Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—Bighead Carp <em>Hypophthalmichthys nobilis </em>and Silver Carp <em>H. molitrix </em>are native in the Yangtze River and extremely important economically and culturally as food fishes; however, the two species have declined due to overfishing and anthropogenic modifications to hydrology and water quality. Bighead Carp and Silver Carp were imported to North America in the early 1970s, escaped confinement, and have now become undesirable and problematic invasive species. The two carps have become the most abundant fish species in many portions of their invaded range, which continues to expand. We compare the biology, status, and management of these species between their natal range in the Yangtze River and their invaded habitats of the Mississippi River basin.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—Lakes are very important resources for fisheries production in China. The total area of lakes for commercial fisheries in China reaches 1.02 million ha, which accounts for 18% of the total freshwater aquaculture area. China has gained rich experience developing lake commercial fisheries over the past 60 years. In the 1950s, lake fisheries were primarily focused on the capture of natural aquatic animal species. With the success of the artificial reproduction of the four domestic carps (Silver Carp <em>Hypophthalmichthys molitrix</em>, Bighead Carp <em>H. nobilis </em>(also known as <em>Aristichthys nobilis</em>), Grass Carp <em>Ctenopharyngodon idella</em>, and Black Carp <em>Mylopharyngodon piceus</em>), stock-enhanced fisheries became the main production method in the 1960s and 1970s. During this period, large-scale resources investigations all over China were conducted, some stocking and management theories that were based on primary production developed, and fish production potentials for lakes were determined. The united fishing method was created during this period, which significantly increased the capture efficiency in large lakes. In the 1980s, semi-intensive and intensive aquaculture methods, including application of fertilizers and artificial feeds, cage culture, and pen culture, were applied to lake and reservoir fisheries, which substantially increased fishery production and also the income of fishermen. However, intensive aquaculture in lakes has caused serious environmental problems, such as ecosystem degradation, exhaustion of natural fisheries resources, decreased biodiversity, and increased eutrophication. Sustainable development of fisheries in lakes of the Yangtze River basin has been facing unprecedented challenges, both to the environment and to human society. More and more attention has focused on the balance between fisheries development and environmental protection in the past two decades. Ecofishery is a possible solution to this potential conflict. As a strategy for lake fisheries reform, it is suggested that use of natural food resources in lakes should be more efficient than present, and lake fisheries should be developed based on ecosystem restorations.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—Ecosystem restoration of the Mississippi River main stem has been ongoing since the early 1970s. After the passage of environmental laws in the late 1960s to the early 1970s, private citizens and state and federal natural resource agency managers began to seek programs and funding for restoration and conservation that eventually resulted in mitigation measures of adverse impacts. Environmental-type actions that include the Great River Environmental Action Team, the Avoid and Minimize program, the middle Mississippi River biological opinion, and the lower Mississippi River conservation plan and biological opinion originated from laws or legal action. The Upper Mississippi River Restoration, Navigation and Ecosystem Sustainability Program, Restoring America’s Greatest River, and Operation and Maintenance activities, which support system ecological restoration measures, are, to a large extent, done in a cooperative setting to improve the river for multiple benefits. This coalition of agencies and professions has resulted in the application of hundreds of different types of measures to restore form and function to the third largest river in the world. Over the years, dredging and disposal practices have improved in an effort to minimize the impacts from these activities. Lost floodplain islands have been replaced, backwater lakes and channel depths have been recovered, active river flow has been reintroduced to backwaters, and microhabitats for special concern species have been restored, all to recreate broad functional floodplain habitat. Wing-dike and side-channel closure structures have been shortened, notched, or removed to recover flow along the main-channel border and side channels, increasing hydraulic residence time and recovering valuable habitat along with restoring nutrient and sediment assimilation processes the floodplain provides. Field monitoring has shown positive responses from endangered and threatened species, migratory and resident aquatic and wildlife species, abiotic conditions like water quality, and increased use by humans enjoying the benefit of a restored river system. Collectively, this work is some of the most extensive large river restoration in the world, but it only represents a small contribution to what is necessary to maintain a diverse and resilient Mississippi River. The information provided in this chapter provides a basis for continuing restoration efforts that should become a routine part of Mississippi River management.