Dahlheim et al.: Interactions, injuries, and mortalities of Orcinus orca during fishing operations 85 
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Figure 4 
Percentage of monitored hauls with recorded interactions of killer whales (Orcinus orca) with fishery operations from 2001 
through 2016, by type of interaction, category of observer coverage (full or partial), and year, in the waters of the Bering Sea, 
Aleutian Islands, and Gulf of Alaska. Note that the scale of the y-axis (percentage of monitored hauls) varies among panels. 
number of hauls with interactions with killer whales in the 
pot gear fishery notably increased after 2008 because of the 
inclusion of a new interaction code (i.e., feeding off discards) 
that was reported from a few pot vessels. 
The number of monitored hauls varied by year and sam- 
pling stratum. Given the low numbers of hauls that were 
monitored during their operations, the BSAI rockfish longline 
fishery (137 hauls for all years), GOA flatfish longline fishery 
(43 hauls for all years), and GOA rockfish longline fishery (28 
hauls for all years) were not included in the fishery-specific 
graphs presented here. The following fisheries for which no 
interactions were reported were also excluded from the anal- 
ysis: the BSAI Pacific cod pot, GOA pollock trawl, Alaska 
GOA rockfish trawl, and GOA Pacific cod pot fisheries. Data 
for all fisheries are summarized in Supplementary Table 3, 
A and B (online only), and in Figures 6 and 7. 
Injuries 
Photographic images were reviewed to document the types 
of injuries seen on Alaska killer whales. Relatively few 
injuries were directly witnessed by observers, and most of 
the photographs depicted old injuries. Similar to the inju- 
ries observed in other populations of killer whales, the 
minor injuries we documented include the following: body 
scratches or nicks on the trailing edge of the dorsal fin 
that resulted from interactions with either conspecifics or 
prey items; wounds caused by attachments of cookiecutter 
sharks (Isistius brasiliensis), Pacific hagfish (Hptatretus 
stoutil), or barnacles; and small wounds made during prior 
biopsy sampling or satellite tagging research. Killer whales 
with more severe injuries were also photo-documented by 
observers. The top of the dorsal fin of several killer whales 
appeared to be injured or missing. At least 3 large males 
were seen with dorsal fins that were completely flopped 
over; one of these whales also had severe spinal damage. 
Most injuries appeared to be healed, indicating that a pre- 
vious injury had occurred. However, the most severe injury 
was that of a killer whale whose dorsal fin had been com- 
pletely cut off and who had severe damage to its head and 
lateral region; photographs of this animal were collected as 
it fed on discards (Fig. 8, A and B). 
Mortalities 
Between 1991 and 2016, 24 dead killer whales were 
reported by NMFS observers, and all of these dead animals 
were observed in the Bering Sea, 23 of them in the full- 
coverage stratum. Of the 24 dead whales, 14 animals were 
killed by fishing gear and 10 whales were killed by propel- 
lers (Table 1). Of the 14 mortalities associated with fishing 
gear, 7 deaths resulted from entanglements in longline gear 
(Fig. 9) and 7 deaths occurred during trawling operations. 
For the 10 killer whales killed by propellers, all mortalities 
resulted from interactions with flatfish, rockfish, or Atka 
mackerel trawl operations. Deaths of killer whales were 
reported for 6 of the 23 observed fisheries: the BSAI flatfish 
trawl, BSAI pollock trawl, BSAI rockfish trawl, BSAI Atka 
mackerel trawl, BSAI Greenland turbot longline, and BSAI 
Pacific cod longline fisheries. 
Five reports documented live killer whales entangled 
in gear (Table 2). In all cases, the killer whales were 
