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Fishery Bulletin 120(1) 
Table 3 
Details about tissues collected for genetic analysis from dead killer whales (Orcinus orca) brought aboard fish- 
ing vessels in various Alaska fisheries in the Bering Sea and Aleutian Islands (BSAI) and in the Gulf of Alaska 
(GOA) from 1999 through 2004. Genetic analysis was used to determine the ecotype of each whale: resident, 
transient, and offshore. Stock IDs were assigned by using ecotype and the region where the dead animal was 
sampled. All residents are identified as belonging to a single stock (i.e., the Alaska stock). Transient whales 
are identified as from either the AT1 stock or the GOA-BSAI stock. The age, sex, and cause of death recorded 
by observers for each whale are presented. A dash indicates that a whale’s age class or sex was undetermined. 
Sampling date Fishery Stock ID 
Pollock trawl 
Flatfish trawl 
Pollock trawl 
Pollock trawl 
Pollock trawl 
Pacife cod longline 
Flatfish trawl 
Flatfish trawl 
Flatfish trawl 
20-Aug-1999 
11-Aug-2001 
12-Mar-2002 
20-Mar-2003 
22-Jul-2003 
9-Sep-2003 
7-Apr-2004 
21-Apr-2004 
22-Apr-2004 
and other fish species are seasonally available to killer 
whales in this area. It is no surprise that killer whales 
would be attracted to fishery operations knowing that 
food is easily available. Killer whales may not normally 
consume many of the fish species that they target during 
fishery interactions. Sablefish are found at depths rang- 
ing from 366 m to 1829 m (AFSC°), depths believed to be 
beyond the foraging capabilities of killer whales (Baird 
et al., 2005). Although an abundance of fish species are 
available for this ecotype, the availability and reliance on 
commercially caught fish and discards may likely cause 
populations of killer whales to increase. If the population 
level of killer whales is currently sustained by the depen- 
dence of whales on food obtained during commercial fish- 
ery operations, a significant reduction in the availability 
of caught fish coinciding with possible decreases in abun- 
dance of their natural prey (i.e., salmonids) may cause 
populations of killer whales to decline. 
Conclusions 
Our results provide information on the potential effects that 
commercial groundfish fisheries could have on Alaska killer 
whales, particularly the fish-eating resident stock. Given 
that 100% observer coverage is lacking for all fisheries and 
hauls, the total numbers of interactions, injuries, and mor- 
talities reported here most likely represent underestimates. 
As currently defined, the Alaska resident killer whale 
stock ranges from Southeast Alaska to the Bering Sea 
(Muto et al., 2016). Results of recent studies indicate that 
the Alaska resident killer whale population may be more 
finely structured than previously thought, evidence of the 
® AFSC (Alaska Fisheries Science Center). 2021. Alaska sablefish 
fisheries and assessment. Website. [Last modified 27 August 2021.] 
AT1 transient 
Alaska resident 
GOA-BSAI transient 
GOA-BSAI transient 
Alaska resident 
Alaska resident 
Alaska resident 
Alaska resident 
Alaska resident 
Whale age Whale 
class sex Comment 
Killed by gear 
Killed by propeller 
Killed by gear 
Killed by gear 
Decomposed 
Killed by gear 
Juvenile Decomposed 
Juvenile Hit by propeller 
- Hit by propeller 
Juvenile 
Juvenile 
Juvenile 
Juvenile 
Juvenile 
Juvenile 
likelihood of multiple stocks (Parsons et al., 2013). When 
compared to those of other cetaceans, populations of killer 
whales are small with low birth rates (Olesiuk et al., 1990; 
Dahlheim and Heyning, 1999); therefore, a take level that 
appears small may significantly affect a population of killer 
whales, especially if stock structure is found to be more 
finely structured. Within pods of resident killer whales, 
individual membership is stable over time and can consist 
of 2-3 generations. Given this social structure, the loss of a 
whale or whales from a pod may also have significant impli- 
cations in how individuals in the pod respond to mortality 
events (Busson et al., 2019). 
Given the long history of killer whales interacting with 
Alaska groundfish fishery operations (from the early 
1960s to the present time) it is likely that interactions 
of killer whales with Alaska fisheries, events that lead to 
whale injuries and mortalities, will continue. The range 
where fishery interactions with killer whales occur may 
expand, and these interactions may become more fre- 
quent over time if the following scenarios occur: 1) the 
fishery expands in range and duration, 2) natural pop- 
ulations of fish stocks that are normally targeted by 
killer whales are reduced, 3) populations of killer whales 
increase, 4) more groups of killer whales learn this dep- 
redating behavior and start targeting fishing operations, 
and 5) killer whales become even more dependent on this 
reliable food source. 
Acknowledgments 
Our thanks are extended to the observers that spend 
several months at sea documenting fishery interactions 
involving Alaska killer whales. Staff from the North Pacific 
Observer Program provided instructions for the collection 
and recording of information on marine mammals. J. Waite, 
