Scientists recently confirmed that the majority of the buffalo fish swimming around a remote desert lake in eastern Arizona, the United States are older than 100.

The discovery builds on other recent research that has upended beliefs about the little-studied buffalo fish, a genus of five freshwater fish species native to North America.

Just a few years ago, scientists thought that these fish, which come in an array of colors from chestnut brown to bluish, only lived into their mid-20s. However, a 2019 study revealed that bigmouth buffalo fish could live up to 112 years, making it the oldest known freshwater teleost, a group of about 12,000 ray-finned fish species found worldwide. Then in January, researchers announced the discovery of a 127-year-old bigmouth in Saskatchewan, Canada.

The new study, published in Scientific Reports, confirmed that two more buffalo fish species — the smallmouth buffalo and the black buffalo — can live more than 100 years, making it the only known genus of animal besides the marine rockfish, Sebastes, that has three centenarian species.

For the Arizona study, a few dozen anglers caught 222 buffalo fish at Apache Lake from July 2018 to July 2023. Twenty-three were humanely euthanized and donated to the research team, who estimated their ages by removing and analyzing tiny ear stones called otoliths. These calcium carbonate structures, which allow fish to hear and sense vibrations in the water, form a new layer each year that can be read somewhat like tree rings.

Researchers identified individuals of all three species studied past 100 years old.

What’s more, research has revealed that buffalo fish continue to live their best lives into their upper 80s and 90s.

“The one takeaway is that buffalo fish do not conform to preconceived notions,” says study leader Alec Lackmann, a fish expert at the University of Minnesota.

Buffalo fish can go decades between successful reproductions because they require very specific environmental conditions — most of which are still unknown — to procreate. That’s why the fish evolved to live so long: It’s an evolutionary adaptation to account for long periods without breeding, according to Lackmann.

In Saskatchewan, where buffalo fish can go up to 50 years without producing offspring, the fish only attempt to spawn within a narrow range of water-level fluctuations that may rarely occur.

A 2021 study on bigmouth buffalo fish confirmed that older fish are less stressed and have stronger immunity than younger ones. Older individuals could fight off bacteria better than younger animals. Not only that, the elderly fish had a lower ratio of neutrophils to lymphocytes in the blood, an indication of lower stress levels.

“They are still advancing into prime condition at a century old, which is astonishing,” Lackmann says. (SD-Agencies)

Words to Learn 相关词汇

【颠覆】diānfù upend affect to the point of being upset or flurried

【安乐死】ānlèsǐ euthanize kill in a relatively painless way for reasons of mercy

科学家最近证实，生活在美国亚利桑那州东部一个偏远沙漠湖里的大多数水牛鱼都超过100岁了。

这一发现建立在其他研究的基础上，此前的研究已颠覆了人们对水牛鱼的看法，这种淡水鱼原产于北美，包括五个分支。

几年前，科学家还以为这些栗色、蓝色的鱼只能活到20多岁。然而，一项2019年的研究揭示，大口水牛鱼能活到112岁，是已知最古老的淡水硬骨鱼，属于射线鳍鱼类，全球范围内约有12000种。今年1月，研究人员宣布在加拿大萨斯喀斯温省发现了一只127岁的大口水牛鱼。

发表在《科学报告》上的研究证实，又有两种水牛鱼 ——小口水牛鱼和黑水牛鱼 —— 可以活过一百岁，这使其成为除了海洋岩鱼（鲷鱼）之外，唯一已知拥有三种能活百年物种的动物属。

2018年7月至2023年7月，几十名垂钓者在亚利桑那州的阿帕契湖捕获了222条水牛鱼。其中23条被安乐死后捐赠给研究小组，科学家摘取并分析了鱼的微小耳石来估计它们的年龄。耳石是碳酸钙结晶，让鱼类能够听到和感知水中的振动，就像树木的年轮，耳石每年都会形成新的一层。

研究者们估算三种研究物种都有个体年龄达到百岁以上。

此外，研究表明，水牛鱼八九十岁时仍能保持最佳身体状态。

明尼苏达大学鱼类专家、研究负责人亚历克•拉克曼说：“结论是，水牛鱼打破了我们的常规认识。”

因为对环境的要求特殊，水牛鱼可能数十年才能成功繁殖一次，具体需要什么条件，基本上还是个谜。这就是水牛鱼长寿的原因： 拉克曼认为，长寿是针对繁殖间隔长的进化适应策略。

萨斯喀斯温省的水牛鱼甚至50 年不产后代，它们只在罕见的水位低波动窗口产卵。

2021年一项关于大口水牛鱼的研究证实：年长比年轻的水牛鱼压力更小，免疫力更强。

年老比年轻的个体能更好地对抗细菌。不仅如此，老年鱼的血液中中性粒细胞/淋巴细胞的比例更低，这是压力水平较低的表现。拉克曼说：“它们在百岁年纪仍处于身体最佳状态，令人惊讶。”

(Translated by Debra)