233 
Abstract— The effects of commercial 
fishing with crab pots on the physical 
condition of the snow crab (Chion- 
oecetes opilio ) and southern Tanner 
crab (C. bairdi) were investigated in 
the Bering Sea and in Russian wa- 
ters of the Sea of Okhotsk. In crabs 
that were subjected to pot hauling, 
the presence of gas embolism and 
the deformation of gill lamellae 
were found in histopathological in- 
vestigations. Crab vitality, which was 
characterized subjectively through 
observation of behavioral responses, 
depended on not only the number of 
pot hauls but also the time between 
hauls. Immediately after repeated 
pot hauls at short time intervals 
(<3 days), we observed a rapid de- 
cline in vitality of crabs. When haul- 
ing intervals were increased to >3 
days, the condition of crabs did not 
significantly change. After repeated 
pot hauls, concentration of the re- 
spiratory pigment hemocyanin ([He]) 
was often lower in the hemolymph 
of crabs than in the hemolymph of 
freshly caught animals. Our research 
indicated that changes in [He] in 
crabs after repeated pot hauls were 
caused by the effects of decompres- 
sion and not by starvation of crabs 
in pots or exposure of crabs to air. 
We suggest that the decrease in [He] 
in hemolymph of snow and southern 
Tanner crabs was a response to the 
adverse effects of decompression and 
air-bubble disease. The decrease in 
[He] in affected crabs may be a re- 
sult of mechanisms that regulate in- 
ternal pressure in damaged gills to 
optimize respiratory circulation. 
Manuscript submitted 20 April 2012. 
Manuscript accepted 15 May 2013. 
Fish. Bull. 111:233-251 (2013). 
doi 10.7755/FB.111.3.3 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necesarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Effects of pot fishing on the physical condition 
of snow crab iChionoecetes opilio ) and southern 
Tanner crab iChionoecetes bairdi ) 
Sergey I. Moiseev (contact author ) 1 
Svetlana A. Moiseeva 2 
Tatyana V. Ryazanova 3 
Anna M. Lapteva 4 
Email address for contact author: moiseev@vniro.ru 
1 Department of Marine Commercial Invertebrates and Algae 
Russian Federal Research Institute of Fisheries and Oceanography 
17 Krasnoselskaya Upper Street 
Moscow, 107140 Russia 
2 Institute of Cell Biophysics 
Russian Academy of Science 
3 Institutskaya Street 
Pushchino, 142290 Russia 
3 Kamchatka Research Institute of Fisheries and Oceanography 
18 Naberezhnaia Street 
Petropavlovsk-Kamchatsky, 683000 Russia 
4 Polar Research Institute of Marine Fisheries and Oceanography 
6 Knipovich Street 
Murmansk, 183038 Russia 
Commercial fishing for crabs in most 
countries is currently carried out 
with the use of baited crab pots. With 
this method of catching crabs, it is 
possible to reduce the effects of fish- 
ing on crab populations by sorting 
the catch, because females, sublegal- 
size males, and crabs with missing 
legs are returned to the sea alive. 
However, some of the discards die 
from body injuries and physiological 
stress associated with temperature 
changes and exposure to air. In sur- 
viving crabs, physiological imbalance 
and altered behavior can affect their 
ecological functions, such as predator 
avoidance, feeding, migration, and 
reproduction. Crabs are discarded in 
high proportions in relation to land- 
ings, and comprehensive information 
on the fate of the discards and their 
survival rate is required to make 
management decisions in a fishery. 
Prediction of discard survivability un- 
der a wide range of fishing conditions 
requires fundamental knowledge of 
the effects of catch-related stressors 
on crab physical condition. 
To date, many studies have exam- 
ined the effects of stressors, such as 
trauma from the hauling of pots, air 
exposure, and adverse temperatures, 
that are associated with capture, 
handling, and discarding of crabs 
(van Tamelen, 2005; Tallack, 2007; 
Stoner, 2009; Darnell et al., 2010). 
Decompression due to fast transport 
through the water column is one of 
the stressors that affect crabs dur- 
ing fishing with pots. Decompression 
results in air-bubble disease, the for- 
mation of gas bubbles in the blood 
and body fluids of crabs (Ryazanova, 
2009). Gas bubbles form in the hemal 
system, organs, and tissues of crabs, 
causing hemal stasis, disruption and 
displacement of tissues. Although 
decompression is a constant and un- 
avoidable adverse factor associated 
with pot fishing, relatively little at- 
tention has been paid to its effects 
on crab condition. Traditionally, de- 
compression is not considered to be a 
substantial source of discard mortal- 
ity (Stoner, 2012). However, gas-bub- 
ble disease caused by decompression 
could have prolonged deleterious ef- 
fects on crab condition because air 
bubbles may persist in the body of a 
crab for a long time (Johnson, 1976). 
