Description
Morone saxatilis (female) X M. chrysops (male) (Striped Bass X White Bass, Palmetto Bass) is an artificial hybrid first created in 1965 in SC. This combination is the hybrid most commonly stocked. The female M. chrysops X male M. saxatilis is called 'Sunshine Bass' (Harrell et al. 1990 1990; Jenkins and Burkhead 1993).
Potentially Misidentified Species - Morone chrysops (White Bass) is a potential invader, which is introduced in some reservoirs in the watershed. Morone saxatilis (Striped Bass) is native. Morone. saxatilis X M. americana (Striped BassX White Perch, Virginia Bass) is an artificial hybrid. Other hybrids have been produced including backcross combinations and hybrids with Morone mississippiensis (Yellow Bass), but are rarely utilized (Harrell et al. 1990).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Chordata | Osteichthyes | Perciformes | Moronidae | Morone |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1968 | Unknown | Contracting | Introduced | Regular Resident | North America | North America | Fisheries(Fisheries Intentional) |
History of Spread
Morone saxatilis X Morone chrysops (Striped Bass X White Bass, Palmetto Bass) is an artificial hybrid, first created in 1965 in SC. This hybrid was the result of an effort to create fish for reservoir stocking which would have some of the qualities of M. saxatilis but be more tolerant of hatchery and reservoir conditions (Gleason 1982; Harrell et al. 1990). It has been widely stocked in late 1960's to the present in inland reservoirs throughout the U.S. (31 states) for recreational fishing (Fuller et al. 1999). There is some evidence for successful reproduction (Harrell 1984), and also backcrossing with native Morone saxatilis (Avise and Van Den Avyle 1984; Harrell et al. 1993; Wirgin et al. 1992). At present, hybrid bass are not usually stocked in river systems with naturally reproducing M. saxatilis populations (Harrell 1996), but they are increasingly reared as an aquaculture fish (Kerby et al. 1990; Nerrie and Reid 1992). Harrell could not estimate the number of aquaculture operations rearing Morone hybrids in the Chesapeake watershed, but said that there were at least a dozen on the Eastern shore of MD (Harrell 1996 personal communication).
Morone saxatilis X Morone chrysops were stocked in VA reservoirs in the James and York drainages from 1966 onwards (Kerby et al. 1971). As late as 1986, 135,000 hybrids were stocked in VA. Hybrid bass stocking in MD ended in 1984, in VA in 1986, but was still being continued in the Susquehanna drainage, PA, at least as late as 1991. Most hybrid fish collected in 1990-91 were 5 years old (Harrell et al. 1993). Stocking of M. saxatilis X M. chrysops hybrids ended in PA in 1993. Aquaculture represents a source of future escapes, but culture is prohibited in open-water systems, and pond operations require screens on water intakes and outlets to prevent escapes (Harrell 1996).
Hybrid bass are probably frequently overlooked in Chesapeake Bay due to morphological similarity with M. saxatilis, so records are sporadic. Genetic methods are being used to identify hybrids and possible backcrosses (Avise and van den Avyle 1984; Harrell et al. 1993; Wirgin et al. 1992).
Rappahannock River - Ninety-nine M. saxatilis X M. chrysops were caught in 1968-69, but we have no further records (Kerby et al. 1971).
Potomac River - Hybrid bass (M. saxatilis X M. chrysops) were reported, but not verified in 1969-70 (Kerby et al. 1971). They were stocked in impoundments up to 1986. Eight hybrids were collected in Occoquan River in 1991 (Wirgin et al. 1992).
Patuxent River- 268,000 fingerlings and fry of M. saxatilis X M. chrysops were stocked in 1984 (Harrell et al. 1993).
Upper Bay - In 1980-84, M. saxatilis X M. chrysops were introduced in Chesapeake Bay tributaries by the Maryland Department Natural Resources as a 'marked population' for recruitment estimations. In the winter of 1991, they constituted 12.6% of Upper Chesapeake Bay harvestable striped bass stock (Harrell et al. 1993).
Delaware River- M. saxatilis X M. chrysops was stocked in DE in 1981 in Moores Lake, and in Silver Lake in 1985 (Raasch and Altemus 1991). Hybrids have been collected in Delaware Bay (Woodland Beach, Augustine Beach) DE (Raasch and Altemus 1991).
