Data Name (This will be the displayed title in Catalog)
Forage Fish Energy Density
Indicator Name (as exists in ecodata)
energy_density
Family (Which group is this indicator associated with?)
[ ] Oceanographic
[ ] Habitat
[ ] Lower trophic levels
[X] Megafauna
[ ] Social
[ ] Economic
Data Description
Energy density of alewife, butterfish, sand lance, and Atlantic mackerel varies seasonally, with seasonal estimates both higher and lower than estimates from previous decades. The data presented are the seasonal (Spring and Fall) energy density (kJ/g) for eight important forage species; Alewife, Atlantic Herring, Silver Hake, Northern Sand Lance, Atlantic Mackerel, Butterfish, Northern Shortfin Squid, and Inshore Longfin Squid. Samples are obtained from the NEFSC seasonal bottom trawl surveys and processed in the lab to estimate energy content.
Introduction to Indicator (Please explain your indicator)
The energy density of prey indicates the the amount of energy passing from lower trophic levels to higher predators. Changes in ecosystem productivity and/or bioenergetic demands (e.g. metabolic increases due to rising temperature) can impact energy density. Energy density of fishes can vary widely (several fold), particularly for some species that undergo seasonal cycles in energy allocation to reproduction, energy allocation to migration, or seasonal/ontogenetic shifts in energy storage. The value of forage species to higher trophic levels is a function of the their energy density.
Forage energy density measurements from NEFSC trawl surveys 2017-2022 are building toward a time series to evaluate trends
Key Results and Visualization
Variable plotted are the mean energy density (kJ/g) for eight species across seasons and years. The reference lines represent estimates from prior studies where available for comparison. The energy content of Atlantic herring from the NEFSC trawl surveys has increased to over 7 kJ/g wet weight in spring 2023, but is still well below that observed in the 1980s and 1990s (10.6-9.4 kJ/ g wet weight). Silver hake, longfin squid (Loligo in figure) and shortfin squid (Illex in figure) remain lower than previous estimates [@steimle_energy_1985; @lawson_important_1998]. Energy density of alewife, butterfish, sand lance, and Atlantic mackerel varies seasonally, with seasonal estimates both higher and lower than estimates from previous decades.
Implications
The nutritional content of forage fish changes seasonally in response to ecosystem conditions, with apparent declines in energy density for Atlantic herring and Illex squid relative to the 1980s, but similar energy density for other forage species.
Spatial Scale
Full shelf
Temporal Scale
Spring and Fall Bottom Trawl Survey
Synthesis Theme
[X] Multiple System Drivers
[ ] Regime Shifts
[X] Ecosystem Reorganization
Define Variables
Energy Density (kJ/g) for each species.
Indicator Category
[ ] Published Methods
[X] Extensive analysis, not yet published
[ ] Syntheses of published information
[ ] Database pull
[ ] Database pull with analysis
[ ] Other
If other, please specify indicator category
No response
Data Contributors
Mark Wuenschel
Point(s) of Contact
Mark Wuenschel (mark.wuenschel@noaa.gov)
Affiliation
NEFSC
Public Availability
Source data are NOT publicly available.
Accessibility and Constraints
Email mark.wuenschel@noaa.gov for further information. Data tables are being created to make this readily available soon.
Primary Contact
mark.wuenschel@noaa.gov
Secondary Contact
No response
Data Name (This will be the displayed title in Catalog)
Forage Fish Energy Density
Indicator Name (as exists in ecodata)
energy_density
Family (Which group is this indicator associated with?)
Data Description
Energy density of alewife, butterfish, sand lance, and Atlantic mackerel varies seasonally, with seasonal estimates both higher and lower than estimates from previous decades. The data presented are the seasonal (Spring and Fall) energy density (kJ/g) for eight important forage species; Alewife, Atlantic Herring, Silver Hake, Northern Sand Lance, Atlantic Mackerel, Butterfish, Northern Shortfin Squid, and Inshore Longfin Squid. Samples are obtained from the NEFSC seasonal bottom trawl surveys and processed in the lab to estimate energy content.
Introduction to Indicator (Please explain your indicator)
The energy density of prey indicates the the amount of energy passing from lower trophic levels to higher predators. Changes in ecosystem productivity and/or bioenergetic demands (e.g. metabolic increases due to rising temperature) can impact energy density. Energy density of fishes can vary widely (several fold), particularly for some species that undergo seasonal cycles in energy allocation to reproduction, energy allocation to migration, or seasonal/ontogenetic shifts in energy storage. The value of forage species to higher trophic levels is a function of the their energy density.
Forage energy density measurements from NEFSC trawl surveys 2017-2022 are building toward a time series to evaluate trends
Key Results and Visualization
Variable plotted are the mean energy density (kJ/g) for eight species across seasons and years. The reference lines represent estimates from prior studies where available for comparison. The energy content of Atlantic herring from the NEFSC trawl surveys has increased to over 7 kJ/g wet weight in spring 2023, but is still well below that observed in the 1980s and 1990s (10.6-9.4 kJ/ g wet weight). Silver hake, longfin squid (Loligo in figure) and shortfin squid (Illex in figure) remain lower than previous estimates [@steimle_energy_1985; @lawson_important_1998]. Energy density of alewife, butterfish, sand lance, and Atlantic mackerel varies seasonally, with seasonal estimates both higher and lower than estimates from previous decades.
Implications
The nutritional content of forage fish changes seasonally in response to ecosystem conditions, with apparent declines in energy density for Atlantic herring and Illex squid relative to the 1980s, but similar energy density for other forage species.
Spatial Scale
Full shelf
Temporal Scale
Spring and Fall Bottom Trawl Survey
Synthesis Theme
Define Variables
Energy Density (kJ/g) for each species.
Indicator Category
If other, please specify indicator category
No response
Data Contributors
Mark Wuenschel
Point(s) of Contact
Mark Wuenschel (mark.wuenschel@noaa.gov)
Affiliation
NEFSC
Public Availability
Source data are NOT publicly available.
Accessibility and Constraints
Email mark.wuenschel@noaa.gov for further information. Data tables are being created to make this readily available soon.