Cyclopterus Research Articles

Effects of reduced water exchange rate and oxygen saturation on growth and stress indicators of juvenile lumpfish (Cyclopterus lumpus L.) in aquaculture

Lumpfish (Cyclopterus lumpus) is currently used as cleaner fish in Norwegian Atlantic salmon (Salmo salar) farming to control parasitic lice on salmon. The need for high numbers of lumpfish necessitates intensive farming of this species but very limited knowledge is available on the environmental requirements of lumpfish in culture. The present study was therefore carried out to investigate the tolerance of lumpfish to varying water exchange rates and oxygen saturations. Four triplicated treatment groups were established at different water exchange rates, which caused oxygen saturations of 55% (0.7Lmin−1), 69% (1.2Lmin−1), 81% (1.9Lmin−1) and 96% (6Lmin−1). Decreasing water exchange rate and oxygen saturations negatively affected growth, even in the fish groups held at 81% oxygen saturation. The fish group held at 55% oxygen saturation had almost no growth in body mass and showed sign of fin-infections and were terminated halfway through the experiment. A high workload associated with oxygen extraction and reduced appetite is considered the reason for reduced growth at lower oxygen saturations. While plasma cortisol levels in the groups held at 81 and 96% oxygen saturation corresponded to those considered typical for unstressed fish (<10ngmL−1), the levels of plasma cortisol of fish in the 69 and 55% oxygen saturation groups were above 20ngmL−1 in November, indicating a state of chronic stress. A fast, albeit weak, cortisol response to stressors in the lumpfish was confirmed in a separate, 2h long acute handling and hypoxia experiment. Lack of differences between treatments in plasma lactate levels indicates that the lumpfish reduced their food intake and locomotory activity sufficiently to avoid resorting to anaerobic metabolism when exposed to reduced oxygen saturations. It is concluded that the juvenile lumpfish is sensitive to reduced water oxygen saturations and that oxygen saturations below 80% in aquaculture should be avoided.

Use of lumpfish for sea‐lice control in salmon farming: challenges and opportunities

AbstractEfficient sea‐lice control remains one of the most important challenges for the salmon farming industry. The use of wrasse (Labridae) as cleaner fish offers an alternative to medicines for sea‐lice control, but wrasse tend to become inactive in winter. Lumpfish (Cyclopterus lumpus) continue to feed on sea‐lice at low temperatures, and commercial production has escalated from thousands of fish in 2010 to well over 30 million juveniles deployed in 2016. However, production still relies on the capture of wild broodstock, which may not be sustainable. To meet global industry needs, lumpfish production needs to increase to reach c. 50 million fish annually and this can only come from aquaculture. We review current production methods and the use of lumpfish in sea cages and identify some of the main challenges and bottlenecks facing lumpfish intensification. Our gap analysis indicates that the areas in most need of research include better control of maturation for year‐round production; formulation of appropriate diets; artificial selection of elite lines with desirable traits; and development of vaccines for certified, disease‐free juvenile production. The welfare of farmed lumpfish also needs to be better quantified, and more information is needed on optimal densities and tank design. Finally, the risk of farmed lumpfish escaping from net pens needs to be critically assessed, and we argue that it might be beneficial to recover cleaner fish from salmon cages after the production cycle, perhaps using them as broodstock, for export to the Asian food markets or for the production of animal feeds.

Phylogenetic relationships and a new classification of the family Cyclopteridae (Perciformes: Cottoidei).

Phylogenetic relationships of the family Cyclopteridae were reconstructed based on osteological and external characters. The monophyly of the family was strongly supported by 47 commonly recognized synapomorphies, including six autapomorphies (plus one additional autapomorphy, presence of a dorsal process on the pelvis, recognized after the phylogenetic analysis) among the suborder Cottoidei. As a result of the cladistic analysis, a single most parsimonious phylogeny was obtained, based on characters in 32 transformation series. A new classification of Cyclopteridae based on reconstructed relationships, including three subfamilies [Liparopsinae, Cyclopterinae and Eumicrotreminae (newly established)] and four genera (Aptocyclus, Cyclopsis, Cyclopterus and Eumicrotremus), is proposed.

