Data Name (This will be the displayed title in Catalog)
Forage Fish Index
Indicator Name (as exists in ecodata)
forage_index
Family (Which group is this indicator associated with?)
[ ] Oceanographic
[ ] Habitat
[ ] Lower trophic levels
[X] Megafauna
[ ] Social
[ ] Economic
Data Description
Aggregate forage fish biomass index from fish stomach contents
Introduction to Indicator (Please explain your indicator)
The amount of forage fish available in the ecosystem combined with the energy content of the forage species determines the amount of energy potentially available to predators in the ecosystem. Changes in the forage base could pose a risk to managed and protected species production. This spatially-explicit forage index estimated the combined biomass of 21 forage species using stomach contents information from 22 predatory fish species collected on bottom trawl surveys.
In addition to an index of forage abundance in each EPU, the coastwide center of gravity for the combined forage biomass was estimated. Consistent movement of the center of gravity towards the north or east indicates a distribution shift for combined forage fish.
Key Results and Visualization
Variables plotted are Fall Forage Fish Biomass Estimate and Spring Forage Fish Biomass Estimate with error bands from Fall Forage Fish Biomass Estimate SE and Spring Forage Fish Biomass Estimate SE, respectively. Time series were extended back to 1982 and forward to 2023 in this update, but this did not change the trends reported previously for 1982-2022.
Implications
The resulting indices for the Mid-Atlantic show a long term decrease in fall and overall higher forage fish in fall relative to spring (Fig. \@ref(fig:MAforagebio)), with highest forage biomass during fall in the early-1980s.
In New England, the forage index shows an overall higher forage fish biomass in fall relative to spring (Fig. \@ref(fig:NEforagebio)). There is a long-term increasing trend in the spring in GOM.
Changes in the distribution of forage biomass also affects predator distribution. Since 1982, the fall center of gravity of forage fish has moved to the north and east. The spring forage center of gravity shows higher variability than fall, and a significant trend to the north.
Spatial Scale
by EPU and full shelf
Temporal Scale
Spring (January-June), Fall (July-December)
Synthesis Theme
[X] Multiple System Drivers
[ ] Regime Shifts
[ ] Ecosystem Reorganization
Define Variables
Spring Forage Fish Biomass Estimate = aggregate forage fish biomass months 1-6, units relative grams per stomach
Spring Forage Fish Biomass Estimate SE = standard error of aggregate forage fish biomass months 1-6, units relative grams per stomach
Fall Forage Fish Biomass Estimate = aggregate forage fish biomass months 7-12, units relative grams per stomach
Fall Forage Fish Biomass Estimate SE = standard error of aggregate forage fish biomass months 7-12, units relative grams per stomach
Fall Eastward Forage Fish Center of Gravity = average eastward location of forage fish biomass months 7-12, units kilometers
Fall Eastward Forage Fish Center of Gravity SE = standard error of average eastward location of forage fish biomass months 7-12, units kilometers
Fall Northward Forage Fish Center of Gravity = average northward location of forage fish biomass months 7-12, units kilometers
Fall Northward Forage Fish Center of Gravity SE = standard error of average northward location of forage fish biomass months 7-12, units kilometers
Spring Eastward Forage Fish Center of Gravity = average eastward location of forage fish biomass months 1-6, units kilometers
Spring Eastward Forage Fish Center of Gravity SE = standard error of average eastward location of forage fish biomass months 1-6, units kilometers
Spring Northward Forage Fish Center of Gravity = average northward location of forage fish biomass months 1-6, units kilometers
Spring Northward Forage Fish Center of Gravity SE = standard error of average northward location of forage fish biomass months 1-6, units kilometers
Indicator Category
[X] Published Methods
[ ] 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
Sarah Gaichas, James Gartland, Brian Smith, Anthony Wood, Elizabeth Ng, Michael Celestino, Katie Drew, Abigail Tyrell, and James Thorson
Primary Contact
Sarah.Gaichas@noaa.gov
Secondary Contact
No response
Data Name (This will be the displayed title in Catalog)
Forage Fish Index
Indicator Name (as exists in ecodata)
forage_index
Family (Which group is this indicator associated with?)
