20080868 Ver 2_Section II D Q4 Managed Fish 2021 PCS Creeks Report_20220605

D. Question 4- Has mining altered the use of the creek by managed fish?
Multivariate cluster analysis using a similarity profile test (SIMPROF) of managed fish
species composition and abundance from all creeks and all years, for both trawl and fyke net
creeks, revealed three distinct clusters in the trawl analysis and five in the fyke net analysis (Figure
II-D1 and Figure II-D2). to date 13 managed fish species have been collected (Table II-D1). (Note:
included in previous reports as a managed species, Crevalle jack (Caranx hippos) was removed
from the snapper grouper complex in April 2012 by the South Atlantic Fishery Management
Council; therefore, this fish is excluded from this report section.) To simplify discussion of the
data set, colored lines on the cluster dendrograms represent non -significant structure among
factors (e.g., years, creeks) at the 1 percent level (P = 0.01). Comparison of interannual variability
between clusters by means of similarity percentages (SIMPER) revealed that dissimilarity ranged
from 77 to 89 percent in trawl creeks and 73 to 99 in fyke net creeks.
In the trawl analysis, cluster A contained seven of the 11 PA2 years with a mixture of other
pre -Mod Alt L and post Mod creek/years. The majority of creek/years grouped into cluster B,
which contained years from every creek in the study, excluding Broomfield Swamp Creek. Cluster
C contained all three Broomfield Swamp Creek years with one other pre -Mod Alt L, post -Mod Alt
L, and control creek/year. Cluster A, in the fyke net analysis, contained one post -Mod Alt L creek
(Huddles 2015) grouped with two DCUT19 control creek/years. Only Huddles 2014 grouped into
cluster B. Post -Mod Alt L and control creek/years from all three fyke net creeks were represented
in cluster C. Cluster D contained the majority of Huddles pre and post -Mod Alt L years and control
creek DCUT19 2020. Eight of nine DCUT11 years and DCUT19 2015-2016 placed in group E.
Number and Type of Creek/Year per Cluster
Total Number of Years by Creek Type
Cluster ID Creek/Years Pre Post Control Notes
Trawl
A 18 5 2 11 Seven PA2 years, three Jacks years and six other creeks
B 114 20 37 57 All creeks except Broomfield Swamp
C 6 4 1 1 All Broomfield years and one year from Jacks, Tooley, and SCUT1
Fyke
A 3 0 1 2 DCUT19 2017, 2019 and Huddles Cut 2015
B 1 0 1 0 Huddles Cut 2014
C 6 0 2 4 All three fyke creeks represented
D 16 6 9 1 15 of 18 Huddles years and DCUT19 2020
E 10 5 3 2 Eight of nine DCUT11 years and DCUT19 2015-2016
In the trawl creek analysis, all impact creeks with post -Mod Alt L years were represented
in B alongside at least one corresponding pre -Mod Alt L year and 57 different control creek/years.
The two remaining groups also contained a mixture of control, pre-, and post -Mod Alt L
creek/years (Figure II-D1). The two largest groups in the fyke net analysis, D and E, contained
most pre- and post -Mod Alt L years for both Huddles Cut and DCUT11 respectively. Excluding
B, every cluster contained at least one DCUT19 control creek/year (Figure II-D2).
Comparison of interannual variability between clusters by means of similarity percentages
(SIMPER) was used to determine which managed fish species drove cluster formation. A
summary of average CPUE of the 13 managed fish species in the eight clusters across both
analyses is shown in Table II-D1. The most commonly caught managed fishes in trawls included:
spot, Atlantic croaker, and Atlantic menhaden. Cluster A was characterized by high CPUE of spot
and Atlantic menhaden; it contained the most managed species of any group (Table II-D1). Group
B formed as a result of high spot and Atlantic croaker CPUE (Table II-D1). Cluster C represented
the lowest CPUE and diversity within any of the groups (Table II-D1). The most commonly
II-D-1