Skin mucus proteins of lumpsucker (Cyclopterus lumpus)

Fish skin mucus serves as a first line of defense against pathogens and external stressors. In this study the proteomic profile of lumpsucker skin mucus was characterized using 2D gels coupled with tandem mass spectrometry. Mucosal proteins were identified by homology searches across the databases SwissProt, NCBInr and vertebrate EST. The identified proteins were clustered into ten groups based on their gene ontology biological process in PANTHER (www.patherdb.org). Calmodulin, cystatin-B, histone H2B, peroxiredoxin1, apolipoprotein A1, natterin-2, 14-3-3 protein, alfa enolase, pentraxin, warm temperature acclimation 65kDa (WAP65kDa) and heat shock proteins were identified. Several of the proteins are known to be involved in immune and/or stress responses. Proteomic profile established in this study could be a benchmark for differential proteomics studies.

Low levels of extracellular glucose limit cardiac anaerobic metabolism in some species of fish.

There is a wide interspecific range in plasma glucose levels in teleosts from less than 0.5 to greater than 10 mmol l-1 Here we assessed how glucose availability influences glucose metabolism in hearts of Atlantic cod (Gadus morhua), rainbow trout (Oncorhynchus mykiss), lumpfish (Cyclopterus lumpus) and short-horned sculpin (Myoxocephalus scorpius) under normoxic and hypoxic conditions. These species had plasma glucose levels of 5.1, 4.8, 0.9 and 0.5 mmol l-1, respectively. Rates of glucose metabolism and lactate production were determined in isolated hearts perfused with medium containing physiological levels of glucose. Under normoxic conditions there was no significant difference in rates of either glucose metabolism (average 15 nmol g-1min-1) or lactate production (average 30 nmol g-1min-1) across species. Under hypoxia (12% of air saturation) there were significant increases in rates of glucose metabolism and lactate production in hearts from Atlantic cod (glucose-130; lactate-663 nmol g-1 min-1) and rainbow trout (glucose-103; lactate-774 nmol g-1 min-1); however, there was no change in rate of glucose metabolism in hearts from either lumpfish or short-horned sculpin and only increases in lactate production to rates much lower than the other species. Furthermore, Atlantic cod hearts perfused with medium containing low non-physiological levels of glucose (0.5 mmol l-1) had the same rates of glucose metabolism under normoxic and hypoxic treatments. Anaerobic metabolism supported by extracellular glucose is compromised in fish with low levels of plasma glucose, which in turn may decrease performance under oxygen-limiting conditions at the whole-animal level.

Application of real-time PCR for specific detection of Lepeophtheirus salmonis in fluid samples from lumpfish (Cyclopterus lumpus) stomachs

The Norwegian Food Safety Authority recently stated that stomach flushing is in violation of the Animal Welfare Act. The objective of our research was to develop a genetic method for the routine identification of Lepeophtheirus salmonis in stomach fluid samples taken through the mouth of lumpfish. The established method was based on a previously published real-time PCR assay targeting the mitochondrial cytochrome oxidase I (mtCOI) gene in L. salmonis. Lumpfish were fed with L. salmonis, then captured upon ingestion and subsequently transferred to an incubation tank. The method was used to test 62 fluid samples collected during the first, second and third days post L. salmonis consumption. No DNA extraction or purification was used prior to the real-time PCR. The results were compared with visual examination subsequent to dissection. Visual identification was able to identify 51 L. salmonis (82%) whereas real-time PCR was able to detect 59 L. salmonis (95%) out of the 62 examined samples. The results indicate that real-time PCR assays can be used for specific detection of L. salmonis in fluid samples from the stomach of lumpfish. Furthermore, our study demonstrates that the PCR assay offers a reliable non-lethal alternative to dissection or stomach flushing and the subsequent visual identification of L. salmonis.

Redescription and phylogenetic position of Myxobolus aeglefini and Myxobolus platessae n. comb. (Myxosporea), parasites in the cartilage of some North Atlantic marine fishes, with notes on the phylogeny and classification of the Platysporina

