无论是在海洋上漫游还是封闭在浮动的饲养场中，大西洋鲑鱼都是冷水鱼类。但是，随着气候危机温暖世界的海洋和水道，冷水变得越来越难以找到，这意味着这些长期存在的鱼可能面临着迄今为止最大的挑战。
大西洋鲑鱼是动荡不安的，在淡水和盐水环境之间移动。几千年来，它们在美国东北部，加拿大东部和北欧的河流中产生，然后迁移到格陵兰和冰岛海岸。在那里，他们逐渐成熟，然后返回其出生河流以生下新一代。
长期以来的旅程一直是危险的。自工业革命黎明以来，污染，大坝，过度捕捞和栖息地破坏已经减少了大西洋鲑鱼的数量。鲑鱼曾经在数千万中的数以千计的人消失了，野生鲑鱼几乎从他们的所有祖先水中消失了。气候变化对野生鲑鱼和工业笔中包含的鲑鱼构成了强大的新威胁。
二十年来，研究人员已经证明了水温升高对海洋生态系统的影响深远。非营利组织北大西洋鲑鱼保护组织的数字说明了影响的一个方面。在1990年之前，在海上第一年中，只有1000个受精卵中只有一条鱼。从2007年到2016年，单鲑鱼需要2,000个鸡蛋。
NOAA警告说，气候变化代表了对某些野生鲑鱼的潜在灭绝水平危险。
The danger extends beyond the marine environment. A study by the state of Washington in 2020 found that as the air warms, snowmelts dwindle, and droughts increase, less cold water remains in streams and rivers in summer, when salmon need it the most.
Warmer water also contains less oxygen, which makes it harder for salmon to breathe. Temperatures above 64 degrees F (18 degrees C) speed up the salmon’s metabolism, increasing the need for oxygen and forcing the fish to expend more energy to swim farther in search of food and cooler water.
With global warming predicted to intensify, the National Oceanic and Atmospheric Administration has warned that climate change represents a potential extinction-level danger to some species of wild salmon.
大西洋鲑鱼联合会主席比尔·泰勒（Bill Taylor）是一个致力于保护野生鲑鱼和恢复栖息地的非政府组织，分享了这种恐惧。泰勒告诉我们：“气候变化是目前对鲑鱼的最大影响，这将是几十年来。”“从雷头河流到西部格陵兰岛的喂养场有直接影响。鲑鱼只是受气候变化影响的一种物种，但我们认为它是煤矿中的金丝雀。”
北大西洋的法罗群岛附近的一个鲑鱼农场。Martin Zwick / Reda＆Co / Universal Images通过Getty Images
几十年来，野生鲑鱼一直在努力抗衡，现在必须再次适应。海洋生物学家最近已将太平洋和大西洋鲑鱼追踪到北极寻找冷水。这些所谓的“热移民”可以在这种基石物种的演变中打开新的章节，前提是鱼在气候时钟耗尽之前可以适应。
Farmed salmon, of course, face similar climate-related pressures. But unlike their wild relatives, they have no hope of migrating to cooler water. Since farmed salmon cannot adapt, the aquaculture industry itself must change — or face its own decline.
公正地解释了行业的风险死亡损失,英国的研究组织Just Just Economics进行了一项2021年的研究。该研究说：“大西洋鲑鱼只能在某些条件下耕种，随着海洋温暖和可用地点的利用，该行业的新农场的可行地点不足。”“这意味着新的增长来源正在逐渐减少，造成了压力以在不合适的环境中定位农场并增加库存密度，从而进一步加剧了环境压力。”
我们花了两年的时间来研究我们最近出版的书《全球鲑鱼农业行业的实践》，鲑鱼战：我们最喜欢的鱼的黑暗腹部。我们采访了水产养殖业务中的科学家，医师，环保主义者和人。气候变化成为对鲑鱼农民面临的最关键的环境和鱼类福利挑战之一，引起了人们对该行业在变暖海洋上的未来的怀疑。
一种2019 die-off of farmed salmon in Canada was primarily caused by higher water temperatures, researchers say.
自1960年代末和1970年代初在挪威峡湾的起源以来，开放式净鲑鱼养殖已成为世界上增长最快的食品领域，在北美食用的大西洋鲑鱼中多达90％。少数跨国公司在业务中占主导地位，并在四个地区（挪威，智利，加拿大和苏格兰）生产了全球96％的养殖鲑鱼。少数农场位于缅因州，爱尔兰，塔斯马尼亚州和法罗群岛的海岸附近。
The industry’s rapid expansion and intensive farming methods have generated considerable controversy. While the industry promotes its product as sustainable, some scientists and conservation groups question the farms’ impacts on both the environment and fish welfare.