captured managed species in fyke nets included: spot, Atlantic menhaden, and striped mullet
(Mugil cephalus) (Table II-D1). In the fyke net analysis, group A saw spot represent the highest
CPUE within the cluster of relatively low CPUEs (Table II-D1). Both clusters B and C contained
high CPUE of Atlantic menhaden but were separated due to higher CPUE of spot in C (Table II-
D1). Cluster D contained all managed fish species in the study and represented the most diversity
and highest CPUE of fyke net groups. Contrary to D, group E contained the lowest CPUEs of
any group (Table II-D1).
Comparison of interannual variability by means of ANOSIM detected no spatial differences
of significance between pre- and post -Mod Alt L managed fish assemblages within drainage
basins of Jacobs Creek, Huddles Cut, Porter Creek, and DCUT11; however, spatial differences
of significance were detected between pre- and post -Mod Alt L managed fish assemblages within
Jacks Creek, Tooley Creek, and Drinkwater Creek [Global R = 0.338; P = 0.004, Global R = 0.354;
P = 0.029 and Global R = 0.547; P = 0.036].
As discussed earlier in Section II-C Question 3 (forage base), low total CPUE observed
locally throughout South Creek and surrounding tributaries in both 2016-2017 was repeated for
CPUE of managed species as well. An overall decline in CPUE of spot was observed in most
creeks since 2013; however, 2016-2017 represented the lowest or close to the lowest CPUE of
spot experienced within all creeks/years. Similar to total CPUE, CPUE of spot for Jacks Creek
2016-2017 represented two of the three lowest CPUE's for spot across all trawl creeks/years;
post -Mod Alt L spot catch for Jacks Creek was most affected by this trend, as 2016-2017 comprise
two of the six post -Mod Alt L years. The decrease in CPUE of spot throughout South Creek and
surrounding tributaries along with significant increases in CPUE of Atlantic croaker in post -Mod
Alt L years of both Drinkwater and Tooley creeks [small (n) = 26, big (n) = 117; T = 1,121.0; P =
<0.001 and small(n) = 65, big(n) = 130; T = 5,035.35; P = <0.001] accounted for differences
between managed fish assemblages in pre- and post -Mod Alt L years.
As also discussed earlier in Section II-C Question 3 (forage base), low total CPUE for
Huddles Cut since 2009 was likely affected to a large degree by the formation of a sandbar at the
mouth of Huddles Cut. This sandbar limits water exchange and fish access into and out of the
creek and likely affected CPUE for managed fish as well. Spot, striped mullet, and Atlantic
menhaden were the three most abundant species of managed fish captured in Huddles Cut, with
spot typically the most abundant of the three. Along with impeded access into and out of the
mouth of Huddles Cut, there was the overall decline in CPUE of spot from 2013-2015 mentioned
above; however, Huddles Cut was the only creek where CPUE of spot increased from 2015-2020.
Spot CPUE at Huddles Cut in 2016 was over 10 times the CPUE observed for spot in 2015, nearly
doubled from 2016 to 2017, doubled from 2017 to 2018, and continued to increase in 2019 and
2020 to the second highest CPUE of spot encountered for the 18 Huddles Cut years. Although
striped mullet catch was nearly non-existent in both 2015 (seven individuals) and 2017 (five
individuals) at Huddles Cut, CPUE of striped mullet in Huddles Cut remained higher than in
DCUT19 2013-2016 and 2018-2021 (a control creek also fyke netted and adjacent to the Pamlico
River) with a large catch increase in 2020 and 2021 (251 and 238 individuals). The increase in
CPUE of spot at Huddles Cut in recent post -Mod Alt L years likely resulted in no spatial differences
of significance being detected between pre- and post -Mod Alt L managed fish assemblages within
the drainage basin of Huddles Cut through 2021.
The data do not specifically indicate that mine activities have altered managed fish
communities. When pre- and post -Mod Alt L years from four of seven creeks were compared,
there was no statistical indication of any detectable difference. It is also not valid to assume
reduction of the drainage basin of the other three creeks has altered fish assemblage since only
one cluster contained only a post -Mod Alt L creek/year (Huddles 2014) and most post -Mod Alt L
II-D-2

