Dr. León-Muñoz, Jorge

Chile is the world’s leading exporter of farmed mussels, with an annual harvest of about 400,000 tonnes; this production is based on the capture of wild seeds, the availability of which may be threatened by climate change and overfishing. Climate change has led to a decrease in annual precipitation, which increases the salinity of the water column and may affect the vertical distribution of mussel populations in fjords. In Reloncaví Fjord, Chile, observed changes in precipitation are reducing freshwater inputs, leading to potential shifts in the habitat and distribution of the economically important Chilean mussel (Mytilus chilensis) and a competing species, Aulacomya atra. This study analyses the vertical dynamics of mussel beds in relation to changing environmental conditions, including freshwater inputs, salinity and hydrological regimes in a fjord exploited for mussel seed collection. The results suggest that decreasing trends in precipitation could lead to increased surface salinity, reducing M. chilensis beds while favouring A. atra, with negative consequences for wild seed collection, thus threatening the Chilean mussel farming industry and predicting socio-economic consequences for small-scale aquaculture. This study also describes the increasing fishing pressure on wild mussel larvae, suggesting joint effects that cannot be disentangled with the information currently available and that represent a key challenge for the design of adaptation measures to climate change. Therefore, this study highlights the need for better monitoring of mussel beds together with seed production and oceanographic conditions, as well as improving aquaculture practices that reduce unnecessary pressure on mussel beds through seed collection in the face of changing environmental conditions.

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.

This study addresses the risk and vulnerability of Chilean salmon production to hazards resulting from the COVID-19 pandemic threat, including limited access to farms, limited processing capacity and reduced market demand. The role of different management approaches in reducing risk and vulnerability is also explored. Results suggest that concession areas having the largest accumulated and current biomass have the highest risk, which is also transferred to the municipal level. The scenarios modelled with better management practices that reduce diseases were able to reduce risks by 30–40%. The largest risk reduction is achieved when production biomass is divided in a more equitable manner among concession areas, suggesting the need for strategic improvements in spatial planning of the activity in the marine environment according to ecosystem carrying capacity and better practices. Improving adaptation capacity can reduce vulnerability between 20% and 30% for municipalities; for example, providing local employment can be a win-win management measure under the COVID-19 threat because it reduces movement of people and facilitates handling and responses to emergencies. A larger footprint in local economies and employment can also improve social perception and acceptance of the sector, thus contributing to improve adaptation changes and governance to face the threats. The framework used here to perform a risk and vulnerability assessment of salmon farming to the pandemic-associated threats can also be useful for other aquaculture systems elsewhere, provided that relevant information is available.