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Mysis relicta- Natural History and as Food for Fish
Al Sabetta 7/2002
Native and Introduced History
Mysis relicta evolved as a fresh water shrimp from another shrimp, Mysis oculata, thru a process where melting glaciers decreased the saline content waters that M. oculata lived in. The shrimp adapted and evolved into the fresh water species known as Mysis relicta. This shrimp is naturally found in some northern Lakes of North America where it plays a very important part in the food chain, notably in the Great lakes region where it feeds primarily on phytoplankton., and is consumed by many native fish that it evolved with. It has acquired the common name of opossum shrimp.
Because of its role in the Great Lakes Food chain, this shrimp was artificially introduced into other northern lakes in the United States and Canada in the hopes that it would serve as a food source for various important salmon species. This was done in the 1940s in a British Columbia lake, Lake Kootenay. The target predator was to be the Sockeye Salmon, [Oncorhynchus nerka. These salmon are then fed on by very large strain of rainbow trout Oncorhynchus mykiss ,known as Gerrard trout. It was hoped this would boost the Gerrard Trouts Populations, but it didn’t. It did however boost another population of Salmon, Kokanee.and which resulted in an excellent sports fishery for the next couple of decades, until the Kokanee population crashed in the 1990’s for what is thought to be many reasons, including the Mysis.
The success of Lake Kootenay introduction lead to further introductions elsewhere where the Kokanee Salmon existed, in the hopes that it would do the same there . In 1966 the shrimp were introduced to Okanagan Lake - British Columbia., where the shrimp populations grew to very high densities , and the Kokanee salmon population Crashed. Researchers discovered that though the Mysis shrimp were a great food source for the Kokanee adults, the Mysis shrimp were preying on the fry of the salmon! The densities in this Lake grew to such proportions that it now supports a commercial shrimp fishery, Piscine Energetics (Mysis.com), which supplies this shrimp as food for Aquarium fish.
In other Lakes where they have been introduced, like Flathead Lake-Montana, the shrimp have also had a negative impact on the natural ecosystems. In general introductions of exotic species in any ecosystem, usually have a very negative impact on the native flora and fauna.. This has been demonstrated time after time.
Biology and reproduction….
The biology of these shrimp is direct without any naupliar stages, meaning from hatching the young look like the adults only smaller. Upon hatching they go thru several stages of growth called instars, where they shed their chitinous exoskeleton so that growth may occur. Males have four instar stages of development, females have five stages. Sexual maturity is usually 1 year, but in colder lakes , can be up to two years. Mating typically occurs in the winter, the males then die and the females remain alive for several more months , carrying the fertilized eggs in a special brood pouch (the source of its common name- Opossum Shrimp). The eggs hatch in 3-4 months and the young emerge fully developed..
Mysis as an Aquarium Fish Food…
As stated earlier the high populations and nutritious composition of Mysis relicta has created an opportunity for commercial harvesting , packaging, and marketing of this product for public, private, and institutional use as a healthy fish food. There are many benefits associated with Mysis relicta as a food source, foremost among them are a high protein content and an excellent fatty acid profile.