creek/years clustered among other pre -Mod Alt L creeks/years for the same creek, and/or control
creeks/years in both analyses (see Section III for further analysis).
As the number of creeks sampled increased since 2011, capture of managed fish species
also increased. In all, 13 managed species have been captured, with a low of five species in
2004 (Jacks and Muddy creeks were the only creeks sampled) to a high of 11 species in 2001
and 2012. Huddles Cut in 2020 had the highest number of managed species captured in an
individual creek/year with nine. The most abundant managed species captured across all creeks
were spot, Atlantic croaker, and Atlantic menhaden. Of the 13 managed species captured, four
diadromous species were collected across all creeks/years: alewife (Alosa pseudoharengus),
American eel (Anguilla rostrata), American shad (Alosa sapidissima), and striped bass (Morone
saxatilis). These four diadromous species represented a total of 405 individuals; however,
American eel alone accounted for 360 (89 percent).
Penaeid shrimp and blue crabs are also managed species but were not enumerated
during the creeks study from 1999 through 2010. Collection of more detailed qualitative
information on shrimp and crabs was initiated in 2011 in conjunction with fish collections (via trawl
at all creeks except Huddles Cut, DCUT11, and DCUT19 which are via fyke nets; DCUT11 and
DCUT19 were sampled in 2013 for the first time). The limited data prevent detailed evaluation;
however, penaeid shrimp were most frequently captured (69 percent of samples) from Duck
Creek in 2011 and the highest numbers of penaeid shrimp collected were from PA2 Creek in
2021. The frequency and numbers of penaeid shrimp seemed to be in decline in all creeks since
2011-2012, until a slight increase in 2015-2021 in all creeks except for DCUT11. No penaeid
shrimp were captured in DCUT11 upstream or downstream fyke nets in any year and were
captured only in 2013, 2018, 2020, and 2021 in DCUT19 upstream fyke net. Additionally, no
penaeid shrimp were captured in 2013 from PA2 (trawl) or Huddles Cut downstream fyke net, in
2014 trawls from Jacks Creek, Little Creek, PA2, Long Creek, Porter Creek, or Huddles Cut
downstream fyke net, in 2015 from Huddles Cut upstream fyke net, in 2016 trawls from both Jacks
Creek and Porter Creek, in 2017 from Porter Creek, in 2019 from Huddles Cut downstream fyke
net, or Broomfield Swamp Creek, SCUT1 and Duck Creek trawls, in 2020 from Broomfield Swamp
Creek, or in 2021 from Broomfield Swamp Creek and SCUT1 (Table II-C3).
The frequencies at which blue crab were captured and the numbers collected were both
highest among all creeks for one of the two Huddles Cut fyke nets from 2016-2021; the upstream
Huddles Cut fyke net frequency tied with Jacobs Creek in 2017 for highest. No blue crabs were
captured at DCUT11 during 2013-2016, 2018, 2020 and 2021; however, blue crabs were
collected in DCUT11 downstream fyke net in 2017 and in both fyke nets in 2019. Blue crabs were
also absent in 2013 trawls from Jacks Creek and Little Creek, and from DCUT19 downstream
fyke net; furthermore, none were captured in 2014 trawls from Long Creek, Muddy Creek, and
Duck Creek, or DCUT19 upstream fyke net, in 2019 in Broomfield Swamp Creek, and in 2021 in
Porter Creek, SCUT1, and Broomfield Swamp Creek (Table II-C3). The frequencies at which
both penaeid shrimp and blue crab were captured and the numbers collected were highly variable
across all creeks except DCUT11 where no penaeid shrimp have been captured and blue crab
have only been collected twice. No apparent trends can be detected from the 11 years where
blue crab data was enumerated.
Answer: The multivariate cluster analysis of managed fish for all creeks, all
collection years, and both gear types reveals some separation between pre -Mod Alt L and
post -Mod Alt L years within clusters; however, the analysis does not reveal distinct
changes in the assemblages of managed fish due to mine activities within the drainage
basins of Jacks Creek, Jacobs Creek, Drinkwater Creek, Tooley Creek, Huddles Cut, Porter
Creek, and/or DCUT11.
II-D-3

Comparison of interannual variability by means of ANOSIM detected spatial
differences of statistical significance between pre- and post -Mod Alt L managed fish
assemblages of Jacks Creek, Tooley Creek and Drinkwater Creek. Low total CPUE
observed locally throughout South Creek and surrounding tributaries in 2016-2017 trawl
samples also likely affected CPUE of all managed species in every creek; however, low
CPUE of spot and higher CPUE of Atlantic croaker likely contributed to separation of post -
Mod Alt L years from pre -Mod Alt L years in Tooley Creek. Lower CPUE of spot in post -
Mod Alt L years in Jacks Creek likely contributed to separation of post -Mod Alt years from
pre -Mod Alt L years as two of the six post -Mod Alt L years for Jacks Creek were 2016 and
2017. An increase in Atlantic croaker CPUE in post -Mod Alt L years likely caused
separation between pre- and post -Mod Alt L years in Drinkwater Creek.
Although there is a decline in CPUE of some managed species in Huddles Cut in
post -Mod Alt L years, the continued increase in CPUE of spot at Huddles Cut in post -Mod
Alt L 2015-2020 and persistent catches of Atlantic menhaden in both pre- and post -Mod Alt
L years contributed to no detection of spatial differences of significance between pre- and
post -Mod Alt L managed fish assemblages through 2021. Both diversity and abundance
of managed fish captured at Huddles Cut remain higher than most all other sampled creeks
and higher than DCUT11 and DCUT19 for 2013-2021 (data period for the only other creeks
sampled via fyke nets).
No data set for some pre -Mod Alt L years in some creeks and variability in the
frequency and numbers of both penaeid shrimp and blue crab collected make it difficult to
discern any mine -related spatial patterns in the abundance of either species.
II-D-4