Myxobolus ‘aeglefini’ Auerbach, 1906 was originally described from cranial cartilage of North sea haddock (Melanogrammus aeglefinus), but has subsequently been recorded from cartilaginous tissues of a range of other gadoid hosts, from pleuronectids and from lumpsucker (Cyclopterus lumpus) in the North Atlantic and from a zoarcid fish in the Japan Sea (Pacific).We obtained partial small-subunit rDNA sequences of Myxobolus ‘aeglefini’ from gadoids and pleuronectids from Norway and Iceland. The sequences from gadoids and pleuronectids represented two different genotypes, showing 98.2% identity. Morphometric studies on the spores from selected gadids and pleuronectids revealed slight but statistically significant differences in spore dimensions associated with the genotypes, the spores from pleuronectids were thicker and with larger polar capsules. We identify the morpho- and genotype from gadoids with Myxobolus ‘aeglefini’ sensu Auerbach, and the one from pleuronectids with Sphaerospora platessae Woodcock, 1904 as Myxobolus platessae n. comb. The latter species was originally described from Irish Sea plaice (Pleuronectes platessa). Myxobolus albi Picon et al., 2009 described from the common goby Pomatoschistus microps in Scotland is a synonym of M. ‘aeglefini’. The Pacific Myxobolus ‘aeglefini’ represents a separate species, showing only 97.4–97.6% identity to the Atlantic species. In phylogenetic analyses based on SSU rDNA sequences, these and some related marine chondrotropic Myxobolus spp. form a distinct well supported group. This clusters with freshwater and marine myxobolids and Triangula and Cardimyxobolus species, in a basal clade in the phylogeny of the Platysporina. Members of family Myxobilatidae, Ortholinea spp. (currently Ortholineidae) and sequences of some other urinary system infecting myxosporeans form a well supported clade among members of the suborder Platysporina. Based on phylogenetic analyses, we propose the following changes to the classification of Myxosporea: i) Ortholineidae is dismantled and Ortholinea spp. transferred to Myxobilatidae, and ii) Myxobilatidae is transferred from suborder Variisporina to Platysporina.

Genetic structure of West Greenland populations of lumpfish Cyclopterus lumpus.

In this study, 11 microsatellite markers were used to determine the structure of West Greenlandic lumpfish Cyclopterus lumpus populations across six spawning locations spanning >1500 km and compared with neighbouring populations in Canada and Iceland. To evaluate whether data allow for identification of origin of C. lumpus in Greenlandic waters, genetic assignment analysis was performed for 86 C. lumpus sampled on a feeding migration. Significant structuring with isolation by distance was observed in the West Greenland samples and two major subpopulations, north and south, were suggested. Based on FST values, closer relationships were observed between Greenland and Canada, than Greenland and Iceland. Surprisingly, the North Greenland population showed more similarities with Canadian samples, than did the geographically closer south-west Greenland population. Origin could be assigned for a high proportion of non-spawning fish and demonstrated a marked east-west spatial separation of fish of Greenlandic and Icelandic genotypes.

Characterization of IgM in Norwegian cleaner fish (lumpfish and wrasses)

The use of cleaner fish in Norwegian aquaculture has to a large extent been based on wild catches, but breeding of lumpfish and ballan wrasse is currently increasing. Due to disease problems and required vaccine development, tools to study immune responses and a better understanding of the immune system in these species is demanded. The present study comprises lumpfish (Cyclopterus lumpus) and five species of wrasses: Ballan wrasse (Labrus bergylta), rock cook (Centrolabrus exoletus), cuckoo wrasse (Labrus mixtus), corkwing wrasse (Symphodus melops), and goldsinny wrasse (Ctenolabrus rupestris). We present a comparison of the IgM sequences, phylogenetic relationship to other teleosts and characteristic features of IgM in the species studied. The lumpfish IgM heavy chain sequence was assembled from high throughput cDNA sequencing whereas the wrasse sequences were determined by molecular cloning. The secreted form of the IgM heavy chain from all species consisted of four constant Ig domains. IgM was purified from lumpfish and ballan wrasse sera by gel filtration followed by anion exchange chromatography, and polyclonal sera were produced against these proteins. Antisera against ballan wrasse IgM showed cross-reactivity to all analyzed species of wrasses, some cross-reactivity to lumpfish, very low reaction to salmon, and no reaction to cod. Anti- IgM sera against lumpfish cross-reacted to the light chain of all species studied. Wrasses and lumpfish IgM showed high binding affinities for protein A. IgM concentration in adult ballan wrasse (700–800 g) was measured by single radial immunodiffusion assay and found to be 13.4 mg/ml which is about 36% of the total protein concentration. The IgM concentration in lumpfish (600–3600 g) was estimated to 1–2.6 mg/ml, which corresponds to approximately 3% of the total protein concentration.