History References - Avise and van Den Avyle 1984; Fuller et al. 1999; Gleason 1982; Harrell 1984; Harrell 1996 personal communication); Harrell et al. 1993; Jenkins and Burkhead 1993; Kerby et al. 1990; Kerby et al. 1971; Nerrie and Reid 1992; Raasch and Altemus 1991; Wirgin et al. 1992.
Invasion Comments
Native Region- Morone saxatilis (Striped Bass) is native to Chesapeake Bay and Atlantic and Gulf drainages From Lake Ponchartrain to St. Lawrence River (Page and Burr 1991). Morone chrysops is native to Missisippi, Gulf, and Great Lakes drainages from North Dakota to the St. Lawrence River south to TX and AL (Page and Burr 1991).
Vector(s) of Introduction- Early estuarine records of this hybrid resulted when fish escaoed from a stocked impoundment at Fort A.P. Hill on the Rappahannock River during flooding (Kerby et al. 1971). There were many intentional plantings in reservoirs in Chesapeake Bay drainage. this fish was also introduced in Chesapeake Bay tributaries by the Maryland Department of Natural Resources as a 'marked population' for recruitment estimations (Harrell et al. 1993).
Range Status- Stocking of Morone saxatilis X Morone chrysops in MD, VA, and PA has ended (Harrell et al. 1993; Harrell 1996 personal communication) and there are regulatory requirements for aquaculture operations to prevent/reduce escape of hybrids (Nerrie and Reid 1992; Harrell 1996 personal communication).
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 0.0 | 34.0 | 10.0 | 15.6 |
| Salinity (‰) | 0.0 | 36.0 | 0.0 | |
| Oxygen | well-oxygenated | |||
| pH | 5.0000000000 | 10.0000000000 | ||
| Salinity Range | fresh-poly |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 280.0 | 280.0 |
| Typical Adult Size (mm) | 600.0 | 600.0 |
| Maximum Adult Size (mm) | 815.0 | 815.0 |
| Maximum Longevity (yrs) | 8.0 | 8.0 |
| Typical Longevity (yrs | 4.5 | 4.5 |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Morone saxatilis X Morone chrysops (Palmetto Bass) was widely introduced in the Chesapeake Bay watershed in the late 1970s and early 1980s, but stocking of hybrids has ceased in MD, VA, and PA (Harrell et al. 1993; Harrell 1996). Occasional escapes from aquaculture operations are possible despite required precautions. It seems to be an increasingly accepted policy that hybrids should not be introduced into river systems with established M. saxatilis populations (Gleason 1982; Harrell 1996).
Fisheries Costs - Given the high value of the M. saxatilis (Striped Bass, 'Rockfish') fishery, protection of the M. saxatilis gene pool appears to be a priority, justifying the current ban on stocking of M. saxatilis X chrysops. However rate of introgression of M. chrysops genes appears to be low and declining due to the cessation of stocking (Harrell et al. 1993).
Fisheries benefits - Morone saxatilis X Morone chrysops (Palmetto Bass) was widely stocked for sportfishing in the Chesapeake drainage, but concern about protection of the M. saxatilis population has led to cessation of stocking, in MD, VA, and PA (Harrell et al. 1993; Harrell 1996). However, this hybrid is increasingly important as an aquaculture fish in VA (Nerrie and Reid 1992) and MD (Harrell 1996). The hybrid grows more rapidly than its parent species (Kerby et al. 1983), leading to increased use in aquaculture. In Maryland in 1997, 285,000 lbs. of cultured hybrid Morone saxatilis were harvested (Maryland State Archives 1998).
References - Harrell et al. 1993; Harrell 1996 personal communication; Kerby et al. 1983; Maryland State Archives 1998; Nerrie and Reid 1992.
Economic Impacts Outside of Chesapeake Bay
Morone saxatilis X Morone chrysops (Palmetto Bass) is widely stocked as a gamefish, especially in the southeast U.S., and increasingly used in aquaculture (Harrell et al.1990). Gleason (1982) listed positive and negative features in considering possible introduction to CA. Benefits included: hardiness, rapid growth, control of forage fish populations especially Dorosoma petenense (Threadfin Shad), adding to diversity of sportfish in reservoirs, and an early 'spawning run' making them available at times when other fish are less active, and a low frequency of reproduction in wild (Gleason 1982).
