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The use of lumpfish (Cyclopterus lumpus L.) to control sea lice (Lepeophtheirus salmonis Krøyer) infestations in intensively farmed Atlantic salmon (Salmo salar L.)

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The use of lumpfish (Cyclopterus lumpus L.) to control sea lice (Lepeophtheirus salmonis Krøyer) infestations in intensively farmed Atlantic salmon (Salmo salar L.)

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... Biological control [1,2], using cleanerfish that pick the sea lice from salmonids [3][4][5][6] has been effective in reducing lice numbers and is being adopted widely by the salmon farming industry. The advantages of cleaner fish are environmental, with a reduction in medicine use [7], they are a natural form of control and provide continuous cleaning of lice [3][4][5][6][7]. ...
... Biological control [1,2], using cleanerfish that pick the sea lice from salmonids [3][4][5][6] has been effective in reducing lice numbers and is being adopted widely by the salmon farming industry. The advantages of cleaner fish are environmental, with a reduction in medicine use [7], they are a natural form of control and provide continuous cleaning of lice [3][4][5][6][7]. As a cold-water cleanerfish alternative, the common lumpfish Cyclopterus lumpus L. has been demonstrated to work effectively in small-scale cage trials [4,[8][9][10][11], and there is increasing evidence of efficacy in larger commercial pens [12][13][14][15]. ...
... The advantages of cleaner fish are environmental, with a reduction in medicine use [7], they are a natural form of control and provide continuous cleaning of lice [3][4][5][6][7]. As a cold-water cleanerfish alternative, the common lumpfish Cyclopterus lumpus L. has been demonstrated to work effectively in small-scale cage trials [4,[8][9][10][11], and there is increasing evidence of efficacy in larger commercial pens [12][13][14][15]. ...
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Full-text available
Lumpfish are widely used for removing sea lice in salmonid sea-based aquaculture. If these fish are to be harvested and used for human consumption, it is necessary to know how the physical strain associated with removing the lumpfish from the net-cages affects the fish in the short-term, and if live-storage in tanks, well-boats, or nets awaiting slaughter, will result in stress and mortalities. In this study, we investigated the effect of physical stress and mortality in a group of lumpfish recaptured from commercial net-cages, transported to holding tanks, and stored for one week. In addition to cortisol (primary stress response), we analyzed ions directly related to osmoregulation (Na+ and Cl−), osmotic stress (Ca2+), and blood plasma pH as an indicator of a secondary stress response. The aim of the study was to increase the basic physiological understanding of the physiological effects of handling procedures and transport in lumpfish. Only minor, and temporary, effects on primary stress response and secondary stress response were seen in lumpfish recaptured from net-cages and transported to holding facilities, indicating that lumpfish cope well with short transport (here 5 h). These findings are important in a context where lumpfish are harvested for reuse, e.g., human consumption or processing, following their lice-eating stage in net-cages.
... Cleaner fish, like wrasses (Labridae) and lumpfish (C. lumpus L.), may represent sustainable solutions for reducing the lice problem in the salmon industry (Treasurer, 2002;Imsland et al., 2014aImsland et al., , 2014bImsland et al., , 2014cImsland et al., , 2015aImsland et al., , 2015b. Wrasse exhibit winter dormancy, proving ineffective delousers below 6 • C (Kelly et al., 2014), therefore there has been increasing interest in the use of lumpfish, which can target the parasite across all seasons (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cEliasen et al., 2018;Powell et al., 2018). ...
... lumpus L.), may represent sustainable solutions for reducing the lice problem in the salmon industry (Treasurer, 2002;Imsland et al., 2014aImsland et al., , 2014bImsland et al., , 2014cImsland et al., , 2015aImsland et al., , 2015b. Wrasse exhibit winter dormancy, proving ineffective delousers below 6 • C (Kelly et al., 2014), therefore there has been increasing interest in the use of lumpfish, which can target the parasite across all seasons (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cEliasen et al., 2018;Powell et al., 2018). As lumpfish tolerate lower temperatures than wrasse species, their implementation was boosted principally in the northern parts of Norway (Imsland et al., 2014a), Scotland , the Faroe Islands Johannesen et al., 2018) and Iceland (Steinarson and Á rnason, 2018). ...
... Wrasse exhibit winter dormancy, proving ineffective delousers below 6 • C (Kelly et al., 2014), therefore there has been increasing interest in the use of lumpfish, which can target the parasite across all seasons (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cEliasen et al., 2018;Powell et al., 2018). As lumpfish tolerate lower temperatures than wrasse species, their implementation was boosted principally in the northern parts of Norway (Imsland et al., 2014a), Scotland , the Faroe Islands Johannesen et al., 2018) and Iceland (Steinarson and Á rnason, 2018). They are used as cleaner fish for all sizes of Atlantic salmon during their production cycle in sea (Imsland et al., 2014a. ...
Article
Lumpfish (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.
... trol using cleaner fish that pick the sea lice from salmonids is effective in reducing lice density and is adopted widely by salmon farming industry. As an alternative of coldwater cleaner fish, the common lumpfish, Cyclopterus lumpus L., is currently used to control sea lice infestation (Imsland et al., 2014a(Imsland et al., , b, c, 2015a. ...
... However, to this date, there exists no systematic knowledge and guiding line of the effect of lumpfish on C. elongatus. Earlier researches have clearly indicated that lumpfish prefer to graze the adult female L. salmonis (Imsland et al., 2014a(Imsland et al., , c, 2016. However, lumpfish in sea pens can be classified as the strongly opportunistic (Imsland et al., 2014c) and they do not restrict themselves to graze a single food source if others exist. ...
... In this mini review, we summarized the findings from both small and large scale trials with lumpfish where grazing on C. elongatus has been reported in order to give recommendations on the possible use of lumpfish to combat C. elongatus on Atlantic salmon in sea pens. Imsland et al. (2014a) investigated the efficacy of lumpfish grazing on attached C. elongatus on Atlantic salmon at two different lumpfish densities, 10% and 15%. C. elongatus were counted every two weeks during the trial (54 days). ...
Article
In this mini review, we systematized current knowledge about the number of Caligus elongatus on farmed Atlantic salmon in relation to the use of lumpfish as cleaner fish. The review was prompted by reports of an unusually large number of sea lice (C. elongatus) infestation of farmed salmon in northern Norway, Faroese Islands and Iceland and the urgent need to determine if common lumpfish can be used to reduce the number on farmed Atlantic salmon by actively grazing on sea lice. Available data from Norway clearly indicate that lumpfish grazes on C. elongatus, and it is possible to enhance this grazing with the assistances of live-feed conditioning prior to sea pen transfer and selective breeding. Observations from Iceland, Faroese Islands and Scotland also indicate that lumpfish can effectively lower infestations of C. elongatus on salmon. Overall, this mini review expresses that lumpfish can actively lower the number of C. elongatus on farmed Atlantic salmon.
... The biological control of sea lice using cleaner fish has become a feasible option due to the increased occurrence of resistance towards medical treatments in salmon lice, Lepeophtheirus salmonis. Previous studies have shown up to 93-97% less sea lice infestation (adult female lice) in sea cages with lumpfish compared to salmon in sea cages without lumpfish present (Imsland et al., 2014a). Significant individual differences in feed intake and preference for sea lice has been seen (Imsland et al., 2014a(Imsland et al., , 2014c(Imsland et al., , 2015, and genetic influence has been suggested to be a possible factor (Imsland et al., 2016a). ...
... Previous studies have shown up to 93-97% less sea lice infestation (adult female lice) in sea cages with lumpfish compared to salmon in sea cages without lumpfish present (Imsland et al., 2014a). Significant individual differences in feed intake and preference for sea lice has been seen (Imsland et al., 2014a(Imsland et al., , 2014c(Imsland et al., , 2015, and genetic influence has been suggested to be a possible factor (Imsland et al., 2016a). If these differences are genetically influenced, certain genotypes may be better suited than others for stocking in open cages with Atlantic salmon. ...
... Recent data indicate that lumpfish graze on C. elongatus (Imsland et al., 2020a) but to this date there exists little knowledge if there are differences in C. elongatus grazing related to the genetic background of the lumpfish deployed in commercial sea pens. Earlier research has clearly indicated that lumpfish prefer the adult female L. salmonis (Imsland et al., 2014a(Imsland et al., , 2014c(Imsland et al., , 2016a(Imsland et al., , 2016b(Imsland et al., , 2018a, but lumpfish in sea pens can be classified as strongly opportunistic (Imsland et al., 2014c(Imsland et al., , 2015 and the fish do not restrict themselves or rely on a single food source if others are present. They may, therefore, readily graze on C. elongatus but whether this may depend on the parental background is at present unclear. ...
Article
To 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.
... Today, the salmon farmers in Norway use two families of cleaner fish to remove parasites: wrasses (e.g., Ballan wrasse (Labrus bergylta) and goldsinny wrasse (Ctenolabrus rupestris)) and lumpfish (Cyclopterus lumpus). Wrasses have been used for many years (Bjordal, 1991), whereas the use of lumpfish is more recent (Imsland et al., 2014a(Imsland et al., , 2014b. The use of lumpfish is gaining popularity among farmers because unlike wrasses, which stop feeding at temperatures below 6 • C (Sayer and Reader, 1996), they perform well at low water temperatures and can be used for delousing purposes year-round (Imsland et al., 2016). ...
... Small lumpfishes are more effective at delousing salmon than larger individuals, which increases the motivation for farmers to employ smaller individuals in the farms (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014c. Imsland et al. (2016) reported that lumpfish with total length between 10 and 18 cm (~50-180 g) have good delousing traits, but in Norway the most commonly used sizes are fish between 6 and 9 cm long (~20 and 30 g) (Salmar AS, personal communication). ...
... Because farmers prefer to use small lumpfish, it is likely that the lumpfish added to the cages are as close to the established lower size limit as possible, which substantially increases the risk of escape. The preference for small lumpfish is driven by their delousing efficiency, which has been reported to decrease with increasing size (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014c. Additional advantages include shorter rearing time (costs) and the possibility for coexistence with wrasses, which can be harassed by larger lumpfish (Imsland et al., 2016). ...
Article
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.
... The growth rates for fish fed with pelleted feed observed during this study were similar to growth rates from previous studies (Imsland et al., 2014a(Imsland et al., , 2014c(Imsland et al., , 2015a(Imsland et al., , 2015b. In line with previous small-scale study (Imsland et al., 2019) growth rates were significantly lower for fish fed feed blocks although both feed types were offered at a daily feeding rate of 2% BW −1 . ...
... This makes slow to moderate and uniform growth of lumpfish more desirable than fast growth for its optimal use as cleaner fish in salmon aquaculture (Imsland et al., 2016b). Additionally, lower feed input may encourage not fully satiated lumpfish to seek out alternative food sources such as attached sea lice due to their opportunistic feeding behaviour previously reported by Imsland et al. (2014aImsland et al. ( -c, 2015a. ...
... A previous study showed that growth rates were low for lumpfish stocked at 20 g in small-scale cages (Imsland et al., 2016a). Rearing in commercial cages (Imsland et al., 2018a, b, c) is probably more challenging for the lumpfish to adapt compared to the small cages used in previous studies (Imsland et al., 2014a, b, c, Imsland et al., 2016a highlighting the need for acclimation period. As the study progressed, it became evident that infestation levels increased for pre-adult lice and mature female lice at week 45/46. ...
Article
To investigate possible differences survival and welfare of lumpfish fed either feed blocks or commercially available pelleted feed in commercial cages, eight 90 m polar circle cages containing approximately 50,000 Atlantic salmon with a mean weight of 2 kg were stocked with 3800 lumpfish with a mean weight of 52 g in each cage. Four of the cages were fed with a standard commercial pelleted feed and four with feed blocks. Growth was significantly lower for fish fed feed blocks although both feed types were offered at a daily feeding rate of 1.5% BW⁻¹ based on biomass gain. There were differences in the number of mortalities recorded between the two treatments with fish fed with pelleted feed had higher mortality and was more sensitive towards mechanical treatment that occurred during the study period. Operational welfare indictors (OWI) were developed to assess health and condition for lumpfish. The OWIs showed a lower score in the feed block group indicating better health status in this group. Overall, the findings of the present study show that feed blocks can give more controlled growth, increased survival and better overall health status of lumpfish in sea pens with Atlantic salmon.
... The problems of adverse welfare outcomes associated with infestations and increased infestation pressure have escalated with the commercial production of Atlantic salmon (Salmo salar L) and rainbow trout (Oncorhynchus mykiss Walbaum) in sea cages [1,2,4]. Biological control using cleaner fish that pick the sea lice from salmonids [5][6][7] has been effective in reducing lice numbers, and is being adopted widely by the salmon farming industry [5,6,[8][9][10][11][12]. ...
... The problems of adverse welfare outcomes associated with infestations and increased infestation pressure have escalated with the commercial production of Atlantic salmon (Salmo salar L) and rainbow trout (Oncorhynchus mykiss Walbaum) in sea cages [1,2,4]. Biological control using cleaner fish that pick the sea lice from salmonids [5][6][7] has been effective in reducing lice numbers, and is being adopted widely by the salmon farming industry [5,6,[8][9][10][11][12]. ...
