Norwegian Aquaculture Research Articles

Epidemiology of bacterial diseases in Norwegian aquaculture--a description based on antibiotic prescription data for the ten-year period 1991 to 2000.

In Norway, antibacterial drugs for use in farmed fishes have to be prescribed by a veterinarian. Moreover, a national surveillance programme requires that copies of all prescriptions be sent to the Directorate of Fisheries. The prescriptions give information regarding fish farm and locality, weight and species of fish to be medicated, diagnosis, type and amount of drug prescribed, and date. These prescription data for the 10 yr period 1991 to 2000 have been recorded and systematised. A total of 6322 prescriptions issued for 11 fish species were registered; Atlantic salmon represented 87% of the prescriptions, rainbow trout 4.5%, arctic char 0.3%, turbot 3.8%, halibut 2.1%, Atlantic cod 1.2%, and European eel 0.3%. European sea-bass, wolf-fish, coalfish and wrasse represented a total of 0.4% of the prescriptions. Furunculosis was the most frequently given diagnosis in Atlantic salmon, accounting for 79% of all prescriptions for this species. Furunculosis was more frequent during the summer and early autumn, and in the western parts of Norway. Fish weighing more than 1 kg seemed to be the most susceptible. However, furunculosis has almost disappeared in Norwegian aquaculture since 1993. Vibriosis gave cause for antibiotic treatments in almost all fish species, and was the most common diagnosis in rainbow trout, halibut, turbot, cod and European eel. In Atlantic salmon, fish of small and medium size (up to 1 kg) seemed to be more at risk from vibriosis, and outbreaks were more frequent during summer, and in the western counties. Cold-water vibriosis was the second most frequently treated disease in Atlantic salmon, creating severe problems mainly in larger fish, in the northern parts of the country, and during winter and spring. The seasonal distribution was similar for winter ulcer disease, the only disease which seemed to be of increasing importance in Atlantic salmon. Non-specific diagnoses, such as 'bacterial infection' and 'fry disease', were given in a much higher proportion of prescriptions for marine fish species than in prescriptions for salmonids.

Cardiomyopathy syndrome in farmed Atlantic salmon Salmo salar: occurrence and direct financial losses for Norwegian aquaculture.

Cardiomyopathy syndrome (CMS) was first diagnosed in the mid-1980s in farmed Atlantic salmon in Norway, and later also in Scotland and the Faeroe Islands. In Norway the number of diagnosed cases increased from 25 to 103 in the period from 1998 to 2001 according to the National Veterinary Institute (NVI) records. Very little is known about the causes of the disease and there is no documentation of its impact on the farmed salmon industry. This field survey was performed to collect information on occurrence, risk factors and the economic importance of CMS in sea farmed Atlantic salmon Salmo salar in Norway. Data were collected in January 2001 from a total of 174 groups of farmed salmon which had been previously transferred to sea during 1999 and 2000. Approximately 11.5% of all groups of salmon in our study experienced cases of CMS. Affected fish were presumably in generally good condition prior to time of death. In fish which had completed the seawater production cycle, CMS occurred more than 1 yr (median 395 d, >2 kg body weight) after seawater transfer. In fish transferred into the sea during autumn 2000 which had not completed the seawater cycle during the study period, CMS was diagnosed at a weight as low as 700 g. Although sudden death is characteristic, CMS may be regarded as a chronic disease, with moderately elevated mortality rates at site level. Affected groups showed significantly increased mortality, causing a direct annual financial loss for the industry of Euros 4.5 to 8.8 million on fish farms. Preventive prescheduled slaughtering of salmon, which is performed on many affected farms, may be too costly when done too early.

