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Status and Management of Mississippi River Fisheries - H.L. Schramm Jr.


U.S. Geological Survey, Mississippi Cooperative Fish and Wildlife Research Unit Mississippi State, Mississippi 39762 USA E-mail: hschramm atcfr.msstate.edu

ABSTRACT

The Mississippi River has been variously altered for navigation and flood control but supports a diverse and relatively productive fish assemblage. In the upper, impounded reach, commercial fish harvest has increased for most species since 1945. The upper reach provides an extensive and moderately used recreational fishery resource. Limited information for the lower, un-impounded reach of the Mississippi River indicates commercial harvest is increasing. Neither the commercial nor recreational fisheries appear to be over harvested; however, fisheries for sturgeon and paddlefish should be carefully monitored. Future fisheries production may be threatened by loss of aquatic habitat, altered spatial and temporal aspects of floodplain inundation and nuisance species invasions. Water quality in most reaches has improved substantially from formerly severely degraded conditions. Navigation traffic affects fish survival and recruitment and increases in navigation are forecast. Future conservation and management of the fisheries and aquatic resources of the Mississippi River will require substantial investment in effective assessment programs and achieving societal recognition of the diverse values of the resource.

INTRODUCTION

The Mississippi River is the largest river in North America. Its 3.25 million km2 watershed includes parts of two Canadian provinces and parts or all of 31 U.S. states (Figure 1). Daily discharge (measured in the lower river at Vicksburg, Mississippi) ranges from 3 568 to 55 558 m3 s-1 and averages 17 358 m3 s-1. The Mississippi and its major tributaries - the Arkansas, Illinois, Missouri and Ohio rivers - have been central to the social and economic development of the United States. As a major transportation corridor, the river has been greatly altered for navigation and by developments in its watershed and floodplain for agriculture, industry and urbanization. Comprehensive treatments of the historic and present conditions in the Mississippi River are provided in Scarpino (1985); Fremling et al. (1989); Baker, Killgore and Kasul (1991); Rasmussen (1994); Weiner et al. (1998); U.S. Geological Survey (1999) and Fremling and Drazkowski (2000).

Figure 1. Mississippi River basin and Mississippi River. Mississippi River basin figure from Meade (1995).

Ten thousand years ago, the Mississippi River was a continuum typical of a floodplain river. Beginning as a small stream in the forested headwaters of Lake Itasca, Minnesota, the river flowed through virgin forests and unbroken prairie to its deltaic outlet into the Gulf of Mexico in Louisiana. From headwaters to the mouth, the river increased in size and discharge and decreased in slope. Initially, the young river flowed through a small valley bordered by wetlands and lakes. Along its downstream course, the river changed from a single to a braided channel in its mid-reaches and finally to a meandering, constantly changing channel downstream. Its valley changed rather steadily from a narrow floodplain flanked by tall bluffs upstream to a vast, flat floodplain downstream.

In its present form, the Mississippi River changes dramatically and rather incrementally along its 3 731 km journey from headwaters to the Gulf of Mexico. The headwaters reach, the upper 824 km from Lake Itasca to St. Anthony Falls, Minnesota, flows alternately through forests and wetlands. Dams have been built to form 11 small reservoirs and modify the elevation and discharge of several natural river lakes. These dams variously function for flood control, electric generation, water supply, or recreation.

The Upper Mississippi River (UMR) reach stretches 1 075 km from St. Anthony Falls to Alton, Illinois, a few km above the confluence with the Missouri River[28]. The UMR is impounded by 28 locks and dams built for commercial navigation and one dam (Keokuk, Iowa) built for navigation and hydropower generation. These dams are operated to maintain minimum navigation channel depth (9 feet, 2.7 m); thus, the dams have little effect on the river stage and discharge during spring floods. The dams, however, have increased the river elevation throughout the annual cycle (Figure 2). The timing and relative increase during the spring rise resembles the pre-dam condition, but the natural summer drawdown and the autumn rise are missing. Throughout the UMR, the dams have increased the area of aquatic habitat at low-water river stage from 971 km2 before dams to 1 495 km2 after dam construction, essentially permanently inundating 23 percent of historic wetlands and seasonally inundated floodplain (49 km2 of marsh and 820 km2 of floodplains; J. Rogala, U.S. Geological Survey, unpublished data). Navigation channel depth and alignment in the open river is maintained by wing dykes[29], closing dykes[30], bank revetment[31] and dredging. Most of these structures are remnants of the former channel before impoundment, but some are new and many require routine maintenance. The navigation channel retains substantial flow even during low river stages; however, flows through aquatic habitats lateral to the navigation channel are greatly reduced resulting in off-channel sedimentation, stagnation and deep-water habitat loss. Because the dams, to maintain a minimum navigation depth, dampen drawdown, less floodplain is exposed during lower-flow periods and less floodplain area is inundated during the annual spring rise. In the lower third of the UMR, the natural bluffs flanking the floodplain diminish and the floodplain expands laterally. Here, levees and railroad embankments have been built relatively close to the riverbank to contain floodwaters and reclaim fertile bottomlands for agriculture, reducing the floodplain to a fraction of its former area.

