The effects of cryogenically preserved sperm on the fertilization, embryonic development and hatching success of lumpfish C. lumpus

Under embargo until: 2023-09-10Lumpfish (C. lumpus) are used as cleaner fish in the Atlantic salmon (Salmo salar) farming industry to remove parasitic sea lice. At present, wild lumpfish broodstock are used which puts strain on wild populations. By successfully cryopreserving lumpfish sperm, the number of wild males required will be reduced and it enables the long-term storage of sperm for use in breeding programmes. The present study compared the use of fresh sperm and sperm which was cryogenically frozen for 24 h to test whether it is a viable method of preservation. The fresh and frozen sperm from 5 males was used (in equal volumes) to fertilize eggs pooled from 5 females and the difference between fertilization success, percentage of eggs which reached the eyed stage, and the hatching success was measured. A group of 100 hatched larvae were on-grown for two weeks to test whether there was a difference weight between treatment groups. The results of the trial showed that fresh sperm produced a significantly higher percentage of fertilized eggs (fresh 92.6 ± 0.8%, frozen 77.9 ± 1.8%, mean ± SEM), a higher percentage of eggs surviving to the eyed stage (fresh 93.9 ± 0.5% and frozen 80.8 ± 1.4%) and had a more successful hatch rate (fresh 72.3 ± 6.6% and frozen 63.6 ± 5.0%). There was no difference in mean weight (± SEM) of the two-week old larvae between treatments (fresh 0.63 g ± 0.024, frozen 0.59 g ± 0.028). In conclusion, this study showed that the same volume of cryogenically preserved lumpfish sperm produced fewer viable lumpfish larvae than fresh sperm. Despite this difference, the use of cryopreserved sperm did produce relatively high results at each stage of testing.acceptedVersio

Effects of different feeding frequencies on growth, cataract development and histopathology of lumpfish (Cyclopterus lumpus L.)

Under embargo until: 2020-11-13Three duplicate groups of individually tagged lumpfish (mean initial weight: 22.3 ± 2.5 g) were fed either daily (7DW); four days per week (4DW) or three days per week (3DW) at a feeding rate of 2% body weight day−1 for a period of 126 days. There were significant differences in growth rates between the groups with the 7DW fish having the highest growth rates. Cataract prevalence was 53% lower in the 3DW group compared to the 7DW group. Histological examination showed that in some individuals in all three groups there was moderate expansion of the lamina propria in the mid and hind gut regions of the intestine with tissue most likely to represent fibrous tissue with scattered leucocytes. The severity of inflammation appeared to increase the more frequent the fish were fed with the 7DW fish having the highest inflammation score in these tissues. Feeding fish daily also resulted in higher levels of liver vacuolisation and chronic inflammation of the lamina propria in the mid and hind gut region of the intestines. Results from the present study show that restricted feeding regimes can be used to control growth and improve gut and eye health in lumpfish.acceptedVersio

Resistant calcification responses of Arctica islandica clams under ocean acidification conditions

Ocean acidification (OA) directly impacts marine calcifying organisms including ecologically and commercially important shellfish species such as Arctica islandica (A. islandica). To test whether documented growth resilience of A. islandica to OA is a general response across ages and populations or a function of adaptation to local habitat, we cultured juvenile and adult clams collected from an environment with little pH variation under four pH levels (7.5, 7.7, 7.9, and 8.1) for three months and integrated our understanding with relevant literature. The average shell growth over the experiment among all (69) individuals was 57 ± 55 μm, and there were no statistically significant differences in growth among pH treatments, including the control treatment, despite the general growth rate differences between juveniles and adults. Our results show that A. islandica can maintain its shell growth even in aragonite undersaturated (Ω < 1) conditions (0.65 and 0.83 for pH 7.5 and 7.7 treatments, respectively), supporting the hypothesis that resistance to OA conditions is likely a generalized response across populations. Although the present results show A. islandica can maintain their shell growth under short-term OA, long-term impacts of OA on A. islandica shell growth and other physical parameters including shell density and microstructure are still needed to better assess the sustainability of A. islandica in a more acidified future and to provide guidance on managing this important shellfish stock.publishedVersio

