We observed low and consistently stable, Hg concentrations (yearly, least-square means range = 0.022–0.037 mg/kg wet wt.) in length-normalized fish, with a slight decline in the most recent sampling periods despite a significant increase in Barents Sea temperature, and a sharp decline in regional sea ice extent. Overall, our data suggest that recent Arctic amplification of ocean temperature, "Atlantification," and other perturbations of the Barents Sea ecosystem, along with rapidly declining sea ice extent over the last ∼30 years did not translate into major increases or decreases in Hg bioaccumulation in Northeast Arctic cod. Our findings are consistent with similar long-term, temporal assessments of Atlantic cod inhabiting Oslofjord, Norway, and with recent investigations and empirical data for other marine apex predators. This demonstrates that Hg bioaccumulation is highly context specific, and some species may not be as sensitive to current climate change-contaminant interactions as currently thought. Fish Hg bioaccumulation-climate change relationships are highly complex and not uniform, and our data suggest that Hg temporal trends in marine apex predators can vary considerably within and among species, and geographically. Hg bioaccumulation regimes in biota are highly nuanced and likely driven by a suite of other factors such as local diets, sources of Hg, bioenergetics, toxicokinetic processing, and growth and metabolic rates of individuals and taxa, and inputs from anthropogenic activities at varying spatiotemporal scales. Collectively, these findings have important policy implications for global food security, the Minamata Convention on Mercury, and several relevant UN Sustainable Development Goals. [Display omitted] • Temporal trends (1994–2021) of total mercury (Hg) in Northeast Arctic cod fillets from Barents Sea were assessed. • Climate change indicators including sea temperature and sea ice extent were also evaluated. • Length-adjusted cod Hg was low and stable with annual means ranging from 0.022 to 0.037 mg/kg wet weight. • Sea ice extent and sea temperature were not associated with fish Hg trends. • Effects of climate change on marine fish Hg bioaccumulation rates are context specific. [ABSTRACT FROM AUTHOR]

A quantity of studies have documented how greater condition and older age of individual fish enhances reproductive success via a variety of processes from egg production to larval survival. If these relations translate into relationships between stock demography and recruitment, maintaining a "healthy" age composition may be a key step towards ensuring stock productivity. We examined the correlation between indicators of the age and size composition and the residual-variation from the stock-recruitment relationship (i.e. the variation not explained by the spawning stock biomass) in eleven commercially exploited fish stocks in the North Sea. We also analyzed to what extent spawner age and size composition responded to variations in fishing mortality. Before detrending to accommodate any temporal patterns, recruitment residuals correlated negatively with the relative age composition in all eleven stocks (plaice, whiting, and saithe being significant). However, after detrending the recruitment residuals, the correlations weakened and only nine out of eleven stocks correlated negatively. Lastly, we also conducted a delay difference analysis, which yielded a more or less even distribution between negative and positive correlations, and in addition two stocks (cod and Norway pout) came out showing significant positive correlations between recruitment residuals and age composition. In contrast, eight of the eleven stocks showed positive correlations between spawner weight and recruitment residuals and correlations were significant for plaice, cod, and saithe. After detrending the data, the significant correlations disappeared, but the overall tendency towards positive correlations between spawner weight and recruitment residuals prevailed. Overall, these results suggest that fish condition is more likely to show positive relationships with recruitment success than age composition. Lastly, it was found that the majority of stocks showed a strong link between fishing mortality and the two indicators of age composition, and when looking across stocks, the age composition appears to have returned to the same level as in the 1960 s. Conversely, spawner weight at age have not recovered, and considering the indications of a positive link between spawner weight and recruitment, recruitment success of the North Sea stocks may remain low in spite of the apparently successful rebuilding of the age composition. • A large proportion of old fish coincided with increased recruitment in Atlantic cod and Norway pout. • Individual weight of old fish in the spawning stock was often positively correlated with recruitment. • As expected, the age composition responded directly to changes in fishing pressure. • There was a general declining trend over time in the individual weight of fish in the spawning stock. [ABSTRACT FROM AUTHOR]