The following Nutritional analysis was generously provided by Piscine Energetics (Mysis.com)
Frozen Mysis (% concentration)
· Protein 10.46
· Crude Fat 3.29
· Moisture 82.27
· Ash 1.65
· Carbohydrates (by subtraction) 2.3
·
Freeze Dried Mysis (% concentration)
· Min Crude Protein 69.5
· Min crude Fat 8.35
· Max crude fiber 2.75
· Max ash 5.5
Fatty Acid % Profile of Freeze Dried Mysis
· C14:0…………Myristate…...……..8.47mg/g
· C16:0…………Palmitate…..……...24.73mg/g
· C16:1…………Palmitoleate……….11.59mg/g
· C18:0…………Stearate……..……..0.89mg/g
· C18:1…………Oleate……………..17.07mg/g
· C18:2(n-6)……Linoleate…………..7.39 mg/g
· C20.0…………Arachidate………....0.00mg/g
· C18:3(n-3)……Linolenate…………..7.14 mg/g
· C20:1…………Eicosaenoate………. 0.00mg/g
· C20:3(n-3)……Eicosatrienoate….….9.87 mg/g
· C20:4(n-6)……Eicosatetraenoate…...0.00mg/g
· C20:5(n-3)……Eicosapentaenoic…...17.85mg/g
· C24:0…………Nervonate…………...0.00mg/g
· C22:5(n-6)……Docosapentaenoic..…0.00mg/g
· C22:5(n-3)……Docosapentaenoic… 0.00mg/g
· C22:6(n-3)……Docosahexaenoic….12.53mg/g
Other Values of nutritional interest
· Energy…………………84 Cal/100g
· Energy…………………350 KJoules/100g
In conclusion, Though this small fresh water shrimp may have had a questionable affect on native populations of fish where it has been introduced. The resulting success of it in these cold water lakes has provided and ideal food for hobbyists that require nutritious food for their fish. It contains many fatty acids that are recommended for healthy fish , and has a high % of protein. This makes it a very good food for carnivorous fresh water and saltwater fish.
As a post note , the authors personal experience with the use of Mysis relicta as a food for Discus Fish, Symphysodon spp. , has been a very positive. It is one of the staples that he feeds to his discus. It appears to have a marked effect on energy levels of the fish, increases spawning behavior, and is an excellent growth food.
References……
Related literature of interest….
Balcer, B.D., N.L. Korda, S.I. Dodson. 1984. Zooplankton of the Great Lakes. The University of Wisconsin Press, Ltd. London, England. pp. 103-106
Chess, D.W., J.A. Stanford. 1998. Comparative energetics and life cycle of the opossum shrimp Mysis relicta in native and non-native environments. Freshwater Biology 40(4):783-794
Grossnickle, N.E. 1982. The herbivorous and predaceous habits of Mysis relicta in Lake Michigan. PHD Thesis, University of Wisconsin-Madison
Lasenby, D.C., M. Furst. 1981. Feeding of Mysis relicta on macrozooplankton. Institute of Freshwater Research Drottingham Report 0(59):75-80
Lehman, J.T., J.A. Bowers, R.W. Gensemer, G.J. Warren, D.K.
Branstrator. 1990. Mysis relicta in Lake Michigan (USA): abundances and relationships with their potential prey, Daphnia. Canadian Journal of Fisheries and Aquatic Sciences 47(5):977-983
Tohtz, J. 1993. Lake whitefish diet and growth after introduction of Mysis relicta to Flathead Lake, Montana. Transactions of the American Fisheries Society 122(4):629-635
Gal, G., L. G. Rudstam, & C. H. Greene, 1999. Acoustic characterization of Mysis relicta. Limnol. Oceanogr. 44: 371-381
Pothoven, S.A., G. L. Fahnenstiel, H. A. Vanderploeg, & M. Luttenton, 2000. Population Dynamics of Mysis relicta in southeastern Lake Michigan, 1995-1998. J. Great Lakes Res. 26: 357-365.
Clements, W.A., D.S. Rawson, and J.L. McHugh. 1939. A biological survey of Okanagan Lake, British Colombia. Fisheries Research Board of Canada Bulletin 56.
Nesler, T.P. and E.P. Bergersen. 1991. Mysids and their impacts on fisheries: an introduction to the 1988 Mysid-Fisheries symposium. Pages 1-4
In: T.P. Nesler and E.P. Bergersen, editors. Mysids in fisheries: hard lessons from headlong introductions. American Fisheries Society Symposium 9, Bethesda, Maryland.
Pennak, R.W. 1989. Fresh-water invertebrates of the United States, protozoa to mollusca. John Wiley & Sons, New York, 3rd ed.
Mysis relicta Lovén into Kootenay Lake, British Columbia. Journal of the Fisheries Research Board of Canada 21:1325-1327
All rights reserved , Al Sabetta, Copyright July 2002
Al Sabetta 7/2002
Native and Introduced History
Mysis relicta evolved as a fresh water shrimp from another shrimp, Mysis oculata, thru a process where melting glaciers decreased the saline content waters that M. oculata lived in. The shrimp adapted and evolved into the fresh water species known as Mysis relicta. This shrimp is naturally found in some northern Lakes of North America where it plays a very important part in the food chain, notably in the Great lakes region where it feeds primarily on phytoplankton., and is consumed by many native fish that it evolved with. It has acquired the common name of opossum shrimp.