Industrial Agglomeration and Production Costs in Norwegian Salmon Aquaculture

During the last decade, empirical evidence of regional agglomeration economies has emerged for some industries. This paper argues that externalities from agglomeration are not only present in some manufacturing and service sectors, but can also occur in primary industries, such as aquaculture. Econometric analyses in this literature have primarily estimated rather restrictive production function specifications on aggregated industry data. Here, cost functions are estimated on firm-level observations of Norwegian salmon aquaculture farms. This approach provides us with measures of the cost savings due to agglomeration externalities. Furthermore, we avoid aggregation biases and can test a rich set of hypotheses on how these externalities affect the structure of costs at the firm level. According to the econometric estimates, there are significant cost savings associated with localization in regions with a large salmon aquaculture industry, suggesting the presence of positive agglomeration externalities. In fact, the results here suggest that for small firms localized in clusters, agglomeration externalities can compensate for internal economies of scale, making them competitive relative to larger firms localized outside clusters. The econometric results imply that there are significant welfare gains to be made from changes in the government regulation of the industry.

Norwegian Salmon Aquaculture and Sustainability: The Relationship Between Environmental Quality and Industry Growth

This paper discusses the relationship between industry growth and environmental quality in the context of salmon aquaculture. It is argued that industry growth can reduce pollution by inducing more technological innovations for industry-specific, pollution-reducing inputs. This increases the elasticity of substitution between conventional factors of production on the one hand, and pollution on the other, and therefore enables a greater degree of internalization of environmental problems. Four indicators of pollution are examined for Norwegian salmon aquaculture. The salmon aquaculture industry is one in which growth is associated with reduced environmental problems not only in relative, but also in absolute terms.

Monitoring and regulation of marine aquaculture in Norway

Norwegian marine aquaculture is dominated by the production of salmon and rainbow trout. The Ministry of Fisheries is the main authority responsible for the licensing of new farms (1 licence = 12 000 m3> production volume) and the control of the industry. There is a tight co-operation with other authorities (such as environment, disease control, local government and labour) and the aquaculture industry. The aquaculture industry in Norway is strictly regulated, with an obligation to keep very detailed records at each farm. The regulatory system is based on environmental standards, set to meet the requirements for different kinds of use (such as aquaculture, recreation and fishing). It is left to the local authorities to set the limits allowed for each farm. Increasingly, the Modelling Ongrowing fish farms Monitoring system, or parts of it, is used to regulate the production and environmental impact of aquaculture at the farm level. Norway follows the EU regulations regarding food quality standards and the licensing process for medicines and pesticides, with a zero-detection limit for permitted levels of medicines and pesticides in aquaculture products at harvesting. The control system for the use of medicines in Norwegian aquaculture makes it possible to have detailed records of the use of all medicines at site level. Norway has the most detailed database registration of this kind in the world.

Surveillance by the Use of Prescription Data

Antibacterial drug treatment in aquaculture during 1991-1996 was investigated using prescription data provided by the Norwegian Government Fish Inspection and Quality Control Service (NFCS). The majority of prescriptions (n = 5401) were for Atlantic salmon and rainbow trout (salmonids), while 383 prescriptions were for other species. Of the 13 different single substances or combinations prescribed during the study period, only 5 were approved for or had been subjected to clinical trials in salmonids. Of the prescriptions for the salmonids, 99% were for approved drugs or drugs subjected to clinical trials. The major proportion of the antibacterial drugs prescribed for other fish species were drugs which were approved for or which had been subjected to clinical trials in salmonids. In all fish species, the prescribing of antibacterial drugs which were neither approved for nor had been subjected to clinical trials was mainly for fish far below slaughter weight. The prescription data were validated against the drug statistics from the wholesalers and feed mills. It was concluded that the data indeed represented antibacterial drug prescribing in Norwegian aquaculture. The prescribing of antibacterial drugs proved to be almost completely reported to NFCS, which is responsible for the control of drug residues in farmed fish in Norway.

Environmental problems, productivity and innovations in Norwegian salmon aquaculture

Environmental issues have been of central importance throughout the history of salmon aquacuiture in Norway. In this paper we will examine some of the issues, and show that while there are still problems, many have also been resolved. A major reason for this is the fact that salmon farmers have internalized many of the environmental effects into their decision‐making due to the relationship between environmental impact and productivity. Another reason, particularly when it comes to treatment of diseases, is that lack of private innovative activity due to different market failures has been compensated for by government‐sponsored research and development.