Genomic Signatures of Local Adaptation under High Gene Flow in Lumpfish—Implications for Broodstock Provenance Sourcing and Larval Production

Aquaculture of the lumpfish (Cyclopterus lumpus L.) has become a large, lucrative industry owing to the escalating demand for “cleaner fish” to minimise sea lice infestations in Atlantic salmon mariculture farms. We used over 10K genome-wide single nucleotide polymorphisms (SNPs) to investigate the spatial patterns of genomic variation in the lumpfish along the coast of Norway and across the North Atlantic. Moreover, we applied three genome scans for outliers and two genotype–environment association tests to assess the signatures and patterns of local adaptation under extensive gene flow. With our ‘global’ sampling regime, we found two major genetic groups of lumpfish, i.e., the western and eastern Atlantic. Regionally in Norway, we found marginal evidence of population structure, where the population genomic analysis revealed a small portion of individuals with a different genetic ancestry. Nevertheless, we found strong support for local adaption under high gene flow in the Norwegian lumpfish and identified over 380 high-confidence environment-associated loci linked to gene sets with a key role in biological processes associated with environmental pressures and embryonic development. Our results bridge population genetic/genomics studies with seascape genomics studies and will facilitate genome-enabled monitoring of the genetic impacts of escapees and allow for genetic-informed broodstock selection and management in Norway.publishedVersio

Temperature and size-dependency of lumpfish (Cyclopterus lumpus) oxygen requirement and tolerance

Under embargo until: 2023-10-09Lumpfish are currently produced and utilized as cleaner fish, to control sea lice infestation rates in salmon net pens, but information on environmental requirements is still limited. This study aimed to determine the zone of environmental hypoxia for two relevant fish sizes (15 and 60 g) and temperatures (5 and 12 °C), using intermittent flow respirometry (referred to as 15:5, 15:12, 60:5, 60:12), and to investigate parameters of stress in response to acute changes in dissolved oxygen (DO, % air saturation) from normoxia to 47, 63, 98 (control), 148 and 194% O2 at 10 °C. The standard and maximal metabolic rates (SMR and MMR) were measured in normoxia (n = 8), and MMR was measured at 5–6 DO levels ranging from 20−160% O2 (n = 8 per DO) to define the upper and lower boundaries of the hypoxic zone (DOlim and DOcrit). SMR, MMR and the aerobic metabolic scope (AS) increased with temperature and decreased with fish size. Similar effects of temperature and size were found on DOcrit – DOlim ranges: 20–55 (15:5), 35–147 (15:12), 21–53 (60:5) and 22–89 (60:12) % O2 air saturation. Results from acute exposure tests resulted in elevated cortisol levels at 63 and 47% O2, although not statistically significant at 47% O2. Other parameters of hypoxic or hyperoxic stress (lactate, pH, osmolality, lipid peroxidation rates, catalase activity) were not affected. Results from the present study suggest that lumpfish may experience oxygen levels in sea cages that restricts metabolism, performance and induce hypoxic stress.acceptedVersio

Quantification of grazing efficacy, growth and health score of different lumpfish (Cyclopterus lumpus L.) families: possible size and gender effects

