Moiseev et al: Effects of pot fishing on the physical condition of Chionoecetes opilio and Chionoecetes bairdi 
249 
mechanisms to cope with such impairments. The rapid 
degradation of He that we observed in our experiments 
may be one of these mechanisms. Increased degradation 
of blood protein, especially of He, has been observed in 
several euryhaline crab species during hyperosmotic 
stress (Gilles, 1977). In our experiments on snow and 
southern Tanner crabs, a similar phenomenon was ob- 
served in stenohaline crabs for the first time. 
A single lift in a pot to the water surface apparently 
does not have significant effects on a crab. All of the 
crabs in our experiments survived at least 1 pot lift, the 
lift when they were captured. Therefore, experiments 8 
and 9 on long-term starvation for 25 and 55 days, re- 
spectively, also can be considered for study of the de- 
layed mortality of crabs after decompression. At the end 
of these experiments, all the animals were alive and had 
a high vitality. The negative effect of decompression sig- 
nificantly increases if the same crab is recaptured with- 
in a few days. However, the probability of such an event 
is very low. Crabs normally move actively in search of 
food; however, it is unlikely that discarded crabs will do 
so while they recover from their first capture. 
On the basis of our experiments, a crab can survive 
(without serious harm) a recapture event that occurs 
more than a few days after its first capture. However, 
a decrease in [He] due to stress response would pose a 
challenge for snow and southern Tanner crabs. If its O 2 
transport system fails to meet all of the demands for 
energy during locomotion, a crab would not be able to 
sustain its normal level of activity. The reduction in [He] 
in crabs after a single lift in a pot obviously would de- 
pend on the initial condition of the animals and external 
factors. As shown in our experiments, this reduction in 
[He] can be very significant. 
Several studies have shown that the synthesis of 
He in crustaceans depends on the quality of food eaten 
(Hagerman, 1983). It is assumed that food, not seawater, 
is the most important source of copper in crustaceans 
(Baden, 1990; and references therein). Copper reserves 
in the hepatopancreas may be used to reconstitute He, 
but significant accumulation of copper was not found 
in our experiments in the hepatopancreas of snow and 
southern Tanner crabs during degradation of He due to 
decompression. Therefore, the recovery of [He] in affect- 
ed crabs would depend greatly on the availability and 
quality composition of the fodder base in their habitat. 
Conclusions 
Our research has shown that pot fishing has a signifi- 
cant effect on the physical condition of snow and south- 
ern Tanner crabs. Gill damage caused by ambient pres- 
sure differences and gas-bubble disease could have long- 
term effects on the vitality of crabs returned to sea from 
commercial catches after sorting. Both species of crabs 
have effective mechanisms for physiological adaptation 
to the adverse effects of pot fishing. The decrease in 
[He] that we observed in affected crabs is a long-term 
adjustment of the internal fluid volume of crabs that 
reduces pressure in damaged gills and optimizes respi- 
ratory circulation. The vital activity of crabs returned 
to sea after sorting of catches would depend on their 
condition before capture and the challenges presented 
by the specific environmental conditions at the time of 
their release. 
Biochemical assays of He have proved to be a useful 
tool for the investigation of the effects of pot fishing 
on the physical condition of snow crab and southern 
Tanner crab. The plasticity of He content constitutes an 
efficient mechanism for crustaceans to cope with meta- 
bolic or environmental challenges. In our experiments, 
the greatest changes in [He] that resulted from stress 
response to impairment of blood flow in gills occurred 
in the most viable crabs. Therefore, [He] can be a useful 
indicator of the health of crabs in conditions that can 
lead to gill dysfunction. 
Acknowledgments 
This research was part of the studies of marine re- 
sources conducted by Russian Federal Research Insti- 
tute of Fisheries and Oceanography, Moscow, Russia. 
We thank the crews of the vessels Sorvind and Evening 
Star for valuable assistance during experiments. We 
are especially grateful to the captain of the Shprvind, 
V. Gubsky, for his unfailing help and support. We ap- 
preciate very much the critical reading by V. Bizikov of 
an earlier version of this manuscript. 
Literature cited 
Baden, S. R, M. H. Depledge, and L. Hagerman. 
1994. Glycogen depletion and altered copper and man- 
ganese handling in Nephrops norvegicus following star- 
vation and exposure to hypoxia. Mar. Ecol. Prog. Ser. 
103:65-72. 
Baden, S. P., L. Pihl, and R. Rosenberg. 
1990. Effect of oxygen depletion on the ecology, blood 
physiology and fishery of the Norway lobster Nephrops 
norvegicus. Mar. Ecol. Prog. Ser. 67:141-155. 
Barrento, S., A. Marques, P. Vaz-Pires, and M. L. Nunes. 
2009. Live shipment of immersed crabs Cancer pagu- 
rus from England to Portugal and recovery in stocking 
tanks: stress parameter characterization. ICES J. Mar. 
Sci. 67:435-443. 
Bell, T. A., and D. V. Lightner. 
1988. A handbook of normal penaeid shrimp histology, 
114 p. World Aquacult. Soc.. Baton Rouge, LA. 
Blatchford, J. G. 
1971. Haemodynamics of Carcinus maenas < L. ). Comp. 
Biochem. Physiol. A: Comp. Physiol. 39:193-202. 
Borisov, V. V., V. Stepanenko, and V. F. Tolkacheva 
2003. Processing technology of crab in the Barents Sea. 
In Red king crab in the Barents Sea, p. 299-311. PIN- 
RO Publ., Murmansk, Russia. [In Russian.] 