The spatial complexity of coastal ecosystems represents a challenge for the management of inshore resources. Here we compared two large fjord systems in northern Norway that have been closed for all bottom trawling for 50 years to a fjord with continuous shrimp fishery with bottom trawls. No significant differences were found between fjords with and without commercial trawling in population density and stock composition of northern shrimp (Pandalus borealis) and their main predator, Atlantic cod (Gadus morhua). Shrimp density was instead linked with bottom depth, while shrimp size and stage composition as well as cod density were explained by seasonal effects and shrimp density. For shrimp, a large degree of the observed variation was captured by spatial correlation that could not be explained by other covariates. The results underline the complex ecology in heavily structured coastal habitats and indicate that coastal shrimp dynamics are shaped by an interplay of multiple ecological and environmental drivers, possibly in concert with local genetic adaptations. The substantial fine-scale spatial variation adds to the challenges of assessing and managing fisheries resources in these fjord ecosystems. Because shrimp are an important forage species, notably as prey for cod, there are potential management conflicts between rebuilding cod stocks and reopening closed shrimp trawling areas. • Differences in fishing and fjord ecology shape shrimp and cod populations. • Cod density was correlated with shrimp density. • Substantial spatial variation in shrimp populations linked to ecological processes. • Management conflict between rebuilding cod stocks and reopening for trawling. [ABSTRACT FROM AUTHOR]

There is strong evidence that ecolabeled seafood commands a price premium in the retail market in Northern European countries. At the same time, there is significant uncertainty as to whether these markups are passed on to the fishers. This is important because producer benefits are required for an ecolabel to provide incentives for sustainable fishery management and fishing practices. Therefore, we investigate whether fishers obtained price premiums for certified cod in Norway. A unique setting for this investigation was created when a part of the fishery, the one conducted within the Norwegian territorial waters, lost its certification by the Marine Stewardship Council (MSC), while it was maintained for the offshore part of the fishery. Using a difference-in-difference approach, analyzing a large and detailed dataset, we find that on average, there is no premium for certified cod, and that other factors are more important. When controlling for buyer types, the loss of the MSC certification resulted in a price reduction for cod sold to producers who make fillets for Northern European markets. However, we found no significant price effect for cod sold to the other buyer types. This highlights the difficulty of obtaining a price premium when there are alternative sources of the product. • First study on MSC suspension's impact on Norwegian cod prices, considering buyer types and market segments. • We find on average no evidence for a price premium for certified cod. • The loss of the MSC certification lowered cod prices for fillet producers in Northern Europe. • Results show the difficulty in obtaining a price premium when there are alternative destinations for the product. [ABSTRACT FROM AUTHOR]

The management of the Norwegian Northeast Atlantic cod fishery has in many ways been a success story; quotas have been high (but now declining), profitability has been higher than most other industries and there is great interest among young recruits to enter the fishery. However, over the last decade illegal fishing of allocated quotas and black-market transactions throughout the value chain have become a significant of the political debate in the fishey, especially in northern Norway. Fisheries crime has been described as a priority area for law enforcement. To combat illegal overfishing the introduction of new automatic catch monitoring technologies onboard fishing vessels is considered a key strategy by the Norwegian Directorate of Fisheries. However, the new quota control measures are met with considerable resistance by the fishermen. This paper outlines the key elements of modern fisheries management to address sustainability goals, how the institutional subsystems connect with each other, and how illegal overfishing may threaten the stability of the entire management system. The gravity of illegal overfishing supports the authorities' new strategies to increase catch- and quota control. Nevertheless, the implementation of new control technologies may not be straightforward. Especially small-scale fishermen have presented a number of valid arguments against the proposed control measures. Thus, this study outlines how the implementation process may gain increased support from the fishermen. [ABSTRACT FROM AUTHOR]

Capture-based aquaculture (CBA) is an important branch of the aquaculture industry that differs from closed cycle farming in that the stocking material consists of captured wild fish or other aquatic organisms. By skipping the difficult early production stages of fish farming, producers can test whether assumed market advantages such as high quality and consistent supply result in higher prices – and whether these are high enough to incentivize further development of CBA and eventually close the production cycle. CBA-initiatives can also be supported by different policy measures to stimulate the activity. Since these measures involve costs, it is important to know at what level and for how long these measures should be implemented to promote economically sustainable CBA activities. We study CBA of Atlantic cod (Gadus morhua) in Norway and find an average price premium of 26% compared to wild harvested cod, but with large interannual variation. However, declining quantities of cod from CBA following reductions in a quota bonus scheme to stimulate activity, indicates that the price premium is not sufficiently large to incentivize further development of the CBA branch of the Norwegian cod industry. • Catch-based aquaculture (CBA) is an important production mode for many species. • In Norway, CBA took over when the closed cycle aquaculture industry could not cope with disease. • We show that there is an average price premium of 26% for the CBA cod. • The premium vary signficantly between years, suggesting that it is highly quantity sensitive. [ABSTRACT FROM AUTHOR]

