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Depletion of emamectin benzoate residues from the fillet tissue of rainbow trout (Oncorhynchus mykiss) treated with SLICE®-medicated feed in recirculating and flow-through aquaculture systems Completed

By Upper Midwest Environmental Sciences Center January 9, 2018

The results from this study may lead to an expansion of the SLICE® label allowing for treatment of freshwater-reared fish infested with copepods.  Label expansion would enhance production on hatcheries throughout the United Sates.

Introduction

SLICE® is a fish feed premix containing emamectin benzoate (EB) and butylated hydroxyanisole (preservative) used to control sea lice (e.g. Lepeophtheirus salmonis and Caligus elongates) infestations in marine farmed salmon and trout.  Emamectin is the active ingredient.  SLICE® is currently approved for use to control sea lice on marine-reared fish in the United Kingdom, Europe, Norway, Chile, and Canada.  In addition to its proven efficacy for the control of marine copepods (Stone et al. 1999, 2000a, 2000b, 2000c; Armstrong et al. 2000), SLICE® has also been shown to be effective reducing infestations of freshwater copepods on freshwater-reared fish (Dunston and Cusack 2002; Stone et al. 2002; Hakalahti et al. 2004; Roberts et al. 2004; Bowker et al. 2012; Gunn et al. 2012).  Therefore, there is interest in pursuing approval of SLICE® for freshwater uses.

Emamectin belongs to the avermectin family of chemicals.  Avermectins do not have antibacterial or antifungal properties, however, they do demonstrate effective action against ecto- and endo-parasites (Fisher and Mrozik 1989).  Avermectins increase the permeability of cell membranes to chloride ions.  Specifically for sea lice control, sea lice feeding on a host fish treated with SLICE® will ingest emamectin from the fish tissues, become paralyzed, die, and drop off.

Emamectin is the 4”-deoxy-4”methylamino derivative of avermectin produced by the fermentation of soil by the gram positive bacterium Streptomyces avermitilis.  Emamectin consists of a mixture of the emamectin B1a and emamectin B1b homologues in a ratio of 9:1 (or higher) emamectin B1a: emamectin B1b.  Emamectin B1a is the marker residue for EB residues in fish fillet tissue (Kim-Kang et al. 2004).

Emamectin B1a depletion from the fillet tissue of salmonids dosed in seawater has been well characterized (Kim-Kang et al. 2004; Sevatdal et al. 2005; Roy et al. 2006; Whyte et al. 2011).  There are no published data describing the disposition of emamectin residues in fillet tissue from fish dosed in freshwater.  To address the data gap, rainbow trout will be dosed with SLICE® at 50 µg EB/kg body weight (BW)/d in a freshwater recirculating aquaculture system with a water temperature favorable for rainbow trout culture (15°C) and in a flow-through aquaculture system with a water temperature near the lower end of the range for rainbow trout culture (6°C).  After administering the last dose of SLICE® medicated feed, fish will be sacrificed at predetermined times through a post-dosing period and emamectin B1a concentrations determined in fillet tissue using a validated determinative/confirmatory method for emamectin B1a.

 

USGS scientist removing fillet from rainbow trout to evaluate chemical build up.
Sources/Usage: Public Domain. View Media Details
USGS scientist removing fillet from rainbow trout to evaluate chemical build up.(Credit: Theresa Schreier, Upper Midwest Environmental Science Center. Public domain.)

Objective

Characterize the depletion of EB residues from the fillet tissue of rainbow trout dosed with SLICE® medicated feed in a recirculating aquaculture system (water temperature 15°C) and a flow-through aquaculture system (water temperature 6°C).

References

Armstrong, R., D. MacPhee, T. Katz, and R. Endris.  2000.  A field efficacy evaluation of emamectin benzoate for the control of sea lice in Atlantic salmon.  Canadian Veterinary Journal 41:607–612.