... Lumpfish are now extensively used as cleaner fish in Norway [6,8,9,23], Ireland [24], Scotland [25], Iceland [26], and the Faroe Islands [27]; however, there is a need to systematize knowledge and produce guidelines on the effect of lumpfish on L. salmonis. Earlier research has indicated that lumpfish prefer adult female L. salmonis [6,9,28,29], but lumpfish in sea pens can be classified as strongly opportunistic [9,10,27], and the fish do not restrict themselves or rely on a single food source if others are present [10]. ...
Article
Full-text available
In this review, we have systematized current knowledge about the effect of stocking lumpfish (Cyclopterus lumpus) as cleaner fish to control Lepeophtheirus salmonis infestations on farmed Atlantic salmon (Salmo salar L.). The review was prompted by recent reports in which the usefulness of lumpfish has been doubted, and the urgent need to investigate whether common lumpfish can be used to reduce L. salmonis numbers on farmed Atlantic salmon by active grazing on this species. Available published data clearly indicate that lumpfish graze on L. salmonis, and can significantly lower the lice burden in Atlantic salmon farming. It is possible to enhance the lice grazing behavior of lumpfish with the assistance of live feed conditioning prior to sea pen transfer, and with selective breeding. Data indicate that lice grazing of lumpfish is size dependent, and grazing effect is low for lumpfish larger than 200–250 g. Observations from large-scale rearing of Atlantic salmon in open sea cages in Norway, Iceland, the Faroe Islands, and Scotland also indicate that lumpfish can be effective in lowering infestations of L. salmonis on salmon. Overall, this present review reveals that lumpfish can actively contribute to lower numbers of L. salmonis on farmed Atlantic salmon.
... 17. Imsland et al. 2014a-c, 2015a-b, Powell et al. 2018b. 18. Sayer and Davenport 1996. ...
... This makes slow to moderate and uniform growth of lumpfish more desirable than fast growth. 186 Additionally, lower feed input may encourage not fully satiated lumpfish to seek out alternative food sources such as attached sea lice due to their opportunistic feeding behaviour previously reported by Imsland et al. (2014aImsland et al. ( -c, 2015a. ...
... The lumpfish has been shown to be an effective alternative for cold water production in Norway, Iceland and the Faeroe Islands and winter alternative in Scotland (Imsland et al. 2015, Powell et al. 2018. Lumpfish have been observed actively feeding on the gravid female louse (Imsland et al. 2014a), suggesting they could potentially be an effective cold-water replacement for the ballan wrasse. They require a higher stocking density (10-15 % vs 5 % for ballan wrasse) within the pens to effectively reduce the louse population (Imsland et al. 2014b), however there have been no observed effects on the production of salmon with this increased stocking level despite being observed competing with the salmon for food. ...
... 1985, Haauft. 2015; however, lumpfish can spawn after one to two years in captivity (Imsland et al. 2014a, Powell et al. 2018). ...
Thesis
The lumpfish (Cyclopterus lumpus) has been proposed as a sustainable solution to sea lice infestations in Atlantic salmon (Salmo salar) aquaculture. Current production is reliant on wild caught broodstock and closed life cycle management is essential to improve sustainability and allow for stock improvement. This thesis aimed to address knowledge gaps in the broodstock management of the species. Holding temperature for broodstock during the spawning season should be kept below 10° C to improve egg quality and spawning performance. In order to extend the spawning season, temperatures can be safely lowered to 6° C without impeding egg quality. Oocyte histology and distribution data suggests that lumpfish are a batch spawning species and provided the first histological oocyte development scale for the species. Subsequent research, aimed to address challenges associated with gamete management to improve artificial fertilisation protocols. Ex vivo egg ageing suggested that the window of overripening for lumpfish is 24 hours before significant reduction in egg quality. Sperm concentration was also affected by high broodstock holding temperature for this species. Research into milt quantification and storage identified two extender solutions and two rapid methods for assessing sperm concentration to aid milt management. Research into egg quality determinants identified several candidates within egg composition which strongly associated with hatching success within lumpfish. Increased levels of essential fatty acids such as EPA and DHA as well as minerals such as calcium and total levels of pigment within eggs correlated with high hatching success. Analysis of the lumpfish ovarian fluid proteome also identified several protein biomarkers for egg quality through analysis of wild, captive “good” and “bad quality eggs, it also Identified several potential biomarkers for overripe eggs in lumpfish. Overall, this research provides important baseline data on the management of broodstock and the optimisation of hatchery protocols to close the life cycle of the species. URI- http://hdl.handle.net/1893/32611
... However, lumpfish is the preferred species for the biocontrol of sea lice due to its performance in cold environments and biomass availability [10,11]. In contrast to other cleaner fish species, lumpfish actively remove sea lice from farmed salmon in cold environments, and they have been industrialized in the North Atlantic region [12][13][14][15]. Use and demand for lumpfish in salmon farms in Ireland, the United Kingdom (UK), Norway, the Faroe Islands, Iceland, and Canada have increased in recent years [13,16]. ...
... In contrast to other cleaner fish species, lumpfish actively remove sea lice from farmed salmon in cold environments, and they have been industrialized in the North Atlantic region [12][13][14][15]. Use and demand for lumpfish in salmon farms in Ireland, the United Kingdom (UK), Norway, the Faroe Islands, Iceland, and Canada have increased in recent years [13,16]. For example, 11.8 and 0.8 million juveniles were used in Norway and in the UK in 2015, respectively [17]. ...
Article
Full-text available
Citation: Dang, M.; Cao, T.; Vasquez, I.; Hossain, A.; Gnanagobal, H.; Kumar, S.; Hall, J.R.; Monk, J.; Boyce, D.; Westcott, J.; et al. Oral Immunization of Larvae and Juvenile of Lumpfish (Cyclopterus lumpus) against Vibrio anguillarum Does Not Influence Systemic Immunity.
... However, these methods can result in poor welfare and increased mortalities (Overton et al., 2018a(Overton et al., , 2018b, in addition to salmon lice developing a resistance to many of the chemical therapeutants (Grøntvedt et al., 2013;Aaen et al., 2015;Helgesen et al., 2015). Lice-eating cleaner fish on the other hand, have become widely accepted as a biological control of salmon lice due to a lack of negative effects on salmon welfare compared to chemical or physical delousing methods (Deady et al., 1995;Treasurer et al., 2002;Skiftesvik et al., 2013;Imsland et al., 2014a). ...
... The condition factor of lumpfish is higher than most other teleost, but the species follow an isometric growth pattern so the method of using condition factor is valid (Coull et al., 1989), and has been used as an indicator in several papers describing lumpfish growth (ex. Imsland et al., 2014aImsland et al., , 2018aImsland et al., , 2018bImsland et al., , 2019b. Specific growth rate (SGR) was calculated according to the formula of Houde and Schekter (1981) SGR = (e g − 1) × 100, where g = ln (W 2 ) − ln (W 1 ) / (t 2 − t 1 ) and W 2 and W 1 are weights on days t 2 and t 1 , respectively. ...
Article
Full-text available
Cleaner fish used as a biological control agent against salmon lice is rapidly increasing in Atlantic salmon aquaculture. However, concerns have been raised about the welfare and mortality of cleaner fish in salmon cage systems, which could in turn affect their performance in controlling salmon lice. In a 4-month autumn-winter study, we monitored growth, welfare, mortality and daytime depth distribution of the most commonly used cleaner fish, farmed ballan wrasse and lumpfish, in six salmon production sea cages where thermo- and haloclines were present. Ballan wrasse did not grow (SGR: small: −0.01% day−1, large: −0.06% day−1), while lumpfish significantly doubled in size (SGR: 0.87% day−1) during the study. High losses (registered mortality + unregistered loss) were observed in both species (57 and 27% of ballan wrasse and lumpfish, respectively). The welfare status of remaining individuals generally improved over the study period, regardless of species. Brief daytime camera observations at hides found ballan wrasse were typically deeper at warmer (median 12.4 °C) more saline (median 31.7 ppt) depths, where salmon were expected to reside during day periods, compared to lumpfish generally occupying colder (median 7.3 °C), brackish (median 18.9 ppt) water in surface layers. Considerable mortalities, minimal feeding (inferred from ceased growth) by ballan wrasse and a possible mismatch in lumpfish and salmon depths (inferred from limited daytime camera observations) suggest that cleaner fish may have low long-term effectiveness against salmon lice in stratified salmon sea cages over autumn-winter. Similar studies across seasons, locations and cage types (e.g. depth-based cage technologies) are vital to understand the extent of these issues in salmon aquaculture more broadly.,
... Recently, biocontrol strategies have gained significant attention, and the proposed treatment of ectoparasite infections in aquaculture has the advantages of requiring reduced labor, and being cheaper and more sustainable (Powell et al., 2018). For instance, lumpfish Cylopterus lumpus were used to control sea lice Lepeophtheirus salmonis infestations attributed to this fish can graze on attached ectoparasite in Atlantic salmon (Imsland et al., 2014(Imsland et al., , 2016(Imsland et al., , 2019, and polyculture with shrimp protected farmed grouper from C. irritans infection and reduced C. irritans tomonts (Vaughan et al., 2018). ...
... lumpus) has been used to control sea lice (L. salmonis) infestations, which can reduce the use of chemicals (Imsland et al., 2014). This study presents the first use of hyperhaline-tolerant red tilapia to control C. irritans infection by polyculture. ...
Article
Marine cultured fish in tropical and sub-tropical regions often suffer from white spot disease, caused by Cryptocaryon irritans infection. This can lead to mass mortality and economic loss. This study investigated the use of seawater-adapted red tilapias (Oreochromis niloticus × O. mossambicus) as scavengers for cleaning tomonts, to protect susceptible marine fish from C. irritans infection. The sensitivity of red tilapia to C. irritans infection, the effectiveness of red tilapia in consuming tomonts, and the efficacy for protecting the vulnerable Trachinotus ovatus from C. irritans infection were evaluated. The results showed that the susceptibility of red tilapia to C. irritans infection was significantly lower than T. ovatus and the rate of tomonts consumption by red tilapia was positively correlated with the number of tomonts in the seawater. The relative percent survival of T. ovatus infected with C. irritans and co-cultured with red tilapias (at a density of 19 red tilapias/m²) was 97.78% at the12 days post-infection. This study indicates that polyculture with red tilapia could be a potential alternative biocontrol strategy to eliminate tomonts, for controlling C. irritans reinfection.
... Farmed cleaner fish are preferred due to better biosecurity through vaccination and screening programs, stocking at optimum times and sizes, and in reducing reliance on wild caught fish (Brooker et al., 2018). Cleaner fish are now used as a biological control for sea lice on farmed salmon in Europe and Canada (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cImsland et al., 2021;Skiftesvik et al., 2014;Boyce et al., 2018;Powell et al., 2018). As lumpfish, Cyclopterus lumpus, tolerate lower temperatures than wrasse species, their implementation was boosted principally in the northern parts of Norway (Imsland et al., 2014a). ...
... Cleaner fish are now used as a biological control for sea lice on farmed salmon in Europe and Canada (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cImsland et al., 2021;Skiftesvik et al., 2014;Boyce et al., 2018;Powell et al., 2018). As lumpfish, Cyclopterus lumpus, tolerate lower temperatures than wrasse species, their implementation was boosted principally in the northern parts of Norway (Imsland et al., 2014a). In the beginning, the production of juveniles was solely based on wildcaught brood fish, where eggs were stripped, incubated, hatched, and reared to suitable size for transfer to commercial cages (Jonassen et al., 2018). ...
Article
Lumpfish is now the single most important cleaner fish species to date and there is an extensive lumpfish translocation along the Norwegian coast. A reliable baseline information about the population genetic structure of lumpfish is a prerequisite for an optimal managing of the species to minimize possible genetic translocation and avoid possible hybridisation and introgression with local populations. The current study is a follow up of the study of Jónsdóttir et al. (2018) using expressed sequence tag-short tandem repeats (EST-STRs) markers. Samples (N = 291) were analysed from six sample locations along the Norwegian coastline from south to north, with additional 18 samples of first-generation (from wild fish) reared fish from a fish farm outside Tromsø (North Norway). Present findings show a lack of population differentiation among lumpfish sampling population along the Norwegian coast using EST-STRs, which is in accordance with the findings of Jónsdóttir et al. (2018) where genomic STRs (g-STRs) were analysed. Present findings indicate that should translocated lumpfish escape from salmon sea pens in Norway, this will probably have little impact on the genetic composition of the local lumpfish population.
... In Atlantic salmon (Salmo salar) aquaculture, certain wrasse species (Labridae) and lumpfish (Cyclopterus lumpus) are utilized as cleaner fish to combat ectoparasites (Bjordal, 1990;Imsland et al., 2014a;Blanco Gonzalez and de Boer, 2017). Failing to control epidemics of the sea lice copepod Lepheophteirus salmonis have both economic and environmental consequences (Costello, 2009;Torrissen et al., 2013;Øverli et al., 2014). ...
