Historical Changes in Large River Fish Assemblages of the Americas

<em>Abstract.</em>—The present ichthyofauna (1965–2001) of the Wabash River system is compared to that of three periods: presettlement through 1820, 1875–1900, and 1940– 1950. This second largest Ohio River tributary flows freely for 350 mi. However, its environment and watershed have been altered greatly from presettlement times; twothirds has been converted to agriculture, eliminating all prairies and most forests and wetlands. Canals, large and small dams, channelization, and effluents have extinguished 12 fish species, diminished some, and favored others. Thirteen of approximately 175 species are recent, including 3 aliens. Better municipal and industrial waste treatment has improved water quality, but excessive agricultural runoff remains detrimental to many fishes. Degraded habitats exacerbate these problems. Many sensitive species are today either absent or severely reduced in distribution and abundance compared to 50 years ago. Smallmouth bass <em>Micropterus dolomieu </em>has been replaced by largemouth bass <em>M. salmoides </em>or spotted bass <em>M. punctulatus, </em>and few visual piscivores occur except near reservoirs.

<em>Abstract.</em>—The Ohio River Valley Water Sanitation Commission (ORSANCO), along with cooperating state and federal agencies, sampled fish assemblages from the lockchambers of Ohio River navigational dams from 1957 to 2001. To date, 377 lockchamber rotenone events have been conducted, resulting in the collection of nearly three million fishes, representing 116 taxa, including 7 hybrids, in 19 families. We observed significant temporal trends in Ohio River fish riverwide at the assemblage, guild, and species levels. Modified index of well-being (MIWB) scores and changes in guild structure indicated significantly (<em>p </em>< 0.05) improving fish assemblages throughout the Ohio River. Quantile regression of the abundance of individual species by year revealed significant declines (<em>p </em>< 0.05) in populations of several pollution-tolerant species (e.g., <em>Ameiurus </em>spp., goldfish <em>Carassius auratus</em>) with time, while some intolerant species (e.g., smallmouth redhorse <em>Moxostoma breviceps, </em>smallmouth bass <em>Micropterus dolomieu, </em>and mooneye <em>Hiodon tergisus</em>) have increased in recent years. In all, 40 of the 116 taxa collected in the lockchamber surveys changed significantly over time. Sixteen species did not change. Sixty species could not be analyzed either because of incomplete data or insufficient abundance. Fish assemblage metrics that would be expected to decrease with improving conditions in the Ohio River (percent tolerant individuals, percent nonindigenous individuals, and percent detritivore individuals) also declined (<em>p </em>< 0.05). These changes coincide with marked improvement of the water quality in the Ohio River over the last 50 years, particularly in the aftermath of the Clean Water Act (1972). Some species and metric responses may also be due to the replacement of the 50 wicket dams by the construction of 18 high-lift dams.


<em>Abstract.</em>—The Saint John River is located on the mainland of eastern North America, forming in northern Maine–southeastern Quebec, and flows east and south through New Brunswick. Fish collections were conducted at sites located from 135 to 625 km above the mouth in 2000 and 2001. Methods development trials demonstrated that the highest success was achieved with a standardized netting protocol consisting of a combination of dusk seining, nighttime electrofishing, and short-term gill net sets. A total of 36 species of fish were collected, with the greatest diversity occurring at the farthest downstream site. Upstream migration of anadromous species is restricted by the absence or poor performance of fish passage facilities at the five hydroelectric dams along the river system. The downstream migration of introduced muskellunge <em>Esox masquinongy </em>and upstream range expansions of introduced smallmouth bass <em>Micropterus dolomieu </em>and rainbow trout <em>Oncorhynchus mykiss </em>were observed. Fish species and abundances varied along the river, but the cumulative effects of human activities were not easily identified within the fish assemblage. There may have been a critical threshold within the fish assemblage defined by an accumulation of 20 anthropogenic developments. Cyprinid species declined in abundance and yellow perch <em>Perca flavescens </em>and brown bullhead <em>Ameiurus nebulosus </em>increased in abundance downstream of this apparent threshold.


Koedoe ◽  
2001 ◽  
Vol 44 (2) ◽  
Author(s):  
I.A. Russell

Fish assemblages were sampled at six sites in the Breede River in the Bontebok National Park during 1999 and 2000. A total of 380 fish from 12 species was recorded. Indigenous fish collected included one freshwater species (Barbus andrewi), two catodromous species (Anguilla mossambica, Myxus capensis). and three estuarine species (Gilchris- tella aestuaria, Monodactylusfalciformis, Mugil cephalus). Four of the species recorded were aliens (Tinea tinea, Lepomis macrochirus, Micropterus salmoides, Micropterus dolomieu) and two species translocated from other South African rivers (Tilapia sparrmanii, Clarias gariepinus). A further two indigenous species (Sandelia capensis, Pseudobarbus biirchelli) could potentially occur within the park, though the high abundance of alien predators means that there is little chance for recolonisation from tributaries higher in the Breede River system. There is little opportunity to meaningfully conserve most indigenous freshwater fish in Bontebok National Park.