Bowker, J.D., D.G. Carty, N. Wandelear, J. Schaffer, W. Swee, and S.E. LaPatra.  2012.  Efficacy of SLICE Premix (0.2% emamectin benzoate) for reducing infestations of Salmincola spp. On freshwater-reared rainbow trout.  North American Journal of Aquaculture 74:428-437.

Duston, J. and R.R. Cusack.  2002.  Emamectin benzoate:  an effective in-feed treatment against the gill parasite Salmincola edwardsii on brook trout.  Aquaculture 207:1-9.

Gunn, C., D. Carty, P. G. Walker, P. A. Colburn, and J. D. Bowker.  2012.  Pilot field trial to evaluate SLICE (0.2% emamectin benzoate)–medicated feed to reduce a natural infestation of Salmincola californiensis in freshwater-reared rainbow trout.  North American Journal of Aquaculture 74:424–427.

Fisher, M.h. and H. Mrozik.  1989.  Chemistry.  In:  Ivermectin and Abamectin.  Ed. W.C. Campbell.  Springer Verlag, New York, pp. 1-23.  Pg 1 and 3.

Hakalahti, A., Y. Lankinen, and E. T. Valtonen.  2004.  Efficacy of emamectin benzoate in the control of Argulus coregoni (Crustacea: Branchiura) on rainbow trout Oncorhynchus mykiss.  Diseases of Aquatic Organisms 69:197–204.

Kim-Kang, H., Bova, A., Crouch, L.S., Wislocki, P.G., Robinson, R.A., and Wu, J.  2004.  Tissue distribution, metabolism, and residue depletion study in Atlantic salmon following oral administration of [3H]emamectin benzoate.  Journal of Agricultural and Food Chemistry 52:2108-2018.

Roberts, R. J., K. A. Johnson, and M. T. Casten.  2004.  Control of Salmincola californiensis (Copepoda: Lernaeapodidae) in rainbow trout, Oncorhynchus mykiss (Walbaum): a clinical and histopathological study.  Journal of Fish Diseases 27:73–79.

Roy, W.J., N. Gillan, L. Crouch, R. Parker, H. Rodger, and R. Endris.  2006.  Depletion of emamectin residues following oral administration to rainbow trout, Oncorhunchus mykiss.  Aquaculture 259:6-16.

Sevatdal, S., Å. Magnusson, K. Ingebrigtsen, R. Haldorsen, and T.E. Horsberg.  2005.  Distribution of emamectin benzoate in Atlantic salmon (Salmo salar L.).  Journal of Veterinary Pharmacology and Therapeutics 28:101-107.

Stone, J., W. J. Roy, I. H. Sutherland, H. W. Ferguson, C. Sommerville, and R. Endris.  2002.   Safety and efficacy of emamectin benzoate administered in-feed to Atlantic salmon, Salmo salar L., smolts in freshwater, as a preventative treatment against infestations of sea lice, Lepeophtheirus salmonis (Krøyer).  Aquaculture 210:21–34.

Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and R. G. Endris.  2000a.  The duration of efficacy following oral treatment with emamectin benzoate against infestations of sea lice, Lepeophtheirus salmonis (Krøyer), in Atlantic salmon, Salmo salar L.  Journal of Fish Diseases 23:185–192.

Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  1999.  The efficacy of emamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (Krøyer), infestations in Atlantic salmon, Salmo salar L.  Journal of Fish Diseases 22:261–270.

Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  2000b.  Commercial trials using emamectin benzoate to control sea lice Lepeophtheirus salmonis infestations in Atlantic salmon Salmo salar.  Diseases of Aquatic Organisms 41:141–149.

Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  2000c.  Field trials to evaluate the efficacy of emamectin benzoate in the control of sea lice, Lepeophtheirus salmonis (Krøyer) and Caligus elongates Nordmann, infestations in Atlantic salmon Salmo salar L.  Aquaculture 186:205–219.

Whyte, S.K., J.D. Westcott, P. Byrne, and K.L. Hammell.  2011.  Comparison of the depletion of emamectin benzoate (SLICE®) residues from skeletal muscle and skin of Atlantic salmon (Salmo salar), for multiple dietary dose regimens at 10°C.  Aquaculture 315:228-235.