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—The Hanjiang River is the largest tributary of the Yangtze River and contains Danjiangkou Dam, which forms Danjiangkou Reservoir in the middle and upper reaches of the river. During the past 50 years, fisheries resources have changed significantly in the middle and lower Hanjiang River and in Danjiangkou Reservoir. Spawning grounds for major carps and other commercially important fishes have disappeared. Downstream of Danjiangkou Dam, total egg quantity spawned by major carps and other commercially im portant fishes have decreased while similar measures from small-bodied fishes have increased. Important commercial fishes have experienced delayed spawning times and decreased growth. Overall catches of commercial fishes have decreased downstream of the dam, though increased upstream. Some exotic fishes captured in the Danjiangkou Reservoir were likely escapees from cage-culture fish farms in the reservoir or from land-based fish farms around the reservoir. Changes in fisheries resources were presumed related to reservoir management strategies, which produced a narrower range of year-round water temperatures and caused decreases in seasonal water flow variation downstream, overfishing, and eutrophication in the reservoir. To implement a national water diversion policy in central China, the height of the Danjiangkou Dam was increased 15 m in 2012, which significantly increased the impoundment area of the Danjiangkou Reservoir at the end of 2014. Further changes in fisheries resources can be expected in the future. At the present time, management and conservation strategies for fisheries resources need to be developed to ensure future fisheries sustainability for both the Hanjiang River and the Danjiangkou Reservoir.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—Substantial investment in the engineering of the Mississippi River and its tributaries over the past ~200 years by the U.S. federal government has resulted in its transformation into one of the most regulated and intensively managed river systems in the world. The regulation and management of the Mississippi River system for a select set of ecosystem services has provided substantial economic benefits to the United States. These economic benefits include the transportation of goods, the reduction of flood risk to floodplain communities and agricultural lands, securing or increasing water supply, and reliable energy production. However, these benefits have come with substantial externalities such as altered hydrology, altered river hydraulics, decreased sediment load, changes in the pattern of delta sedimentation, increased nutrient loads, reduced habitat diversity, decreased ecological diversity, and degraded water quality. In this chapter, the natural, management, and engineering histories of the Mississippi River are reviewed. The purpose of this review is to describe the evolution of river management for harnessing the current services the river provides and the environmental and social externalities resulting from the management actions. It is hoped this holistic review of the Mississippi River will assist in leading toward a more complete and integrated vision for the management of this coupled natural–human river system.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—The Yangtze River is the largest river in China, with a drainage area encompassing a land area of 1.8 × 10⁶ km². The river main stem flows approximately 6,300 km from west to east through 11 provinces, eventually emptying into the East China Sea. The total basin area of the Yangtze River provides more than 40% of China’s gross domestic product, sustains nearly 500 million people, and plays a vital role in the overall socioeconomic development of China. Because of longitudinal differences in geomorphology, the Yangtze River is often divided into upper, middle, and lower reaches for the purposes of study and description. In general, the Yangtze River basin has a warm climate and abundant rainfall. The subtropical monsoon climate accounts for 70–80% of its annual rainfall, which produces predictable annual flood events during summers of each year. The Yangtze River ecosystem also has diverse aquatic habitats that support high biodiversity. The Yangtze River main stem contains more than 3,000 tributaries and approximately 4,000 lakes that provide important habitats for thousands of aquatic species, which include 378 fish species. Yet, the ecological communities of the Yangtze River have been dramatically impacted in recent decades due to high degrees of anthropogenic activities associated with the economic development of China. Significant biodiversity declines occurring throughout the basin have been largely attributed to hydropower dam construction, overexploitation of major fisheries, water pollution, and habitat fragmentation. In addition, widespread disconnection of the Yangtze River main stem from its floodplain lakes, lake reclamation projects, invasions by exotic species, and other serious ecological problems