First record of Tetramicra brevifilum in lumpfish (Cyclopterus lumpus, L.).

A microsporidian species with 98.3-98.4% nucleotide identity to Tetramicra brevifilum (Journal of Fish Diseases, 3, 1980, 495) was diagnosed in lumpfish (Cyclopterus lumpus, L.) broodstock held at a breeding and rearing facility in western Ireland. The fish were wild-caught from the west coast of Ireland, and the first case was diagnosed one year after capture. Clinical signs included severe bloating, lethargy, exophthalmos, anorexia, white patches on the cornea and externally visible parasitic cysts on skin and fins. Necropsy revealed severe ascites, white nodules and vacuoles in all the internal organs and partial liquefaction of the skeletal muscle. On histological examination, microsporidian xenomas were observed in all internal organs, the skin, skeletal muscle, gills and the eyes. The microsporidian species was identified by molecular analysis and transmission electron microscopy. This is the first record of T. brevifilum infecting lumpfish, and the disease is considered to be of potential significance to the rising aquaculture industry of this species.

Method for quantifying NSAIDs and clofibric acid in aqueous samples, lumpfish (Cyclopterus lumpus) roe, and zebrafish (Danio rerio) eleutheroembryos and evaluation of their bioconcentration in zebrafish eleutheroembryos.

Pharmaceuticals such as nonsteroidal anti-inflammatory drugs (NSAIDs) and lipid regulators are being repeatedly detected at low concentrations (pg · mL-1-ng · mL-1) in the environment. A large fraction of these compounds are ionizable. Ionized compounds show different physico-chemical properties and environmental behavior in comparison to their neutral analogs; as a consequence, the quantification methods currently available, based on the neutral molecules, might not be suitable to detect the corresponding ionized compounds. To overcome this problem, we developed a specific analytical method to quantify NSAIDs and lipid regulators (i.e., ibuprofen, diclofenac, naproxen, and clofibric acid) and their ionized compounds. This method is based on three steps: (1) the extraction of the organic compounds with an organic solvent assisted with an ultrasonic probe, (2) the cleaning of the extracts with a dispersive SPE with C18, and (3) the determination of the chemical compounds by GC-MS (prior derivatization of the analytes). We demonstrated that the proposed method can successfully quantify the pharmaceuticals and their ionized compounds in aqueous samples, lumpfish eggs, and zebrafish eleutheroembryos. Additionally, it allows the extraction and the cleanup of extracts from small samples (0.010g of wet weight in pools of 20 larvae) and complex matrixes (due to high lipid content) and can be used as a basis for bioaccumulation assays performed with zebrafish eleutheroembryos in alternative to OECD test 305.

Investigation of behavioural interactions between lumpfish (Cyclopterus lumpus) and goldsinny wrasse (Ctenolabrus rupestris) under controlled conditions

A series of studies were undertaken to determine the behavioural interactions between three different size classes (110, 70 and 32 g) of lumpfish, Cyclopterus lumpus L., and one size class (30 g) of goldsinny wrasse, Ctenolabrus rupestris L. The study attempted to determine whether goldsinny wrasse could coexist with juvenile lumpfish in an attempt to enhance lice grazing potential of Atlantic salmon by using both species simultaneously. The results indicate that both lumpfish and goldsinny exhibit quite a limited and similar palette of behavioural traits. Size-dependent dominance behaviour of lumpfish against goldsinny wrasse was found. When large (110 g) lumpfish were reared together with small goldsinny wrasse (30 g), aggression towards goldsinny was seen in 15 % of the time, whilst for 70 and 32 g lumpfish, aggressive behaviour against goldsinny accounted for only 6 % of all observations.

Lumpfish (Cyclopterus lumpus L.) develop amoebic gill disease (AGD) after experimental challenge with Paramoeba perurans and can transfer amoebae to Atlantic salmon (Salmo salar L.)