  • Overview

    The results from this study may lead to an expansion of the SLICE® label allowing for treatment of freshwater-reared fish infested with copepods.  Label expansion would enhance production on hatcheries throughout the United Sates.

    Introduction

    SLICE® is a fish feed premix containing emamectin benzoate (EB) and butylated hydroxyanisole (preservative) used to control sea lice (e.g. Lepeophtheirus salmonis and Caligus elongates) infestations in marine farmed salmon and trout.  Emamectin is the active ingredient.  SLICE® is currently approved for use to control sea lice on marine-reared fish in the United Kingdom, Europe, Norway, Chile, and Canada.  In addition to its proven efficacy for the control of marine copepods (Stone et al. 1999, 2000a, 2000b, 2000c; Armstrong et al. 2000), SLICE® has also been shown to be effective reducing infestations of freshwater copepods on freshwater-reared fish (Dunston and Cusack 2002; Stone et al. 2002; Hakalahti et al. 2004; Roberts et al. 2004; Bowker et al. 2012; Gunn et al. 2012).  Therefore, there is interest in pursuing approval of SLICE® for freshwater uses.

    Emamectin belongs to the avermectin family of chemicals.  Avermectins do not have antibacterial or antifungal properties, however, they do demonstrate effective action against ecto- and endo-parasites (Fisher and Mrozik 1989).  Avermectins increase the permeability of cell membranes to chloride ions.  Specifically for sea lice control, sea lice feeding on a host fish treated with SLICE® will ingest emamectin from the fish tissues, become paralyzed, die, and drop off.

    Emamectin is the 4”-deoxy-4”methylamino derivative of avermectin produced by the fermentation of soil by the gram positive bacterium Streptomyces avermitilis.  Emamectin consists of a mixture of the emamectin B1a and emamectin B1b homologues in a ratio of 9:1 (or higher) emamectin B1a: emamectin B1b.  Emamectin B1a is the marker residue for EB residues in fish fillet tissue (Kim-Kang et al. 2004).

    Emamectin B1a depletion from the fillet tissue of salmonids dosed in seawater has been well characterized (Kim-Kang et al. 2004; Sevatdal et al. 2005; Roy et al. 2006; Whyte et al. 2011).  There are no published data describing the disposition of emamectin residues in fillet tissue from fish dosed in freshwater.  To address the data gap, rainbow trout will be dosed with SLICE® at 50 µg EB/kg body weight (BW)/d in a freshwater recirculating aquaculture system with a water temperature favorable for rainbow trout culture (15°C) and in a flow-through aquaculture system with a water temperature near the lower end of the range for rainbow trout culture (6°C).  After administering the last dose of SLICE® medicated feed, fish will be sacrificed at predetermined times through a post-dosing period and emamectin B1a concentrations determined in fillet tissue using a validated determinative/confirmatory method for emamectin B1a.

     

    USGS scientist removing fillet from rainbow trout to evaluate chemical build up.
    Sources/Usage: Public Domain. View Media Details
    USGS scientist removing fillet from rainbow trout to evaluate chemical build up.(Credit: Theresa Schreier, Upper Midwest Environmental Science Center. Public domain.)

    Objective

    Characterize the depletion of EB residues from the fillet tissue of rainbow trout dosed with SLICE® medicated feed in a recirculating aquaculture system (water temperature 15°C) and a flow-through aquaculture system (water temperature 6°C).

    References

    Armstrong, R., D. MacPhee, T. Katz, and R. Endris.  2000.  A field efficacy evaluation of emamectin benzoate for the control of sea lice in Atlantic salmon.  Canadian Veterinary Journal 41:607–612.

    Bowker, J.D., D.G. Carty, N. Wandelear, J. Schaffer, W. Swee, and S.E. LaPatra.  2012.  Efficacy of SLICE Premix (0.2% emamectin benzoate) for reducing infestations of Salmincola spp. On freshwater-reared rainbow trout.  North American Journal of Aquaculture 74:428-437.