Figure 2. Average stage at Upper Mississippi River Lock and Dam 15 tailwaters, Rock Island, Illinois. 1900-1925 is pre-impoundment; 1940-2002 is post-impoundment.

Downstream from the confluence of the Missouri River, the Mississippi flows un-dammed for 1 834 km to Head of Passes where it branches into several distributaries that carry water to the Gulf of Mexico. The 314 km reach from the mouth of the Missouri River to the mouth of the Ohio River is referred to as the Middle Mississippi River (MMR) by management agencies. Flows from the Missouri River almost double the volume of water flowing through the MMR (Meade 1995). The 1 570 km reach from the Ohio River to Head of Passes is referred to as the Lower Mississippi River (LMR). Water from the Ohio River increases Mississippi River discharge 150 percent (Meade 1995). Although discharge and channel size differ between the two reaches, both share similar hydrologic conditions, methods and levels of channelization and loss of connectivity with the historic floodplain. Thus, I will refer to the MMR and LMR collectively as the Aopen River reach. The MMR fluctuates an average of 4 m throughout the year (Figure 3), while the LMR, influenced by Ohio River discharge (60 percent of LMR discharge), fluctuates an average of almost 10 m (Figure 4). Nevertheless, hydrographs of the two reaches are similar. As in the UMR, the U.S. Army Corps of Engineers is mandated to maintain a 9-feet (2.7 m) deep, 300-feet (91 m) wide navigation channel in the open river reach. To maintain access to harbours and cargo ports and to preserve waterfront developments, it is also necessary to maintain current channel alignment. Navigation channel depth and alignment in the open river is maintained by wing dykes, closing dykes, bank revetment and dredging. Historically, the open river reach had a seasonally inundated (active) floodplain that extended from several to almost 200 km from the riverbank. A continuous (except for breaks at tributary river mouths) levee system lining both banks of the MMR and LMR was completed after the record 1927 flood and has severed the floodplain from the river. In the MMR, levees have reduced the active floodplain (the portion inundated by the spring flood pulse) by 50 percent (Duyvejonck 2002). Throughout the 1 000 km LMR, the levees have severed connection of the river from 90 percent of its historic 103 000 km2 floodplain.

Figure 3. Average stage in the Middle Mississippi River, Chester, Illinois. 1900-1925 is before mainline levee construction; 1940-2002 is after mainline levee construction.

Classification of river reaches based on the form and consequences of anthropogenic perturbations is convenient, even desirable, from both ecological and management perspectives. The ecological structure and function of the headwaters, UMR and open river segments are expected to differ and these differences should influence assessment and research questions. Similarly, management goals and strategies are expected to differ among reaches. However, it also is important to recognize that each reach represents a continuum as the river traverses a latitudinal gradient, grows with each added tributary and the amount of floodplain increases (Schramm, Eggleton and Minnis 1999).

FISHERIES HABITAT

Several ecological classification schemes have been developed to delineate and define the diversity of Mississippi River habitats (e.g. Sternberg 1971; Cobb and Clark 1981; Baker et al. 1991; Wilcox 1993). Although illuminating habitat diversity, defining the different habitats and providing a foundation for effective fisheries and habitat assessment (e.g. stratified sampling), the classification systems are neither uniform, nor necessarily applicable, throughout the entire Mississippi River. For example, a widely used classification for the UMR recognizes main channel, channel border (which can be a very extensive habitat in the lower portions of the navigation impoundments), slough (side channels with current) and backwater lake habitats (Sternberg 1971; Rasmussen 1979). A second scheme developed for the UMR by Wilcox (1993) lists 44 different aquatic habitats. In addition to physical location, Wilcox uses other parameters (i.e. depth, current velocity and turbulence, water temperature, dissolved oxygen, suspended solids, light, substrate type and cover type) to further define aquatic habitats. A classification scheme developed for the LMR recognizes channel, natural and revetted banks, lentic and lotic sandbars, two types of abandoned channels and three types of floodplain lakes or ponds (Baker et al. 1991). Undoubtedly, habitat diversity was greater prior to channelization and impoundment. Nevertheless, if only diversity of current velocity (up to 3 m s-1), substrate, depth (up to 40 m) and aquatic vegetation (head-waters and UMR only) conditions are considered, the Mississippi River, even in its altered state, provides diverse fish habitats. Water level fluctuations further increase habitat diversity as rises transform some lentic habitats to lotic and terrestrial habitats become diverse, complex aquatic habitats.