Negative features reported by Gleason (1982) were: confusion with M. saxatilis (Striped Bass), affecting protection of that species; slow growth in absence of clupeid prey (Dorosoma petenense, threadfin shad); downstream migration from reservoirs; possible colonization of new river systems through marine migrations; predation or competition with salmonids; risks of reproduction, backcrossing or competition with M. saxatilis; possible surprises in the biology of a relatively 'new' and incompletely known fish. Gleason (1982) recommended caution in hybrid bass introductions. This hybrid has now been introduced to 35 states (Fuller et al. 1999).
References - Fuller et al. 1999; Gleason 1982; Harrell et al.1990
Ecological Impacts on Chesapeake Native Species
Morone saxatilis X Morone chrysops (Palmetto Bass) was widely introduced in the Chesapeake Bay watershed in the late 1970s and early 1980s, but stocking of hybrids has ceased in MD, VA, and PA (Harrell et al. 1993; Harrell 1996 personal communication). Occasional escapes from aquaculture operations are possible despite required precautions. It seems to be an increasingly accepted policy that hybrids should not be introduced into river systems with established Morone saxatilis (Striped Bass) populations (Gleason 1982; Harrell 1996 personal communication).
Competition - Competition with Morone saxatilis and Morone americana (White Perch) is likely but has not been documented.
Hybridization - These hybrids are fertile, and there is evidence of backcrossing with native M. saxatilis, suggesting possible introgression of M. chrysops genes into M. saxatilis populations. In Chesapeake Bay, 2% (2 of 99 fish examined) of identified hybrids were backcrosses. Backcrosses are probably between male hybrids and female M. saxatilis (Harrell et al. 1993). The frequency of F1 reproduction and backcrossing was also low (1%) in the Savannah river system, GA, but higher (up to 29%) in some southeastern reservoirs (Avise and van Den Avyle 1984; Forshage et al. 1986).
Eggs of Chesapeake M. saxatilis float, which probably aids survival and retention, while hybrid eggs sink.
Stocking in VA and MD tributaries has ceased (Harrell et al. 1993), and aquaculture of hybrid Morone spp. is regulated to minimize release of hybrids (Nerrie et al. 1993), so the frequency of hybrid fish as well as the probability of backcrossing is expected to decline (Harrell et al. 1993). Stocking of sterile triploids could reduce risk of genetic alteration of M. saxatilis stock (Kerby et al. 1990).
Predation- Morone saxatilis X M. chrysops hybrids, like their parent species are predators. However, their impacts would not be distinguishable from that of native M. saxatilis. Prey of hybrids in an OK reservoir included Dorosoma cepedianum (Gizzard Shad) and Menidia beryllina (Inland siverside), both native to Chesapeake Bay), (Gilliland and Clady 1981).
References - Avise and van Den Avyle 1984; Forshage et al. 1986; Gilliland and Clady 1981; Gleason 1982; Harrell et al. 1993; Harrell 1996 personal communication; Houde and Lubbers 1986
Ecological Impacts on Other Chesapeake Non-Native Species
Morone saxatilis X M. chrysops (Palmetto Bass) was widely introduced in the Chesapeake Bay watershed in the late 1970s and early 1980s, but stocking of hybrids has ceased in MD, VA, and PA (Harrell et al. 1993; Harrell 1996).
Competition- Some food overlap was observed between M. saxatilis X M. chrysops and adult Micropterus salmoides (Largemouth Bas), in Sooner Lake OK, but was considered not significant (Gilliland and Clady 1981).
Predation- Morone saxatilis X M. chrysops hybrids, like their parent species are predators. However, their impacts would not be distinguishable from that of native M. saxatilis. Prey in Sooner Lake included Lepomis spp.(Sunfish), probably species introduced in Chesapeake Bay) and Pomoxis spp. ('crappies'). 'The introduction of hybrids does not seem to affect largemouth bass or catfish fisheries' (Gleason 1982).
References - Gleason 1982; Gilliland and Clady 1982.
References
Avise, John C.; Van den Avyle, Michael J. (1984) Genetic analysis of reproduction of hybrid white bass X striped bass in the Savannah River, Transactions of the American Fisheries Society 113: 563-570Forshage, Allen A.; Harvey, William D.; Kulzer, Kathryn E.; Fries, Loraine T. (1986) Natural reproduction of white bass X striped bass hybrids in a Texas reservoir, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 40: 9-14
Fuller, Pam. L.; Nico, Leo; Williams, J. D. (1999) Nonindigenous fishes introduced into inland waters of the United States, , Bethesda MD. Pp.
