Long et al.: Effects of ghost fishing on the population of Parcilithodes camtschaticus in Womens Bay, Alaska 
109 
for crustaceans (Leffler, 1972), or shortly after molting, 
when they are particularly vulnerable to predation 
(Shirley et ah, 1990; Ryer et ah, 1997; Marshall et ah, 
2005). However, for the intermolt period of red king 
crab, our estimate is likely an accurate picture of mor- 
tality. Roughly a third of all crabs that died suffered 
predation, a sixth of them were poached, and the cause 
of death could not be determined for the remaining 
half. Ironically, no tagged male crabs of legal size were 
taken by fishermen in this study; no doubt, zero fishing 
mortality was due in part to the fact that few legal-size 
crabs were tagged and to the low fishing mortality for 
this species in the study area (Fig. 2). During another 
study in Bristol Bay, instantaneous mortality rates es- 
timated for the red king crab ranged from 0.02 to 1.75 
yearn 1 and most estimates ranged between 0.02 and 
1.00 year -1 (reviewed in Zheng, 2005). Our estimates 
for rates of mortality from sources other than ghost 
fishing were 0.30 and 0.27 year -1 , values that fall well 
within that range. 
The estimated mortality rate from ghost fishing is 
high enough to have a devastating effect on the popu- 
lation of red king crab in Womens Bay. A 60-mm-CL 
crab is at least 2 years from attaining reproductive 
maturity (Weber, 1967), and females must brood their 
eggs for a year after attaining maturity before they can 
reproduce successfully for the first time (Stevens and 
Swiney, 2007). Therefore, on the basis of our conser- 
vative and upper estimates of ghostfishing mortality 
(16-37% per year), we estimate, with the assumption 
that crabs become vulnerable to ghost fishing at a size 
of 60 mm CL, that 29-60% of male crabs and 41-75% 
of female crabs were killed in ghostfishing gear before 
they were able to reproduce for the first time during 
our study. 
To put those high mortality rates in context, the tar- 
get rate for fishing mortality designed to maintain a 
healthy stock size in Bristol Bay is <15% of the mature 
male biomass and only negligible numbers of nontar- 
geted mature female and immature crabs are allowed 
to be taken as bycatch (Zheng and Siddeek 5 ). Because 
the fecundity of females increases more than an order 
of magnitude with crab size (Swiney et ah, 2012), ghost 
fishing keeps many females from reaching their full 
reproductive potential by killing them when they are 
small and have relatively low fecundity; moreover, be- 
cause ghost fishing indiscriminately removes both im- 
mature and mature crabs, including ovigerous females, 
it compounds its effects as it reduces the reproductive 
capacity of the local population, as well as the size of 
the local population itself. 
5 Zheng , J., and M. S. M. Siddeek. 2010. Bristol Bay red 
king crab stock assessment in spring 2010. In Stock assess- 
ment and fishery evaluation report for the king and Tanner 
crab fisheries of the Bering Sea and Aleutian Islands regions. 
2010 Crab SAFE, p. 135-246. North Pacific Fishery Man- 
agement Council, Anchorage, AK. [Available from http:// 
www.npfmc.org/wp-content/PDFdocuments/resources/SAFE/ 
CrabSAFE/CRABSAFE2010.pdf.l 
How typical Womens Bay may be among areas in 
the Gulf of Alaska is unknown. Its proximity to the 
city of Kodiak makes it a popular site for sport, sub- 
sistence, and commercial fisheries. The greater fishing 
effort and boat traffic in this bay, compared with such 
activities in other areas, has likely led to a higher rate 
of fishing gear loss. Additionally, participants in the 
sport and subsistence fisheries may be less likely to 
know about or comply with the requirements for escape 
mechanisms on pots. Supporting this premise, home- 
made pots found in our study were almost certainly 
not used for commercial purposes, and their structure 
was frequently noncompliant with established require- 
ments for escape rings and biodegradable release. En- 
forcement of regulations in the sport and subsistence 
fisheries also probably is less stringent than it is in the 
commercial fishery because there are far fewer com- 
mercial fishermen to monitor (who fish with numerous 
pots per boat) than subsistence fishermen (who fish 
with few pots per boat). It is likely that other coastal 
bodies of water with high densities of crabs near pop- 
ulation centers in Alaska have similar rates of ghost 
fishing and that bodies of water farther from human 
population centers have a lower rate. 
If ghost fishing does have the profound effect that 
is indicated by our data on the population of red king 
crab in Womens Bay, measures to reduce ghost fish- 
ing are warranted. Of the different types of gear, crab 
pots were the major cause of ghostfishing mortality; 
in contrast, gill nets were responsible for only one 
death. Therefore, efforts to reduce ghost fishing on the 
red king crab should focus on pots (although remov- 
ing nets may be a priority for other species, such as 
marine birds [Good et al., 2009; 2010]). Existing ghost 
pots can be located by side-scan sonar and removed by 
grappling (Stevens et al., 2000) and their threat elimi- 
nated as a result. Removal of ghost pots would be most 
effective in shallow areas of high fishing intensity, such 
as Womens Bay. 
The observed effects of ice deserve a special note. 
Womens Bay frequently had a fresh water lens from 
various freshwater sources (Long, 1972) that can freeze 
during the winter. Ice embedded pot floats and when 
the ice broke up, pots were dragged into deeper water, 
where their float lines were not long enough to reach 
the surface, or they were dragged into shallow water, 
where pot owners were not likely to look for them. The 
strain of being dragged across the bottom of the bay 
could have caused lines to break. Additionally, tides or 
wind moved thin sheets of ice that abraded floats and 
lines and caused them to sink. Ice and boats dragged 
pots across the bottom of the bay, flipping some of them 
upside down or partially burying them — outcomes that, 
in the case of Dungeness crab pots, rendered the es- 
cape mechanism, if present, ineffective. If areas af- 
fected by ice were closed during months when ice was 
a concern, the rate of pot loss could be reduced. This 
closure would not substantially affect fishing because 
crab pots cannot be checked during times of ice cover. 
