Article
Fisheries
M. B. O. Huserbraten, I. A. Johnsen, Carrie Byron
Summary: The high infestation of salmon louse raises concerns about the sustainability of the Norwegian Atlantic salmon aquaculture industry. The connectivity of infective pelagic lice stages among farms plays a vital role in louse population dynamics, but the processes regulating this connectivity are not well understood. A biophysical dispersal model using ocean currents was employed to study the connectivity network among salmon farms in western Norway, showing that the complex geography of the fjords governs the long-term topology of the network, but there is also a strong seasonal component to network fragmentation.
ICES JOURNAL OF MARINE SCIENCE
(2022)
Article
Fisheries
Melanie Andrews, Tor Einar Horsberg
Summary: This study investigated the effects of thermal treatment on the copepodid and pre-adult II stages of seven populations of L. salmonis. The results showed that while all stages of the parasite had an immediate reaction to thermal treatment, the majority of them recovered over time. Variations in baseline sensitivity were observed between populations, emphasizing the importance of routine in vitro bioassays to determine treatment efficacy.
Article
Fisheries
Cameron Thompson, Samantha Bui, Sussie Dalvin, Rasmus Skern-Mauritzen
Summary: This investigation focused on the fecundity of salmon louse and found that the total length of female lice is the primary determinant of clutch size. The study also revealed that female louse total length is partially influenced by the sampling temperature. Moreover, the investigation showed that incorporating female louse sexual maturity and clutch size parameter related to female lice's total length could improve the forecasts of salmon louse production.
AQUACULTURE ENVIRONMENT INTERACTIONS
(2023)
Article
Biology
Hulda Maria Hardardottir, Rune Male, Frank Nilsen, Sussie Dalvin
Summary: Chitin synthase is a crucial enzyme involved in the survival and reproduction of aquatic organisms, with different expressions and functions in different tissues. Through RNA interference experiments, it was found that the chitin synthases of L. salmonis have significant impacts on the external cuticle and internal organs of lice at different developmental stages.
Article
Fisheries
Rodrigo M. Montes, Renato A. Quinones, Cristian Gallardo-Escarate
Summary: Sea louse infestations pose a threat to the sustainability of the global salmon farming industry, particularly in the southern marine ecosystem of Chile. Wavelet analysis revealed a significant impact of sea surface temperature and salmon stocking density on the dynamics of sea louse juveniles and ovigerous females, especially within one-year and two-year cycles. These findings suggest the importance of continuous temperature effects on louse development, particularly during spring-summer outbreaks, and highlight the need for a stocking density regulation model based on periodic variability to prevent major outbreaks in the future.
Article
Biodiversity Conservation
Thomas Bohn, Rune Nilsen, Karl Oystein Gjelland, Martin Biuw, Anne Dagrun Sandvik, Raul Primicerio, Orjan Karlsen, Rosa Maria Serra-Llinares
Summary: The study found that sea trout in areas with high salmon farm densities on the West coast of Norway had lice infestation rates exceeding 50%, and even in areas with salinities below louse tolerance levels, there were still high lice infestation rates, indicating possible infections elsewhere. This suggests that sea trout are at a higher risk of lice infestations from industrial salmon farming, raising concerns about the environmental sustainability of current aquaculture practices in intensive farming areas.
JOURNAL OF APPLIED ECOLOGY
(2022)
Article
Biochemistry & Molecular Biology
Claudia Tschesche, Michael Bekaert, Joseph L. Humble, James E. Bron, Armin Sturm
Summary: The pyrethroid deltamethrin and the macrocyclic lactone emamectin benzoate are used to treat farmed salmon infestations by parasitic salmon lice. Drug resistance in the lice is associated with overexpression of ace1b, a member of the functionally diverse carboxylesterases family. The study identified 21 CaEs genes/pseudogenes in L. salmonis, with overexpression of ace1b observed in multi-resistant lice compared to susceptible ones.