... Nonetheless, Imsland et al. (2014b) observed no antagonistic behavior during cohabitation with the two species. While cleaner-client behavioral interactions have been documented for decades in aquaculture (Bjordal, 1990), including almost 10 years of research on lumpfish (Imsland et al., 2014a), knowledge gaps still exist on the underlying mechanisms that regulate sea lice grazing. Recently, the neurobiological, and neuro-molecular mechanisms involved in interspecific interaction have been investigated in other cleaner fish species (Soares, 2017;Ramírez-Calero et al., 2021). ...
Article
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Lumpfish are utilized to combat ectoparasitic epidemics in salmon farming. Research gaps on both cleaning behavior and client preferences in a natural environment, emphasizes the need to investigate the physiological impacts on lumpfish during cohabitation with piscivorous Atlantic salmon. Lumpfish (39.9 g, S.D ± 8.98) were arranged in duplicate tanks ( n = 40 per treatment) and exposed to Live Atlantic salmon (245.7 g, S.D ± 25.05), salmon Olfaction or lifelike salmon Models for 6 weeks. Growth and health scores were measured every second week. In addition, the final sampling included measurements of neuromodulators, body color, and plasma cortisol. A stimulation and suppression test of the hypothalamic-pituitary-interrenal (HPI) axis was used for chronic stress assessment. Results showed that growth, health scores, and body color remained unaffected by treatments. Significant reductions in levels of brain dopamine and norepinephrine were observed in Live compared to Control. Plasma cortisol was low in all treatments, while the stimulation and suppression test of the HPI axis revealed no indications of chronic stress. This study presents novel findings on the impact on neuromodulators from Atlantic salmon interaction in the lumpfish brain. We argue that the downregulation of dopamine and norepinephrine indicate plastic adjustments to cohabitation with no negative effect on the species. This is in accordance with no observed deviations in welfare measurements, including growth, health scores, body color, and stress. We conclude that exposure to salmon or salmon cues did not impact the welfare of the species in our laboratory setup, and that neuromodulators are affected by heterospecific interaction.
... While elevated temperature promotes growth and feed efficiency as observed in farmed ballan wrasse juveniles [22]. The clear evidence of lumpfish grazing efficacy on sea lice was also reported by Imsland et al., [23], through gastric lavage which was performed every 2 weeks for 54 days farmed in low temperature (9-12℃). The efficiency was manifested by lower average numbers of pre-adult, mature males and females stages of L. salmonis per salmon. ...
... And several studies proved that the use of commercial cleaner fish has no effect on the growth and condition factor of farm salmon. And one of those is the work of Imsland et al., [23] in which findings showed that the presence of lumpfish did not have any negative short and long-term effects on feed conversion ratio (FCR) or specific growth rate (SGR) in salmon. ...
Article
Cleaner fish is a keystone species in their natural ecosystem for they have specialized feeding habits that are removing and eating ectoparasites which are colonizing the skin, mouth, and gill cavities of larger fish. Their presence dictates the species distribution, diversity, recruitment, and abundance of different teleost species. They play a very important role in the survival, growth, and welfare of other fishes. They established cleaning stations where a certain location turns into a very rich fishing ground visited by various species of demersal, pelagic including migratory and cartilaginous fishes, that made a stopover and an influx of visiting species that search for it. They formed an interaction known as "cleaning symbiosis" in which cleaners gain nutrition and protection from predators and in return for a cleaning service. Aquaculture, on the other hand, is one of the destructive anthropogenic activities if not well managed. One of the highlighted effluents from aquaculture is the use of pharmaceutical chemical treatments to ease diseases of cultured stocks. Hence, a sustainable and eco-friendly approach to mitigate and eradicate diseases is one of the main concerns of the aquaculturist nowadays. Salmon aquaculture encountered fish louse as one of the most destructive parasites in the industry. However, these parasites have been controlled by a cleaner fish to the extent of suppressing them. These cleaning potentials provide a long-term control of sea louse infestation over a production cycle, provided that cleaner fish are maintain healthy and confined. Thus, the ecological and aquaculture impact of the cleaner fish is being highlighted in this review.
... For identification of early warning signs, some salmon production companies carry out periodical samplings after deployment to assess the welfare of their lumpfish stocks. Moreover, several parameters have been investigated to help expand the limited knowledge on welfare of the species, such as behaviour in pens 17,18 , coexistence with salmon 17 , food preferences 19,20 and delousing efficiency 19,[21][22][23][24][25] . In some of these studies it was observed that farmed lumpfish shows a wide range of liver colouration, and they were classified in six different liver colours, ranging from very pale to dark reddish-brown 24,25 , in contrast to the orange colour displayed in livers sampled from wild (and presumably healthy) lumpfish. ...
Article
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Ensuring lumpfish health and welfare in salmon farms is vital to reduce the high mortality rates reported and to guarantee a high delousing efficiency. Recent observations of farmed lumpfish livers have shown colours ranging from pale (colours 1 and 2), through bright orange (colours 3 and 4), to dark reddish-brown (colours 5 and 6), some of which may be related to welfare condition. To characterize the status of lumpfish deployed in four Faroese salmon farms, several welfare indicators were assessed: a weight-length relationship, scoring of external physical damage, and after dissection, stomach content and liver colour scoring. Liver samples were weighed, stored and analysed for lipid content, lipid classes, total pigments, fatty acid profile and histopathology to explain the differences between the mentioned liver colours. Bright orange livers, liver colours 3 and 4, were related to increased levels of carotenoid pigments rather than levels of lipids and appear to reflect good fish welfare. However, dark reddish-brown colours, liver colours 5 and 6, were associated with very low levels of triacyl glycerides in the liver, indicating use of lipid reserves and poor welfare condition. Histopathology confirmed that the dark reddish-brown livers, liver colours 5 and 6, formed a distinct group. Thus, liver colour was shown to be a good welfare indicator and should be monitored in farms.
... Some submerged cages include a ''snorkel'', which is a vertical tunnel providing access for salmon to the surface without exposing them to the surrounding surface waters (Oppedal et al., 2017). Other methods of avoiding parasite infection include the use of skirts and cleaner fish (Imsland et al., 2014;Frank et al., 2015). Transitioning away from sheltered sites with low currents may decrease infection pressure due to the more rapid dispersal of infectious sea lice in locations with strong currents (Kragesteen et al., 2018). ...
Article
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Disease, pest control, and environmental factors such as water quality and carrying capacity limit growth of salmon production in existing farm areas. One way to circumvent such problems is to move production into more exposed locations with greater water exchange. Farming in exposed locations is better for the environment, but may carry unforeseen costs for the fish in those farms. Currents may be too strong, and waves may be too large with a negative impact on growth and profit for farmers and on fish welfare. This study employed two major fish monitoring methods to determine the ability of Atlantic Salmon ( Salmo salar ) to cope with wavy conditions in exposed farms. Echosounders were used to determine vertical distribution and horizontal preference of fish during different wave and current conditions as well as times of day. Video cameras were used to monitor shoal cohesion, swimming effort, and fish prevalence in locations of interest. The results indicate complex interacting effects of wave parameters, currents, and time of day on fish behaviour and vertical distribution. During the day, hydrodynamic conditions had stronger effects on vertical distribution than during the night. In weak currents, fish generally moved further down in taller waves, but stronger currents generally caused fish to move upwards regardless of wave conditions. Long period waves had unpredictable effects on vertical distribution with fish sometimes seeking deeper water and other times moving up to shallower water. It is unclear how much the cage bottom restricted vertical distribution and whether movement upwards in the water columns was related to cage deformation. In extreme cases, waves can reach below the bottom of a salmon cage, preventing fish from moving below the waves and cage deformation could exacerbate this situation. Farmers ought to take into consideration the many interacting effects on salmon behaviour within a cage as well as the potential for cage deformation when they design their farms for highly exposed locations. This will ensure that salmon are able to cope when storms and strong currents hit at the same time.
... Cleaner fish are usually deployed and restocked in net pens several times per year, and the stocking density comprises between 1% and 10% of the standing salmon stock in each pen (Bui et al. 2020;Overton et al., 2020;Treasurer, 2002,). Imsland et al. (2014) suggested that lumpfish preferentially consume adult female lice, but so far there are no studies explicitly reporting on physical findings of egg strings in cleaner fish guts. If female salmon lice release their egg strings when attacked by cleaner fish, this would comprise a substantial amount of egg strings regularly being dispersed from net pens throughout a salmon production cycle. ...
Article
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The increasing number of Atlantic salmon farming locations in Norway has led to a complex dynamic network of sea lice infestation routes modulated by the local currents. Salmon lice (Lepeophtheirus salmonis , Krøyer 1837) egg strings normally hatch from the distal end while still attached to the female louse; however, the female can release their egg strings if stressed during crowding and delousing events. Eggs continue developing normally after being detached. This paper presents empirical measurements of sinking velocities of L. salmonis egg strings of different lengths and maturities. Moreover, we evaluated the potential dispersal distance of detached egg strings from salmon net pens by numerical model simulations for different current flow rates to indicate how far released egg strings could disperse from salmon farms. Theoretical transport distance of egg strings varied between 250 m for the fastest sinking velocity of 11 mm/s and the lowest simulated horizontal current velocity of 0.05 m/s and 6.11 km for the lowest sinking velocity of 9 mm/s and the fastest horizontal velocity of 1 m/s. This study is the first to model egg string transport and to consider its role in larval sea lice dispersal and infestation dynamics.
... Included are possible louse traits selected for by each strategy, the underlying genetic and environmental factors that influence these traits, the implications of evolution for louse ecology and the potential for synergistic or antagonist interactions with other strategies. (Skiftesvik et al. 2013;Imsland et al. 2014;Leclercq et al. 2014). Cleaner fish use first emerged in the late 1980s to early 1990s but increased dramatically from 2009, with approximately 60 million fish now stocked on farms worldwide (Fig. 1a, b; Treasurer, 2002;Norwegian Directorate of Fisheries, 2018;Overton et al., 2020). ...
Article
Ectoparasitic salmon lice (Lepeophtheirus salmonis) present a major challenge to Atlantic salmon (Salmo salar) aquaculture. The demand for effective louse control has produced diverse management strategies. These strategies essentially impose novel selection pressures on parasite populations, driving the evolution of resistance. Here we assess the potential for salmon lice to adapt to current prevention and control methods. Lice have evolved resistance to at least four of five chemical therapeutants, and use of these chemicals has declined significantly in recent years. The industry has shifted to alternative non‐chemical approaches, yet lice may adapt to these as well. Early research suggests that phenotypic variation exists in the louse population upon which non‐chemical selection pressures could act and that this variation may have a genetic basis. From the existing evidence, as well as an examination of evolutionary processes in other relevant parasite and pest systems, we conclude that the evolution of non‐chemical resistance is an emergent concern that must be considered by the industry. We recommend areas for focused research to better assess this risk. It is also important to determine whether phenotypic shifts in response to non‐chemical selection may shift the ecological niche of the parasite, as this may have cascading effects on wild salmon populations. We also recommend further research to identify strategy combinations that have antagonistic selective effects that slow louse evolution and those with synergistic effects that should be avoided. Greater understanding of evolutionary processes can inform aquaculture policies that counteract the rise of resistant parasite populations.
... While these treatments were effective in the short term, they ultimately led to the development of resistance with succeeding generations of sea lice (Aaen et al., 2015;Jansen et al., 2016). Therefore, the industry continuously implements integrated pest management, which utilizes a diverse palette of control measures that include: physical barriers to infection (Stien et al., 2016;Wright et al., 2017;Grøntvedt et al., 2018), biological controls via cleaner fish (Skiftesvik et al., 2013;Imsland et al., 2014), freshwater treatments (Wagner et al, 2004), and mathematical models that predict infection timing and severity (Johnsen et al., 2014;Rittenhouse et al., 2016;Salama et al., 2016;Sandvik et al., 2016;Samsing et al., 2017). ...
Article
The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects wild and farmed salmonids throughout the northern hemisphere. L. salmonis represents the largest economic hurdle of the Atlantic salmon (Salmo salar) industry, with an estimated annual cost of nearly $1 billion globally due to production losses and anti-parasitic control measures. Salmon farming in Maine has existed for decades and is a critical economic driver, yet the region is underrepresented in global sea lice research. The aim of this work was to examine parasites in the context of animal trophic transfer and characterize physiological condition by quantifying the flow of stable isotopes and seasonal energy reserves in sea lice, respectively. A meta-analysis of fish host-parasite stable isotopes was conducted, as well as stable isotope analysis in a case study of farmed and wild S. salar in Maine and their respective parasites, L. salmonis and Argulus foliaceus. Across the literature, endoparasites were depleted in d15N relative to their hosts, ectoparasites demonstrated a range of d15N enrichment patterns, and d13C enrichment varied extensively across taxa. L. salmonis and A. foliaceus demonstrated contrasting d15N and d13C enrichment patterns relative to their hosts, and none were in agreement with current animal standards. Results suggest that parasites do not conform to traditional predator-prey standards, and that, even among closely related ectoparasites, there does not appear to be a universal enrichment pathway. To quantify lipid and thermal energy reserves in sea lice embryos, histology and differential scanning calorimetry were respectively employed. Both reserve types exhibited seasonal patterns, with peak lipid quantities in the spring and lower levels in colder seasons, and the highest thermal energy content (via specific heat capacity, Cp) in the summer. Daily changes in Cp varied between months, although values generally declined between initial and final sampling days. Collectively, maximal lipid reserves and energy content aligned with the beginning of typically observed annual infection surges on farms and optimal conditions for L. salmonis development. With the earliest opportunity for population forecasting at the understudied embryo stage, these indicators of condition may contribute to more accurate infection models that inform pest management.