Cleaner fish such as lumpfish (Cyclopterus lumpus L.) and ballan wrasse (Labrus bergylta A.) are increasingly used to delouse farmed Atlantic salmon (Salmo salar L.). In 2014, >20 million cleaner fish were placed into net-pens with farmed salmon in Norway. Amoebic gill disease (AGD), caused by the opportunistic, parasitic amoeba Paramoeba perurans, is emerging in salmon farming in Northern Europe. The amoeba displays low host specificity as it has been isolated from a range of fish species in addition to salmonids, such as wrasse and lumpfish cohabitating with farmed salmon. It is, however, not known to which degree lumpfish respond to P. perurans challenge, to which extent lumpfish may develop AGD, and if they can function as a vector for the spread of P. perurans to salmon. The present study shows that lumpfish can be infected with P. perurans under experimental conditions and develop AGD. However, lumpfish are more resistant and the development of pathology is slower compared to salmon. It is also shown that lumpfish can act as carriers and transmit parasitic amoebae to Atlantic salmon. Importantly, it is demonstrated that the gill lesion score system extensively used for evaluating AGD in Atlantic salmon is less suitable for lumpfish infected with P. perurans as the disease develops more slowly in lumpfish and because lumpfish may be non-symptomatic carriers. Statement of relevance1)The last few years, lumpfish have been used as cleaner fish in order to delouse farmed Atlantic salmon. However, nothing is yet known about its susceptibility to the parasitic amoeba P. perurans.2)Currently, nothing is known about amoebic gill disease (AGD) development in lumpfish and the possibility that amoeba may be transferred from lumpfish to salmon.3)There is currently little information about the pathology (macroscopic and histological changes) in lumpfish.4)We have found that the commonly used gill scoring system for salmon is not applicable for lumpfish, and we recommend that the lumpfish is screened, not scored before transfer to net-pens with salmon.

Is cleaning behaviour in lumpfish (Cyclopterus lumpus) parentally controlled?

To investigate the possible family influence on sea lice grazing of lumpfish on Atlantic salmon, nine families of lumpfish (N=360) with a mean (±SD) weight of 169.4±8.3g were distributed among nine sea cages (5×5×5m) each stocked with 400 Atlantic salmon with a mean (±SD) weight of 123.3±12.3g. For each family, 20 lumpfish were stocked into one of nine sea cages and 20 into another cage thus establishing duplicate treatments for each genetic family giving two families stocked per cage. There were significant differences in behaviour, feeding preferences and mortality between the nine families of lumpfish. Fish from family 2 were found to be more predisposed to exploiting natural food sources within the cage environment and showed a higher incidence of sea lice grazing from Atlantic salmon. Using mixed linear model to analyse the data revealed significant maternal and paternal effect on sea lice grazing. In contrast, fish from family 5 were observed choosing to compete with salmon and consume pellets more than the other eight families and were found to be less inclined in seeking out alternative food sources. Further, there were differences in the mortality rates between the nine families as a result of a Pasteurella spp. outbreak. This is probably the first study in fish aquaculture investigating the variation in a specific behavioral trait linked to different family background. Statement of relevanceThe data presented here are highly relevant for aquaculture.

Vaccination and adaptive immune response of lumpfish (Cyclopterus lumpus L)

Farmed lumpfish (Cyclopterus lumpus L.) is with great success used for biological control of salmon louse (Lepeoptheirus salmonis). Along with the rapid increase in the farming of lumpfish in Norway bacterial disease problems has emerged. The most commonly isolated pathogenic agents are Vibrio sp., atypical Aeromonas salmonicida and Pasteurella sp. To further the efficiency of the use of lumpfish in the net pens, efficient vaccines are required. Analysis of the lumpfish adaptive immune responses upon immunization and vaccination indicate that vaccination will be successful for this species.

Immune responses in lumpfish (Cyclopterus lumpus L.) leukocytes UPON bacteria challenge

Lumpfish (Cyclopterus lumpus L.) has shown to be an efficient biological tool in the fight against salmon lice (Lepeophtheirus salmonis) and are chosen by many fish farmers in Norway as an alternative to medicinal treatment. However, to improve the fish health and increase the overall efficiency of the cleaner fish strategy, more knowledge about its immune system and protective vaccines are required. We will present the current knowledge of its immune cells and its innate and adaptive immune responses upon bacteria challenge.

Oxygen dependence of upper thermal limits in fishes.

