根據一份詳細評估近20年淡水魚類保育情形的報告顯示，過去美國國內溪流、河川與湖泊常見的淡水魚種正在消失，將近40%魚種的存續也面臨著威脅。
該報告指出，目前約61種魚類被假定為絕種，280種被列入瀕絕名單。此外，190種的生存環境受到威脅，230種則已界臨絕種關口。
美國地質測量局主任梅爾（Mark Myers）表示，淡水魚數量減少的跡象出現於1970年代，最主要的成因不外棲地破壞、規模縮減，以及外來物種入侵等；而氣候的變遷將可能進一步惡化這些脆弱的魚類。
在這些淡水魚中，受到威脅程度最大的是太平洋沿岸與西部山區的鮭魚和鱒魚。另外，內陸地區的鯉魚、吸盤魚與鯰魚；美國東南部的射水魚；以及分佈在墨西哥與美國西南部的鏘魚、孔雀魚、蝴蝶魚等大型原生家族，亦深受極大威脅。
釣客及捕撈業者所鎖定的魚群也接近絕種。美國釣魚運動中熱門魚類之一的條紋鱸魚，已經在瀕絕名單列上一席。此外，翻車魚家族包含有黑鱸、大翻車魚和石鱸等熟知的魚種，已有22%被列入危險名單。
美國東南、中太平洋海岸、大河區低地與墨西哥盆地等地，因內陸河川末端無法觸及海口，使得流域內淡水魚種消失的速度較其他地區來得快。
地質測量局研究與該報告執筆者霍華（Howard Jelks）指出，「人類在這些重要的分水嶺頻繁活動，對這些水域生態帶來負面影響」。
河川流域向來是地區中極富生物多樣性的熱點，同時也可作為生物續存的指標，而美國田納西州內的指標則反映出嚴重的問題。當地58種魚類處於險境；莫比爾河中57種魚類面臨危險；而東南部大西洋斜面的河川系統中，亦有34種魚類的存續遭受威脅。
再者，該報告指出，近太平洋的中央谷、大盆地西部、大河區及墨西哥中部河川，所孕育生態之豐富，卻已有大量魚群正面臨絕種的命運。
許多續存遭受威脅的魚種已局限於只能存活在單一外流河。
該報告對照美國漁業協會1989年公佈的魚類瀕絕名單，項目中89%的魚類不是仍等同保育狀態，就是處境變得更加危險；而僅11%在保育工作上有所嶄獲或脫離瀕絕名單。
研究人員強調，人類必須提升公共意識並採行積極管理策略，才有機會提高保護與復育水生物種的機會。
Fishes that once were abundant in North American streams, rivers and lakes are now disappearing, with nearly 40 percent of all species in jeopardy, according to the most detailed assessment of the conservation status of freshwater fishes in the last 20 years.
The report shows that 61 fishes are presumed extinct, and 280 species are classed as endangered. In addition 190 are considered threatened, and 230 fishes are listed as vulnerable to extinction.
"Freshwater fish have continued to decline since the late 1970s, with the primary causes being habitat loss, dwindling range and introduction of non-native species," said Mark Myers, director of the U.S. Geological Survey. "In addition, climate change may further affect these fish."
The fish at greatest risk are the salmon and trout of the Pacific Coast and western mountain regions. Also at great risk are minnows, suckers and catfishes throughout the continent; darters in the southeastern United States; and pupfish, livebearers, and goodeids, a large, native fish family in Mexico and the southwestern United States.
Fish families important for sport or commercial fisheries are also vulnerable to extinction. One of the most popular game species in the United States, striped bass, has populations on the list. Twenty-two percent of sunfishes, a family which includes the well-known species such as black bass, bluegill and rock bass, are listed as at risk.
The southeastern United States, the mid-Pacific coast, the lower Rio Grande and basins in Mexico that do not drain to the sea are losing their freshwater fish species more quickly than other regions.
"Human populations have greatly expanded in many of these watersheds, compounding negative impacts on aquatic ecosystems," said Howard Jelks, a USGS researcher and the senior author of the paper.
River systems that are both hotspots of regional biodiversity and also show the greatest levels of endangerment are the Tennessee, where 58 fishes are in jeopardy; the Mobile River with 57 fishes at risk; and the southeastern Atlantic Slope river systems where 34 fishes are imperiled.
The Pacific central valley, western Great Basin, Rio Grande and rivers of central Mexico also have high diversity and numbers of fish at risk of extinction, according to the report.
Many of the fish populations at risk are restricted to only a single drainage.
Of fish on the American Fisheries Society's 1989 imperiled list, 89 percent are either still listed with the same conservation status or have become even more at risk. Only 11 percent improved in status or were delisted.
The authors emphasize that improved public awareness and proactive management strategies are needed to protect and recover these and other aquatic species.
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