SMART Indicator Report: Forage Fish Index

1 Indicator category

[Fill by hand, needs decision by Council]

2 Indicator name

Forage Fish Index

Includes variable(s): Fall Eastward Forage Fish Center of Gravity, Fall Eastward Forage Fish Center of Gravity SE, Fall Forage Fish Biomass Estimate, Fall Forage Fish Biomass Estimate SE, Fall Northward Forage Fish Center of Gravity, Fall Northward Forage Fish Center of Gravity SE, Spring Eastward Forage Fish Center of Gravity, Spring Eastward Forage Fish Center of Gravity SE, Spring Forage Fish Biomass Estimate, Spring Forage Fish Biomass Estimate SE, Spring Northward Forage Fish Center of Gravity, Spring Northward Forage Fish Center of Gravity SE

3 Indicator brief description

Aggregate forage fish biomass index from fish stomach contents

4 Indicator 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.

5 Indicator documentation

5.1 Are indicators available for others to use (data downloadable)?

## Yes

5.1.1 Where can indicators be found?

## Data: https://noaa-edab.github.io/ecodata/index.html 
## Description:  https://noaa-edab.github.io/catalog/forage_index.html 
## Technical documentation:  https://noaa-edab.github.io/tech-doc/forage_index.html

5.1.2 How often are they updated? Are future updates likely?

[need sequential look at datasets for update frequency. Future requires judgement]

5.1.3 Who is the contact?

Sarah Gaichas (Sarah.Gaichas@noaa.gov)

5.2 Gather indicator statistics

5.2.1 Units

Indicator	Units
Fall Eastward Forage Fish Center of Gravity	km
Fall Eastward Forage Fish Center of Gravity SE	km
Fall Forage Fish Biomass Estimate	relative grams per stomach
Fall Forage Fish Biomass Estimate SE	relative grams per stomach
Fall Northward Forage Fish Center of Gravity	km
Fall Northward Forage Fish Center of Gravity SE	km
Spring Eastward Forage Fish Center of Gravity	km
Spring Eastward Forage Fish Center of Gravity SE	km
Spring Forage Fish Biomass Estimate	relative grams per stomach
Spring Forage Fish Biomass Estimate SE	relative grams per stomach
Spring Northward Forage Fish Center of Gravity	km
Spring Northward Forage Fish Center of Gravity SE	km

5.2.2 Length of time series, start and end date, periodicity

General overview: Spring (January-June), Fall (July-December)

Indicator specifics:

Indicator	EPU	StartYear	EndYear	NumYears	MissingYears
Fall Eastward Forage Fish Center of Gravity	ALLEPU	1982	2023	42	0
Fall Eastward Forage Fish Center of Gravity SE	ALLEPU	1982	2023	42	0
Fall Forage Fish Biomass Estimate	AllEPU	1982	2023	42	0
Fall Forage Fish Biomass Estimate	GB	1982	2023	42	0
Fall Forage Fish Biomass Estimate	GOM	1982	2023	42	0
Fall Forage Fish Biomass Estimate	MAB	1982	2023	42	0
Fall Forage Fish Biomass Estimate SE	AllEPU	1982	2023	42	0
Fall Forage Fish Biomass Estimate SE	GB	1982	2023	42	0
Fall Forage Fish Biomass Estimate SE	GOM	1982	2023	42	0
Fall Forage Fish Biomass Estimate SE	MAB	1982	2023	42	0
Fall Northward Forage Fish Center of Gravity	ALLEPU	1982	2023	42	0
Fall Northward Forage Fish Center of Gravity SE	ALLEPU	1982	2023	42	0
Spring Eastward Forage Fish Center of Gravity	ALLEPU	1982	2023	42	0
Spring Eastward Forage Fish Center of Gravity SE	ALLEPU	1982	2023	42	0
Spring Forage Fish Biomass Estimate	AllEPU	1982	2023	42	0
Spring Forage Fish Biomass Estimate	GB	1982	2023	42	0
Spring Forage Fish Biomass Estimate	GOM	1982	2023	42	0
Spring Forage Fish Biomass Estimate	MAB	1982	2023	42	0
Spring Forage Fish Biomass Estimate SE	AllEPU	1982	2023	42	0
Spring Forage Fish Biomass Estimate SE	GB	1982	2023	42	0
Spring Forage Fish Biomass Estimate SE	GOM	1982	2023	42	0
Spring Forage Fish Biomass Estimate SE	MAB	1982	2023	42	0
Spring Northward Forage Fish Center of Gravity	ALLEPU	1982	2023	42	0
Spring Northward Forage Fish Center of Gravity SE	ALLEPU	1982	2023	42	0