... The lumpfish (Cyclopterus lumpus), a native fish of the North Atlantic Ocean, is utilized as a cleaner fish to control sea lice (Lepeophtheirus salmonis) infestations in the Atlantic salmon (Salmo salar) industry [9][10][11]. The lumpfish performs well in cold environments, removing nearly 90% of the sea lice at sea-cages (with a feeding rate of 0.3 sea-lice per day) [9,12,13]. ...
Article
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Vibrio anguillarum is a Gram-negative marine pathogen causative agent of vibriosis in a wide range of hosts, including invertebrates and teleosts. Lumpfish (Cyclopterus lumpus), a native fish of the North Atlantic Ocean, is utilized as cleaner fish to control sea lice (Lepeophtheirus salmonis) infestations in the Atlantic salmon (Salmo salar) aquaculture industry. V. anguillarum is one of the most frequent bacterial pathogens affecting lumpfish. Here, we described the phenotype and genomic characteristics of V. anguillarum strain J360 isolated from infected cultured lumpfish in Newfoundland, Canada. Koch's postulates determined in naïve lumpfish showed lethal acute vibriosis in lumpfish. The V. anguillarum J360 genome was shown to be composed of two chromosomes and two plasmids with a total genome size of 4.56 Mb with 44.85% G + C content. Phylogenetic and comparative analyses showed that V. anguillarum J360 is closely related to V. anguillarum strain VIB43, isolated in Scotland, with a 99.8% genome identity. Differences in the genomic organization were identified and associated with insertion sequence elements (ISs). Additionally, V. anguillarum J360 does not possess a pJM1-like plasmid, typically present in virulent isolates from the Pacific Ocean, suggesting that acquisition of this extrachromosomal element and the virulence of V. anguillarum J360 or other Atlantic isolates could increase.
... The aquaculture and utilization of lumpfish as cleaner fish to control sea-lice infestation in the Atlantic salmon (Salmo salar) industry has become commercially relevant in the last 10 years (1)(2)(3)(4)(5), making the study and protection of this species increasingly important. Sea-lice are copepod ectoparasites that immune compromise the fish host, increasing susceptibility to infections (6), resulting in significant losses and high treatment costs (7)(8)(9). ...
Article
Full-text available
Lumpfish (Cyclopterus lumpus), a North Atlantic “cleaner“ fish, is utilized to biocontrol sea-lice (Lepeophtheirus salmonis) in Atlantic salmon (Salmo salar) farms. Lumpfish require excellent vision to scan for and eat louse on salmon skin. The lumpfish eye immune response to infectious diseases has not been explored. We examined the ocular response to a natural parasite infection in wild lumpfish and to an experimental infection in cultured lumpfish. Cysts associated with natural myxozoan infection in the ocular scleral cartilage of wild adult lumpfish harbored cells expressing cluster of differentiation 10 (CD10) and immunoglobulin M (IgM). Experimental Vibrio anguillarum infection, which led to exophthalmos and disorganization of the retinal tissues was associated with disruption of normal CD10 expression, CD10+ cellular infiltration and IgM expression. We further describe the lumpfish CD10 orthologue and characterize the lumpfish scleral skeleton in the context of myxozoan scleral cysts. We propose that lumpfish develop an intraocular response to pathogens, exemplified herein by myxozoan and V. anguillarum infection involving novel CD10+ cells and IgM+ cells to contain and mitigate damage to eye structures. This work is the first demonstration of CD10 and IgM expressing cells in a novel ocular immune system component in response to disease in a teleost.
... Recent research has shown that lumpfish (Cyclopterus lumpus), a pelagic fish species naturally found in the North Atlantic Ocean, is an effective cleaner fish in combating infestation with sea lice (Lepeophtheirus salmonis and Caligus elongatues) among farmed salmon (Imsland et al. 2014), which is a growing problem in that industry (Costello 2009a). Commercial production of lumpfish juveniles is ongoing in Norway (Schaer & Vestvik 2012;Willumsen 2001), and in the Faroe Islands, the aim is to establish a year-round production of lumpfish juveniles. ...
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This study has established a successful protocol to cryopreserve lumpfish Cyclopterus lumpus (Linnaeus, 1758) milt. Three cryosolutions were tested based on Mounib’s medium; the original medium including reduced l-glutathione (L-Glu), the basic sucrose and potassium bicarbonate medium without L-Glu, or with hen’s egg yolk (EY). Dimethyl sulphoxide (DMSO) was used as the cryoprotectant along with all three diluents in a 1 to 2 dilution. Cryopreservation was performed with the mentioned cryosolutions at two freezing rates. Motility percentages of spermatozoa were evaluated using ImageJ with a computer assisted sperm analyzer (CASA) plug-in. Findings revealed that spermatozoa cryopreserved in Mounib’s medium without L-Glu had a post-thaw motility score of 8.64 percentage points (pp) higher than to that with added L-Glu, and an addition of EY to the Mounib’s medium lowered the post-thaw motility score by 15.07 pp. The difference in motility between both freezing rates was 5.23 pp, and samples cryopreserved on a 4.8 cm high tray resulted in a better post-thaw motility score. Cryopreserved milt had a 23.76 pp lower post-thaw motility score when compared with fresh milt. Cryopreservation of lumpfish milt has, to our knowledge, never been successfully carried out before. The established protocol will be a main contributing factor in a stable production of lumpfish juveniles in future.
... Many marine teleosts rely on high visual acuity to navigate in their environment, hunt prey and evade predators. Lumpfish (Cyclopterus lumpus) and several other marine teleosts are being cultured and used as "cleanerfish" (versus mechanical or chemical treatments) to efficiently "see", target and eat salmon louse (Lepeophtheirus salmonis) on infested skin of farmed Atlantic salmon (Salmo salar) [1,2]. While lumpfish remain economically important, recent literature offers evidence that wild lumpfish are globally threatened, including in Canada [3]. ...
Article
Full-text available
Immune responses to infectious diseases impacting lumpfish (Cyclopterus lumpus) eye tissue are only starting to be studied at a molecular and histopathological level. In this study, we extend our understanding of lumpfish sensory organ anatomy, of components of the lumpfish nasal and ocular immune system and the nature of the intraocular response to Vibrio anguillarum infection. We have evaluated the expression of cluster of differentiation (CD) 45 protein, a tyrosine phosphatase, in larval and juvenile lumpfish tissues in order to spatially survey ocular and related head structures that may participate in early stages of intraocular immune responses. We provide here a histological mapping of the larval lumpfish nasal chamber system since its connectively with the eye though mucosal epithelia have not been explored. These results build upon our growing understanding of the lumpfish intraocular immune response to pathogens, exemplified herein by experimental nasally delivered V. anguillarum infection. CD45 is developmentally regulated in lumpfish eyes and periocular anatomy with early expression appearing in larvae in corneal epithelium and in nasal structures adjacent to the eye. Normal juvenile and adult lumpfish eyes express CD45 in the corneal epithelium, in leukocyte cells within blood vessel lumens of the rete mirabile, choroid body and choriocapillaris vasculatures. Experimental nasally delivered V. anguillarum infection led to qualitative and quantitative changes in CD45 expression in head kidney renal tubule tissues by 7 days post infection (dpi). The same animals showed redistribution and upregulation of corneal epithelial CD45 expression, corneal epithelial dysplasia and an increased frequency of CD45⁺ cells in ocular vasculature. Interestingly, while CD45 upregulation and/or CD45⁺ cell infiltration into inner ocular and retinal tissues was not observed under this experimental scenario, subtle neural retinal changes were observed in infected fish. This work provides new fundamental knowledge on North Atlantic teleost visual systems and vision biology in general.
... The aquaculture and utilization of lumpfish as cleaner fish to control sea-lice infestation in the Atlantic salmon (Salmo salar) industry has become commercially relevant in the last 10 years (1)(2)(3)(4)(5), making the study and protection of this species increasingly important. Sea-lice are copepod ectoparasites that immune compromise the fish host, increasing susceptibility to infections (6), resulting in significant losses and high treatment costs (7)(8)(9). ...
Article
Full-text available
Lumpfish ( Cyclopterus lumpus ), a North Atlantic “cleaner“ fish, is utilized to biocontrol salmon louse ( Lepeophtheirus salmonis ) in Atlantic salmon ( Salmo salar ) farms. Lumpfish require excellent vision to scan for and eat louse on salmon skin. The lumpfish eye immune response to infectious diseases has not been explored. We examined the ocular response to a natural parasite infection in wild lumpfish and to an experimental bacterial infection in cultured lumpfish. Cysts associated with natural myxozoan infection in the ocular scleral cartilage of wild adult lumpfish harbored cells expressing cluster of differentiation 10 (CD10) and immunoglobulin M (IgM). Experimental Vibrio anguillarum infection, which led to exophthalmos and disorganization of the retinal tissues was associated with disruption of normal CD10 expression, CD10 ⁺ cellular infiltration and IgM expression. We further describe the lumpfish CD10 orthologue and characterize the lumpfish scleral skeleton in the context of myxozoan scleral cysts. We propose that lumpfish develop an intraocular response to pathogens, exemplified herein by myxozoan and V. anguillarum infection involving novel CD10 ⁺ cells and IgM ⁺ cells to contain and mitigate damage to eye structures. This work is the first demonstration of CD10 and IgM expressing cells in a novel ocular immune system component in response to disease in a teleost.
... Lumpfish (Cyclopterus lumpus), also known as lumpsucker, are used as a biological means of preventing or reducing sea lice infestations in open net-pen farming of Atlantic salmon (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014cPowell et al., 2018). This has resulted in a rapid increase in their production, reaching 42.4 million fish in 2019 (Norwegian Directorate of Fisheries, 2019), making lumpfish the second most important aquaculture species in Norway. ...
Article
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Lumpfish is used to control sea lice in open net-pen farming of Atlantic salmon, but little is known about their nutritional requirements. The aim of this study was to investigate the effects of replacing marine oil (MO) with rapeseed oil (RO), in diets incorporating 50 % plant protein concentrates, on the growth, chemical and fatty acid (FA) composition of juvenile lumpfish. Four extruded diets, nearly iso-lipidic (14–15% DM) and iso-nitrogenous (53–54% DM) were produced with either 10 % MO (fish oil : krill oil constant proportion 2.3 : 1; Control), or the MO replaced with either 25 %, 50 % or 100 % replacement with RO to give the diets identified as RO25, RO50 and RO100, respectively. Triplicate groups of fish (7 ± 0.18 g) were fed the experimental diets ad libitum during 6 weeks. No significant effects were found on growth parameters, specific growth rate, hepatosomatic index (HSI), visero-somatic index, condition factor (CF), and whole body chemical composition when 50 % of MO was replaced by RO. Monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) in whole body, liver and muscles were also not affected by the 50 % replacement of MO. Total substitution of MO with RO significantly reduced the growth performance, and CF, but increased the HSI, and crude lipid in whole body and liver, accompanied by lipid deposition. At the end of the experiment, saturated fatty acids (SFA), PUFA, n-3 FA and eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) in whole body, muscles, and liver decreased (p < 0.05), while MUFA, and total n-6 FA increased (p < 0.05) in fish fed RO100. In conclusion, the results of the present study suggest that dietary inclusion of 50 % RO in diets where the protein content was derived from marine/plant origin (50/50), did not impair the growth of juvenile lumpfish.
... C. lumpus has particular application in colder waters (Powell et al., 2017;Treasurer, 2013), where most studies suggest it is an effective cleaner of the parasitic sea louse (Lepeophtheirus salmonis, Krøyer 1873 and Caligus elongatus, Burmeister, 1834) and more robust and active in winter conditions than wrasse Eliasen et al., 2018;Imsland, 2020;Imsland et al., 2014Imsland et al., , 2018Imsland et al., , 2021Overton et al., 2020;Powell et al., 2017). ...
Article
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Quantitative and qualitative measures of fish health and welfare are essential for management of both wild capture and aquaculture species. These measures include morphometric body condition indices, energetic condition, and aquaculture operational welfare indicators (OWI). Measures vary in ease of measurement (and may require destructive sampling), and it is critical to know how well they correlate with fish health and welfare so appropriate management decisions can be based on them. Lumpfish (Cyclopterus lumpus) is a new farming species that needs non-destructive OWIs to be developed and validated. In this study, we developed a C. lumpus fin damage score. Four different body condition indexes based on individual weight relative to either length-weight relationships, or relative to other fish in its local environment were tested (using model selection) as predictors of individual fin damage. Results showed severity of fin damage was predicted by small size relative to the other individuals in the tank or cage. Body condition based on length-weight relationship was not found to predict fin damage, indicating that using established indices from fisheries or from other species would not predict welfare risks from fin damage. Implications are that especially in hatchery conditions grading will improve the condition index, and is expected to mitigate fin damage, but that low weight at length was not of use in predicting fin damage. Model selection to choose between a suite of possible indices proved powerful, and should be considered in other applications where an easily measured index is needed to correlate with other health measures. This article is protected by copyright. All rights reserved.