Postponed access: the file will be available after 2022-09-12To investigate the possible family influence on sea lice grazing of lumpfish on Atlantic salmon, ten families of lumpfish (N = 480) with a mean (± SD) weight of 54.8 ± 9.2 g were distributed among ten sea cages (5 × 5 × 5 m) each stocked with 400 Atlantic salmon with a mean (± SD) weight of 621.4 ± 9.2 g. All the ten cages were stocked with 48 lumpfish (12% stocking density). The stocking of cages was such that each cage consisted of two random families where full- and paternal half-sib families were randomly allocated to the different cages. There were clear differences in sea lice grazing efficacy, growth and cataract prevalence between the ten families assessed in this study. Lumpfish from families 2, 6 and 10 had the lowest mean weights but showed comparable growth rates compared to the other families throughout the study and this may be as a direct result of genetic influence. In addition, fish from these families had a significantly higher incidence of lice grazing of both L. salmonis and C. elongatus compared to the other families. Using mixed linear model to analyse the data revealed significant family and paternal effect on sea lice grazing. There was a trend for a reduction in sea lice grazing with increased size within each family. The results indicated that it was the smallest size classes of lumpfish (40–140 g) which exhibited higher sea lice grazing potential compared to the larger size classes within families. There were no clear differences in the lice grazing potential between male and female lumpfish within and between families. Overall, present findings showed that sea lice grazing of both L. salmonis and C. elongatus can be enhanced using targeted family production and if this behaviour has a genetic basis it may further enhanced through selection and targeted breeding programs.acceptedVersio

Effect of incubation temperature on eggs and larvae of lumpfish (Cyclopterus lumpus)

Two batches of lumpfish eggs were incubated at three temperature regimes; 1-Ambient seawater 4–6 °C (cold), 2-Ambient seawater for 10 days followed by a gradual increase to 10 °C (gradient), 3-Constant 10 °C seawater (warm). The eggs incubated in cold water had the highest egg mortality (38.5% ± 15.7) and lowest hatching success (46.1% ± 7.2), while the gradient group regime showed highest hatching success (74.9% ± 4.2). Larvae from the gradient regime showed the most synchronized hatching as hatching started at 280 dd (35 days post fertilization (DPF)) and reached the hatching peak the same day with almost 80% of all larvae hatching. Hatching started at 279 dd (28 DPF) in the warm regime, reached a hatching peak (50% of total hatching) at 3 days post hatch (DPH), and ended at 9 DPH. In the cold temperature group hatcing started at 285 dd (63 DPF) and the hatching peak was reached at 3 DPH. Hatching lasted until 13 DPH. Hatched larvae from the cold regime were longest (6.11 mm) and heaviest (5.55 mg), followed by larvae from the gradient (5.71 mm, 4.88 mg) and warm (5.33 mm, 4.37 mg) regimes respectively. Newly hatched larvae from the warm group had the highest occurrence (34.7%) of body deformities compared to 8.9 and 7.6% in the gradient and cold water groups. Studies of organ and tissue histomorphology of hatched and two weeks old larvae did not reveal obvious developmental differences between the groups at these timepoints