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY
(2021)
Article
Genetics & Heredity
Jay Joshi, Anne-Marie Flores, Kris A. Christensen, Hollie Johnson, Ahmed Siah, Ben F. Koop
Summary: This study used long-read sequencing technology to update the genome assemblies of Atlantic and Pacific salmon lice, and identified unique genomic features of their sex chromosomes. Moreover, conserved orthologous protein sequences were found between the W- and Z-chromosomes.
G3-GENES GENOMES GENETICS
(2022)
Article
Multidisciplinary Sciences
Aina-Cathrine Overgard, Helena M. D. Midtbo, Lars A. Hamre, Michael Dondrup, Gro E. K. Bjerga, Oivind Larsen, Jiwan Kumar Chettri, Kurt Buchmann, Frank Nilsen, Sindre Grotmol
Summary: This study reveals the presence of charged glandular proteins in the salmon louse that have immune modulation and anti-coagulant properties. These proteins play important roles in regulating the parasite's life cycle and feeding behavior in the host.
SCIENTIFIC REPORTS
(2022)
Article
Fisheries
Sean C. Godwin, Martin Krkosek, John D. Reynolds, Andrew W. Bateman
Summary: The study shows that current sea louse control policies may become ineffective in high-temperature years, highlighting the need for careful management. Delousing treatments are effective in controlling sea louse abundance, but may need to be increased in high-temperature years. Non-salmonids may play a role in sea louse transmission to farms.
ICES JOURNAL OF MARINE SCIENCE
(2021)
Article
Fisheries
Ian Bricknell, Michael Pietrak
Summary: This study investigates the environment of the digestive tract in fed and starved sea lice, with a focus on digestion and osmoregulation. The findings show that starved sea lice have a digestive tract similar in osmolarity to seawater. Even in lice with blood in their digestive system, the haemoglobin level is surprisingly low. Lice that have been feeding on salmon have a higher osmolarity in their digestive tract compared to starved animals, indicating a higher food content. The study confirms that sea lice are osmoconformers, with the haemolymph closely following the osmolarity of the environment.
Article
Fisheries
Nathalie van Walraven, Helene Borretzen Fjortoft, Anne Stene
Summary: The relationship between biomass density and sea lice infestation was studied in marine salmonid aquaculture, comparing organic and conventional salmon production. Organic salmon had significantly higher sea lice levels than conventionally produced salmon, but there were no significant differences in mortality rate and growth rate between the two production strategies.
Article
Multidisciplinary Sciences
Andreas Borchel, Anna Zofia Komisarczuk, Frank Nilsen
Summary: Salmon lice, ectoparasites on salmonids, have a significant impact on the aquaculture industry. This study successfully developed a sex determination assay for salmon lice, allowing for early identification of the developmental speed and sex-specific SNPs. However, only a few genes showed differential expression between the sexes.
Article
Environmental Sciences
Lone S. Jevne, Maria Guttu, Anna S. Batnes, Yngvar Olsen, Kjell I. Reitan
Summary: This study demonstrates the significant impact of temperature on the density of planktonic sea lice, the effectiveness of lice skirts in reducing adult sea lice on salmon and planktonic sea lice, and the successful reduction of planktonic sea lice density during the fallowing period.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Environmental Sciences
D. Hamoutene, S. Marteinson, M. Kingsbury, K. McTavish
Summary: The aim of this study is to construct acute aquatic species sensitivity distributions (SSD) and proposed HC5 values for two aquaculture anti-sea lice bath pesticides, azamethiphos and hydrogen peroxide, which can be used to establish environmental quality standards (EQS). Through the examination of literature data and using limited exposure times, SSDs and HC5 values for mortality and sublethal endpoints have been generated for each pesticide. The resulting threshold concentrations in environmental seawater are 0.10 μg/L for azamethiphos and 0.15 mg/L for hydrogen peroxide. Further considerations and study are needed to better understand the environmental risks of using these bath pesticides.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)