1 Descriptive Section

1.1 Indicator category

[1] “Fish”

1.2 Indicator name

Expected Number of Species

Includes variable(s): Albatross-FALL, Albatross-SPRING, AlbatrossSD-FALL, AlbatrossSD-SPRING, Bigelow-FALL, Bigelow-SPRING, BigelowSD-FALL, BigelowSD-SPRING

1.3 Indicator brief description

Diversity metric from the Northeast Fisheries Science Center (NEFSC) Bottom Trawl Surveys.

1.4 Indicator visualization

Due to the shift to the NOAA vessel Henry B. Bigelow in 2009 and the inability to correct for species composition, the time series is broken into Albatross and Bigelow stanzas. There is an apparent trend in the data from the Albatross time period in the Gulf of Maine. There is a declining trend in the Mid-Atlantic data from the spring Bigelow period.

2 SMART Attribute Section

2.1 Indicator documentation

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

Yes

2.1.1.1 Where can indicators be found?

Data: https://noaa-edab.github.io/ecodata/index.html

Description: https://noaa-edab.github.io/catalog/exp_n.html

Technical documentation: https://noaa-edab.github.io/tech-doc/exp_n.html

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

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

2.1.1.3 Who is the contact?

Andrew Beet (Andrew.Beet@NOAA.gov)

2.1.2 Gather indicator statistics

2.1.2.1 Units

Indicator	Units
Albatross-FALL	n species per 1000 ind
Albatross-SPRING	n species per 1000 ind
AlbatrossSD-FALL	n species per 1000 ind
AlbatrossSD-SPRING	n species per 1000 ind
Bigelow-FALL	n species per 1000 ind
Bigelow-SPRING	n species per 1000 ind
BigelowSD-FALL	n species per 1000 ind
BigelowSD-SPRING	n species per 1000 ind

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

General overview: Spring (March-May) and Fall (September-November)

Indicator specifics:

Indicator	EPU	StartYear	EndYear	NumYears	MissingYears
Albatross-FALL	GB	1963	2008	46	0
Albatross-FALL	GOM	1963	2008	46	0
Albatross-FALL	MAB	1963	2008	46	0
Albatross-FALL	SS	1963	2008	46	0
Albatross-SPRING	GB	1968	2008	41	0
Albatross-SPRING	GOM	1968	2008	41	0
Albatross-SPRING	MAB	1968	2008	41	0
Albatross-SPRING	SS	1968	2008	41	0
AlbatrossSD-FALL	GB	1963	2008	46	0
AlbatrossSD-FALL	GOM	1963	2008	46	0
AlbatrossSD-FALL	MAB	1963	2008	46	0
AlbatrossSD-FALL	SS	1963	2008	46	0
AlbatrossSD-SPRING	GB	1968	2008	41	0
AlbatrossSD-SPRING	GOM	1968	2008	41	0
AlbatrossSD-SPRING	MAB	1968	2008	41	0
AlbatrossSD-SPRING	SS	1968	2008	41	0
Bigelow-FALL	GB	2009	2024	15	1
Bigelow-FALL	GOM	2009	2024	15	1
Bigelow-FALL	MAB	2009	2024	14	2
Bigelow-FALL	SS	2009	2024	15	1
Bigelow-SPRING	GB	2009	2024	15	1
Bigelow-SPRING	GOM	2009	2024	15	1
Bigelow-SPRING	MAB	2009	2024	15	1
Bigelow-SPRING	SS	2009	2024	15	1
BigelowSD-FALL	GB	2009	2024	15	1
BigelowSD-FALL	GOM	2009	2024	15	1
BigelowSD-FALL	MAB	2009	2024	14	2
BigelowSD-FALL	SS	2009	2024	15	1
BigelowSD-SPRING	GB	2009	2024	15	1
BigelowSD-SPRING	GOM	2009	2024	15	1
BigelowSD-SPRING	MAB	2009	2024	15	1
BigelowSD-SPRING	SS	2009	2024	15	1

2.1.2.3 Spatial location, scale and extent

General overview: By EPU

Indicator specifics:

Indicator	EPU
Albatross-FALL	GB
Albatross-FALL	GOM
Albatross-FALL	MAB
Albatross-FALL	SS
Albatross-SPRING	GB
Albatross-SPRING	GOM
Albatross-SPRING	MAB
Albatross-SPRING	SS
AlbatrossSD-FALL	GB
AlbatrossSD-FALL	GOM
AlbatrossSD-FALL	MAB
AlbatrossSD-FALL	SS
AlbatrossSD-SPRING	GB
AlbatrossSD-SPRING	GOM
AlbatrossSD-SPRING	MAB
AlbatrossSD-SPRING	SS
Bigelow-FALL	GB
Bigelow-FALL	GOM
Bigelow-FALL	MAB
Bigelow-FALL	SS
Bigelow-SPRING	GB
Bigelow-SPRING	GOM
Bigelow-SPRING	MAB
Bigelow-SPRING	SS
BigelowSD-FALL	GB
BigelowSD-FALL	GOM
BigelowSD-FALL	MAB
BigelowSD-FALL	SS
BigelowSD-SPRING	GB
BigelowSD-SPRING	GOM
BigelowSD-SPRING	MAB
BigelowSD-SPRING	SS

2.1.2.4 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]

2.1.2.5 Uncertainty metrics

Uncertainty is captured in these variables:

[1] “AlbatrossSD-FALL” “AlbatrossSD-SPRING” “BigelowSD-FALL” “BigelowSD-SPRING”

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

Yes

2.1.3.1 Can the indicator be calculated from current documentation?

The expected number of species (\(E(S_n)\)) was calculated for each survey tow as: \[\begin{equation} E(S_n) = \sum_{i=1}^S{ \Bigg( 1 - \frac{\binom{N-N_i}{n}}{\binom{N}{n}} \Bigg) } \end{equation}\] where \(S\) is the total number of species present, \(N\) the total number of individuals, and \(N_i\) the number of individuals of ith species. The result represents a sample of n individuals randomly selected from the tow without replacement. The calculation is made using the rarefy function of the vegan package (Dixon 2003) using an n of 1000. The number of species represented in these samples of 1000 fishes are then averaged over the survey for each Ecological Production Unit. Due to the lack of survey calibration factor to account for differences in the number of species caught between the NOAA Ship Albatross IV and NOAA Ship Henry B. Bigelow, the time series are kept separate.

2.1.3.2 Is code publicly available? up to date?

2.1.3.3 Have methods changed over time?

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

Source data are publicly available.

2.1.4.1 Where are source data stored?

Data used for the calculation of the expected number of species come from the Northeast Fisheries Science Center’s survey database (SVDBS) as pulled in the Survdat data set. These data are available to qualified researchers upon request. More information on the data request process is available under the “Access Information” field here.

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

Andy Beet, andrew.beet@noaa.gov

[likelihood of source data updates requires judgement, enter by hand]

2.1.4.3 How often are they updated?

[Update by hand, look for source, may require judgement]

2.2 Indicator analysis/testing or history of use

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

Diversity estimates have been developed to understand whether the overall structure of the ecosystem has remained stable or is changing. There are a large number of diversity indices that can be used to measure diversity; for the purposes of the State of the Ecosystem report we report on the expected number of species in a sample size (E(Sn)). These “rarefied” samples allow for comparisons between sample sites with varying number of species present. The estimate of (E(Sn) is less biased than other diversity indices which usually increase with sample size. It also has a more meaningful biological interpretation than other indices. For example, if a predator eats 10 random individuals, E(Sn) will predict the number of species consumed.

2.2.2 What implications of the indicators are currently listed?

Diversity is used as a proxy for stability. Changes in ecological diversity over time may indicate altered ecosystem structure with implications for fishery productivity and management [53]. This indicator shows that the underlying ecosystem is relatively stable with the possibility that the Gulf of Maine is becoming more diverse. Increasing adult diversity in the Gulf of Maine suggests an increase in warm-water species and should be closely monitored. Recent declining adult diversity in the Mid-Atlantic should also be closely monitored for management implications.

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

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

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

Unknown

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