Figure 4. Average stage in the Lower Mississippi River, Vicksburg, Mississippi. 1900-1925 is before mainline levee and cutoff construction; 1940-2002 is after mainline levee and cutoff construction. Horizontal dashed line is bank full stage, the stage at which floodplain inundation begins.

Baker et al. (1991) used multivariate analyses to delineate habitats. Although a progressive and promising approach, the results of such analyses are constrained by inability to measure habitat conditions (e.g. current direction and velocity are usually measured near the surface), by selectivity of fish sampling gear and by temporal fluctuations in river stage and discharge. Although Baker et al. (1991) described their resulting habitat delineations as microhabitats, the inherent variability in river conditions over a spatial scale greater than several meters precludes considering a habitat even as homogeneous as a sand bar as a single microhabitat. Further, habitat use changes over time as both river conditions and biological requirements follow their seasonal chronology. In the LMR, the abundance of several fishes at steep natural banks (a microhabitat listed by Baker et al. 1991) varied significantly when current velocity was reduced, suggesting a single variable changing over time can determine habitat suitability for a species (Schramm et al. 1998; Schramm et al. 1999). Conversely, changes at the macroscopic level also can affect fish abundance. The abundance of fishes collected in a sandbar habitat changed significantly following hydraulic changes in the adjacent channel, even though the physical conditions of the areas sampled remained similar over time (Schramm et al. 1999).

FISHERIES RESOURCES

As would be expected for a river that grows from a first to a tenth or eleventh order stream (Strahler 1952) and flows more than 3 500 km from its origin in a cool temperate climate to its subtropical outlet, the Mississippi River supports a rich fish assemblage. In their comprehensive assessment, Fremling et al. (1989) list 193 freshwater species in 27 families for the Mississippi River. Although no thorough ichthyofaunal surveys have been conducted in at least the past 30 years, additional inventories have been compiled since 1989 (Baker et al. 1991; Pitlo, Van Vooren and Rasmussen 1995; Warren, Burr, Walsh et al. 2000). Table 1 is offered as a current assessment of Mississippi River fishes. The table includes those species reported by Fremling et al. (1989); Baker et al. (1991); Pitlo et al. (1995) and Warren et al. (2000) and has been reviewed by six ichthyologists familiar with Mississippi River fauna (Table 1). Excluded from the table are fishes considered strays (i.e. fishes likely from a tributary or from stocking) by Fremling et al. (1989) and Pitlo et al. (1995) and marine species collected only in the lower 150 km of the river. Information from the published papers and reports cited elsewhere in this paper was supplemented with synoptic life history information available in Carlander (1969, 1977, 1997); Pflieger (1975); Becker (1983); Robison and Buchanan (1988); Etnier and Starnes (1993); Mettee, O’Neil and Pierson (1966) and Ross (2001) to qualitatively designate habitat zones each species is likely to occupy and to classify it as backwater dependent, riverine dependent, or peripheral. Limited and inconsistent information precluded the use of quantitative classification procedures. Given the lack of a standardized habitat classification, the insufficiency of data for a microhabitat approach (sensu Baker et al. 1991) and the paucity of information about habitat requirements, preferences and tolerances of even some of the common Mississippi River fishes, I have assigned each species to one or more of three habitat zones: main channel[32], channel border[33] and backwater[34]. Fishes are considered backwater dependent if they require conditions such as no current, soft-sediment bottom, or aquatic or inundated terrestrial vegetation during at least some portion of their life cycle. Although usually present in a variety of habitats in the backwater zone, these conditions may also be found in isolated areas of the channel border zone. Riverine-dependent fishes are those that require flowing water and sand, gravel, or rock substrate during at least some portion of their life cycle; these conditions may be found in the main channel or channel border zones. A species is considered peripheral to the Mississippi River if available life history information indicates that the species inhabits tributary rivers or streams, prefers small rivers or streams, or avoids or is rare in large rivers. All designations of habitat zone and dependency are specific to the reach of the Mississippi River where the species occurs; for example a shallow, riffle-dwelling species may occupy the main channel in the upper headwaters reach but may be restricted to the channel border in the UMR or open river reaches.

Excluding marine, diadromous and peripheral species and species not recently collected (hereafter, resident species), 140 species are resident in the Mississippi River; 4 of these species are introduced. Sixty-one species are resident in the Headwaters, 107 species in the UMR and 109 species in the open river. Sufficient evidence was available to consider 55 resident species backwater dependent and 17 resident species riverine dependent. Of the 137 resident species I was able to assign to habitat zones, none are expected to reside in main channel habitats throughout their life cycle, 24 are expected to occupy one or more channel border habitats throughout their life cycle and 50 species are expected to reside in one or more backwater habitats throughout their life cycle. A substantial number of fish were considered rare by Fremling et al. (1989) or Baker et al. (1991). Including fish not recently collected (Fremling et al. 1989), 23 resident species are rare in the Headwaters, 24 species are rare in the UMR and 24 species are rare in the open river.