... At present, there are five different species used as cleaner fish in Norwegian aquaculture: lumpfish (Cyclopterus lumpus), ballan wrasse (Labrus bergylta), goldsinny wrasse (Ctenolabrus rupestris), corkwing wrasse (Symphodus melops) and rock cook (Centrolabrus exoletus), the latter in lower numbers. Lumpfish, whose potential use as a cleaner fish was discovered in 2014, has since become the most commonly used cleaner fish (Imsland et al., 2014). The majority of lumpfish are farmed while almost all wrasses are caught wild and transported to aquaculture facilities. ...
Article
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Translocation and introduction of non‐native organisms can have major impacts on local populations and ecosystems. Nevertheless, translocations are common practise in agri‐ and aquaculture. Each year, millions of wild caught wrasses are transported large distances to be used as cleaner fish for parasite control in marine salmon farms. Recently, it was documented that translocated cleaner fish are able to escape and reproduce with local wild populations. This is especially a challenge in Norway, which is the world's largest salmon producer. Here, a panel of 84 informative SNPs was developed to identify the presence of non‐local corkwing wrasse (Symphodus melops) escapees and admixed individuals in wild populations in western Norway. Applying this panel to ~2000 individuals, escapees and hybrids were found to constitute up to 20% of the local population at the northern edge of the species’ distribution. The introduction of southern genetic material at the northern edge of the species distribution range has altered the local genetic composition, and could obstruct local adaptation and further range expansion. Surprisingly, in other parts of the species distribution where salmon farming is also common, few escapees and hybrids were found. Why hybridization seems to be common only in the far north, is discussed in the context of demographic and transport history. However, the current lack of reporting of escapes makes it difficult to evaluate possible causes for why some aquaculture‐dense areas have more escapees and hybrids than others. The results obtained in this study, and the observed high genomic divergence between the main export and import regions, puts the sustainability of mass‐translocation of non‐local wild wrasse into question, and suggest that the current management regime needs re‐evaluation.
... Skiftesvik et al. [67] used the cultured vs. wild Ballan wrasse (Labrus bergylta) for the Atlantic salmon delousing. Similarly, lumpfish (Cyclopterus lumpus L.) was used for the biological control of sea lice (Lepeophtheirus salmonis Krøyer) infestation in Atlantic salmon intensive farms [68]. ...
Article
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Crustaceans during a parasitism relationship with fish cause biological disruption and diseases to the hosting fish that threaten their life. Several crustacean groups were reported to parasitize different fish species as definitive hosts. Copepods, Isopods, and Branchiura are the major fish parasitic groups under the crustacea. They are mainly ectoparasites and occasionally, the small and microscopic members can infest the internal organs of their fish hosts. The infected fish are suffering from serious clinical signs and the infested organs are usually suffering from severe pathological disruptions and lesions. Treatment is taking place by several chemical and biological facilities. Here in the current article, the major crustaceans that parasitize on fish are reviewed by describing their corresponding harms to the hosting fish. Factors affecting the prevalence of the crustacean parasites and some of their hazardous effects on the infected fish were considered. In addition, trials for the chemical and biological control of the crustacean infestations are summarized.
... One approach to salmon lice control is the use of cleaner fish. Wrasse (Labridae spp.) have been used for this purpose since the early 1990s (Bjordal, 1990;Deady et al., 1995), and lumpfish (Cyclopterus lumpus) are an effective alternative, with the advantage of being easier to farm and more suited to cold water temperatures than wrasse species (Bolton-Warberg, 2017;Imsland et al., 2014). Demand for cleaner fish has grown steadily and it is estimated that a total of 50 million individuals will be required in Northern Europe in 2020, most of which is expected to be farm-reared lumpfish (Powell et al., 2018). ...
Article
European North Atlantic ranavirus (ENARV, Iridoviridae), is a ranavirus species recently isolated from lumpfish (Cyclopterus lumpus, L.), which are used as cleaner fish in Atlantic salmon (Salmo salar) farming in Northern Europe. This study aimed to investigate (1) the virulence of ENARV isolates from Ireland, Iceland and the Faroe Islands to lumpfish; (2) horizontal transmission between lumpfish; and (3) virulence to Atlantic salmon parr. Lumpfish were challenged in a cohabitation model using intraperitoneally (IP) injected shedders, and naïve cohabitants. IP challenge with isolates from Iceland (1.9 × 107 TCID50 ml−1) and the Faroe Islands (5.9 × 107 TCID50 ml−1) reduced survival in lumpfish, associated with consistent pathological changes. IP challenge with the Irish strain (8.6 × 105 TCID50 ml−1) did not significantly reduce survival in lumpfish, but the lower challenge titre complicated interpretation. Horizontal transmission occurred in all strains tested, but no clinical impact was demonstrated in cohabitants. Salmon parr were challenged by IP injection with the Irish isolate, no virulence or virus replication were demonstrated. A ranavirus qPCR assay, previously validated for fish ranaviruses, was first used to detect ENARV in tissues of both in lumpfish and Atlantic salmon. This study provides the first data on the assessment of virulence of ENARV isolates to lumpfish and salmon, guidelines for the diagnosis of ENARV infection, and poses a basis for further investigations into virulence markers.
... Lumpfish is a semi-pelagic cold-water fish distributed across the North-Atlantic Ocean, and is highly prized for its roe (ripe egg masses) in commercial fisheries. Moreover, the lumpfish is utilized for biologically control of sea louse infestations in Atlantic salmon mariculture farms due to its delousing performance under low temperatures [39][40][41]. Additionally, we assembled the mitogenomes of another four species based on available data from GenBank: the common seasnail Liparis liparis (Linnaeus 1766), Tanaka's snailfish Liparis tanakae (Gilbert and Burke 1912), the hadal snailfish Pseudoliparis swirei [33,108], and the Mariana snailfish (Pseudoliparis sp. ...
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We determined the mitogenome of Cyclopterus lumpus using a hybrid sequencing approach, and another four closely related species in the Liparidae based on available next-generation sequence data. We found that the mitogenome of C. lumpus was 17,266 bp in length, where the length and organization were comparable to those reported for cottoids. However, we found a GC-homopolymer region in the intergenic space between tRNALeu2 and ND1 in liparids and cyclopterids. Phylogenetic reconstruction confirmed the monophyly of infraorders and firmly supported a sister-group relationship between Cyclopteridae and Liparidae. Purifying selection was the predominant force in the evolution of cottoid mitogenomes. There was significant evidence of relaxed selective pressures along the lineage of deep-sea fish, while selection was intensified in the freshwater lineage. Overall, our analysis provides a necessary expansion in the availability of mitogenomic sequences and sheds light on mitogenomic adaptation in Cottoidei fish inhabiting different aquatic environments.
... Cleaner fish such as wrasse have been used in salmon aquaculture for several decades, but in recent years it is the small lumpfish that has caught the attention of a salmon industry struggling to deal with the threat of sea lice. There are several advantages of the lumpfish over other cleaner fish species: they can be introduced into salmon cages at a much younger age than other cleaner fish; they continue to eat sea lice at much lower temperatures, which is important for producers in Iceland, the Faroe Islands, and northern parts of Norway, Canada and Scotland; and, most importantly, is the evidence that they can dramatically reduce sea lice infestations in salmon cages (Imsland et al., 2014a(Imsland et al., , 2016a. The potential value of lumpfish to the salmon aquaculture industry has generated huge investments in production facilities for this fish across the North Atlantic (CBC News, 2019;Holmyard, 2018;Powell et al., 2018), it has led to several new university-industry research alliances aimed at better understanding this relatively unknown species, 1 and it has led to calls for enhanced veterinarian expertise in lumpfish physiology (Imsland et al., 2016b). ...
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Research in animal geographies is increasingly paying attention to hierarchies and inequalities within and between nonhuman animals. The way that animals are valued differently and hierarchically within this growing body of scholarship has tended to focus on a range of biopolitical differences between and within species. Collard and Dempsey’s recent contribution, in contrast, points to the importance of hierarchy and difference in the valuation of nonhuman animals under capitalism. Their framework identifies five orientations of human and nonhuman bodies in relation to capitalist value, which in turn provides a heuristic to explore how capitalist accumulation produces and depends on differentially oriented natures. Our contribution to these debates – and to the Collard and Dempsey framework – draws on our ongoing research in Eastern Canada where salmon aquaculture is a growing yet highly contested industry. We focus on two instances of multispecies hierarchy and difference in and around the salmon cage that are central to this form of ocean-based production. In focusing on multispecies relations, we build on Collard and Dempsey's framework in two main ways. First, we show how valuation and devaluation reflect competing but relational capitalist interests, which rely on and produce different natures refracted through the logic of the nature/culture divide: Atlantic salmon are valued as game fish, and as the key species for Canada's aquaculture sector. Second, we show how capital's valuation of one species, in our case farmed salmon, implicates the valuation of others, namely sea lice and lumpfish. Our case studies extend Collard and Dempsey's framework by demonstrating how capitalist differentiation produces violence through and outside of commodification in terms of multispecies difference and hierarchy; the lives and futures of wild and farmed salmon, lumpfish and sea lice are entangled, and reflect relational and changing orientations to capitalist value over time.
... The historical use of chemical treatment to cope with sea lice (Lepeophtheirus salmonis) in Norwegian Atlantic salmon (Salmo salar) farms resulted in the appearance of drug resistant parasites (28) and negative environmental effects (1). Farmed ballan wrasse (Labrus bergylta) is a potent candidate to be used as biological control for large-scale delousing of salmon as it is environmentally sustainable and cause no apparent stress to salmon (29)(30)(31)(32). Nonetheless, the novel cultivation of this specie faces some challenges such as lack of appetite resulting in high mortality and poor growth (32). ...
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Serotonin (5-HT) is pivotal in the complex regulation of gut motility and consequent digestion of nutrients via multiple receptors. We investigated the serotonergic system in an agastric fish species, the ballan wrasse (Labrus bergylta) as it represents a unique model for intestinal function. Here we present evidence of the presence of enterochromaffin cells (EC cells) in the gut of ballan wrasse comprising transcriptomic data on EC markers like adra2a, trpa1, adgrg4, lmxa1, spack1, serpina10 , as well as the localization of 5-HT and mRNA of the rate limiting enzyme; tryptophan hydroxylase ( tph1 ) in the gut epithelium. Second, we examined the effects of dietary marine lipids on the enteric serotonergic system in this stomach-less teleost by administrating a hydrolyzed lipid bolus in ex vivo guts in an organ bath system. Modulation of the mRNA expression from the tryptophan hydroxylase tph1 (EC cells isoform), tph2 (neural isoform), and other genes involved in the serotonergic machinery were tracked. Our results showed no evidence to confirm that the dietary lipid meal did boost the production of 5-HT within the EC cells as mRNA tph1 was weakly regulated postprandially. However, dietary lipid seemed to upregulate the post-prandial expression of tph2 found in the serotonergic neurons. 5-HT in the intestinal tissue increased 3 hours after “exposure” of lipids, as was observed in the mRNA expression of tph2 . This suggest that serotonergic neurons and not EC cells are responsible for the substantial increment of 5-HT after a lipid-reach “meal” in ballan wrasse. Cells expressing tph1 were identified in the gut epithelium, characteristic for EC cells. However, Tph1 positive cells were also present in the lamina propria. Characterization of these cells together with their implications in the serotonergic system will contribute to broad the scarce knowledge of the serotonergic system across teleosts.
... Control over sea lice (Lepeophtheirus salmonis and Caligus sp.) infestation rates has become an increasing challenge for salmon aquaculture worldwide. Cleaner fish represent a biological means of control, and lumpfish (Cyclopterus lumpus) is widely used due to its tolerance for low temperatures, the successful up-scaling of juvenile production, and reports of lice gracing (Imsland et al., 2014a(Imsland et al., , 2014b(Imsland et al., , 2014c(Imsland et al., , 2015a(Imsland et al., , 2015b(Imsland et al., , 2016. The commercial production in Norway has grown fast, reaching 38 million individuals in 2019 (Norwegian Directorate of Fisheries, 2020). ...
Article
Lumpfish are currently produced and utilizes 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.
... The mortality of the lumpfish in the net cages is known to be high, but the survival rate is rapidly improving, close up to 80% in some facilities ( Nøstvold et al., 2016 ). Re-use of the lumpfish as cleaner fish is not an option as it stops eating lice when it becomes mature at about 14 -16 months ( Brooker et al., 2018;Imsland et al., 2014b ). ...