Environmental problems, productivity and innovations in Norwegian salmon aquaculture

Abstract Environmental issues have been of central importance throughout the history of salmon aquacuiture in Norway. In this paper we will examine some of the issues, and show that while there are still problems, many have also been resolved. A major reason for this is the fact that salmon farmers have internalized many of the environmental effects into their decision‐making due to the relationship between environmental impact and productivity. Another reason, particularly when it comes to treatment of diseases, is that lack of private innovative activity due to different market failures has been compensated for by government‐sponsored research and development.

Production Risk and Productivity Growth: Some Findings for Norwegian Salmon Aquaculture

This paper deals with estimation of primal panel data models of production risk, focusing on measurement of risk properties of inputs and productivity growth. Under production risk one should estimate technical change separately for the deterministic part and risk part of the technology, since risk averse producers will take into account both the mean and variance of output when they rank alternative technologies. For a panel of Norwegian salmon farms fish feed and fish input are found to increase output risk, while labor has a risk-decreasing effect on output. In the analysis of technical change by the first order stochastic dominance criterion the increase in mean output dominates the increase in output risk.

Norwegian Aquaculture:Technology for a Sustainable Development

Norwegian Aquaculture:Technology for a Sustainable Development

Post-vaccination intra-abdominal adhesions as a marker to identify Atlantic salmon, Salmo salar L., escaped from commercial fish farms

Intraperitoneal vaccination of Atlantic salmon, Salmo salar L., against furunculosis using oil adjuvanted vaccines causes visible intra-abdominal markers of apparently permanent character. The feasibility of these side-effects for discrimination between fish from vaccinated and unvaccinated populations was evaluated in an open study using samples of vaccinated and unvaccinated farmed salmon, and in a blind study using individually tagged fish from a sea ranching vaccination trial. Vaccines were trivalent, oil adjuvanted bacterins extensively used in Norwegian aquaculture. Adhesions between internal organs and the gut wall were more sensitive and more specific for identifying fish from vaccinated populations than pigmentations on the peritoneum or on the viscera of the fish. Samples of farmed fish drawn from 3 to 35 months after vaccination yielded sensitivities of 93–100% and a specificity of 100% for this marker trait. In the blind study, intraperitoneal inoculation of saline as a placebo was found to induce minor adhesions, thus reducing the specificity of the adhesion marker to 75%. Using the observed sensitivities and specificities in a data simulation, the intra-abdominal adhesion marker proved feasible for the identification of fish from unvaccinated populations even under unfavourable sampling situations. Provided the current practices of vaccinating farmed salmon prevail, exclusion of individual fish carrying the intra-abdominal adhesion marker is recommended when estimating the number of wild salmon stocks, and when selecting broodfish for propagation of specific river populations of Atlantic salmon.

Trade Disputes and Productivity Gains: The Curse of Farmed Salmon Production?

Trade Disputes and Productivity Gains: The Curse of Farmed Salmon Production?

From consensus to specialization: Institutional aspects of Norwegian aquaculture research

Aquaculture research has been part of the Norwegian aquaculture policy since the appointment of the Lys0 Commission in 1972. In 1993 a major reorganization of the national research system took place. Here the organization of the aquaculture research system, with particular emphasis on the 1980s, is the focus. When the Norwegian government required aquaculture as a priority area for industrial growth in the budget proposal of 1985, a follow‐up of the first governmental initiatives, there was a signal to the research community that the future would bring increased opportunity and funding. The expectations were high in the research community, because aquaculture was a new arena, and it was available to everyone. Because of the rigid structures of the three industrial research councils, the extraordinary governmental funding level was absorbed by the established research system, and the intentions of extraordinary governmental effort impaired. The result is that, as argued here, the governmental effort has maintained intersectoral boundaries in the research system rather than breaking them down in favor of the new discipline known as aquaculture research. The conclusion is that the coordinating and governing institutions must have greater impact in the administration of aquaculture research. Industry‐related research is a political instrument, and as such has to be governed in accordance with democratic institutions.