To increase our understanding of the interaction between fish and baited fishing gear we quantitatively described the behaviour of cod (Gadus morhua), saithe (Pollachius virens), and haddock (Melanogrammus aeglefinus) to baited pots in a fjord in northern Norway. Detailed video analyses were made to describe species specific responses and examine the effect of lifting the pot off the bottom. The majority of both cod and saithe approached the pots in an upstream direction, and fish approached floated pots higher in the water column than bottom set pots. Cod tended to approach a pot along the seabed and were more likely to encounter the bottom set pot than the floated pot, whereas saithe more often approached in the water column. The capture efficiency was low for all species, but cod were more likely to be caught than saithe and haddock. Cod showed a high encounter rate, low entrance rate and high escape rate. For saithe, a low encounter rate was the chief factor limiting capture efficiency. The observed differences between cod and saithe were explained by species-specific food-search strategies. No difference in entrance rate, escape rate or catch efficiency between the two pot types were found. [ABSTRACT FROM AUTHOR]

Resolving the relationship between demersal fish and sublittoral biotic habitats and substrates is a key element in the protection of important nursery grounds for strengthening fish recruitment. In Norway, coastal Atlantic cod (Gadus morhua L.) is a commercially and culturally important demersal fish for Norwegian coastal communities, and in recent decades the stock has declined to such an extent that a plan to rebuild the stock to biologically safe limits has been implemented. Yet, little is known about the specific biotic and abiotic habitat associations of the early-life stages of coastal cod, which is important for the management and protection of the species. The same shallow, sublittoral zones are inhabited by juveniles and adults of other commercial demersal gadoids and wrasses. This study presents novel findings on associations between juvenile coastal cod and other demersal fish species with seafloor substrates and biological habitats, inferred from five years of extensive fyke net surveys. Newly settled 0-group cod were typically associated with eel grass and red algae biotic habitats on sand and shell sand substrates. However, there was an ontogenic habitat shift amongst one year old (1-group) individuals that became more ubiquitous with their biotic habitat or substrate type choices. The juvenile gadoids saithe (Pollachius virens) and pollack (Pollachius pollachius), were most associated with hard bottom dominated sites with saithe being more abundant at exposed sites, compared to pollack. Goldsinny wrasse (Ctenolabrus rupestris) and corkwing wrasse (Symphodus melops) appeared to favor sugar kelp forests and red algae. Overall, the study identifies the specific sublittoral biotic habitats and substrates important to different early life stages of juvenile coastal cod and other commercially important demersal fish, providing critical information needed for identifying candidate coastal habitats for protection. • Newly settled 0-year Atlantic cod prefer red algae habitats as well as eelgrass. • Atlantic cod juveniles over 1 year do not show specific habitat associations. • Red algal habitats and sugar kelp forests favored by wrasse. • Saithe associated with exposed bedrock sites while more pollack were in mixed substrates in more sheltered areas. • Knowledge of specific sublittoral habitat associations to improve cod and demersal fish management. [ABSTRACT FROM AUTHOR]

A farmed triploid pug-headed specimen of the Atlantic cod, Gadus morhua measuring 501 mm TL was obtained from IMR Parisvatn Field Station, Norway. The abnormal specimen had the following aberrant characters: short neurocranium and upper jaw, very short snout in comparison with the normal specimens, and asymmetrical upper and lower jaws. The right side of the head and the pre-maxilla were deformed, twisted downward and forward. The lower jaw was slightly distorted to the left. Causes for such aberrations are discussed. [ABSTRACT FROM AUTHOR]

In the important coastal fishery for Atlantic cod in Norway quality-based pricing is largely absent. Thus, driven by a focus on fish quantity, not quality, a high share of downgraded fish is landed. This study identified some encouraging exceptions with actors trying to align incentives and increase revenues in both fishing and processing. More specifically, we examine two cases involving quality-enhancing fishing and find indications of substantial improvements in fish quality and importantly, that this is rewarded with higher prices. In a revenue-sharing arrangement with a focus on high quality fish delivered outside of the main season, fishers obtain approximately 50 % higher prices than comparable vessels fishing with the same gear in the same period. In the other case, fishers' "skip" the Norwegian ex-vessel market and sell their high-quality cod catches at Danish auctions at significantly higher prices than comparable vessels fishing in the same area and delivering in South Norway. The cases may guide fishers and fish buyers in increasing revenues through quality-enhancing fishing but also involve important dilemmas for policymakers which are highlighted and discussed. [ABSTRACT FROM AUTHOR]