Fish production has not been estimated and biomass estimates are limited. Individual estimates are highly variable but tend to range from 300-900 kg ha-1 (Table 2). Standing stocks appear greater in the LMR than in the UMR, but comparability may be limited by habitat differences. Standing stock in UMR backwaters, sloughs and side channels was 38 percent commercial species (excluding catfishes), 30 percent gizzard shad, 14 percent panfish (white bass, sunfishes, crappies, yellow perch) and 5 percent catfishes (Pitlo 1987). Pitlo (1987) found no longitudinal or temporal trends in total fish biomass but noted decreases in catfish and predator fish and increases in shad and pan-fishes over time. In the LMR backwaters, gizzard shad were 44 percent of the biomass, common carp 15 percent, freshwater drum 7 percent, bigmouth buffalo 6 percent and threadfin shad 5 percent of the total biomass; collectively, commercial species were 34 percent of the biomass and sport fishes were 10 percent (Lowery et al. 1987). Levee borrow pits contained an average of 688 kg ha-1; shads and buffalo fishes dominated the catch (Cobb et al. 1984). Lentic dyke pools can contain over 3 800 kg ha-1 of fish and larger pools average over 2 000 kg ha-1 (Baker et al. 1991). The high biomass is primarily from abundant shads and occasionally large numbers of buffalo fishes, catfishes, crappies, gars and white bass (Nailon and Pennington 1984; Baker et al. 1991). Nailon and Pennington (1984) noted substantial differences between lentic and lotic dyke pools, the latter supporting more blue sucker, blue catfish and flathead catfish.

Table 1: Distribution and abundance of fishes in the headwaters (HW), upper (UMR), or open river (OR) segments of the Mississippi River. Fish are resident in the Mississippi River unless noted otherwise (Residence). Data were compiled from Fremling et al. (1989), Baker et al. (1991), Pitlo et al. (1995), and Warren et al. (2000). Fish categorized as strays by Fremling et al. (1989) and marine fishes collected only in the lower 150 km of the Mississippi River are excluded. Backwater dependent or riverine dependent indicates those taxa that are dependent on backwater or riverine conditions to complete their life cycle. Probable zone is the area of the river from which the fish have been or are likely to be collected.

Modified from Pitlo et al. 1995, Schlicht, Diederman, Bartels

Family species

Residence1

HW2

UMR2

OR2

Back water dependent

Riverine dependent

Probable zone3

Petromyzontidae








Chestnut lamprey, Ichthyomyzon castaneus (Girard)



O/U

O/R



MC, CB

Silver lamprey, Ichthyomyzon unicuspis (Hubbs and Trautman)



O

R



MC, CB

American brook lamprey, Lampetra appendix (DeKay)



R




MC, CB, BW

Ascipenseridae








Lake sturgeon, Acipenser fulvescens (Rafinesque)



O4

R4


Yes

MC, CB

Atlantic sturgeon, Acipenser oxyrhynchus (Mitchill)

D



R5



MC, CB

Pallid sturgeon, Scaphirhynchus albus (Forbes and Richardson)



R

O


Yes

MC, CB

Shovelnose sturgeon, Scaphirhynchus platorynchus (Rafinesque)



O

O


Yes

MC, CB

Polyodontidae








Paddlefish, Polyodon spathula (Walbaum)



O

O


Yes

MC, CB, BW

Lepisosteidae








Alligator gar, Atractosteus
spatula
(Lacepede)




R

Yes


BW

Spotted gar, Lepisosteus
oculatus
(Winchell)



U

O

Yes


BW

Longnose gar, Lepisosteus osseus (Linnaeus)



O

C

Yes


MC, CB, BW

Shortnose gar, Lepisosteus platostomus (Rafinesque)


H1

C

C

Yes


MC, CB, BW

Amiidae








Bowfin, Amia calva (Linnaeus)


R

C

O

Yes


BW

Anguillidae








American eel, Anguilla rostrata (Lesueur)

D

R

O

U



CB

Hiodontidae








Goldeye, Hiodon alosoides (Rafinesque)



U

O



CB

Mooneye, Hiodon tergisus (Lesueur)



O

U/R



CB

Clupeidae








Alabama shad, Alosa alabamae (Jordan and Everman)

D



R



MC, CB

Skipjack herring, Alosa chrysochloris (Rafinesque)



O/R

C



MC, CB, BW

Gizzard shad, Dorosoma cepedianum (Lesueur)


A

A

A

Yes


MC, CB, BW

Threadfin shad, Dorosoma petenense (Günther)