Because of its role in the Great Lakes Food chain, this shrimp was artificially introduced into other northern lakes in the United States and Canada in the hopes that it would serve as a food source for various important salmon species. This was done in the 1940s in a British Columbia lake, Lake Kootenay. The target predator was to be the Sockeye Salmon, [Oncorhynchus nerka. These salmon are then fed on by very large strain of rainbow trout Oncorhynchus mykiss ,known as Gerrard trout. It was hoped this would boost the Gerrard Trouts Populations, but it didn’t. It did however boost another population of Salmon, Kokanee.and which resulted in an excellent sports fishery for the next couple of decades, until the Kokanee population crashed in the 1990’s for what is thought to be many reasons, including the Mysis.
The success of Lake Kootenay introduction lead to further introductions elsewhere where the Kokanee Salmon existed, in the hopes that it would do the same there . In 1966 the shrimp were introduced to Okanagan Lake - British Columbia., where the shrimp populations grew to very high densities , and the Kokanee salmon population Crashed. Researchers discovered that though the Mysis shrimp were a great food source for the Kokanee adults, the Mysis shrimp were preying on the fry of the salmon! The densities in this Lake grew to such proportions that it now supports a commercial shrimp fishery, Piscine Energetics (Mysis.com), which supplies this shrimp as food for Aquarium fish.
In other Lakes where they have been introduced, like Flathead Lake-Montana, the shrimp have also had a negative impact on the natural ecosystems. In general introductions of exotic species in any ecosystem, usually have a very negative impact on the native flora and fauna.. This has been demonstrated time after time.
Biology and reproduction….
The biology of these shrimp is direct without any naupliar stages, meaning from hatching the young look like the adults only smaller. Upon hatching they go thru several stages of growth called instars, where they shed their chitinous exoskeleton so that growth may occur. Males have four instar stages of development, females have five stages. Sexual maturity is usually 1 year, but in colder lakes , can be up to two years. Mating typically occurs in the winter, the males then die and the females remain alive for several more months , carrying the fertilized eggs in a special brood pouch (the source of its common name- Opossum Shrimp). The eggs hatch in 3-4 months and the young emerge fully developed..
Mysis as an Aquarium Fish Food…
As stated earlier the high populations and nutritious composition of Mysis relicta has created an opportunity for commercial harvesting , packaging, and marketing of this product for public, private, and institutional use as a healthy fish food. There are many benefits associated with Mysis relicta as a food source, foremost among them are a high protein content and an excellent fatty acid profile.
The following Nutritional analysis was generously provided by Piscine Energetics (Mysis.com)
Frozen Mysis (% concentration)
· Protein 10.46
· Crude Fat 3.29
· Moisture 82.27
· Ash 1.65
· Carbohydrates (by subtraction) 2.3
·
Freeze Dried Mysis (% concentration)
· Min Crude Protein 69.5
· Min crude Fat 8.35
· Max crude fiber 2.75
· Max ash 5.5
Fatty Acid % Profile of Freeze Dried Mysis
· C14:0…………Myristate…...……..8.47mg/g
· C16:0…………Palmitate…..……...24.73mg/g
· C16:1…………Palmitoleate……….11.59mg/g
· C18:0…………Stearate……..……..0.89mg/g
· C18:1…………Oleate……………..17.07mg/g
· C18:2(n-6)……Linoleate…………..7.39 mg/g
· C20.0…………Arachidate………....0.00mg/g
· C18:3(n-3)……Linolenate…………..7.14 mg/g
· C20:1…………Eicosaenoate………. 0.00mg/g
· C20:3(n-3)……Eicosatrienoate….….9.87 mg/g
· C20:4(n-6)……Eicosatetraenoate…...0.00mg/g
· C20:5(n-3)……Eicosapentaenoic…...17.85mg/g
· C24:0…………Nervonate…………...0.00mg/g
· C22:5(n-6)……Docosapentaenoic..…0.00mg/g
· C22:5(n-3)……Docosapentaenoic… 0.00mg/g
· C22:6(n-3)……Docosahexaenoic….12.53mg/g
Other Values of nutritional interest
· Energy…………………84 Cal/100g
· Energy…………………350 KJoules/100g
In conclusion, Though this small fresh water shrimp may have had a questionable affect on native populations of fish where it has been introduced. The resulting success of it in these cold water lakes has provided and ideal food for hobbyists that require nutritious food for their fish. It contains many fatty acids that are recommended for healthy fish , and has a high % of protein. This makes it a very good food for carnivorous fresh water and saltwater fish.