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Figure II-D1. Dendrogram of hierarchical clusters of similarity for fish community abundance and composition among managed fish species for all trawl creeks and years
sampled [Bray -Curtis similarity; Log(x+1)]. Black lines within dendrogram represent statistically significant cluster structure and colored lines represent non -significant
cluster structure at the 1 percent level (P = 0.01). Gray creeks/years are pre -Mod Alt L, bold creeks/years are post -Mod Alt L, and blue creeks/years are control creeks.
I I-D-5

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Figure II-D2. Dendrogram of hierarchical clusters of similarity for fish community abundance and composition among managed fish species for all fyke net creeks and
years sampled [Bray -Curtis similarity; Log(x+1)]. Black lines within dendrogram represent statistically significant cluster structure and colored lines represent non-
significant cluster structure at the 1 percent level (P = 0.01). Gray creeks/years are pre -Mod Alt L, bold creeks/years are post -Mod Alt L, and blue creeks/years are control
creeks.
II-D-6

Table II-D1. Catch -per -unit -effort (CPUE) average for managed fish species in the five clusters identified by cluster analysis of all PCS fish collections separated by net type (April,
May, and June of 1999 through 2005 and 2007 through 2021). Number of creek/years in each cluster is shown in parentheses).
Common name
Scientific name
Trawl CPUE average by species per cluster
Cluster A (18)
Cluster B (114)
Cluster C (6)
Alewife
Alosa pseudoharengus
0.00b
0.01
0.00
American eel
Anguilla rostrata
0.68
0.09
0.15
American shad
Alosa sapidissima
0.00
0.00
0.00
Atlantic croaker
Micropogonias undulatus
4.04
17.67
3.38
Atlantic menhaden
Brevoortia tyrannus
16.19
7.51
7.23
Bluefish
Pomatomus saltatrix
0.00b
0.00b
0.00
Red drum
Sciaenops ocellatus
0.00b
0.00b
0.00
Southern flounder
Paralichthys lethostigma
0.07
0.30
0.01
Spot
Leiostomus xanthurus
60.76
98.37
4.40
Spotted seatrout
Cynoscion nebulosus
0.04
0.04
0.00
Striped bass
Morone saxatilis
0.00b
0.00b
0.00
Striped mullet
Mugil cephalus
0.18
0.04
0.00
Summer flounder
Paralichthys dentatus
0.05
0.19
0.00
Table II-D1 continued
Common name
Scientific name
Fyke net CPUE average by species per cluster
Cluster A (3)
Cluster B (1)
Cluster C (6)
Cluster D (17)
Cluster E (9)
Alewife
Alosa pseudoharengus
0.00
0.00
0.00
0.05
0.00
American eel
Anguilla rostrata
0.00
0.08
0.12
0.17
0.12
American shad
Alosa sapidissima
0.00
0.00
0.00
0.00b
0.00
Atlantic croaker
Micropogonias undulatus
0.13
0.23
0.03
3.18
0.00
Atlantic menhaden
Brevoortia tyrannus
0.69
67.62
29.10
21.64
0.01
Bluefish
Pomatomus saltatrix
0.00
0.00
0.00
0.03
0.00
Red drum
Sciaenops ocellatus
0.03
0.00
0.00
0.86
0.00
Southern flounder
Paralichthys lethostigma
0.38
1.15
0.28
1.29
0.01
Spot
Leiostomus xanthurus
6.46
11.54
51.90
237.47
0.26
Spotted seatrout
Cynoscion nebulosus
0.00
0.15
0.01
0.08
0.00
Striped bass
Morone saxatilis
0.00
0.00
0.00
0.00b
0.00
Striped mullet
Mugil cephalus
0.72
4.92
1.85
27.40
0.04
Summer flounder
Paralichthys dentatus
0.05
0.85
0.10
0.75
0.01
a Number of individuals caught during an approximate 16-hour set of fyke nets or one minute, 75-yard trawl
bCPUE average less than 0.00