U

A

Yes


CB, BW

Salmonidae








Cisco, Coregonus artedi (Lesueur)


R

R




BW

Umbridae








Central mudminnow, Umbra limi (Kirtland)


U

O


Yes


BW

Esocidae








Grass pickerel, Esox americanus vermiculatus (Lesueur)



R

R

Yes


BW

Northern pike, Esox lucius (Linnaeus)


O

O


Yes


BW

Muskellunge, Esox masquinongy (Mitchill)


O/U



Yes


BW

Chain pickerel, Esox niger (Lesueur)




R5

Yes


BW

Cyprinidae








Central stoneroller, Campostoma anomalum (Rafinesque)


R

R

H26



MC, CB

Goldfish, Carassius auratus (Linnaeus)

I


U

R

Yes


BW

Grass carp, Ctenopharyngodon idella (Valenciennes)

I


U

U


Yes

MC, CB, BW

Bluntface shiner, Cyprinella camura (Jordan and Meek)

P



H2



CB

Red shiner, Cyprinella lutrensis (Baird and Girard)



O

C/O

Yes


CB, BW

Spotfin shiner, Cyprinella spiloptera (Cope)


C

C

R



CB, BW

Blacktail shiner, Cyprinella venusta (Girard)




O



CB, BW

Steelcolor shiner, Cyprinella whipplei (Girard)

P



R



CB, BW

Common carp, Cyprinus carpio (Linnaeus)

I

C

A

C

Yes


CB, BW

Gravel chub, Erimystax x-punctatus (Hubbs and Crowe)




R



CB, BW

Western silvery minnow, Hybognathus argyritis (Girard)




R



BW

Brassy minnow, Hybognathus hankinsoni (Hubbs)


U

R




CB

Cypress minnow, Hybognathus hayi (Jordan)




R

Yes


BW

Mississippi silvery minnow, Hybognathus nuchalis (Agassiz)



U/R

O

Yes


CB, BW

Plains minnow, Hybognathus placitus (Girard)




U/R


Yes

MC, CB

Clear chub, Hybopsis winchelli (Girard)




R5



CB

Silver carp, Hypophthalmichthys molitrix (Valenciennes)

I


C/O

C



CB

Bighead carp, Hypophthalmichthys nobilis (Richardson)

I


O

O



CB

Striped shiner, Luxilus chrysocephalus (Rafinesque)

P



R



CB

Common shiner, Luxilus cornutus (Mitchill)


C

O/R




MC, CB, BW

Ribbon shiner, Lythrurus fumeus (Evermann)

P



R



BW

Redfin shiner, Lythrurus umbratilis (Girard)

P


R

H2



CB, BW

Speckled chub, Macrhybopsis aestivalis (Girard)



O

C



CB

Sturgeon chub, Macrhybopsis gelida (Girard)




U/R



CB

Sicklefin chub, Macrhybopsis meeki (Jordan and Everman)




U/R



CB

Silver chub, Macrhybopsis storeriana (Kirtland)



C/O

C/O



CB, BW

Pearl dace, Margariscus margarita (Cope)


R





MC, CB, BW

Black carp, Mylopharyngodom piceus (Richardson)

I



R



CB, BW

Hornyhead chub, Nocomis biguttatus (Kirtland)


O

R




CB

Golden shiner, Notemigonus crysoleucas (Mitchill)


O

C/O

U

Yes


BW

Pallid shiner, Notropis amnis (Hubbs and Greene)



R




CB

Emerald shiner, Notropis atherinoides (Rafinesque)


A

A

A



CB, BW

River shiner, Notropis blennius (Girard)



C

C



CB, BW

Bigeye shiner, Notropis boops (Gilbert)

P



R



CB

Ghost shiner, Notropis buchanani (Meek)



R

U/R

Yes


CB, BW

Bigmouth shiner, Notropis dorsalis (Agassiz)


P

O

O/R

R


CB

Blackchin shiner, Notropis heterodon (Cope)


U

O/R


Yes


BW

Blacknose shiner, Notropis heterolepis (Eigenmann and Eigenmann)


U

R




BW

Spottail shiner, Notropis hudsonius (Clinton)


U

U

R



CB

Longnose shiner, Notropis longirostris (Hay)




U5


Yes

MC, CB

Ozark minnow, Notropis nubilus (Forbes)

P


R

R



CB

Chub shiner, Notropis potteri (Hubbs and Bonham)




R



CB

Rosyface shiner, Notropis rubellus (Agassiz)

P


R




CB

Silverband shiner, Notropis shumardi (Girard)



R

O



CB, BW

Sand shiner, Notropis
stramineus
(Cope)

P

R

O

U5



CB

Weed shiner, Notropis texanus (Girard)