As a post note , the authors personal experience with the use of Mysis relicta as a food for Discus Fish, Symphysodon spp. , has been a very positive. It is one of the staples that he feeds to his discus. It appears to have a marked effect on energy levels of the fish, increases spawning behavior, and is an excellent growth food.
References……
Related literature of interest….
Balcer, B.D., N.L. Korda, S.I. Dodson. 1984. Zooplankton of the Great Lakes. The University of Wisconsin Press, Ltd. London, England. pp. 103-106
Chess, D.W., J.A. Stanford. 1998. Comparative energetics and life cycle of the opossum shrimp Mysis relicta in native and non-native environments. Freshwater Biology 40(4):783-794
Grossnickle, N.E. 1982. The herbivorous and predaceous habits of Mysis relicta in Lake Michigan. PHD Thesis, University of Wisconsin-Madison
Lasenby, D.C., M. Furst. 1981. Feeding of Mysis relicta on macrozooplankton. Institute of Freshwater Research Drottingham Report 0(59):75-80
Lehman, J.T., J.A. Bowers, R.W. Gensemer, G.J. Warren, D.K.
Branstrator. 1990. Mysis relicta in Lake Michigan (USA): abundances and relationships with their potential prey, Daphnia. Canadian Journal of Fisheries and Aquatic Sciences 47(5):977-983
Tohtz, J. 1993. Lake whitefish diet and growth after introduction of Mysis relicta to Flathead Lake, Montana. Transactions of the American Fisheries Society 122(4):629-635
Gal, G., L. G. Rudstam, & C. H. Greene, 1999. Acoustic characterization of Mysis relicta. Limnol. Oceanogr. 44: 371-381
Pothoven, S.A., G. L. Fahnenstiel, H. A. Vanderploeg, & M. Luttenton, 2000. Population Dynamics of Mysis relicta in southeastern Lake Michigan, 1995-1998. J. Great Lakes Res. 26: 357-365.
Clements, W.A., D.S. Rawson, and J.L. McHugh. 1939. A biological survey of Okanagan Lake, British Colombia. Fisheries Research Board of Canada Bulletin 56.
Nesler, T.P. and E.P. Bergersen. 1991. Mysids and their impacts on fisheries: an introduction to the 1988 Mysid-Fisheries symposium. Pages 1-4
In: T.P. Nesler and E.P. Bergersen, editors. Mysids in fisheries: hard lessons from headlong introductions. American Fisheries Society Symposium 9, Bethesda, Maryland.
Pennak, R.W. 1989. Fresh-water invertebrates of the United States, protozoa to mollusca. John Wiley & Sons, New York, 3rd ed.
Mysis relicta Lovén into Kootenay Lake, British Columbia. Journal of the Fisheries Research Board of Canada 21:1325-1327
All rights reserved , Al Sabetta, Copyright July 2002
It really is kind of funny.
. Okay I will go food shopping first so I don't get kicked outta the house! :P
I like feeding my Discus mysis also along with homemade beefheart & bloodworms. My only problem is that the mysis clouds up the water really bad and that kills me. After getting my water polished, to see it get so bad. I started to rinse them in a strainer but someone told me that then I was washing awy all the nutients. Is this true ? 
But, gotta havem. Thanks for the response. Scubaboy
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