The following is courtesy of NOAA Fisheries Alaska:
3D render and imaging of topographic map of Alaska showing the Gulf of Alaska, Aleutian Islands and Bering Sea. Satellite images courtesy of NASA. Credit: Frank Ramspott
NOAA Fisheries has released the 2023 Ecosystem Status Reports for the eastern Bering Sea, Aleutian Islands, and Gulf of Alaska. These synthesis reports provide current conditions and trends over time for key oceanographic, biological, and ecological indicators in three Alaska marine ecosystems.
These foundational data and information reports support federal commercial fish and crab fisheries management. Each year, scientists and fishery managers at NOAA, other U.S. federal and state agencies, academic institutions, tribes, and nonprofits, contribute to the reports.
For close to three decades, fishery managers have relied on these reports to better understand how commercial fish and crab populations are being affected by changes in the marine environment.
“Warming at rates four times faster than the rest of the ocean, Alaska’s Arctic ecosystems are a bellwether for climate change. Now more than ever having ecosystem and climate-related data and information is essential to support adaptive resource management and resilient commercial, recreational and subsistence fisheries, and rural and coastal communities,” said Robert Foy, director, Alaska Fisheries Science Center.
This year, data from these reports provided broad, contextual ecosystem information for 45 stock assessments and specifically informed 16 stock-level risk assessments.
2023 Highlights Across Alaska
Looking across the three ecosystems this year, there are several notable indicators amidst continued variability in many marine conditions.
Ocean temperatures in both the Gulf of Alaska and the Bering Sea have cooled relative to the recent marine heatwave conditions while the Aleutians remained warmer than average
Pacific ocean perch continue to be dominant groundfish in the Aleutian Islands, replacing pollock and Atka mackerel in the ecosystem while the Gulf of Alaska ecosystem is now characterized by increased populations of Pacific ocean perch and sablefish and reduced populations of Pacific cod, Pacific halibut, and arrowtooth flounder
There were some positive signs for Pacific cod recruitment in the Gulf of Alaska even though adult population abundance remains low
Notable indicators of ecosystem health and potential threats to wildlife and human health: Harmful algal blooms are becoming more prevalent in the northern Bering Sea and paralytic shellfish toxins in sampled blue mussels from four Aleutian Islands communities were 47 times above the regulatory limit
Gulf of Alaska
Average year of productivity across the shelf marine ecosystem, continuing a multi-year trend that is expected to change in 2024
Total zooplankton biomass (prey for many groundfish species) declined to below average but nutritious large copepods were more abundant in the central and eastern Gulf of Alaska
Prey availability for fish-eating groundfish (e.g., Pacific cod, sablefish, arrowtooth flounder, yelloweye rockfish) varied across the Gulf of Alaska, and included increased capelin
The Gulf of Alaska groundfish community continues to be characterized by relatively increased sablefish and Pacific ocean perch populations and reduced populations of Pacific cod, Pacific halibut, and arrowtooth flounder
Sea surface temperatures are predicted to warm in 2024 due to El Niño conditions, potentially benefiting the survival of some larval groundfish (e.g., sablefish) and potentially harming survival of others (e.g., larval Pacific cod)
Relatively stormy during the winter of 2022–23 and summer of 2023
Warmest winter sea surface temperatures since 1900
Cooler (but still above average) spring-summer conditions
The upper mixed layer extended deeper than during 2022, which potentially impacted the vertical distribution and availability of prey throughout the water column
Seabird reproductive success in the eastern Aleutian Islands was at or above average, indicating wide availability of zooplankton and fish prey
Seabird reproductive success was mixed in the western Aleutian Islands
Eastern Kamchatka pink salmon abundance was the third highest on record
Paralytic shellfish toxins in blue mussels sampled in June were 47 times above the legal limit at Sand Point, Unalaska, False Point, and Akutan
The Bering Sea ecosystem remains in a transitional state, with marine life like zooplankton and fish response lagging, as the ecosystem recovers from record warm conditions during an unprecedented warm stanza (2014–2021)
Chlorophyll-a, the base of the marine food chain, has generally been decreasing over the past decade with 2023 among the lowest across the shelf
In the southeastern Bering Sea, both young and adult pollock and several flatfish species had declining body condition
Jellyfish, a potential competitor with groundfish for prey, have increased over the northern Bering Sea shelf but remained average in the southeastern Bering Sea
Slight increases in juvenile Chinook and chum salmon abundance in the northern Bering Sea
Several crab stocks showed continued declines in the eastern Bering Sea
Seabird reproductive success was mixed at the Pribilof Islands, with seabirds at St. George Island doing better than St. Paul Island
A New Tool to Track Abundance Trends
This year, scientists began testing a new modeling tool. It illustrates how changes in one variable might affect another. The Dynamic Structural Equation Model allows scientists to better understand connections between different indicators and the factors that may be affecting increases and decreases in their abundance.
“We can estimate missing information, lags in indicator response to ecosystem changes, and the strength of connections between indicators,” said Elizabeth Siddon, a fisheries biologist at the Alaska Fisheries Science Center who developed the tool. “We are also excited about the potential for being able to use this tool to project next year conditions for some indicators.”