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Farmed lumpfish (Cyclopterus lumpus) is frequently used as cleaner fish in Norwegian salmon aquaculture. During the period in the net cage, the lumpfish feed on salmon lice. After a time, the fish stop eating the lice and are then withdrawn from the net cage without further exploitation. In this study, the nutritional value of lumpfish was characterized to assess its suitability as a human food. The lumpfish were collected from two separate salmon aquaculture facilities and analyzed for proximate composition, amino acids, fatty acids, vitamins, minerals, environmental pollutants, and heavy metals. The water and protein content were approximately 90 and 6%, respectively. The protein contained all essential amino acids. The fat content ranged from 0.9 to 3.7% with a high level of the long chain polyunsaturated fatty acids EPA (eicosapentaenoic acid; 20:5n-3) and DHA (docosahexaenoic acid; 22:6n-3). Lumpfish may be a good source of B12 and D3 vitamins, however, the content of several minerals was low. The environmental pollutants and heavy metals were below the EU maximum levels, making the lumpfish safe for human consumption. Overall, our results indicate a potential to exploit the lumpfish, even after its time as a cleaner fish.
... The common lumpfish (Cyclopterus lumpus) is an ecologically important marine species that is widely distributed on both sides of the Atlantic Ocean (Simpson et al., 2016;Powell et al., 2017). Further, it is a commercially important species due to the demand for their role as a substitute for sturgeon caviar, and their use as a cleaner fish in the Atlantic salmon (Salmo salar) aquaculture industry (Imsland et al., 2014;Powell et al., 2018). However, due to overfishing/ harvesting, lumpfish have been designated as 'Threatened' by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC, 2017). ...
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Studies on the effects of environmental changes with increasing depth (e.g. temperature and oxygen level) on fish physiology rarely consider how hydrostatic pressure might influence the observed responses. In this study, lumpfish (Cyclopterus lumpus, 200–400 g), which can exhibit vertical migrations of over 100 m daily and can be found at depths of 500 m or more, were implanted with Star-Oddi micro-HRT loggers. Then, their heart rate (fH) was measured in a pressure chamber when exposed to the following: (i) increasing pressure (up to 80 bar; 800 m in depth) at 10°C or (ii) increasing temperature (12–20°C), decreasing temperature (12 to 4°C) or decreasing oxygen levels (101–55% air saturation at 12°C) in the absence or presence of 80 bar of pressure. Additionally, we determined their fH response to chasing and to increasing temperature (to 22°C) at atmospheric pressure. Pressure-induced increases in fH (e.g. from 48 to 61 bpm at 12°C) were associated with hyperactivity. The magnitude of the rise in fH with temperature was greater in pressure-exposed vs. control fish (i.e. by ~30 bpm vs. 45 bpm between 5°C and 20°C). However, the relative increase (i.e. slope of the relationship) was not different between groups. In contrast, 80 bar of pressure eliminated the small (5 bpm) increase in fH when control fish were exposed to hypoxia. Exhaustive exercise and increasing temperature to 22°C resulted in a maximum fH of 77 and 81 bpm, respectively. Our research shows that pressure influences the fH response to environmental challenges and provides the first evidence that lumpfish have a limited capacity to increase fH.
... For instance, the high mortality rate of 15.5% in the Norwegian salmon industry in 2021 is partially attributed to an increase in the number of mechanical and thermal treatments (Sommerset et al., 2022). An alternative to the immediate treatments is continuous non-chemical treatments that do not require any handling, such as cleaner fish (Imsland et al., 2014(Imsland et al., , 2018. However, there are strong concerns regarding the welfare of cleaner fish (Geitung et al., 2020;Overton et al., 2020;Garcia de Leaniz et al., 2022) and others have also questioned their efficiency Barrett et al., 2020a). ...
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Lice shielding skirts are a preventative measure against salmon lice in Atlantic salmon farming. The skirt is wrapped around the top meters of the net cage to divert the current flow around the cage, and thereby keep the salmon lice out. Despite these skirts being used actively in Norwegian aquaculture for the past decade, there is no standardised way of using them, and therefore type, depth and operating procedures vary between sites. The academic literature on the lice shielding efficiency of these skirts is not extensive and reported efficiency varies across studies and sites with some reporting favourable results, while others find none. Some also report of welfare related issues, with dissolved oxygen levels being the most prevalent, but this too varies across sites and through the production cycle. The aim of this paper is to provide a comprehensive overview and summary of relevant academic and grey literature from the last decade to identify knowledge gaps that must be filled to achieve optimal use of lice shielding skirts. This paper focuses on three main topics: lice shielding efficiency, interaction with the current flow and rearing challenges. The positive results from some sites indicate that skirts have potential as a tool against salmon lice, however, to create a best practice recommendation for skirt use, more knowledge is necessary on the interaction between skirt and the environment, and sufficient monitoring procedures and decision-making tools must be established.
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Cleaner fishes remove ectoparasites, mucus and dead tissues from other ‘client’ organisms. These mutualistic interactions provide benefits for the ‘clients’ and, on a larger scale, maintain healthy reef ecosystems. Here, we report two species of angelfishes, Centropyge bicolor and C. tibicen, acting as cleaners of the blue tang Paracanthurus hepatus in an aquarium. This observation is the first time that pygmy angelfishes are recorded cleaning in any environment. This novel cleaning observation raises questions on the ecosystem role of cleaner fishes and which biological traits facilitate cleaning.
Article
Lumpfish (Cyclopterus lumpus) are increasingly being used as cleaner fish to control parasitic sea-lice in salmon farming, but cleaning rates are very variable and not all individuals eat sea-lice, which increases the risk of emaciation and has ethical and practical implications. Selecting good cleaners is a priority to make the industry more sustainable, but there is little information on what behaviours make cleaner fish effective under a commercial setting. We examined variation in lumpfish personalities according to the five-factor personality model that takes into account differences in activity, anxiety (shelter use, thigmotaxis), aggression, sociality, and boldness (neophobia). We then quantified how variation in lumpfish personalities influenced interactions with naïve Atlantic salmon (Salmo salar), without the confounding effects of variation in sea-lice loads. Variation in activity, sociality, aggression and neophobia, but not in anxiety, was repeatable. Neophilic, non-aggressive lumpfish spent more time inspecting salmon than neophobic and aggressive individuals, but salmon fled in the presence of the most active and social individuals, suggesting there may be an optimal cleaner fish personality amenable to artificial selection. The personality screening protocols developed in this study could inform a more efficient use of cleaner fish in salmon farming and reduce the number of individuals required to control sea-lice.
Article
Structural modification of sea cages is continually changing to counter major production issues associated with commercial salmon farming. For example, snorkels and skirts are added to cages to reduce salmon lice infestations, and submerging cages can reduce salmon-lice encounter rates, minimise the effects of storms or avoid other unsuitable sea surface conditions. Unlike snorkels and skirts, the uptake of submerged cages has stalled due to negative effects associated with salmon buoyancy, as salmon require frequent access to the surface to gulp air and fill their swim bladders. Fitting submerged cages with underwater air domes provides an underwater air surface and appears to resolve buoyancy associated issues, but they have not been tested over a full production cycle. Here, we used three 1728 m³ cages submerged to 15 m fitted with air domes and three standard surface cages (i.e. control cages) to grow ~6000 fish per cage from sea transfer (~ 0.2 kg) to harvest size (~5 kg). We tested if growth rates, swimming behaviour, key SWIM (Salmon Welfare Index Model) welfare parameters and lice infestation levels differed between control and submerged cages. Submerged cages had 93% lower lice levels than controls during a large lice pulse event in mid-winter, which was visible through the subsequent lice stages. Swim bladder fullness, swimming behaviour and surface activity rates indicated submerged fish competently used the underwater airdome to maintain neutral buoyancy for the full production cycle. However, after 12 months, harvested mean fish weight was far smaller in submerged (2.8 kg) than control (5 kg) cages and overall mortality 2.5 times higher. Likewise, SWIM welfare scores for eye condition and mouth jaw wounds were worsened in submerged than control cages. The poorer outcomes in submerged cages reflect the suboptimal environmental conditions experienced deeper in the water column, where colder water and/or lower oxygen levels for long periods may have compromised growth. We conclude that while submergence can reduce lice infestation rates, strategies to do so must ensure that fish do not encounter sub-optimal environments for fish growth and welfare.
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Aquaculture can have negative environmental impacts, adding to the suite of anthropogenic stressors that challenge coastal ecosystems. However, a growing body of scientific evidence indicates that the commercial cultivation of bivalve shellfish and seaweed can deliver valuable ecosystem goods and services, including provision of new habitats for fish and mobile invertebrate species. We completed a systematic literature review of studies focused on understanding habitat‐related interactions associated with bivalve and seaweed aquaculture, and a brief meta‐analysis of 65 studies to evaluate fish and mobile macroinvertebrate populations at farms and reference sites. Bivalve and seaweed aquaculture were associated with higher abundance (n = 59, range: 0.05× to 473×, median lnRR = 0.67) and species richness (n = 29, range: 0.68× to 4.3×, median lnRR = 0.13) of wild, mobile macrofauna. Suspended or elevated mussel and oyster culture yielded the largest increases in wild macrofaunal abundance and species richness. We describe the major mechanisms and pathways by which bivalve and seaweed aquaculture may positively influence the structure and function of faunal communities—including provision of structured habitat, provision of food resources and enhanced reproduction and recruitment—and identify the role of the species cultivated and cultivation gear in affecting habitat value. Given the continued deterioration of coastal habitats and increasing investments into their restoration, understanding how industry activities such as aquaculture can be designed to deliver food within ecological limits and have positive influences on ecosystem goods and services is essential in ensuring ecological, social and economic objectives can be achieved.
Article
Cleaner fish such as lumpfish (Cyclopterus lumpus) are widely used as a biological method for delousing in Atlantic salmon (Salmo salar) aquaculture. Previous studies have mainly focused on the number of salmon lice (Lepeophtheirus salmonis) per salmon or on the proportion of individuals grazing on sea lice (L. salmonis and Caligus elongatus) and reported large variations in cleaning efficacy. Understanding what parameters cause these differences in cleaning efficacy is crucial to optimize the use of lumpfish as a biological delouser. In addition, it is uncertain how many sea lice are commonly ingested per lumpfish, even though this constitutes decisive information in the use of lumpfish for delousing. This study focused on the impact of lumpfish weight, diet and sex on cleaning efficacy in commercial Atlantic salmon net pens. A total of 2104 lumpfish were sampled from 8 Norwegian salmon farms over 2 years. Weight and sex was determined for each individual. Stomach content was visually identified and categorized as sea lice, lumpfish feed, salmon feed, biofouling organisms and zooplankton. Proportions of lumpfish with sea lice in their stomachs varied from 0 to 47% (average of 8.7% for the whole study) and the number of ingested sea lice varied from 0 to 120 (average of 0.6) between Atlantic salmon farms and sampling dates. Our results suggested that estimating the average number of sea lice ingested per lumpfish is necessary to determine cleaning efficacy. Weight was found to be a determining factor as lumpfish >300 g were very unlikely to consume sea lice. Individuals with the highest cleaning efficacy were small (< 100 g) and fed on additional prey items, mainly biofouling organisms. Lumpfish sex did not influence cleaning efficacy. We developed a simple model based on logistic regression analysis to predict lumpfish predict cleaning efficacy. The model predicted that maintaining lumpfish in net pens at a relatively small size (< 300 g) may raise grazing up to >1 sea louse per lumpfish.
Article
Infestations by the salmon louse (Lepeophtheirus salmonis Krøyer) represents the major fish health problem that the Atlantic salmon (Salmo salar) industry has to face. Sea lice infestation has a large impact on the economy of fish farmers, which are looking for a cost-effective and environmentally sustainable alternative to chemical or mechanical treatments to delouse fish. The biological control of sea lice using the so-called cleaner fish has been individuated as a feasible delousing approach of Atlantic salmons. In particular, in recent years the lumpfish (Cyclopterus lumpus) has been extensively farmed to be used as a ‘biological weapon’ in salmon farming because of its effectiveness in delousing also in harsh environmental conditions. However, the environmental impact of lumpfish farming is still largely unknown. Thus, the present study aimed at assessing the potential environmental impact of lumpfish production through a life cycle assessment (LCA) approach. Feed and electricity consumption, both for 8 of the 18 evaluated midpoint indicators, are the main responsible of the environmental load while for the Freshwater and Marine eutrophication about 90% of the impact is related to the emission of nitrogen and phosphorous compounds by fishes. These data lay the foundation for further, sustainable improvement of lumpfish farming.
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Lumpfish (Cyclopterus lumpus L.) are widely used for controlling sea lice in salmon farming, but their welfare is often challenged by poor husbandry, stress, and disease outbreaks, which compromise their ability to delouse salmon and cause public concern. It is hence important to identify when the welfare of lumpfish is being compromised in a simple and effective manner so that remedial actions can be taken. We developed, validated and tested a Lumpfish Operational Welfare Score Index (LOWSI) based on a visual assessment of skin and fin damage, eye condition, sucker deformities and relative weight, operational welfare indicators that fish farmers considered to be the most informative and were validated against cortisol measurements. We also present percentile length-weight charts to enable fish farmers to detect underweight and emaciated lumpfish at different stages of development. The lumpish welfare score index was quick and easy to score and was highly repeatable (intra class correlation coefficient = 0.83 ± 0.05). Most lumpfish (71%) displayed good welfare, but significant differences were found between six commercial sites and 28% of lumpfish had lower than normal weights for their length, and 10% were emaciated. The most common welfare problems were sucker deformities and fin damage in hatcheries, and poor eye condition and body damage in sea cages, conditions that may increase the risk of emaciation. Being able to score the welfare of lumpfish quickly and accurately will help improve their welfare, reduce stress-related mortalities, and improve the sustainability of the salmon farming industry.