threaten the survival of the remaining aquatic resources in the basin. To offset the adverse effects of these threats, a number of nature reserves have been established. Additionally, protection and restoration measures, including spring fishing closures, artificial population enhancement strategies, and complete habitat restoration projects, have been implemented throughout the basin. Although these projects have yielded some encouraging results to date, they are still considered inadequate. It is recommended that an integrated strategy that includes cross-functional communication mechanisms, more comprehensive monitoring, ecological rehabilitation, and government legislation is still needed. This will insure that utilization and development in the Yangtze River ecosystem are sustainable and balanced with conservation and ecological needs.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—In this paper, we report fish resources in the upper reach of the Yangtze River from 2011 to 2012. The five sampling locations were Yibin, Hejiang, Mudong, Wanzhou, and Zigui. Yibin and Hejiang are the most upstream locations; Mudong is at the upper end of the Three Gorges Reservoir while Wanzhou and Zigui are in the inundated areas of the Three Gorges Reservoir. During our investigations, we collected 56, 94, 93, 67, and 64 fish species, respectively, from these five locations. Among them, 13, 21, 17, 4, and 4 are endemic to the upper Yangtze River. Catch per unit effort calculated with pooled data were 1,221.6–6,433.9 g/(d• boat). Because Yibin and Hejiang are still in the riverine state, endemic species remain. These areas are also in the national protected areas range. We suggest that commercial fishing should be banned in these areas to protect endemic fish species. However, for Wanzhou and Zigui, because they are in the inundated reservoir area, dominance has shifted from riverine to lacustrine species. Fisheries strategies should also be changed to target on different species, employ different fishing gears, and apply different management strategies.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—The lower Mississippi River encompasses the 1,535-km reach extending from the confluence with the Ohio River at Cairo, Illinois to the Gulf of Mexico. Waters of the lower Mississippi River have historically inundated vast areas of adjacent floodplain during spring flood pulses. Additionally, processes of land building within the river’s deltaic plain supported vast forests and diverse freshwater and salt-marsh habitats. Flood pulses provided a mechanism of lateral exchange of energy and nutrients between the aquatic and terrestrial habitats, while sediment loads continually rebuilt and supported the deltaic plain. As human populations and agriculture expanded throughout the lower Mississippi Valley, construction of flood-protection levee systems and commercial navigational structures severely decreased the connectivity between the lower Mississippi River and its floodplain. The current lower Mississippi River floodplain is more than 90% reduced in area compared to historical conditions. Fluvial dynamics, which are the driving forces that stimulate floodplain function and create diverse habitats, appear to have been altered throughout approximately 80% of the river. As a result, the hydrograph, thermograph, sedimentation patterns, nutrient dynamics, and vegetation communities within the lower Mississippi River floodplain have experienced major changes through time, with many large alterations occurring during the past century. In addition, because most of the sediment load of the lower Mississippi River now enters the northern Gulf of Mexico, land building and associated processes are much reduced in the river’s deltaic plain. This process has allowed intrusion of saltwater into coastal habitats, which has heavily impacted vegetation communities. This paper reviews the consequences of river modification to lower Mississippi River floodplain, current efforts towards restoring the floodplain and deltaic plain, and proposes future strategies towards restoring portions of the historical floodplain.

Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—Paddlefishes (Polyodontidae) and sturgeons (Acipenseridae) are taxa of large, ancient fish shared by the Yangtze and Mississippi River basins. In the Yangtze, native Chinese Paddlefish (also known as Chinese Swordfish) <em>Psephurus gladius </em>are functionally extinct and Chinese Sturgeon <em>Acipenser sinensis </em>and Dabry’s Sturgeon <em>A. dabryanus </em>are maintained through stocking. In the Mississippi River, native Paddlefish <em>Polyodon spathula </em>are secure, Pallid Sturgeon <em>Scaphirhynchus albus </em>are endangered, Shovelnose Sturgeon <em>S. platorynchus </em>are threatened, and Lake Sturgeon <em>A. fulvescens </em>are locally imperiled, although large robust populations of all these species exist in portions of their ranges. Paddlefishes and sturgeons of both rivers are habitat specialists, mature late in life (>7 years), and do not spawn every year (1–3-year intervals). With the exception of the Chinese Sturgeon, populations of all these species can be managed in both rivers through a combination of habitat preservation, habitat restoration, flow regulation, stocking of hatchery-reared fish, and regulation of harvest.