Data from research and commercial use of lumpfish were collected from the research facilities of Gifas (Inndyr, Northern Norway, 67.0° N, 14.0° E). The data were sourced from 12 main lumpfish groups subdivided into 66 subgroups (N = 160,729) delivered to Gifas between 2013 and 2020 and used in cleaner-fish research in (a) land-based facilities, (b) small-scale, or (c) large-scale sea pens. The data were standardised and organised into three main headings. Firstly, background information included transfer time, point of origin, mean starting weight and population size on arrival. Other information included to which site the lumpfish were transferred, volume of cage/tank, whether in the presence of salmon or not, stocking density, days at each site and water quality parameters. Causes of mortality were recorded, when possible, for each group, along with calculated mortality rates, patterns, and analytical information, along with imaging where available. Results show that causes of mortality varied within and between research sites. For lumpfish in hatcheries as well as for those deployed at small-scale sea pens, the primary cause of mortality was identified as pathogenic, while for lumpfish deployed at large-scale sea pens, transporting, grading and mechanical delousing were the primary causes of mortality. The results indicate that more research is required to clarify best practices both in commercial hatcheries and salmon cages and further understanding on lumpfish biological requirements and stress physiology is necessary to develop better methods that safeguard lumpfish welfare and meet their needs.

Lumpfish are broadly used as biological sea lice removers in Norwegian salmon farming and are mostly produced in hatcheries. To date, there is little systematic documentation on the mortality causes of lumpfish in hatcheries. In the current study, data from 12 selected fish groups from four hatcheries in Norway were collected to understand the challenges and opportunities related to the categorization of mortality causes of lumpfish in hatcheries. This study indicated that a high proportion of lumpfish mortality was categorized by the hatcheries as unspecified. When specified, mortality was primarily assessed as due to fin damage. Our analyses showed that mortality categorized as fin damage correlated with the detection of infectious agents in dead fish, suggesting that mortality was due to infections rather than fin damage. It was not possible to conclude whether infection with pathogens present in the environment caused fin damage or if injuries from aggression were a gateway for pathogens. Furthermore, due to the lack of information regarding production conditions, it was not possible to assess risk factors causing eventual aggression or the presence of pathogens. This study revealed that mortality causality—the chain of events leading to death—is mainly unclear in lumpfish hatcheries because (1) mortality categorization does not focus on underlying causes and (2) there is little documentation of production conditions, making it very difficult to relate mortality rates to external factors. The present findings highlight that there are gaps in the registrations made by hatcheries and that there is an urgent need to implement standardized monitoring protocols for lumpfish hatcheries. This will help identify the causes of mortality and, therefore, allow for the implementation of proper measures that will ensure better survival.

The Atlantic salmon aquaculture industry in Norway is frequently confronted by the biological risks associated with the transport, handling, and treatment of live fish in well‐boats. The aim of this study was to collect experience‐based knowledge from the aquaculture industry about well‐boat operations, to make recommendations to lower the biological risk in well‐boat operations. Well‐boat crew, salmon farmers, fish health personnel, and workers in other relevant professions in the industry participated in semi‐structured individual interviews, followed by group interviews and a survey. This study clearly revealed that even though operational/technical factors are critical for lowering the biological risk in well‐boat operations, their successful implementation hinges on three fundamental human factors: (1) experienced personnel in key positions having correct focus, (2) communication, and (3) planning/risk assessment. Those factors deserve greater attention, as the present study highlights that they are not always sufficiently taken into account. An array of recommendations to lower the biological risk for Atlantic salmon in well‐boat operations is identified and summarized based on the findings from the study and literature.