Marine Monitoring Nordland 2016-2017

Målsettingen er å overvåke og angi den økologiske miljøtilstanden i 6 ulike fjordområder i Nordland hvor det er en aktiv akvakulturnæring. 2016-2017 er det gjort undersøkelser i Sjona, Nordfoldfjorden, Sagfjorden, Tysfjorden, Ofotfjorden og Øksfjorden som har omfattet de to biologiske kvalitetselementene planteplankton (klorofyll a) og bløtbunnsfauna samt støtteparametere for disse. Rapporten omfatter resultater fra perioden fra juli 2016 til og med juni 2017 og gir en enkel omtale av resultatene. Bløtbunnsfauna fikk «god» tilstand (klasse II) på alle stasjonene, med unntak av Nordfoldfjorden som fikk «svært god» tilstand (klasse I). Innholdet av organisk karbon (TOC) i sedimentet var lavt, med unntak av Øksfjorden som hadde «svært dårlig» tilstand (klasse V) for organisk innhold i sedimentet. Planteplankton, gjennom klorofyll a, og næringssalter ga «Svært God» økologisk tilstand for stasjonene i Nordfoldfjorden, Tysfjorden, Sagfjorden, Ofotfjorden og Øksfjorden. En stasjon i Ofotfjorden får «god» økologisk tilstand som følge av høy klorofyll a-verdi. 2017-klassifiseringen for næringssaltene i sommerperioden omfatter kun data fra juni, og klassifiseringen av klorofyll a omfatter analyseresultater fra mars til og med juni. Foreliggende klassifisering for 2017 blir derfor ikke fullstendig siden den er basert på resultater til og med juni 2017, men den vil være fullstendig i neste rapportering fra overvåkingen.The aim of the surveys is to monitor and state the ecological environment in 6 different fjords in Nordland where there is an active aquaculture industry. In the years 2016-2017 investigations have been carried out in Sjona, Nordfoldfjorden, Sagfjorden, Tysfjorden, Ofotfjorden and Øksfjorden, which included the two biological quality elements phytoplankton (chlorophyll a) and soft-bottom fauna and supporting parameters for these. We are here reporting the period June 2016 – July 2017. The results from the study of soft sediment fauna showed that all sites had “good” environmental condition (Class II), except for the station in Nordfoldfjorden, which had “very good” condition (Class I). The quality element of soft sediment fauna thus meets the requirement of the water framework directive for at least good ecological status. However, the results showed low abundance of echinoderms and crustaceans, as well as moderate species diversity and abundances. The number of species and abundance has decreased compared with the survey in 2013. The organic carbon (TOC) content in the sediment was low and corresponded to “very good” (Class I) and “good” condition (Class II) on all the sites, except for Øksfjorden which had high organic carbon content in the sediment corresponding to “very poor” condition (class V). The biological quality element phytoplankton (chlorophyll a) and the supporting parameters nutrient salts, gave "very good" ecological status to the stations in the Nordfoldfjord, Tysfjord, Sagfjord, Ofotfjord and Øksfjord, One station in Ofotfjord showed "Good" ecological condition due to high values of chlorophyll a. It is important to point out that the 2017 classification for the nutrients during the summer period only includes data from June, and the calculations of P90 for the classification of chlorophyll a include results only from March through June. Therefore, the current classification for 2017 is tentative, but will be complete when more surveys have been accomplished.NCE-AquaculturepublishedVersio

Comparison of diet composition, feeding, growth and health of lumpfish (Cyclopterus lumpus L.) fed either feed blocks or pelleted commercial feed

Two duplicate groups of individually tagged lumpfish (mean initial weight: 21.5 ± 3.2 g) were fed either a commercially available lumpfish feed or feed blocks for a period of 123 days. The aim was to evaluate and compare the effects of these feed types on growth, cataract development and histopathology in lumpfish. There were significant differences in growth rates between the groups with fish fed pelleted feed having the highest growth rates. The development of cataracts was significantly different with fish fed pelleted feed having a cataract prevalence of 87% at the end of the study period whilst fish fed with feed blocks had 10% prevalence. The results of the histological examination undertaken in this study showed overall small differences between the two dietary treatments. In some individuals in groups receiving both diets, there was mild to moderate expansion of the lamina propria with tissue most likely to represent fibrous tissue with scattered leucocytes. Overall, the findings of the present study show that lumpfish will readily graze from feed blocks and although growth is lower the prevalence of cataract is greatly reduced using feed blocks

Resistant calcification responses of Arctica islandica clams under ocean acidification conditions

Ocean acidification (OA) directly impacts marine calcifying organisms including ecologically and commercially important shellfish species such as Arctica islandica (A. islandica). To test whether documented growth resilience of A. islandica to OA is a general response across ages and populations or a function of adaptation to local habitat, we cultured juvenile and adult clams collected from an environment with little pH variation under four pH levels (7.5, 7.7, 7.9, and 8.1) for three months and integrated our understanding with relevant literature. The average shell growth over the experiment among all (69) individuals was 57 ± 55 μm, and there were no statistically significant differences in growth among pH treatments, including the control treatment, despite the general growth rate differences between juveniles and adults. Our results show that A. islandica can maintain its shell growth even in aragonite undersaturated (Ω This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)