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Combating and controlling sea lice causes large economic costs for the farmers, with estimated values of more than 305 million euros (€) per year. Increased resistance against traditional chemotherapeutants due to evolutionary drivers in the sea lice combined with the lack of an effective vaccine and few other chemical treatments available are expected to cause these costs to increase. Several possible methods for managing sea lice infestations have been investigated, but only cleaner fish has proven to have an effect on lice levels. Cleaning activity is well known in marine fish and has been observed in the wild as a form of symbiosis between two species: one species, the ‘client’ fish, seek out the other species, the ‘cleaner’ fish, to have ectoparasites and dead tissue cleared from its body. The Atlantic lumpfish is a relatively new aquaculture species, and wild‐caught mature fish are used as brood stock for farmed production. This poses a biosecurity risk, as wild fish can carry pathogens, and the use of quarantine and health screening is recommended. Vaccine development is unfortunately lagging far behind relatively to the wide spread and high utilisation of the fish. This review contains description of the main pathogens and diseases that affect cleaner fish.
Chapter
Cleaner fish (wrasse and lumpfish) are now used as a biological control for sea lice on commercially farmed salmon in Europe and Canada. The use of cleaner fish is an environmental and efficient alternative for removal of sea lice. In order to remove lice efficiently, the cleaner fish need to be healthy and the welfare of the cleaner fish is of major importance. Farmed cleaner fish are preferred due to better disease control through vaccination and screening programs. Strict regulations for harvesting wild-caught wrasse are needed to ensure their long-term vitality. In this chapter, the current knowledge of cleaner fish management, applications, and challenges, including brood stock, hatchery, transport, and deployment, in net pens has been summarized. Furthermore, this chapter gives an overview of diseases, antibacterial treatment and vaccination, and what is known about nutrition requirement and health status. Finally, parameters useful for monitoring the health status of the cleaner fish and ethical considerations are discussed.
Article
Teleosts exhibit extensive diversity of sex determination (SD) systems and mechanisms, providing the opportunity to study the evolution of sex determination and sex chromosomes. Here we sequenced the genome of the Common Lumpfish (Cyclopterus lumpus Linnaeus), a species of increasing importance to aquaculture, and identified the SD region and master SD locus using a 70K SNP array and tissue-specific expression data. The chromosome-level assembly identified 25 diploid chromosomes with a total size of 572.89 Mb, a scaffold N50 of 23.86 Mb, and genome annotation predicted 21,480 protein-coding genes. Genome wide association analysis located a highly sex-associated region on chromosome 13, suggesting that anti-Müllerian hormone (AMH) is the putative SD factor. Linkage disequilibrium and heterozygosity across chromosome 13 support a proto-XX/XY system, with an absence of widespread chromosome divergence between sexes. We identified three copies of AMH in the Lumpfish primary and alternate haplotype assemblies localized in the SD region. Comparison to sequences from other teleosts suggested a monophyletic relationship and conservation within the Cottioidei. One AMH copy showed similarity to AMH/AMHY in a related species and was also the only copy with expression in testis tissue, suggesting this copy may be the functional copy of AMH in Lumpfish. The two other copies arranged in tandem inverted duplication were highly similar, suggesting a recent duplication event. This study provides a resource for the study of early sex chromosome evolution and novel genomic resources that benefits Lumpfish conservation management and aquaculture.
Article
Tropical dedicated cleaner fishes communicate with client fishes to enable cooperative parasite removal, however, the ability of temperate facultative cleaner fishes to elicit cooperation through communication has yet to be fully investigated. Understanding the wider dynamics of communication in cleaning mutualism is particularly important for the salmon farming industry, because it uses temperate facultative cleaner fishes to control parasitic salmon-lice. To investigate whether cleaner-client communication might benefit parasite removal by facultative cleaners used in aquaculture, we observed interactions between cunner wrasse (n = 42) and their Atlantic salmon (n = 59) clients, which were either infected or non-infected by chalimus stage salmon-lice. We found that expression of two behavioural cues, cunners posing towards salmon and cunner making body-contact with salmon: (1) was higher when cunners were alongside infected salmon rather than non-infected salmon, (2) reduced the average distance between the cunner and trios of infected salmon, (3) increased the time cunner spent visually inspecting infected salmon, but, (4) did not decrease antagonistic interaction between the cunner and the salmon. Behavioural variation was high among individuals, nevertheless larger cunners (> 100 g) showed significantly higher rates of desirable mutualistic (e.g. inspection, pecking) and communicative (e.g. posing, contact) behaviours than smaller cunners. These findings imply this facultative cleaner wrasse displayed behavioural cues to infected clients which increased proximity and resulted in higher rates of mutualistic behaviours. If these two behavioural cues are subsequently shown to be correlated with delousing performance, then they could be used to identify high-performing elite cleaners for use in sea-farms and in selective breeding programs.
Chapter
Fish and other organisms in aquaculture may be subjected to a wide range of diseases, some of which are mediated by viruses, fungi, and bacteria, or by internal and external parasites. For infectious diseases where a treatment is available, veterinary drugs may be administered by baths or by inclusion of the therapeutic agent in the feed. This chapter gives an outline of medical feed additives in aquaculture, with a main focus on the situation in Norway. The use of antibacterial agents included in aquaculture feeds remains largely unrestricted in several countries with high and growing aquaculture production, even though in recent years nations with export of such products increasingly need to put efforts to comply with the demands from the importer. A range of external and internal parasites pose a challenge in the aquaculture of fish and other organisms. The main ectoparasite problem in the farming of Atlantic salmon is the salmon lice. Before registration of veterinary products, evaluation of safety data on the target species must be performed. To protect public health, maximum limits, residue of a pharmacologically active substance that may be present in food without presenting harm to the consumer, must be established. To ensure that residue level after a treatment is below the established limit, withdrawal periods before slaughtering have been determined. Veterinary drugs used in the aquaculture production may enter the environment around the farming site. The use of antisea lice agents can negatively affect nontarget crustaceans.
Article
Finfish aquaculture in freshwater and marine environments is continuously expanding globally, and the potential for a substantial further increase is well documented. The industry is supplying fish products for human consumption to the same extent as capture fisheries, and new fish species for domestication are still being selected by the industry. The challenge faced by all aquacultured species, classical and novel, is the range of pathogens associated with each new fish type. A fish host in its natural environment carries a series of more or less specific parasites (specialists and generalists). Some of these show a marked ability to propagate in aquaculture settings. They may then elicit disease when infection intensities in the confined aquaculture environment reach high levels. In addition, the risk of transmission of parasites from aquaculture enterprises to wild fish stocks adds to the parasitic challenge. Control programmes of various kinds are needed and these may include chemotherapeutants and medicines as the farmer's first and convenient choice, but mechanical, biological, immunological and genetic control methods are available solutions. New methods are still to be developed by scrutinizing the life cycle of each particular parasite species and pin-pointing the vulnerable stage to be targeted. As parasites exhibit a huge potential for adaptation to environmental changes, one must realize that only one approach rarely is sufficient. The present work therefore elaborates on and advocates for implementation of integrated control strategies for diseases caused by protozoan and metazoan parasites.
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ABSTRACT. Over the last 20 years, the Norwegian production of salmon and rainbow trout has increased by about 10% per year and will exceed 1 million MT in 2010. All on-growing after stocking in sea takes place in open cages in the fjords and along the coast, and the average cage volume has increased by about 300 times since the 1980’s. Out of a total number of 4,000 cages more than 1,200 cages hold 20,000-60,000 m3. In 2005, the term ‘maximum allowable biomass (MAB)’ was introduced and limits the highest annual production to 65 tons per 1,000 m3 licensed volume. Generally, the increasing volume and deeper cages have made the control of the fish stock more challenging. Sea lice attacks, especially in South Norway, have represented a major problem over the last three years. Reduced growth, increased mortality and lice treatment leads to significant losses and extra costs for the industry. Some recent reports indicate that increased use of wrasses in the cages improved the situation in the summer 2010 compared to the previous year. Extensive vaccinating and strict regulations regarding handling, etc. usually result in effective protection against diseases, but still there may occur regional outbreaks of serious diseases, such as pancreas disease (PD) and infectious salmon anaemia (ISA). Attacks of sea lice and escape of salmon and trout from fish farms are considered to be among the main reasons for the strongly reduced wild stocks of sea trout and a reduced return of salmon spawners in the fjords and along the coast of southwest Norway. Keywords: salmon production, cage size, escape, diseases, sea lice, wild stocks, Norway
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Norway has the largest salmon-farming industry in the world, an industry that is still growing, and in recent years production of marine species like Atlantic cod has also increased. At the same time, Norway has the world's largest wild stock of Atlantic salmon and has fjord systems and ocean areas rich in wild marine fish species which form the basis of a large fishing industry. As the aquaculture industry grows and diversifies, there is concern about the potential effects of pathogens spreading from farmed fish to wild populations. The overall health situation in Norwegian aquaculture is good, but some pathogens are not controlled effectively. In particular, salmon lice produced in farms may cause problems for wild salmonids and other parasites may be abundant too. Also, viral diseases in Atlantic salmon and bacterial diseases in Atlantic cod give rise to several disease outbreaks annually. The open design of most aquaculture systems allows the transmission of pathogens from the environment or from wild fish to the farmed fish. The objective of this review is to provide an overview of current knowledge of disease interaction and pathogen exchange between farmed and wild fish populations, with emphasis on Norwegian condition. In addition, the paper contains an evaluation of research methods that would be useful in expanding knowledge of pathogen exchange between wild and farmed fish, and in surveys of diseases in wild fish populations. The impact of pathogen transfer from farmed fish to economically important wild fish populations is assessed together with risk analysis considering possible consequences of pathogen exchange between farmed and wild fish. Finally, the review contains suggestions for future research that will increase the knowledge in the field.
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Natural Caligus elongatus Nordmann infections of wild coastal fishes on the Norwegian south east coast were monitored at various times of the year from 2002 to 2004. The prevalence for all coastal fish (n = 4427) pooled was 15%, and there were great differences between fish species and seasons. Lumpfish Cyclopterus lumpus L. spawners were the most infected fish, with a prevalence of 61% and a median intensity of 4 lice fish(-1), whereas gadids had a mean prevalence of 19% and a median infection of 1 to 2 lice fish(-1). Sea trout Salmo trutta L. and herring Clupea harengus L. carried C. elongatus at prevalence values of 29 and 21%, respectively. The results were compared with infection data for immature North Sea lumpfish. Lumpfish spawners caught on the coast in March to April had fewer lice than North Sea lumpfish in July. Spawners carried mostly adult lice, as did coastal fish hosts in May to June. The low development rates of lice at low spring temperatures and new genetic data suggest that the May to June adult lice could not have been offspring of the March to April lice, indicating transfer of adult lice to coastal fish. Most coastal fish species appeared to acquire new C. elongatus infections between May to June and September. The relatively high numbers of chalimii on North Sea lumpfish suggest that offshore fish sustain an oceanic population of this louse species.
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Wrasse used as cleaner fish with farmed Atlantic salmon Salmo salar can be subjected to large and rapid temperature and salinity fluctuations in late autumn and early winter, when summer-warmed surface water is affected by early snowmelt episodes. Because of their containment in sea cages, wrasse which are essentially acclimated to summer temperatures may be rapidly exposed to winter conditions. Short-term tolerance of low temperature and low salinity by three species of wrasse, goldsinny Ctenolabrus rupestris rock cook Centrolabrus exoletus corkwing Crenilabrus melops caught during the summer, and winter-caught corkwing, was investigated. A 3-day period at 30 or 32‰ salinity and temperature 8, 6 or 4°C (for summer-caught fish; 4°C only for winter-caught) was followed by a decline in salinity to 24, 16 or 8‰ over c. 36h, followed by a further 24 h at these salinities held constant at each of the three temperatures. Controls in 30 or 32‰ were maintained at 8, 6 or 4°C. Mortality of summer- caught corkwing and rock cook was high at 4°C, whereas the influence of salinity on mortality was small. Mortality of goldsinny was low or zero in all treatments. Surviving corkwing and rock cook after 3 days at 4°C and 32‰ salinity had elevated plasma osmolality: in summer-caught corkwing, plasma [Cl-] and [Na+] were high, whereas in rock cook only [Na+] was high. Haematocrit was low in summer-caught corkwing, high in rock cook. In survivors of all three species at the end of the experiment, values of all these parameters were comparable with those of fish at the beginning of the experiment, except that survivors at low salinity (8, 16‰) had low plasma osmolality, at all temperatures, and in surviving rock cook in these treatments haematocrit was high and plasma [Cl-] was low. Winter- caught corkwing had higher osmolality, [Na+] and [Cl-] than summer- caught corkwing; there was no difference in haematocrit. Survival of winter-caught corkwing exposed to four salinities at 4° C was much higher than that of summer-caught corkwing under the same conditions. Little change in blood physiology was recorded for winter-caught corkwing, with only fish subjected to 8‰ and 4°C showing signs of osmoregulatory stress. The interspecific and seasonal differences in survival and blood physiology at low temperature and low salinity are discussed in relation to wrasse survival over winter, both in the field and in salmon farms.
