Applying science to help fisheries managers respond to climate change
by NOAA Fisheries 4 Apr 2019 13:47 UTC
Dutch Harbor Alaska © NOAA Fisheries
The Bering Sea ecosystem, which has experienced unprecedented changes in recent years, provides a real-world testing ground for a new strategy to help marine resource managers anticipate and respond to climate change.
The new strategy, developed by NOAA Fisheries scientists, is outlined in a paper published this week. It calls for evaluating existing management measures and developing climate forecasts for various marine areas in Alaska, over different time frames, to promote sustainable fisheries under changing environmental conditions.
"We're talking about responsive science and management. What's unique about our approach is that we consider interacting climate, biological, and socio-economic changes and how humans are affected by those changes," said Kirstin Holsman, lead author, and scientist at Alaska Fisheries Science Center.
According to Holsman, this is important because changes in social conditions can influence how people respond to management measures and, ultimately, their effectiveness.
"We wanted to provide resource managers with a strategy to help them better understand environmental and socioeconomic variability over time, to help them balance tradeoffs and anticipate tipping points when the transition to a new ecosystem or social state occurs. At that point, it becomes about adaptation."
Climate-Informed Science and Management
Resource managers typically use three types of measures to manage U.S. fisheries:
- Fixed Measures: Developed, implemented and revised over longer timeframes, every ten years or more. Examples include: restrictions on areas where different fishing gear can be used, aggregate harvest limits (catch limits for groups of species), fishing moratoria and marine protected areas.
- Adaptive Measures: Account for annual or multi-year variability of resources and include quota-based fishery management, rotating closure areas or seasonal closure areas that are adjusted annually or periodically (less than five years).
- Dynamic Measures: Used during the fishing year to minimize socio-economic consequences with the help of environmental and ecological forecasts and nowcasts that include real-time input from fishermen. These include in-season adjustments to fishing quotas or areas or continuously updated maps of bycatch high-risk areas.
"When fixed measures are combined with adaptive or dynamic measures they may help stabilize fisheries under climate change," stressed Holsman.
Holsman collaborated with a team of scientists from other NOAA Fisheries west coast science centers and other organizations to lay out a framework or a strategy for helping managers become "climate-ready."
The strategy involves first assessing the risk and vulnerability of species, habitat, management approaches and human communities to climate-induced changes. Second, scientists, resource managers, fishing industry members and others evaluate how the existing suite of management measures would perform under different climate and socioeconomic scenarios and identify gaps in institutional capabilities, jurisdictional relationships and funding. And third, they define the optimal combination of management measures and approaches to facilitate adaptation and resilience.
"It isn't surprising that major climatic shocks like sustained low-oxygen events and marine heatwaves challenge the viability of fish stocks and other living marine resources. We want to help managers anticipate surprises and be poised to respond in a timely way," added Jameal Samhouri, conservation biologist, Northwest Fisheries Science Center.
Scientists recommend also developing a series of predictive tools to augment and maximize the effectiveness of existing management measures. They recommend developing short-term (daily to annually), medium-term (1-20 years) and long-term (10-50 years) climate advice and projections with the help of computer models. On the one end of the spectrum, they want to provide daily climate forecasts so resource managers can allow fisheries to operate that would otherwise not have been able to be open when using coarser information. For example, rather than use coast-wide area closures during high-risk periods of harmful algal blooms, managers could combine frequent testing and near-real-time forecast tools to allow fisheries in certain unaffected areas to continue to operate.
"We also want to provide long-term projections that show how fish stocks, resource users and ecosystem productivity may be altered under different climate conditions," said Elliott Hazen, Southwest Fisheries Science Center. "These projections can help managers evaluate how well fixed policies are going to work in these situations and whether changes need to be made."
The Bering Sea Case Study
The scientific team examined existing management measures currently being used in the Bering Sea that have been central to maintaining sustainability of important U.S. fisheries in Alaska. Measures include fixed ecosystem-based policies aimed at maintaining long-term productivity in the system, such as fishery closure areas, fishery restrictions in marine mammal habitats, and a legislatively mandated two million metric ton limit on total groundfish catch.
"Catch limits, which are annually updated with new data and scientific analysis of stock condition, are existing adaptive measures that may allow fishery managers to adapt to variable conditions and productivity," said Holsman.
In the future, scientists see dynamic tools like in-season catch reporting and near-term ecosystem forecasts as necessary if resource managers are going to be able to quickly respond to climate-driven extreme events. These events are expected to increase in frequency and magnitude under climate change.
Dynamic management in action
In 2018 the Alaska Fisheries Science Center and the resource managers at the North Pacific Fishery Management Council put dynamic management into practice when setting quotas for the 2019 fishing year in the Bering Sea.
The Bering Sea experienced unprecedented warming, markedly reduced winter sea ice formation, and climate-driven declines in productivity that rapidly impacted the top two commercial fisheries in Alaska for pollock and Pacific cod in 2018. The "cold pool" that usually provides a natural barrier for species that inhabit the northern and southern eastern Bering Sea during the summer months was virtually nonexistent, creating open access for commercial fish to move northward.
The Alaska Fisheries Science Center survey team was able to extend its standard eastern Bering Sea continental shelf survey for groundfish and crab into the northern Bering Sea. Collected survey data and information from fishing and coastal communities was used to develop the Bering Sea Ecosystem Status Report, which has been produced annually for more than 20 years. This report provides a snap shot of current environmental conditions. Stock assessment scientists used this information together with catch and bycatch data to determine recommendations for sustainable fishing levels for the 2019 fishing year.
"Through the collective efforts of dozens of Alaska Fisheries Science Center researchers and non-NOAA collaborators, we were able to take quick action to respond to real time changes that we saw in our surveys and that fishermen were seeing in the fishing net," added Holsman.
Holsman is hopeful about the North Pacific Fishery Management Council's ability to respond to emergent challenges in the future because resource managers plan to evaluate climate-change impacts on the region and the performance of climate-resilient fixed-adaptive-dynamic management measures through their Bering Sea Ecosystem Management Plan. and the Alaska Climate Integrated Modeling Project (ACLIM) project, which is a collaboration of diverse researchers aimed at giving decision makers critical information regarding the far-reaching impacts of environmental changes in the Bering Sea.
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