    Duston, J. and R.R. Cusack.  2002.  Emamectin benzoate:  an effective in-feed treatment against the gill parasite Salmincola edwardsii on brook trout.  Aquaculture 207:1-9.

    Gunn, C., D. Carty, P. G. Walker, P. A. Colburn, and J. D. Bowker.  2012.  Pilot field trial to evaluate SLICE (0.2% emamectin benzoate)–medicated feed to reduce a natural infestation of Salmincola californiensis in freshwater-reared rainbow trout.  North American Journal of Aquaculture 74:424–427.

    Fisher, M.h. and H. Mrozik.  1989.  Chemistry.  In:  Ivermectin and Abamectin.  Ed. W.C. Campbell.  Springer Verlag, New York, pp. 1-23.  Pg 1 and 3.

    Hakalahti, A., Y. Lankinen, and E. T. Valtonen.  2004.  Efficacy of emamectin benzoate in the control of Argulus coregoni (Crustacea: Branchiura) on rainbow trout Oncorhynchus mykiss.  Diseases of Aquatic Organisms 69:197–204.

    Kim-Kang, H., Bova, A., Crouch, L.S., Wislocki, P.G., Robinson, R.A., and Wu, J.  2004.  Tissue distribution, metabolism, and residue depletion study in Atlantic salmon following oral administration of [3H]emamectin benzoate.  Journal of Agricultural and Food Chemistry 52:2108-2018.

    Roberts, R. J., K. A. Johnson, and M. T. Casten.  2004.  Control of Salmincola californiensis (Copepoda: Lernaeapodidae) in rainbow trout, Oncorhynchus mykiss (Walbaum): a clinical and histopathological study.  Journal of Fish Diseases 27:73–79.

    Roy, W.J., N. Gillan, L. Crouch, R. Parker, H. Rodger, and R. Endris.  2006.  Depletion of emamectin residues following oral administration to rainbow trout, Oncorhunchus mykiss.  Aquaculture 259:6-16.

    Sevatdal, S., Å. Magnusson, K. Ingebrigtsen, R. Haldorsen, and T.E. Horsberg.  2005.  Distribution of emamectin benzoate in Atlantic salmon (Salmo salar L.).  Journal of Veterinary Pharmacology and Therapeutics 28:101-107.

    Stone, J., W. J. Roy, I. H. Sutherland, H. W. Ferguson, C. Sommerville, and R. Endris.  2002.   Safety and efficacy of emamectin benzoate administered in-feed to Atlantic salmon, Salmo salar L., smolts in freshwater, as a preventative treatment against infestations of sea lice, Lepeophtheirus salmonis (Krøyer).  Aquaculture 210:21–34.

    Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and R. G. Endris.  2000a.  The duration of efficacy following oral treatment with emamectin benzoate against infestations of sea lice, Lepeophtheirus salmonis (Krøyer), in Atlantic salmon, Salmo salar L.  Journal of Fish Diseases 23:185–192.

    Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  1999.  The efficacy of emamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (Krøyer), infestations in Atlantic salmon, Salmo salar L.  Journal of Fish Diseases 22:261–270.

    Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  2000b.  Commercial trials using emamectin benzoate to control sea lice Lepeophtheirus salmonis infestations in Atlantic salmon Salmo salar.  Diseases of Aquatic Organisms 41:141–149.

    Stone, J., I. H. Sutherland, C. Sommerville, R. H. Richards, and K. J. Varma.  2000c.  Field trials to evaluate the efficacy of emamectin benzoate in the control of sea lice, Lepeophtheirus salmonis (Krøyer) and Caligus elongates Nordmann, infestations in Atlantic salmon Salmo salar L.  Aquaculture 186:205–219.

    Whyte, S.K., J.D. Westcott, P. Byrne, and K.L. Hammell.  2011.  Comparison of the depletion of emamectin benzoate (SLICE®) residues from skeletal muscle and skin of Atlantic salmon (Salmo salar), for multiple dietary dose regimens at 10°C.  Aquaculture 315:228-235.