<em>Abstract.</em>—The Virgin–Moapa River system supports nine native fish species or subspecies, of which five are endemic. Woundfin <em>Plagopterus argentissimus </em>and Virgin River chub <em>Gila seminuda </em>are endemic to the main-stem Virgin River, whereas cooler and clearer tributaries are home to the Virgin spinedace <em>Lepidomeda mollispinis</em>. Moapa dace <em>Moapa coriacea </em>and Moapa White River springfish <em>Crenichthys baileyi moapae </em>are found in thermal springs that form the Moapa River, and Moapa speckled dace <em>Rhinichthys osculus moapae </em>is generally found below the springs in cooler waters. The agricultural heritage of the Virgin–Moapa River system resulted in numerous diversions that increased as municipal demands rose in recent years. In the early 1900s, trout were introduced into some of the cooler tributary streams, adversely affecting Virgin spinedace and other native species. The creation of Lake Mead in 1935 inundated the lower 80 km of the Virgin River and the lower 8 km of the Moapa River. Shortly thereafter, nonnative fishes invaded upstream from Lake Mead, and these species have continued to proliferate. Growing communities continue to compete for Virgin River water. These anthropogenic changes have reduced distribution and abundance of the native Virgin–Moapa River system fish fauna. The woundfin, Virgin River chub, and Moapa dace are listed as endangered, and the Virgin spinedace has been proposed for listing. In this paper we document how the abundance of these species has declined since the Endangered Species Act of 1973. Currently, there is no strong main-stem refugium for the Virgin River native fishes, tributary refugia continue to be shortened, and the Moapa River native fishes continue to be jeopardized. Recovery efforts for the listed and other native fishes, especially in the Virgin River, have monitored the declines, but have not implemented recovery actions effective in reversing them.


Author(s):  

<em>Abstract.</em>—The Willamette River is Oregon’s largest river, with a basin area of 29,800 km<sup>2</sup> and a mean annual discharge of 680 m<sup>3</sup>/s. Beginning in the 1890s, the channel was greatly simplified for navigation. By the 1940s, it was polluted by organic wastes, which resulted in low dissolved oxygen concentrations and floating and benthic sludge deposits that hindered salmon migration and boating. Following basin-wide secondary waste treatment and low-flow augmentation, water quality markedly improved, salmon runs returned, and recreational uses increased. However, water pollution remains a problem as do physical habitat alterations, flow modification, and alien species. Fish assemblages in the main-stem Willamette River were sampled systematically, but with different gear, in the summers of 1945, 1983, and 1999. In the past 53 years, tolerant species occurrences decreased and intolerant species occurrences increased. In the past 20 years, alien fishes have expanded their ranges in the river, and four native fish species have been listed as threatened or endangered. We associate these changes with improved water quality between 1945 and 1983, fish migrations, altered flow regimes and physical habitat structure, and more extensive sampling.


2019 ◽  
Vol 26 (6) ◽  
pp. 590-599 ◽  
Author(s):  
Megan K. Schall ◽  
Timothy Wertz ◽  
Geoffrey D. Smith ◽  
Vicki S. Blazer ◽  
Tyler Wagner

<em>Abstract.</em>—Hudson River tributaries serve as spawning areas for substantial numbers of anadromous and potamodromous fishes, and are critical habitat for at least alewife <em>Alosa pseudoharengus</em>, sea lamprey <em>Petromyzon marinus</em>, white sucker <em>Catostomus commersonii</em>, and smallmouth bass <em>Micropterus dolomieu</em>. Those species that are resident in tributary mouths are often common, widespread taxa in the Hudson River system but they are rarely present in large numbers. We document high densities of American eel <em>Anguilla rostrata </em>in one tributary mouth (>13,000 eels/ha; 15–30 g/m<sup>2</sup>) and present observations supporting that this is typical of Hudson River tributaries. We suggest that the biology of American eel substantially determines the structure of the fish community and energy flow within these habitats. The presence of barriers and high density eel populations limit the import of marine and estuarine nutrients into Hudson River tributaries.


2015 ◽  
Vol 32 (5) ◽  
pp. 992-1007 ◽  
Author(s):  
J. Parker ◽  
J. Epifanio ◽  
A. Casper ◽  
Y. Cao

1992 ◽  
Vol 49 (8) ◽  
pp. 1714-1721 ◽  
Author(s):  
Charles F. Rabeni

Energetic links between smallmouth bass (Micropterus dolomieu) and rock bass (Ambloplites rupestris) and their crayfish foods were examined in an Ozark stream. A trophic level energy budget was developed by enumerating food habits for different age (size) fish, estimating annual production for both fish and crayfish, and using laboratory- and literature-derived bioenergetic and gross efficiency data. Both fishes began life feeding on small invertebrates (mayflies and chironomids) but within 3 mo switched to a diet of mainly crayfish and Cyprinidae. Total annual production of smallmouth bass was 0.262 g dry weight∙m−2∙yr−1 (6344 J) and rock bass 0.148 g∙m−2∙yr−1 (3607 J). Total annual production of crayfish was 4.15 g dry weight∙m−2∙yr−1 (55 736 J) for Orconectes luteus and 5.05 g∙m−2∙yr−1 (62 394 J) for O. punctimanus. Only about half of the crayfish production was available to fish, due to size-selective predation and behavioral traits of the prey. A predator–prey model suggested that nearly one third of total crayfish production during their vulnerable period was lost to centrarchids, and that half of the existing biomass was consumed. Fish are probably the major cause of mortality in crayfish and undoubtedly influence crayfish population dynamics and energy flow through the river system.


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