Parasites of Norwegian freshwater salmonids and interactions with farmed salmon—a review

Of the 40 known species of parasites of wild freshwater Norwegian Salmonidae, nine are currently recognised as pathogens in Norwegian freshwater aquaculture of salmonids and/or salvelinids. A further five are known as pathogens of wild Norwegian Salmonidae, while at least eight of the remaining species are known as pathogens in wild or farmed Salmonidae outside of Norway. Some of the Norwegian pathogens have only been recognised as such in the last 5 years. Wild Salmonidae are, in most cases, the only reservoirs for these parasites in Norwegian freshwaters and the number of parasite species and instances of their known pathogenicity are likely to rise at current levels of production.

Public Regulation and Production Factor Misallocation. A Restricted Cost Function for the Norwegian Aquaculture Industry

The purpose of this article is to present an analysis of the cost inefficiency of public regulation of input factors. During the data period used here, individual plants within the Norwegian fish farming industry were regulated in their use of production capacity (pen volume) at different size levels. Given the regulation of production capacity, it is likely that farms will be forced to operate off their expansion paths resulting in two types of regulating effects: misallocation of variable input factors (an input misallocation effect), and failure to exploit economics of scale (a scale effect). A restricted cost function, which invokes the assumption of cost minimization given the level of the fixed factor, was specified to measure the effects of regulation on input allocation and on scale economies. The results indicate that variable inputs are more intensively used for farms which are most heavily regulated. Furthermore, in a comparison of results on economies of scale properties estimated by a total long-run cost function with the present restricted cost function, an upward bias of scale economies was indicated for the total cost function approach.

Investigations of phagocytosis concerning the immunological defence mechanism of Mytilus edulis using a sublethal luminescent bacterial assay ( Photobacterium phosphoreum)

1. 1. A simple method for the determination of phagocytosis activity using mussel hemocytes by measuring the bioluminescence is presented. 2. 2. The immunological defence activity based on phagocytosis is measured and quantified by a luminescent bacterial assay with Photobacterium phosphoreum. 3. 3. The measuring system allows us to establish the stress of the immunological defence mechanism of organisms exposed to chemicals and polluted rivers or sewage. Results with reference substances and the phagocytosis indices of exposed mussels from Norwegian aquaculture plants compared to those of mussels from the German Wadden Sea are given as examples.

The Norwegian aquaculture industry: Industrial structure and cost of production

The Norwegian aquaculture industry: Industrial structure and cost of production

Tilling the sea: Prospects for Norwegian aquaculture

Tilling the sea: Prospects for Norwegian aquaculture

A Cross‐Sectional Analysis of Costs of Farming Atlantic Salmon (Salmo Salar)

Commercial aquaculture, the cultivation of fish in managed systems, has received increasing attention in recent years as an alternative source of fish, employment and income. High value species particularly offer a better prospect of profitable farming. For example, Atlantic salmon, which is one of the more expensive species on the market, is now being farmed in Norway, Scotland, Canada, the United States, and several other countries. Norway has made rapid progress in Atlantic salmon aquaculture; farmed salmon have now replaced cod as her principal export species. In the opinion of some observers, Norway' s success in farming the Atlantic salmon is the most significant event in the history of European aquaculture (United States Department of Commerce, 1984).Commercial aquaculture in Canada is still in its initial stage of development, but recently there has been increased interest in aquaculture as a means of generating incomes and jobs, and of acquiring technological expertise. The Science Council of Canada has urged a commitment towards commercial aquaculture; it cites Norwegian aquaculture that by the year 2000 could be producing fish worth U.S. $3 billion and be employing 50.000 people (Science Council of Canada 1985). In Canada, farming of Atlantic salmon is expanding rapidly on both east and west coasts. Canada' s output of farmed Atlantic salmon reached 174t in 1984 and is forecast to reach 1,200t by 1987, with a further immediate potential on the east coast of 2.000–3,000t. On the west coast, more than a million Atlantic salmon eggs have been imported for hatching and for cultivation in sea pens. The number of Atlantic salmon farms on the west coast is projected to more than double by the end of 1986.