O

U

Yes


BW

Mimic shiner, Notropis volucellus (Cope)


R

C

O



CB, BW

Channel shiner, Notropis wickliffi (Trautman)



C/O

O



MC, CB

Pugnose minnow, Opsopoeodus emiliae (Hay)



O

O

Yes


BW

Suckermouth minnow, Phenacobius mirabilis (Girard)



R

R



CB, BW

Northern redbelly dace, Phoxinus eos (Cope)


C





CB

Southern redbelly dace, Phoxinus erythrogaster (Rafinesque)


P


H1

H2


CB

Finescale dace, Phoxinus neogaeus (Cope)


R





CB, BW

Bluntnose minnow, Pimephales notatus (Rafinesque)


P

O

O

U


BW

Fathead minnow, Pimephales promelas


C/U

U

R

Yes


BW

Rafinesque








Bullhead minnow, Pimephales vigilax (Baird and Girard)


R

O

O

Yes


BW

Flathead chub, Platygobio gracilis gracilis (Richardson)




R


Yes

CB

Eastern blacknose dace, Rhinichthys atratulus (Hermann)

P

U

R



Yes

CB

Longnose dace, Rhinichthys cataractae (Valenciennes)


C/O

R



Yes

CB

Creek chub, Semotilus atromaculatus (Mitchill)


O

R



Yes

MC, CB

Catostomidae








River carpsucker, Carpiodes carpio (Rafinesque)



C

A


Yes

CB, BW

Quillback, Carpiodes cyprinus (Lesueur)


R

C

U



CB, BW

Highfin carpsucker, Carpiodes velifer (Rafinesque)



O/U

R



CB, BW

White sucker, Catostomus commersoni (Lacepüde)


C

C




MC, CB, BW

Blue sucker, Cycleptus elongatus (Lesueur)



O

O


Yes

MC, CB

Creek chubsucker, Erimyzon oblongus (Mitchill)




U



BW

Lake chubsucker, Erimyzon succetta (Lacepüde)




U



BW

Northern hog sucker,
Hypentelium nigricans (Lesueur)


O

R




CB

Smallmouth buffalo, Ictiobus bubalus (Rafinesque)



C/O

A/C

Yes


MC, CB, BW

Bigmouth buffalo, Ictiobus cyprinellus (Valenciennes)


O

C

C/O

Yes


CB, BW

Black buffalo, Ictiobus niger (Rafinesque)



U/R

U

Yes


CB, BW

Spotted sucker, Minytrema melanops (Rafinesque)



C/O

U/R5

Yes


CB, BW

Silver redhorse, Moxostoma anisurum (Rafinesque)


O

C/O

H2



CB, BW

River redhorse, Moxostoma carinatum (Cope)



O/R

R



CB

Golden redhorse, Moxostoma erythrurum (Rafinesque)



O




MC, CB

Shorthead redhorse, Moxostoma macrole


C

C/O

U7



MC, CB

pidotum (Lesueur)








Greater redhorse, Moxostoma valenciennesi (Jordan)


O

R



Yes

MC, CB, BW

Ictaluridae








White catfish, Ameiurus catus (Linnaeus)

P



H3




Black bullhead, Ameiurus melas (Rafinesque)


R

O

U

Yes


BW

Yellow bullhead, Ameiurus natalis (Lesueur)


R

O

U

Yes


BW

Brown bullhead, Ameiurus nebulosus (Lesueur)


R

O


Yes


BW

Blue catfish, Ictalurus furcatus (Lesueur)



O

A



MC, CB

Channel catfish, Ictalurus punctatus (Rafinesque)


O

C

C



CB, BW

Mountain madtom, Noturus eleutherus (Jordan)




H1


Yes

CB

Stonecat, Noturus flavus (Rafinesque)


R

R

O


Yes

CB

Tadpole madtom, Noturus gyrinus (Mitchill)


R

O

U/R

Yes


BW

Freckled madtom, Noturus nocturnus (Jordan and Gilbert)



R

O/U



BW

Northern madtom, Noturus stigmosus (Taylor)




H2



CB, BW

Flathead catfish, Pylodictis olivaris (Rafinesque)


R

C/O

A



MC, CB

Aphredoderidae








Western pirate perch, Aphredoderus sayanus (Gilliams)



R

R

Yes


BW

Percopsidae








Trout-perch, Percopsis omiscomaycus (Walbaum)


O

O


Yes


BW

Gadidae








Burbot, Lota lota (Linnaeus)


O

R




CB, BW

Fundulidae








Golden topminnow, Fundulus chrysotus (Günther)

P



R

Yes


BW

Banded killifish, Fundulus diaphanus (Le Sueur)


R

H1





Starhead topminnow, Fundulus dispar (Agassiz)

P


R

R



BW

Blackstripe topminnow, Fundulus notatus (Rafinesque)