5.2.3 Spatial location, scale and extent

General overview: by EPU and full shelf

Indicator specifics:

Indicator	EPU
Fall Eastward Forage Fish Center of Gravity	ALLEPU
Fall Eastward Forage Fish Center of Gravity SE	ALLEPU
Fall Forage Fish Biomass Estimate	AllEPU
Fall Forage Fish Biomass Estimate	GB
Fall Forage Fish Biomass Estimate	GOM
Fall Forage Fish Biomass Estimate	MAB
Fall Forage Fish Biomass Estimate SE	AllEPU
Fall Forage Fish Biomass Estimate SE	GB
Fall Forage Fish Biomass Estimate SE	GOM
Fall Forage Fish Biomass Estimate SE	MAB
Fall Northward Forage Fish Center of Gravity	ALLEPU
Fall Northward Forage Fish Center of Gravity SE	ALLEPU
Spring Eastward Forage Fish Center of Gravity	ALLEPU
Spring Eastward Forage Fish Center of Gravity SE	ALLEPU
Spring Forage Fish Biomass Estimate	AllEPU
Spring Forage Fish Biomass Estimate	GB
Spring Forage Fish Biomass Estimate	GOM
Spring Forage Fish Biomass Estimate	MAB
Spring Forage Fish Biomass Estimate SE	AllEPU
Spring Forage Fish Biomass Estimate SE	GB
Spring Forage Fish Biomass Estimate SE	GOM
Spring Forage Fish Biomass Estimate SE	MAB
Spring Northward Forage Fish Center of Gravity	ALLEPU
Spring Northward Forage Fish Center of Gravity SE	ALLEPU

5.2.4 Management scale: all species, FMP level, species level, can it be aggregated or separated to different scales?

[Classify by hand, note gridded data if available could be applied to different species ranges]

5.2.5 Uncertainty metrics

5.3 Are methods clearly documented to obtain source data and calculate indicators?

## Yes

5.3.1 Can the indicator be calculated from current documentation?

[Build link to Tech-doc, look for current and previous methods]

5.3.2 Is code publicly available? up to date?

[Build link to Tech-doc, look for current and previous methods]

5.3.3 Have methods changed over time?

[Build link to Tech-doc, look for current and previous methods]

5.4 Are indicator underlying source data linked or easy to find?

[Build link to Tech-doc, look for source, may require judgements]

5.4.1 Where are source data stored?

[Build link to Tech-doc, look for source, may require judgement]

5.4.2 How/by whom are source data updated? Are future updates likely?

[Build link to Tech-doc, look for source, may require judgement]

5.4.3 How often are they updated?

[Build link to Tech-doc, look for source, may require judgement]

6 Indicator analysis/testing or history of use

6.1 What decision or advice processes are the indicators currently used in?

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. Spatially explicit indices of abundance for several forage species were estimated using spatio-temporal modeling (VAST, [10]; [11]). 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.

6.2 What implications of the indicators are currently listed?

The resulting indices for the Mid-Atlantic show a long term decrease in fall and overall higher forage fish in fall relative to spring, 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. 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.

6.3 Do target, limit, or threshold values already exist for the indicator?

[Fill by hand; if not in key results or implications, likely does not exist]

6.4 Have the indicators been tested to ensure they respond proportionally to a change in the underlying process?

[Fill by hand; if not in introduction, key results, or implications, likely not tested]

6.5 Are the indicators sensitive to a small change in the process, or what is the threshold of change that is detectable?

[Fill by hand; if not in introduction, key results, or implications, likely not tested]

6.6 Is there a time lag between the process change and the indicator change? How long?

[Fill by hand; if not in introduction, key results, or implications, likely not tested]

7 Comments

[Fill below by hand once above data complete]

7.1 Additional potential links to management in addition to uses listed above

7.2 What additional work would be needed for the Council to use the indicator?

7.3 What issues are caused if there is a gap or delay in data underlying the indicator