Temperature-induced limitations on the capacity of the cardiorespiratory system to transport oxygen from the environment to the tissues, manifested as a reduced aerobic scope (maximum minus standard metabolic rate), have been proposed as the principal determinant of the upper thermal limits of fishes and other water-breathing ectotherms. Consequently, the upper thermal niche boundaries of these animals are expected to be highly sensitive to aquatic hypoxia and other environmental stressors that constrain their cardiorespiratory performance. However, the generality of this dogma has recently been questioned, as some species have been shown to maintain aerobic scope at thermal extremes. Here, we experimentally tested whether reduced oxygen availability due to aquatic hypoxia would decrease the upper thermal limits (i.e. the critical thermal maximum, CTmax) of the estuarine red drum (Sciaenops ocellatus) and the marine lumpfish (Cyclopterus lumpus). In both species, CTmax was independent of oxygen availability over a wide range of oxygen levels despite substantial (>72%) reductions in aerobic scope. These data show that the upper thermal limits of water-breathing ectotherms are not always linked to the capacity for oxygen transport. Consequently, we propose a novel metric for classifying the oxygen dependence of thermal tolerance; the oxygen limit for thermal tolerance (PCTmax ), which is the water oxygen tension (PwO2 ) where an organism's CTmax starts to decline. We suggest that this metric can be used for assessing the oxygen sensitivity of upper thermal limits in water-breathing ectotherms, and the susceptibility of their upper thermal niche boundaries to environmental hypoxia.

Revalidation of the Eggvin lumpsucker Eumicrotremus eggvinii (Cyclopteridae) and its new finding near Franz Josef Land (Barents Sea)

The species status of a rare species Eumicrotremus eggvinii from the family Cyclopteridae has been revalidated. Some authors considered its specimens as males of close species E. spinosus. In the Zoological Institute collection, males of E. spinosus that are morphologically similar with females of this species have been found. This is evidence of absence of sexual dimorphism in E. spinosus. In new samplings from waters of the Franz Josef Land archipelago (Barents Sea), a specimen of E. eggvinii was found and described. The opinion of some authors that individuals of E. eggvinii represent males of E. spinosus is refuted. A new finding widens the species area to the northeastern limits of the Barents Sea. The number and character of distribution of bone plaques remain reliable taxonomic characters.

Diet of adult and immature North Norwegian Black Guillemots Cepphus grylle

In this first study of adult Black Guillemot Cepphus grille diet in the Norwegian mainland, 62 of 63 birds caught incidentally in Lumpfish Cyclopterus lumpus gill nets in the north of the country in April-June 2012 and 2013 contained food remains in their stomachs. Fourteen prey taxa were identified and crustaceans were present in 90% of the stomachs containing food, with squat lobsters (sub-order Anamura) being most common (in 79%). Rock Gunnel Pholis gunnellus was present in 17 (27%) of the samples. The only other prey types to be found in more than 20% of the samples were sculpins (Cottoidei, probably Cottidae and Agonidae, in 13 samples = 21%) and remains of Caridean shrimps (also in 13 samples). There were no differences in the frequencies of taxa in the diets of immature and adult birds or of males and females.

Observations of vertical movements and depth distribution of migrating female lumpfish (Cyclopterus lumpus) in Iceland from data storage tags and trawl surveys

Abstract Lumpfish (Cyclopterus lumpus) is a high latitude species most abundant in Arctic and sub-Arctic waters of the North Atlantic. Vertical behaviour of this fish is unclear as it is often caught by both pelagic and demersal trawls. To gain greater insight into its behaviour, 41 female lumpfish caught during the Icelandic Groundfish Survey (IGFS) in March were tagged with data storage tags (DSTs); the IGFS finishes ∼1 week before the beginning of the lumpfish fishing season (20 March). Data retrieved from returned tags were compared with information on depth and distribution of catches of lumpfish from the IGFS. Thirteen tags were returned with days at liberty ranging from 20 to 61 d. Maximum depth recorded was 308 m (maximum depth of the tag) but based upon interpolation of temperature recordings, one fish may have descended to ∼418 m. Lumpfish displayed a range of vertical behaviours termed demersal, surface, and pelagic. During March, most exhibited either demersal or pelagic behaviour but the time spent in surface behaviour increased from March to April. During demersal behaviour, depth was rarely constant indicating the fish were not stationary. Both DST and catch data from the IGFS indicate that lumpfish exhibit diel patterns in vertical behaviour. As lumpfish frequently exhibit demersal behaviour, the use of the IGFS to monitor changes in abundance is justified. As lumpfish spend a significant amount of time in both the pelagic and demersal zone, they should be considered as a semi-pelagic (or semi-demersal) fish during this life stage/time of year.