80 
Fishery Bulletin 120(1) 
that are involved in the interactions. Financial losses 
are incurred by fishermen as a result of lost or damaged 
gear, lost fishing time due to having to wait for depre- 
dating killer whales to leave the vicinity of fishing gear, 
catch degradation due to increased gear soak time, and 
overall reduction in harvest of fish (Yano and Dahlheim, 
1995; Tixier et al., 2020). In addition to negative effects 
to the fishing industry, direct interactions between killer 
whales and fishing vessels have resulted in whales being 
seriously injured or killed. 
Here we summarize data collected by the National 
Marine Fisheries Service (NMFS) North Pacific Observer 
Program on fishery interactions of killer whales in the 
waters of the Bering Sea, Aleutian Islands, and Gulf of 
Alaska (GOA) during 2001-2016. 
Materials and methods 
Background 
The Marine Mammal Protection Act of 1972, Public Law 
92-522, title 1, section 118, requires the NMFS to classify 
all U.S. commercial fisheries into 1 of 3 categories based 
on the level of incidental mortality and serious injury of 
marine mammals occurring in those fisheries (Marine . . . 
2020). There are 23 groundfish fisheries operating in the 
Bering Sea, Aleutian Islands, and GOA that are defined in 
the List of Fisheries (LOF; see Breiwick, 2013) for which 
marine mammal bycatch must be estimated (for additional 
] 
3 
54 eceall 
a cos 
MEHTA Islands 
information, see table 1 in the NMFS Office of Protected 
Resources List of Fisheries Summary Tables, available 
from website). These fisheries target different fish species 
by using trawl gear (9 fisheries), longline gear (10 fish- 
eries), and pot gear (4 fisheries). We used this LOF and 
data from the NMFS North Pacific Observer Program to 
assess fisheries interactions with killer whales from 2001 
(the earliest year in which observer data can be assigned 
to a particular fishery) through 2016. 
Observer program data collection 
The North Pacific Observer Program is the largest fish- 
eries observer program in the United States (NMFS, 
2013). The NMFS Alaska Fisheries Science Center’s 
Fisheries Monitoring and Analysis Division is responsible 
for administering this program, which includes observer 
training, logistics, data management, and analyses. Up to 
220 observers are deployed at any one time to collect data 
for use by the NMFS in managing the Alaska groundfish 
fisheries. The collected data are critical to NMFS fish 
stock assessments and to efforts to monitor commercial 
fishing activities throughout the U.S. exclusive economic 
zone in the North Pacific Ocean (Fig. 1) as required by the 
Magnuson-Stevens Fishery Conservation and Manage- 
ment Act (Magnuson-Stevens . . . 2020). At the request of 
the Alaska Fisheries Science Center’s Marine Mammal 
Laboratory (MML), observers record information on sight- 
ings of marine mammals and document fishery interac- 
tions, injuries, and mortalities of killer whales. 
Gulf of Alaska 
180° 170°W 
160°W 
150°W 140°W 
Figure 1 
Map of the National Marine Fisheries Service reporting areas in the U.S. exclusive economic zone in the North Pacific 
Ocean, identified by numbers and outlined with gray lines, where commercial fishing activities are monitored. 