Data Description
Aggregate forage fish biomass index from fish stomach contents
Introduction to Indicator (Please explain your indicator)
The amount of forage fish available in the ecosystem combined with the energy content of the forage species determines the amount of energy potentially available to predators in the ecosystem. Changes in the forage base could pose a risk to managed and protected species production. This spatially-explicit forage index estimated the combined biomass of 21 forage species using stomach contents information from 22 predatory fish species collected on bottom trawl surveys.
In addition to an index of forage abundance in each EPU, the coastwide center of gravity for the combined forage biomass was estimated. Consistent movement of the center of gravity towards the north or east indicates a distribution shift for combined forage fish.
Key Results and Visualization
Variables plotted are Fall Forage Fish Biomass Estimate and Spring Forage Fish Biomass Estimate with error bands from Fall Forage Fish Biomass Estimate SE and Spring Forage Fish Biomass Estimate SE, respectively. Time series were extended back to 1982 and forward to 2023 in this update, but this did not change the trends reported previously for 1982-2022.
Implications
The resulting indices for the Mid-Atlantic show a long term decrease in fall and overall higher forage fish in fall relative to spring (Fig. \@ref(fig:MAforagebio)), with highest forage biomass during fall in the early-1980s.
In New England, the forage index shows an overall higher forage fish biomass in fall relative to spring (Fig. \@ref(fig:NEforagebio)). There is a long-term increasing trend in the spring in GOM.
Changes in the distribution of forage biomass also affects predator distribution. Since 1982, the fall center of gravity of forage fish has moved to the north and east. The spring forage center of gravity shows higher variability than fall, and a significant trend to the north.
Spatial Scale
by EPU and full shelf
Temporal Scale
Spring (January-June), Fall (July-December)
Synthesis Theme
Define Variables
Spring Forage Fish Biomass Estimate = aggregate forage fish biomass months 1-6, units relative grams per stomach Spring Forage Fish Biomass Estimate SE = standard error of aggregate forage fish biomass months 1-6, units relative grams per stomach Fall Forage Fish Biomass Estimate = aggregate forage fish biomass months 7-12, units relative grams per stomach Fall Forage Fish Biomass Estimate SE = standard error of aggregate forage fish biomass months 7-12, units relative grams per stomach Fall Eastward Forage Fish Center of Gravity = average eastward location of forage fish biomass months 7-12, units kilometers
Fall Eastward Forage Fish Center of Gravity SE = standard error of average eastward location of forage fish biomass months 7-12, units kilometers Fall Northward Forage Fish Center of Gravity = average northward location of forage fish biomass months 7-12, units kilometers
Fall Northward Forage Fish Center of Gravity SE = standard error of average northward location of forage fish biomass months 7-12, units kilometers Spring Eastward Forage Fish Center of Gravity = average eastward location of forage fish biomass months 1-6, units kilometers
Spring Eastward Forage Fish Center of Gravity SE = standard error of average eastward location of forage fish biomass months 1-6, units kilometers Spring Northward Forage Fish Center of Gravity = average northward location of forage fish biomass months 1-6, units kilometers
Spring Northward Forage Fish Center of Gravity SE = standard error of average northward location of forage fish biomass months 1-6, units kilometers
Indicator Category
If other, please specify indicator category
No response
Data Contributors
Sarah Gaichas, James Gartland, Brian Smith, Anthony Wood, Elizabeth Ng, Michael Celestino, Katie Drew, Abigail Tyrell, and James Thorson
Point(s) of Contact
Sarah Gaichas (Sarah.Gaichas@noaa.gov)
Affiliation
NEFSC
Public Availability
Source data are publicly available. All data and code are available at https://github.com/NOAA-EDAB/forageindex
Accessibility and Constraints
No response