一个典型的开放型笔鲑鱼农场由12至16个笼子组成，由增强塑料网制成，大约400英尺，深约30英尺。网悬挂在浮子项圈上，并用钢电缆连接到海床上，这使安装可以随着电流和潮汐而移动。一个农场可以容纳一百万或更多的鲑鱼。
从表面上看，鲑鱼农场显得无害。在水线下，笼子如此拥挤，以至于它们成为病毒和疾病的繁殖地。由于农场通常位于鲑鱼迁移路线上，因此疾病和寄生虫的传播如海虱危害野生鱼类。农药和其他化学物质的过量饲料，粪便和残留物通常在农场下方积聚。
Salmon killed in a mass die-off at Porcelana farms in southern Chile in 2021.Alvaro Vidal / AFP通过Getty Images
工业规模的水产养殖所造成的问题与海洋温度有所增加。根据专门从事可持续食品系统的咨询公司Spheric Research的一项研究，在加拿大，挪威，智利和爱尔兰的鲑鱼农场的数量和质量死亡人数越来越明显和规模上，可以看到最明显的影响。
Mortality rates for farmed Atlantic salmon are estimated at between 15 and 20 percent globally. (By contrast, factory chickens have a mortality rate of 5 percent.) But in recent years the salmon industry has, in some places, suffered far higher rates.
一种record die-off occurred in late summer of 2019 off the southwestern coast of Newfoundland, wiping out 2.6 million fish at 10 of Northern Harvest Sea Farm’s operations — nearly half of the operator’s fish. The company blamed the deaths solely on an extended period of ocean temperatures reaching 70 degrees F (21 degrees C). As the surface water warmed, the fish sought refuge in cooler water at the bottom of the cages, where they suffocated from lack of oxygen.
纪念大学的渔业和海洋研究所调查了死亡，发现水温的升高是主要原因。这项研究说，温暖的水只是净笔内“恶化条件恶化”的一个元素。在温水到来之前，使用农药与寄生虫作斗争，这使鱼强调，海湾中的藻类开花进一步耗尽了氧气水平。
Scientists do not know if wild salmon can move to cooler water fast enough to survive warming oceans.
在其他地方也提出了类似的担忧。一种2021研究在里面Journal of Marine Scienceconcluded that warmer water was increasing infestations of sea lice and rendering the usual pesticides ineffective. A 2022 study by the U.S. Environmental Protection Agency found warming water also increases the frequency of harmful algae blooms. The agency noted that marine animals must leave the affected areas to survive. Again, farmed salmon don’t have that option.
The industry counters critics by claiming that salmon farms can meet the world’s growing protein crisis. Astudyby the University of British Columbia’s Institute for the Oceans and Fisheries, however, predicted that aquaculture production — including farmed salmon — in many locations and under a high-emissions scenario will drop by up to 90 percent by mid-century due to the direct impact of ocean warming and the indirect damage to forage fish, essential to the industry as salmon feed.
Some multinational salmon farming corporations are racing to get ahead of warming oceans. Rival companies in Norway are fighting to move their farms to the country’s northernmost fjords. Innovasea, based in Boston, has developed a submersible fish pen that can be lowered to avoid warm surface water and keep fish at optimal temperatures. Researchers in Norway and Australia are taking another route, trying to breed salmon that would better resist heat.
阿拉伯联合酋长国的养鱼场是越来越多的土地项目之一，在坦克中饲养大西洋鲑鱼。Giuseppe Cacace / AFP通过Getty Images
Meanwhile, a radical alternative to ocean salmon farms is emerging. Recirculating aquaculture systems, known as RAS, raise Atlantic salmon in large tanks on land. The water is filtered to remove contaminants, allowing the fish to grow without chemicals. The closed-containment systems ensure that the fish never touch the ocean, which erases any threat to wild salmon or other marine life.
独立的RAS项目正在内陆地区弹出，包括瑞士和阿拉伯联合酋长国。最大的工厂称为Atlantic Sapphire，距佛罗里达州东海岸约13英里。188金宝搏亚洲体育搏彩在威斯康星州，最具创新性的植物可能是优越的新鲜，它只会在淡水中升起鲑鱼，使该设施可以将富含营养的水回收到近13英亩的温室中，该温室在水培中生产叶状绿色蔬菜。
No one knows whether wild salmon can move to cooler water fast enough to avoid succumbing to warming oceans. But some who are studying the new movements are optimistic.
加拿大渔业和海洋部的海洋生物学家卡伦·邓玛尔（Karen Dunmall）说：“鲑鱼具有适应恶劣条件的惊人能力。”“鲑鱼正在做鲑鱼做什么。他们进入新的地方，并试图弄清楚他们如何建立自己。”
