Ecology of the gadoids in the Barents Sea with special reference to long-term changes in growth and age at maturity of Northeast Arctic cod

Dr. Scient. Thesis. / Department of Fisheries and Marine Biology. University of Bergen. Norwa

Using Standardized Revenue and Cost Norm Analyses to Reveal Subsidy Fraud in Contracted Public Transport Services

Author's accepted version (postprint).This is an Accepted Manuscript of an article published by Taylor & Francis in Transport Reviews on 20/10/2009, available online: http://wwww.tandfonline.com/10.1080/01441640902986866.In 2004, one of the biggest ferry operators in Norway was found guilty of having intentionally attempted to defraud the state of about 113 million Norwegian kroner in subsidies by underreporting revenues and overstating costs during the period 1992-2002. The company and five of the top managers were convicted and the case was regarded as one of the most serious subsidy offences ever committed in Norway. The aim of this article is to show that standardized revenue and cost norm models from the state can deter operators from committing such offences and when relevant detecting the fraud attempts at an early stage. Our model suggests that the operator in question overstated costs by about 19% and that the actual subsidy fraud attempt was about three times higher than concluded by the Court

Shorter trawls improve size selection of northern shrimp

Discards of small northern shrimp (Pandalus borealis) are a problem in the Skagerrak northern shrimp trawl fishery. To reduce catches of small shrimp, we studied the effect of trawl belly length on size selectivity in November 2017 and June 2018 onboard 15 and 27 m double-rigged shrimp trawlers. The selectivity of the vessels’ standard trawl was compared with a trawl differing only in the belly length, being 37% shorter. The trawls had 40 mm bottom panels and cod ends of 35 mm mesh sizes. Eleven and 14 hauls were made, respectively, in 2017 aboard the 15 m vessel and in 2018 aboard the 27 m vessel. The trawls fished shrimp above 19 mm carapace length equally, while catch rates of shrimp below 15.5–16 mm carapace length in the shorter trawl were more than halved. The results were consistent between the two vessels. In short, modifying trawl length is a simple design modification that can reduce catches of small shrimp. Bycatch of Norway pout (Trisopterus esmarkii) was slightly reduced in the shorter trawl, unrelated to fish length.acceptedVersio

Size-dependent escape risk of lumpfish (Cyclopterus lumpus) from salmonid farm nets

In the last decade, the salmon aquaculture industry has considerably increased the use of lumpfish juveniles as cleaner fish. Potential escape of reared lumpfish into the wild may spread diseases or genetically contaminate wild stocks. The guidelines for minimum sizes of cleaner fish to use in aquaculture cages are currently based on simple mesh penetration tests. However, these guidelines do not consider the potential compressibility of fish or changes in mesh state due to factors such as sea conditions and maintenance operations. This study shows that the industry-recommended minimum stocking sizes for a given mesh size may result in escape risk and that ignoring fish compressibility and mesh state can lead to underestimation of the lumpfish sizes that are able to escape. Our results can be used to develop new guidelines that will contribute to reduced escape of lumpfish from salmonid farms and lessen the potential environmental consequences.acceptedVersio

Prediction of goldsinny wrasse (Ctenolabrus rupestris) minimum size required to avoid escape through salmon (Salmo salar) farm nets

The salmon (Salmo salar) aquaculture industry has used various practices to treat salmon louse (Lepeophtheirus salmonis) infections, including mechanical, thermal, and chemical treatments. However, due to the environmental and fish welfare issues, and limitations associated with these practices, the use of cleaner fish has become a popular complementary delousing method. The goldsinny wrasse (Ctenolabrus rupestris) is the smallest among the delousing species used, which makes it most susceptible to escape through the salmon cage netting. Escape of goldsinny wrasse into the wild would lead to additional costs for farmers and could spread diseases and genetically contaminate wild stocks, as these cleaner fish are often transported over large distances from the capture site to the aquaculture site. The Norwegian aquaculture industry sets the goldsinny wrasse minimum size for use with different salmon cage mesh sizes using guidelines based on simple penetration tests that do not consider the potential compressibility of fish or changes in mesh state due to factors such as sea conditions and maintenance operations. Using morphological measurements of 100 fish, results of 47,800 penetration tests, and computer simulation, we predicted the minimum sizes required to avoid escape of goldsinny wrasse through and array of salmon farm nets. Our results show that the minimum stocking sizes for goldsinny wrasse in the current guidelines used by the industry may pose escape risk. Further, our findings illustrate the importance of considering fish compressibility and mesh state when estimating the fish minimum sizes required to avoid escape via cage netting mesh penetration. Finally, the results presented here provide the salmon farming industry with new guidelines that will contribute to reducing goldsinny wrasse escape from the cages and ultimately lessen the potential environmental consequences of such escape. For the two most typical mesh-size used by the aquaculture industry in Norway i.e. 30 and 50 mm and under the worst-case scenario i.e. slack state, the minimum recommended lengths for goldsinny wrasse would be ~128 (~28) and ~ 206 mm (~123 g). These sizes represent an underestimation of 16 and 24% in the sizes of goldsinny wrasse necessary to avoid escape compared to the current guidelines based on stiff meshes.publishedVersio

Brand loyalty among Norwegian car owners

Author's accepted version (postprint).Available from 28/04/2019

Competition in complementary transport services

Author's accepted version (postprint).Available from 22/01/201