Article
Over the last 20 years, the Norwegian production of salmon and rainbow trout has increased by about 10% per year and will exceed 1 million MT in 2010. All on-growing after stocking in sea takes place in open cages in the fjords and along the coast, and the average cage volume has increased by about 300 times since the 1980’s. Out of a total number of 4,000 cages more than 1,200 cages hold 20,000-60,000 m3. In 2005, the term ‘maximum allowable biomass (MAB)’ was introduced and limits the highest annual production to 65 tons per 1,000 m3 licensed volume. Generally, the increasing volume and deeper cages have made the control of the fish stock more challenging. Sea lice attacks, especially in South Norway, have represented a major problem over the last three years. Reduced growth, increased mortality and lice treatment leads to significant losses and extra costs for the industry. Some recent reports indicate that increased use of wrasses in the cages improved the situation in the summer 2010 compared to the previous year. Extensive vaccinating and strict regulations regarding handling, etc. usually result in effective protection against diseases, but still there may occur regional outbreaks of serious diseases, such as pancreas disease (PD) and infectious salmon anaemia (ISA). Attacks of sea lice and escape of salmon and trout from fish farms are considered to be among the main reasons for the strongly reduced wild stocks of sea trout and a reduced return of salmon spawners in the fjords and along the coast of southwest Norway. Keywords: salmon production, cage size, escape, diseases, sea lice, wild stocks, Norway.
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The lumpsucker Cyclopterus lumpus is distributed throughout the North Atlantic Ocean and migrates considerable distances between offshore feeding areas and shallow inshore spawning grounds. The number of the lumpsucker has declined since the mid 1980s, probably as a result of overexploitation. The lumpsucker is the preferred host of the sea louse Caligus elongates, which is a problem for marine aquaculture. However, little is known about the biology of the lumpsucker. The aims of the study were to 1) examine the movements of female lumpsucker during the spawning migration, and 2) assess the potential for lumpsucker to act as a vector for transmission of parasites and diseases between aquaculture farms and wild fish. Twenty female lumpsuckers tagged with acoustic transmitters were released during the spawning season in the inner part of Øksfjord, northern Norway and their distribution was recorded by 22 automatic acoustic receivers. The average time until departure from the fjord was 3 days, and within 1 week all fish had left the fjord. Timing of departure from the fjord was unrelated with either tidal current patterns or the time of the day. A high proportion of the fish (75%) were recorded within 200 m of fish farms, but they did not stay for extended periods at these farms. Our results suggest that mature female lumpsucker exhibit a movement pattern characterized by rapid fjord-scale migrations during the spawning season, and that they are not attracted to salmon farms in the same way as a range of other fish species.
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Emamectin benzoate (EMB; SLICE®) has been the drug of choice for the control of sea lice in salmon aquaculture within the past decade due to its ease of administration as well as efficacy on all parasitic stages of sea lice. This over-reliance has led to increased tolerance to the drug and a consequent decline in its use. ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) are known to be involved in drug resistance. The present study investigated 1) the interaction of EMB with P-gp, 2) the effect of increasing EMB concentrations on P-gp mRNA expression in male and female sea lice, Lepeophtheirus salmonis, from Atlantic salmon (Salmo salar) farms in the Bay of Fundy, NB, as well as 3) changes in the mRNA expression of the transporter in archived adult female L. salmonis. Analysis of bioassay results indicated a 4 to 26 fold higher EMB EC50 for samples collected in 2011 compared to a similar study carried out between 2002 and 2004 suggesting loss of EMB efficacy in the parasite. An assay for ATPase activity as well as a competitive inhibition test showed that EMB interacts with the transporter. Emamectin benzoate had a significant concentration-dependent effect on P-gp mRNA expression in the parasite. There was a temporal increase in levels of P-gp mRNA in sea lice samples collected from 2002 to 2011. Our results indicate that EMB is a substrate for P-gp and that the transporter could be involved in the loss of efficacy of the parasiticide in L. salmonis.
Article
Studies of the biology of sea lice have been conducted from various perspectives for two decades. For Lepeophtheirus spp., most of the published literature has centred on the economically important Lepeophtheirus salmonis, while for Caligus spp., research has focused on a wider range of species. The most numerous species of Caligus in North Atlantic waters, however, is Caligus elongatus, which is also economically important to salmon fanning. Since the last review by Pike, A. W., and Wadsworth, S. L. (1999. Sea lice on salmonids: their biology and control. Advances in Parasitology, 44: 234-337.), research on sea lice has developed considerably, including the application of genetic methods. This new research has focused on life history biology, studying developmental stages under different environmental conditions (e.g. temperature and salinity), behaviour, distribution and the dispersal of free-living stages, monitoring practices, population structure, and modelling. The results of this research have informed risk analyses and allowed the refinement of management strategies to reduce sea lice infestations in wild and fanned populations of anadromous salmonids. Molecular techniques have been used to describe population structure and identify differences in genetic characterization of geographically separate populations and population markers. Research has been initiated to understand the parasite-host relationship at a molecular level and to develop a vaccine against sea lice. (c) 2006 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
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Sexual dimorphism in growth and maturation of individually tagged turbot (n= 421), Scophthalmus maximus Rafinesque, was studied in a long-lasting (20 months) growth experiment with four temperature regimes. The influence of onset of puberty and subsequent maturation on growth was evaluated. There were no initial size differences, but the final weight of females was larger than that of males at all temperature regimes, except at the lowest temperature. Surplus energy (sum of increase in somatic weight and gonad weight) in females was on average greater than in males from 8 months prior to first spawning. Significant growth (as specific growth rate, SGR) differences between maturing and immature fish were detected from the age of 9 months post hatch. Maturing females had the highest growth rate and reached the largest size (1.8 kg in 20 months), whereas male body weights reached a plateau and levelled off around 1.0 kg. To optimize production characteristics in turbot aquaculture and achieve more homogeneous growth, methods should be developed to produce all-female broods.
Article
Emamectin benzoate has been used to treat sea lice, Lepeophtheirus salmonis, infestations on farmed Atlantic salmon, Salmo salar. Recent evidence suggests a reduction in effectiveness in some locations. A major challenge in the detection of tolerance emergence can be the typically low proportion of resistant individuals in a population during the early phases. The objectives of this study were to develop a method for determining differences in temporal development of tolerance between sea lice life stages and to explore how these differences might be used to improve the monitoring of treatment effectiveness in a clinical setting. This study examined two data sets based on records of sea lice abundance following emamectin benzoate treatments from the west coast of Scotland (2002-2006) and from New Brunswick, Canada (2004-2008). Life stages were categorized into two groups (adult females and the remaining mobile stages) to examine the trends in mean abundance and treatment effectiveness. Differences in emamectin benzoate effectiveness were found between the two groups by year and location, suggesting that an important part of monitoring drug resistance development in aquatic ectoparasites may be the need to focus on key life stages.
Article
Wrasse used as cleaner fish with farmed Atlantic salmon Salmo salar can be subjected to large and rapid temperature and salinity fluctuations in late autumn and early winter, when summer-warmed surface water is affected by early snowmelt episodes. Because of their containment in sea cages, wrasse which are essentially acclimated to summer temperatures may be rapidly exposed to winter conditions. Short-term tolerance of low temperature and low salinity by three species of wrasse, goldsinny Ctenolabrus rupestris rock cook Centrolabrus exoletus corkwing Crenilabrus melops caught during the summer, and winter-caught corkwing, was investigated. A 3–day period at 30 or 32‰ salinity and temperature 8, 6 or 4° C (for summer-caught fish; 4° C only for winter-caught) was followed by a decline in salinity to 24, 16 or 8‰ over c. 36 h, followed by a further 24 h at these salinities held constant, at each of the three temperatures. Controls in 30 or 32‰ were maintained at 8, 6 or 4° C. Mortality of summer-caught corkwing and rock cook was high at 4° C, whereas the influence of salinity on mortality was small. Mortality of goldsinny was low or zero in all treatments. Surviving corkwing and rock cook after 3 days at 4° C and 32‰ salinity had elevated plasma osmolality: in summer-caught corkwing, plasma [Cl°] and [Na+] were high, whereas in rock cook only [Na+] was high. Haematocrit was low in summer-caught corkwing, high in rock cook. In survivors of all three species at the end of the experiment, values of all these parameters were comparable with those of fish at the beginning of the experiment, except that survivors at low salinity (8, 16‰) had low plasma osmolality, at all temperatures, and in surviving rock cook in these treatments haematocrit was high and plasma [Cl−] was low. Winter-caught corkwing had higher osmolality, [Na+] and [Cl−] than summer-caught corkwing; there was no difference in haematocrit. Survival of wintercaught corkwing exposed to four salinities at 4° C was much higher than that of summercaught corkwing under the same conditions. Little change in blood physiology was recorded for winter-caught corkwing, with only fish subjected to 8‰ and 4° C showing signs of osmoregulatory stress. The interspecific and seasonal differences in survival and blood physiology at low temperature and low salinity are discussed in relation to wrasse survival over winter, both in the field and in salmon farms.
Article
Thesis (M.A.)--State University of New York at Stony Brook, 1983. Includes bibliographical references (leaves 40-43).
Article
There are many examples of successful biological control of pest populations in aquatic environments. This approach to sea louse control has environmental benefits and is cost-effective. The range of possible pathogens of lice is reviewed and epibionts recorded from sea lice, including the monogenean Udonella caligorum and ciliates, are examined. Baculoviruses when ingested by insects form occlusion bodies resulting in severe damage to the digestive system and subsequent death, and this may be a promising approach. Cleaner wrasse (Labridae) have been stocked commercially with farmed salmon since 1989, and recent work on improving the method is reviewed. Wrasse are sourced from a wild fishery and stocked at ratios of 1 to 25-150 salmon. Over 5 million wrasse are stocked annually in Norway and c 30% of smolts in Scotland were stocked with wrasse until 1998, when an outbreak of infections salmon anaemia (ISA) deterred many farmers from transferring wild fish to cages. A case study is given showing that salmon in cages stocked with wrasse had a burden of one to eight lice through the first year compared with up to 40 lice per fish on unprotected and untreated fish. Electivity indices were used to compare the relative composition of lice developmental stages on salmon in stocked and unstocked cages, and adult male and female lice were found to comprise only 6% of the population in cages with wrasse, compared with 49% adults on fish in control cages. Measures to improve the efficacy of wrasse as a way of cleaning salmon in the second production year include the use of refuges to assist over-wintering survival, and stocking ballan wrasse. Health hygiene includes sourcing wrasse in the farm locality, testing for pathogens, vaccination of wrasse and ultimately rearing wrasse for stocking. The role of wrasse in an IPM strategy is described.
Article
In Northern Europe and Canada, the salmon louse, Lepeophtheirus salmonis (Krøyer), seriously affects the marine phase of salmon production. Although the problem is long-standing, the development of sustainable methods of pest management has been unable to keep pace with the intensification of production, leading to large-scale reliance on very few chemotherapeutants. This runs the risk of selecting for genetically determined resistance in target organisms. There are many examples of similar evolutionary adaptations in arthropod pests of arable crops, livestock and human health. Several hundred pest species are now documented as being resistant to one or more chemical classes of insecticides and acaricides. Many of these compounds are identical or closely related to ones currently employed against salmon lice. It is, therefore, opportune to consider what lessons have been learnt from contending with resistance in terrestrial organisms, the implications for sustainable use of chemotherapeutants in aquaculture, and the potential for developing effective resistance management strategies. An EU-funded project named SEARCH (QLK2-CT-2000-00809) has been initiated to explore in more detail the diagnosis, incidence, dynamics and management of resistance to chemotherapeutants in L salmonis.
Article
Sea lice, especially Lepeophtheirus salmonis and Caligus spp., have the greatest economic impact of any parasite in salmonid fish farming and are also a threat to wild salmonids. Here, I review how the biology and ecology of various louse and host species influence their pathogenicity and epidemiology. Recent discoveries of new species and genotypes emphasize the need for more basic research on louse taxonomy and host preferences. Louse development rates are strongly dependent on temperature, and increasing mean sea temperatures are likely to increase infestation pressure on farms and wild fish, as well as affecting the geographical distribution of hosts and parasites. Despite progress in finding L. salmonis larvae in the plankton and in modelling louse production in several countries, more data on larval behaviour and distribution are required to develop dispersal and transmission models for both L. salmonis and Caligus spp. This knowledge could be used to take measures to reduce the risks of lice affecting farmed and wild fish.
Growth rates, rations and cohort consumption of marine fish larvae in relation to prey concentrations
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