O

O

Yes


BW

Blackspotted topminnow,
Fundulus olivaceus (Storer)




O

Yes


BW

Poeciliidae








Western mosquitofish, Gambusia affinis (Baird and Girard)



O

O

Yes


BW

Atherinidae








Brook silverside, Labidesthes sicculus (Cope)


O

C/O

C/O



BW

Inland silverside, Menidia
beryllina
(Cope)




O



CB, BW

Gasterosteidae








Brook stickleback, Culaea inconstans (Kirtland)


R

R




MC, CB

Cottidae








Mottled sculpin, Cottus bairdi (Girard)


R






Percichthyidae








White bass, Morone chrysops (Rafinesque)


R

C

C



CB, BW

Yellow bass, Morone mississippiensis (Jordan and Everman)



R/O

O



BW

Striped bass, Morone saxatilis (Walbaum)7

D



O



MC, CB

Centrarchidae








Rock bass, Ambloplites rupestris (Rafinesque)


C

C/O


Yes


BW

Shadow bass, Ambloplites arriomus (Viosca)

P



U5



BW

Flier, Centrarchus macropterus (Lacepüde)




O

Yes


BW

Banded pygmy sunfish,
Elassoma zonatum (Jordan)




R5

Yes


BW

Green sunfish, Lepomis
cyanellus
(Rafinesque)


R

C/O

U

Yes


BW

Pumpkinseed, Lepomis gibbosus (Linnaeus)


R

C/O


Yes


BW

Warmouth, Lepomis gulosus (Cuvier)



O/U

C/O

Yes


BW

Orangespotted sunfish Lepomis humilis (Girard)



O

O

Yes


BW

Bluegill, Lepomis macrochirus (Rafinesque)


O

A

C

Yes


BW

Longear sunfish, Lepomis megalotis (Rafinesque)




U

Yes


BW

Redear sunfish, Lepomis microlophus (Günther)




U

Yes


BW

Bantam sunfish, Lepomis symmetricus (Forbes)




O5

Yes


BW

Smallmouth bass, Micropterus dolomieu (Lacepüde)


C

O




CB, BW

Spotted bass, Micropterus punctulatus (Rafinesque)

P



R



CB, BW

Largemouth bass, Micropterus salmoides (Lacepüde)


O

C

C

Yes


BW

White crappie, Pomoxis
annularis
(Rafinesque)


R

C

C

Yes


BW

Black crappie, Pomoxis nigromaculatus (Lesueur)


O

C

O/U

Yes


BW

Percidae








Western sand darter, Ammocrypta clara (Jordan and Meek)

P


O

R


Yes

CB, BW

Crystal darter, Crystallaria asprella (Jordan)

P


R

R


Yes

CB

Mud darter, Etheostoma asprigene (Forbes)



O/R

O



BW

Rainbow darter, Etheostoma caeruleum (Storer)

P


R

R



CB

Bluntnose darter, Etheostoma chlorosoma (Hay)



R

U



BW

Iowa darter, Etheostoma exile



R





Fantail darter, Etheostoma flabellare (Rafinesque)

P


R



Yes

CB

Swamp darter, Etheostoma fusiforme (Girard)




U5

Yes


BW

Slough darter, Etheostoma
gracile
(Girard)




U



BW

Johnny darter, Etheostoma nigrum Rafinesque


O

O

R5



CB, BW

Cypress darter, Etheostoma proeliare (Hay)

P



O5



BW

Missouri saddled darter, Etheostoma te trazonum (Hubbs and Black)

P



R5




Banded darter, Etheostoma zonale (Cope)

P


R





Yellow perch, Perca flavescens (Mitchill)


O

C/O


Yes


CB, BW

Log perch, Percina caprodes (Rafinesque)


O

C/O

R5

Yes


CB, BW

Gilt darter, Percina evides (Jordan and Copeland)

P


H1




CB

Blackside darter, Percina maculata (Girard)


C

R





Saddleback darter, Percina vigil (Hay)




U



CB

Slenderhead darter, Percina phoxocephala (Nelson)



R

R5



CB

River darter, Percina shumardi (Girard)



O

O/U



CB

Sauger, Stizostedion canadense (Smith)


R

C

O



CB

Walleye, Stizostedion vitreum (Mitchill)


O

C

U/R



CB, BW

Sciaenidae








Freshwater drum, Aplodinotus grunniens (Rafinesque)


R

A

A


Yes

CB, BW

Mugilidae








Striped mullet, Mugil cephalus (Linnaeus)

M



O



CB

1 Db diadromous, Ib introduced, Mb marine, PB peripheral, typically occupies tributary streams and rivers but may temporarily enter the Mississippi River.

