Byrd et at: Standings as indicators of marine mammal biodiversity and human interactions 
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□ Perinatal all (r?=179) 
□ Nonperinatal HI-CBD (n=451) 
□ Nonperinatal Hl-other (n= 26) 
□ Nonperinatal HI-FI (n=168) 
■ Nonperinatal Hl-no (n=1 21 ) 
Year 
Figure 3 
Number of annual stranding events for perinatal (<125 cm) and nonperinatal 
(>125 cm) coastal bottlenose dolphins ( Tursiops truncatus) in North Carolina. 
Nonperinatal strandings are divided into human interaction (HI) categories: 
HI-CBD (could not be determined), Hl-other (e.g., mutilation, vessel strike), 
HI-FI (fishery interaction), and Hl-no (no evidence of HI). 
als was recorded in 2005 (n- 221) 
and the lowest in 2006 (n=117) 
(Table 1). Annual totals of indi- 
vidual strandings were influenced 
by mass strandings and unusual 
mortality events (UMEs) (MMPA 
16 USC 1361; Gulland, 2006). Two 
of the mass strandings occurred 
on consecutive days in January 
2005 and were designated part of 
the same UME (Table 2) (Hohn 
et ah, 2006). Also in 2005 was an 
UME of harbor porpoises (n=43) 
(Hohn et al., 2013) in the spring 
and a mass stranding of striped 
dolphins (ra=12) in late summer. 
Although the number of strand- 
ings in 2004 was not high, there 
was an UME of pelagic small ce- 
taceans (primarily pygmy sperm 
whales and offshore bottlenose 
dolphins) along the mid-Atlantic 
from July to September 2004 that 
included 13 strandings in NC. 
Annual trends were detected 
only for coastal bottlenose dol- 
phins. The average annual number of coastal bottle- 
nose dolphin strandings was 86.6 (SD=18.6) (Table 1), 
of which the average for perinates was 14.3 (SD=5.2; 
range: 9 [1999 and 2000] to 24 [2001 and 2004]). A 
significant negative annual trend was detected for all 
tested categories of nonperinatal bottlenose dolphin 
stranding events (HI-FI, n=168, P<0.001; Hl-no, n=121, 
P=0.002; HI-CBD, n=451, P=0.05). No trend was de- 
tected for perinates (n= 179, P=0.75) (Fig. 3) or for the 
second and third most numerous species, harbor por- 
poises (n=249, P= 0.59) and harbor seals (n= 73, P=0.86), 
both of which fluctuated greatly among years (Table 1). 
In addition, no annual trend was detected for balae- 
nopterids, pygmy sperm whales, dwarf sperm whales, 
non -Kogia pelagic odontocetes, or non -Phoca pinnipeds. 
Strandings of baleen whales occurred at low levels, but 
there were never fewer than 2 per year. All 5 right 
whales stranded during or after 2002. 
Significant month effects (GLM, all P<0.0001) were 
found for non -Kogia pelagic odontocetes and all test- 
ed categories of coastal bottlenose dolphin events ex- 
cept Hl-no (P=0.69), and no month effect for the other 
groups or species. For many species, strandings peaked 
in the spring (Table 4, Fig. 4). HI-FI and HI-CBD bot- 
tlenose dolphins had a second peak in the fall. 
Other species or species groups showed general 
seasonal patterns (Table 4). Although there were rela- 
tively few sperm whale strandings (n= 8), all occurred 
between December and June. Baleen whales also were 
notably absent during summer months (June-August) 
(Fig. 4). Minke whales and humpback whales were all 
immature according to their length (Table 3). Of the 8 
minke whale strandings, 2 were likely newly weaned 
and 2 were dependent calves. Harbor porpoises oc- 
curred exclusively from January through May, with 
78% of the strandings during March and April (Fig. 4). 
Of the 184 measured harbor porpoises, 96% (n= 177) 
were immature on the basis of length and 70% in- 128) 
were approximately 1 year old or less. Harbor seals oc- 
curred in every month, except August, although 86% 
stranded between January and April (Fig. 4). Eleven 
of 12 gray seals stranded from February through May 
(Table 4). In contrast, 73% of hooded seals stranded 
during July-September. Hooded and gray seals were 
all immature on the basis of length, whereas 85% of 
harbor seals and 86% of harp seals were immature. 
Spatial patterns 
Strandings were not uniformly distributed. Of the 
1847 strandings documented, 88% (n=1624) occurred 
ocean-side and included 1557 events (0.24 events 
per km of ocean coastline). Of the ocean-side strand- 
ing events, 46% occurred north of Cape Hatteras 
(160 km or 30% of coast), and 76% occurred north 
of Cape Lookout (>280 km or 52% of coast) (Figs. 5 
and 6). For all tested categories of coastal bottlenose 
dolphins except Hl-no <x 2 =3.9, n=101, P=0.69), there 
was a segment effect (7 ocean-side segments, Al-D) 
(perinatal, % 2 =26.2, n = 161, P=0.0002; nonperinatal 
HI-FI, x 2 =26.8, n = 145, P=0.0002; nonperinatal HI- 
CBD, % 2 =62.9, n= 357, P<0.0001) (Fig. 7). On the basis 
of standardized residuals (>|1.96|), segment B1 had 
significantly more strandings than expected for these 
3 significant categories. For all other significant seg- 
ments, observed strandings were less than expected 