Germann, Jerome F.; Bunch, Zan E. (1983) Age, growth, and survival of Morone hybrids in Clarks Hills Reservoir, Georgia, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 37: 267-275
Gilliland, Eugene R.; Clady, Michael D. (1981) Diet overlap of striped bass X white bass hybrids and largemouth bass in Sooner Lake, Oklahoma, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 35: 317-330
Gleason, Ellen V. (1982) A review of the life histories of striped bass (Morone saxatilis) and white bass (M. chrysops) hybrids and an evaluation of their suitablity for stocking, Inland Fisheries Adminstrative Report 82-9 , Sacramento, California. Pp.
Harrell, Reginal M. (1984) Tank spawning of first generation striped bass x white bass hybrids, Progressive Fish-Culturist 46: 75-78
Harrell, Reginal M.; Kerby, Jerome H.; Minton, Vernon R. (1990) Culture and propagation of Striped Bass and its hybrids, , Bethesda, MD. Pp.
Harrell, Reginal M.; Merritt, Donald W.; Hochheimer, John N.; Webster, Donald W.; Miller, Wallace D. (1988) Overwintering success of striped bass and hybrid striped bass held in cages in Maryland, Progressive Fish Culturist 50: 121-121
Harrell, Reginal M.; Xu, Xiao Lan; Ely, Bert (1993) Evidence of introgressive hybridization in Chespeake Bay Morone., Molecular Marine Biology and Biotechnology 2: 291-299
Houde, Edward D.; Lubbers, Lawrence III (1986) Survival and growth of striped bass, Morone saxatilis, and Morone hybrid larvae: laboratory and pond enclosure experiments, Fishery Bulletin 84: 905-914
Jenkins, Robert E.; Burkhead, Noel M. (1993) Freshwater fishes of Virginia., , Bethesda, MD. Pp.
Jenkins, Wallace E.; Smith, Theodore I. J. (1985) Natural and induced production of striped bass hybrids in tanks, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 39: 255-260
Kerby, Jerome H. (1979) Meristic characters of two Morone hybrids, Copeia 1979: 513-518
Kerby, Jerome H.; Burrell, V. G.; Richards, C. E. (1971) Occurrence and growth of striped bass x white bass hybrids in the Rappahannock River, Virginia, Transactions of the American Fisheries Society 100: 787-790
Kerby, Jerome H.; Woods, L. C., III; Huish, Melvin T. (1983) Culture of the striped bass and its hybrids: A review of methods, advances, and problems., In: Stickney, Robert R., and Meyers, Samuel P.(Eds.) Proceedings of the Warm-Water Fish-Culture Workshop. , Bethesda MD. Pp. 23-54
1998 Maryland aquaculture.. http://mdarchives.state.md.us.msa/mdmanual/01glance/html.aqua.html
Nerrie, Brian L.; Reid, Albert O. (1992) Aquaculture '92 'Growing Towards the 21st Century, , . Pp.
Page, Lawrence M.; Burr, Brooks M. (1991) Freshwater Fishes., , Boston. Pp.
Raasch, Maynard S.; Altemus, Vaughn L., Sr. (1991) Delaware's freshwater and brackish water fishes: a popular account, , Wilmingotn, Delaware. Pp.
Smith, Theodore I. J.; Jenkins, Wallace E.; Haggerty, Raymond W. (1986) Growth and survival of juvenile striped bass (Morone saxatilis) x white bass (M. chrysops) hybrids reared at different salinities., Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 40: 143-151
Susquehanna River Anadromous Fish Restoration Committee (1997) Restoration of American Shad to the Susquehanna River, , . Pp.
Wattendorf, Robert J.; Shafland, Paul L. (1982) Observations on salinity tolerance of striped bass X white bass hybrids in aquaria, Progressive Fish-Culturist 44: 148-149
Wirgin, I. I.; Maceda, L.; Mesing, C. (1992) Use of cellular oncogene probes to identify Morone hybrids, Journal of Heredity 83: 375-382
Yeager, David M. (1982) Ultrasonic telemetry of striped bass X white bass hybrids in the Escambia River, Florida, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 36: 62-73