Hidden within the seminal 1914 publication by Johan Hjort, we find what is probably one of the first comprehensive teleost time-series ever published. The series is liver size and fat content of northeast Arctic (NEA) cod measured during the traditional winter fishery in Lofoten, Northern Norway, in 1880–1912 and 1883–1913, respectively. The data were collected well before the advent of the great industrialized fisheries in the 1930s. The raw data used by Hjort originate from annual reports of the Lofoten fishery, initiated by Member of Parliament and pioneer fishery inspector of Northern Norway, Ketil Motzfeldt, in 1859. Based on these reports and following various calibration exercises, we present robust estimates of the hepatosomatic index (HSI) from 1859 to 2012 (except 1863), i.e. over 153 years—extending Hjort's analysis both backwards (1859–1879) and forwards (1913–present). This series of bulk HSI contained five major periods: 1859–1880, 1881–1919, 1920–1974, 1975–2003, and 2004–2012; the highest HSI was recorded 1920–1974, whereas the lowest was from the most recent period. Despite variability, total length was a significant predictor of HSI, 1932–2012. A weak but significant relationship existed with both total-stock biomass and ocean temperature, as well as with the North Atlantic Oscillation winter index under a 1-year lag. The present exceptionally long HSI series will give an excellent opportunity for further research on the “quality of the cod” in a historic perspective. [ABSTRACT FROM AUTHOR]

A genetically marked Atlantic cod (Gadus morhua L.) strain was used to identify escapes from commercial cod farms, and to investigate the potential interbreeding between farmed and wild cod. This farmed cod was homozygote for a rare allele (30) in the GPI-1 locus expressed in white muscle tissue. Juveniles were produced from this strain in 2007 and 2008, and 500 000 individuals of each year class were transported to a cod farm in western Norway, where they were raised under commercial conditions. A monitoring fishing program was established from spring 2007 to detect escapees during the farming period. The first farmed cod escapees, identified to the 2007 year class through the genetic mark, age and body size, were detected during the fishing survey in November 2008. The second escape of the same year class was detected during the natural spawning season in early April 2009. A third escape was detected in November 2009, and this time the farmed cod were identified to the 2008 year class. The escapees were spreading through the whole fjord system, including local spawning sites for wild cod. Detailed examination of the escaped cod revealed a substantial degree of sexual maturation, and nearly 1000 cod larvae and early juveniles were therefore collected through spring 2009. The genetic analyses identified eight of these as genetically marked, demonstrating successful reproduction either in the cage or after escape. Interbreeding between escaped and wild cod may also have occurred, but cannot be proven from our material. In all years after the three identified escapes, genetically marked cod were found in the fjord area. In addition, several specimens were observed in adjacent fjord systems, demonstrating long-term survival in the local spawning areas as well as substantial spread over larger distances. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Highest concentration of Hg was not found in the central part but in the northern part of the North Sea. [•] The Hg concentrations in coastal and fjord cod increased southward along the coast. [•] Only three samples out of some 1200 cod muscle showed Hg concentration higher than 0.5mgkg−1, the EU limit for foodstuffs. [•] Cd concentrations in liver of coastal and fjord cod increased northward along the coast. [Copyright &y& Elsevier]

To gain a better understanding of population processes and in the light of the critically endangered status of the Common Guillemot Uria aalge in Norway, we investigate which environmental factors might affect the fitness of guillemot chicks as they depart from the nest site over a 16-year period on a colony in NE Norway. Although prey composition did not seem to influence the fledging body mass of the chicks, there were significant relationships between the yearly variations in chick body mass and abundance of two important prey species (1-group herring Clupea harengus that is an important chick food item and 0-group cod Gadus morhua that is an important adult food item), population size and the sea surface temperature around the colony. The positive influence of young herring and cod on Common Guillemot chick mass occurred during a period of warming in the Barents Sea such that future recruitment into the population will depend partly on the long-term changes in ocean climate in the region. [ABSTRACT FROM AUTHOR]

Bioaccumulation of sediment-associated polychlorinated biphenyls (PCBs) was examined in Atlantic cod ( Gadus morhua) through direct diffusion from the sediment (via the water phase) and through the food chain (dietary exposure). To facilitate direct accumulation from the sediment, it was continuously resuspended. To study the dietary bioaccumulation of PCBs, cod were fed benthic polychaetes ( Nereis virens) previously exposed to test sediments, which were naturally polluted sediments from the inner Oslofjord (Norway). Both exposure experiments had a duration of 129 d. Furthermore, the role of sediments as a source of PCBs accumulated in Oslofjord cod was elucidated, using results from environmental monitoring as a reference. Generally, the results suggest that the contaminated sediments of the inner Oslofjord are an important source of legacy PCBs for accumulation in resident cod, although additional contributions may also be important. Crude estimates of assimilation efficiency of ingested PCBs (through diet) were found to be 30 to 50%; the highest was for the lower chlorinated congeners (PCB-28 and -52). Challenges for applying trophic magnification factors for determining biomagnification in laboratory experiments, in terms of preventive environmental safety, are indicated. The results provide useful information for parameterization of models describing the behavior of hydrophobic persistent contaminants in the foodweb of the Oslofjord and elsewhere. Environ. Toxicol. Chem. 2012; 31: 2472-2481. © 2012 SETAC [ABSTRACT FROM AUTHOR]