National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
é established in 1881 «<= 
Spencer F. Baird G ' 
First U.S. Commissioner a 
of Fisheries and founder ice 
of Fishery Bulletin er 
Abstract—Fishery observer records 
from 2001 through 2016 were exam- 
ined to document interactions, inju- 
ries, and mortalities of killer whales 
(Orcinus orca) associated with fishing 
operations in Alaska. Although wide- 
spread throughout Alaska, the highest 
numbers of such events occurred in the 
southeastern Bering Sea. Killer whales 
of the resident ecotype feeding on catch 
or discarded catch and fishermen using 
whale deterrence measures represented 
96% (number of interactions [n]=3110) 
of all interactions examined in this 
study (n=3245). We found that 87% 
(n=2817) of all interactions occurred 
during longline operations. Both minor 
and serious injuries were documented. 
Twenty-seven killer whales were 
reported dead, but additional mortalities 
are assumed. Most whales killed were 
residents; however, 3 transient whales 
were also taken. Because killer whale 
populations are relatively small, a low 
level of mortality may significantly affect 
populations, especially if multiple sym- 
patric stocks are shown to exist. Given 
the long history (.e., over 6 decades) 
that Alaska killer whales have had with 
fishing operations, it is likely that these 
interactions will continue. 
Manuscript submitted 13 July 2021. 
Manuscript accepted 24 February 2022. 
Fish. Bull. 120:79-94 (2022). 
Online publication date: 24 March 2022. 
doi: 10.7755/FB.120.1.8 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Interactions, injuries, and mortalities of killer 
whales (Orcinus orca) observed during fishing 
operations in Alaska 
Marilyn E. Dahlheim (contact author) (retired)! 
Jennifer Cahalan? 
Jeffrey M. Breiwick (retired)' 
Email address for contact author: orcamom1 @aol.com 
' Marine Mammal Laboratory 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
7600 Sand Point Way NE 
Seattle, Washington 98115 
Present address for contact author: 33906 Bluebird Lane 
Ronan, Montana 59864 
? Pacific States Marine Fisheries Commission 
7600 Sand Point Way NE 
Seattle, Washington 98115 
Throughout the world’s oceans, inter- 
actions of killer whales (Orcinus orca) 
with fishing operations have been well 
documented (Visser, 2000; Purves et al., 
2004; Dalla Rosa and Secchi, 2007; 
Roche et al., 2007; Clark and Agnew, 
2010; Tixier et al., 2010; Belonovich 
and Burkanov, 2012; Tixier et al., 2016). 
In Alaska, Japanese fishermen first 
reported depredation by killer whales 
on longline catches of groundfish in the 
early 1960s (Dahlheim’). Throughout 
the 1980s, fishermen operating in the 
United States reported depredation by 
killer whales on their longline catches 
(Dahlheim’), with additional reports 
provided by both industry and fishery 
observers. Interactions have included 
depredation of longline-caught fish by 
killer whales, the presence of killer 
whales feeding off discards in other 
' Dahlheim, M. E. 1988. Killer whale (Orci- 
nus orca) depredation on longline catches of 
sablefish (Anoplopoma fimbria) in Alaskan 
waters. NWAFC Processed Rep. 88-14, 31 p. 
[Available from Alsk. Fish. Sci. Cent., Natl. 
Mar. Fish. Serv., NOAA, 7600 Sand Point 
Way NE, Seattle, WA 98115.] 
fisheries, and instances of fishermen 
using deterrence (Dahlheim’). 
Killer whales are widely distributed 
and commonly encountered through- 
out the waters of Alaska (Braham and 
Dahlheim, 1982; Zerbini et al., 2007). 
Three ecotypes of killer whales have 
been reported from Alaska: resident, 
transient, and offshore ecotypes. Eco- 
types differ in external morphology, 
acoustic behavior, and prey preferences 
(Baird and Stacey, 1988; Baird and Dill, 
1995; Ford et al., 1998; Dahlheim et al., 
2008). External morphology (i.e., fin or 
saddle shape) combined with natural 
and human-induced scaring allows for 
individual, and therefore group, and 
ecotype identification (Bigg et al., 1990; 
Emmons et al., 2019). Animals with 
such identifiable marks can be tracked 
through time, allowing researchers to 
document injuries to individual whales, 
assess individual and group movements, 
and identify the ecotype involved in spe- 
cific fishery interactions. 
Interactions between killer whales 
and fisheries affect both fishermen and 
the individuals or pods of killer whales 
