Values correspond to estimated total forage biomass in millions of tons
Time series: Between 2015 and 2019 the biomass of forage fish showed a significant downward trend.
Gauge: Gauge value of 58 indicates that between 2015 and 2019 the biomass of forage fish in Alaska was greater than the median value of all forage fish biomass between 1992 and 2019.
0 - 10: The five-year forage fish small pelagics average is very low compared to the median value.
10 - 25: The five-year forage fish small pelagics average is much lower than the median value.
25 - 50: The five-year forage fish small pelagics average is lower than the median value.
50: The five-year forage fish small pelagics average equals the median value.
50 - 75: The five-year forage fish small pelagics average is higher than the median value.
75 - 90: The five-year forage fish small pelagics average is much higher than the median value.
Forage fish or otherwise known as small pelagics are fish and invertebrates (like squids) that inhabit - the pelagic zone - the open ocean. Small pelagic species are often important to fisheries and serve as forage for commercially and recreationally important fish, as well as other ecosystem species (e.g. seabirds and marine mammals). The number and distribution of pelagic fish vary regionally, depending on multiple physical and ecological factors (i.e., the availability of light, nutrients, dissolved oxygen, temperature, salinity, predation, abundance of phytoplankton and zooplankton, etc.). Small pelagics are known to exhibit “boom and bust” cycles of abundance in response to these conditions. Examples include anchovies, sardines, shad, menhaden and the fish that feed on them.
This indicator from the Gulf of Alaska Integrated Ecosystem Assessment Program’s East Bering Sea (EBS) team includes adult and juvenile pollock, other forage fish such as herring, capelin, eulachon, and sandlance, pelagic rockfish, salmon, and squid.
Data background and caveats:
Units, time series, and species vary by region for this indicator, so no national score is provided. Best practices and caveats vary by region:
Information quality for this indicator ranges from a sophisticated highly quantitative stock assessment for pollock (the biomass dominant in the guild) through relatively high variance EBS shelf survey data for forage fish, to no time series data for salmon and squid.