The increasing occurrence of harmful algal blooms (HABs) affecting mariculture has been related to climatic factors but also to increasing eutrophication of coastal zones, to which aquaculture may also contribute. The role of climate change on HABs may be increasingly relevant but scientific efforts to separate this from other causal factors are to date inconclusive. HABs have been a permanent threat to the aquaculture industry in southern Chile, yet government and farmers may have not paid enough attention to scientific information and advice, even when risk-based predictions and warnings have been provided. Here we describe eutrophication risk assessments for water bodies hosting salmon farms and climate change risk maps for the salmon industry in Chilean Patagonia, including the increase of HABs as a main threat. Assessments and maps were delivered in 2020 both to producers and to government. We show that such risk information and mapping could have lessened recent salmon mortality due to HABs (March-April 2021) if government and farmers had followed explicit recommendations to reduce salmon farming production in water bodies with higher risk. This measure would reduce Exposure and Sensitivity under the climate change risk framework used. We provide policy recommendations, including reviewing maximum salmon production in relevant water bodies such as fjords according to eutrophication risks, while paying attention to additional stress from climate change variability and trends.

影响海水养殖的有害藻华（HAB）的发生越来越多与气候因素有关，但也与沿海地区日益富营养化有关，水产养殖也可能对此做出贡献。气候变化对 HAB 的作用可能越来越重要，但迄今为止，将其与其他因果因素区分开来的科学努力尚无定论。HAB 一直是智利南部水产养殖业的永久威胁，但政府和养殖者可能没有对科学信息和建议给予足够的重视，即使提供了基于风险的预测和警告。在这里，我们描述了智利巴塔哥尼亚鲑鱼养殖场的水体富营养化风险评估和鲑鱼产业的气候变化风险图，包括 HAB 的增加作为主要威胁。评估和地图已于 2020 年交付给生产者和政府。我们表明，如果政府和农民遵循明确的建议，减少高风险水体的鲑鱼养殖产量，则此类风险信息和绘图可能会降低近期因 HAB 造成的鲑鱼死亡率（2021 年 3 月至 4 月）。这项措施将减少所使用的气候变化风险框架下的暴露度和敏感性。我们提供政策建议，包括根据富营养化风险审查峡湾等相关水体的最大鲑鱼产量，同时关注气候变化变异性和趋势带来的额外压力。