2 AB abundantly taken in all river surveys. CB commonly taken in most surveys. OB occasionally collected; not generally distributed but local concentrations may occur. UB Uncommon, does not usually appear in survey samples. RB Considered rare. H1B Taxon has been collected in the Mississippi River but no records of collection since 1978 (Fremling et al. 1989). H2B Taxon reported as present by Warren et al. (2000) but abundance not known. H3B Taxon presumed by Warren et al. (2000) to be present but not verified by collection records.

3 MCB main channel CBB channel border BWB backwater.

4 Occasional occurrence in UMR; rare occurrence in OR attributed to stocking.

5 Not listed as present in the open-river reach of the Mississippi River by Warren et al. 2000.

6 Warren et al. (2000) list Mississippi stoneroller (C. a. pullum) as present in the open-river reach of the Mississippi River.

7 Warren et al. (2000) list pealip redhorse (M. m. pisolabrum) as present in the open-river reach of the Mississippi River.

5 The Gulf Coast strain striped bass is native to the Mississippi River. Atlantic Coast strain striped bass have been introduced into numerous impoundments in the Mississippi River basin. Escapees from these introductions have colonized the Mississippi River and likely contribute to occasional collections of striped bass in the UMR and open river.

Fish biomass is usually estimated by recovery of fish after toxicant application; hence, biomass estimation is typically limited to lentic waters where toxicants can be confined. However, Rasmussen, Pitlo and van Vooren (1985) and Pitlo (1987) obtained high biomass in channel border habitats using primacord (explosives), suggesting promise for this method. If fish recovery from primacord sampling can be assumed equivalent to that from rotenone sampling, channel borders support fish biomasses similar to backwaters. Non-ictalurid commercial fishes averaged 73 percent, catfishes 20 percent and gizzard shad 6 percent of the biomass (Pitlo 1987). Dettmers et al. (2001) estimated biomass of benthic fishes in the main channel in the UMR (Pool 26) using trawls. Although the biomass estimates are low (and probably conservative), the trawl caught a wide variety of species and sizes. Hydroacoustic sampling indicated moderate to high densities of fish in LMR main channel and channel border habitats (Baker et al. 1988a, 1988b), with densities in the main channel lower than along banks or in dyke pools (Baker et al. 1987; Baker et al. 1988a, 1988b). Many of the main channel and channel border fish were small (3-30 cm) and the fish were distributed throughout the water column in some areas.


[28] Terminology for different reaches of the Mississippi River is not uniform among different management agencies. For example, the Upper Mississippi River Conservation Committee defines the UMR as the reach of the Mississippi River from St. Anthony Falls, Minnesota, to the confluence with the Ohio River at Cairo, Illinois. The terminology adopted in this paper was chosen for its ecological utility.
[29] Wing dikes are large rock riprap structures that extend from the shore into the main channel. The surface elevation of most dikes is 2-3 m above low water elevation in the MMR and LMR. In the UMR, dikes constructed before impoundment remain in place and, for the most part, remain at or below normal navigation pool surface elevation. The dikes are placed to divert the flow of water, thereby both controlling the path of the main channel and directing the energy to scour the navigation channel. Usually multiple dikes are placed in a longitudinal series, with shorter dikes upstream; these groups of three or more dikes are called dike fields.
[30] Closing dikes, like wing dikes, are large rock riprap structures placed to block or reduce flow to a secondary channel or backwater, thereby increasing flow in the main channel. The main channel contains the thalweg and is used for navigation. Secondary channels are former main channels or channels created when the flow of the river cuts across a point bar forming a new channel. Dike fields often are used to close secondary channels and backwaters.
[31] Revetments are installed on high energy banks to armor the river bank against erosion. Although various materials have been used in the past, present-day revetments consist of large (>0.3 m) rock riprap or, in the LMR, articulated concrete mattress (concrete slabs approximately 30 cm x 70 cm x 7 cm thick connected by stainless steel wire) for lower bank (from 1-3 m above low water elevation to the toe of the channel) protection and large rock riprap for upper bank protection.
[32] Main channel is the portion of the river that contains the thalweg and the navigation channel; water is relatively deep and the current, although varying temporally and spatially, is persistent and relatively strong.
[33] Channel border is the zone from the main channel to the riverbank. Current velocity and depth will vary, generally decreasing with distance from the main channel, but the channel border is a zone of slower current, shallower water, and greater habitat heterogeneity. Channel border includes secondary channels and sloughs, islands and their associated sandbars, dikes and dike pools, and natural and revetted banks of other authors.
[34] The backwater zone includes lentic habitats lateral to the channel border that are connected to the river at least for some time in most years. This zone includes abandoned channels (including floodplain lakes) severed from the river at the upstream or both ends, lakes lateral to the channel border, ephemeral floodplain ponds, borrow pits created when levees were built, and the floodplain itself during overbank stages.

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