Moiseev et al: Effects of pot fishing on the physical condition of Chionoecetes opilio and Chionoecetes bairdi 
247 
experimental conditions. Therefore, the structure of the 
He’s remained unchanged in our experiments. 
Changes in [He] in our experiments, therefore, were 
likely caused by physical and functional impairments 
that resulted from pot hauling. Changes in vitality of 
animals and [He] depended not only on the number of 
pot lifts but also on the time intervals between them. 
Decreases in [He] were related to high vitality of crabs. 
These observations indicate that the physiological im- 
balances caused by repeated pot hauls can be corrected 
if the time interval until the next haul is sufficiently 
long. It is also likely that the stress response involves 
changes in [He]. 
Copper content in the hepatopancreas 
It has been postulated that copper metabolism in de- 
capod crustaceans associated with degradation of He 
(during starvation or before molting) includes the pro- 
cesses of copper translocation to the hepatopancreas and 
storage in the form of complexes with glutathione and 
copper-binding proteins (Djangmah, 1970; Brouwer et 
ah, 2002). Brouwer et al. (2002) showed that metabo- 
lism of the copper-binding protein metallothionein in 
the hepatopancreas of blue crab was related to molt 
stage. Metallothionein isoform 3 was present in premolt 
and softshell crab and was absent in hepatopancreas of 
intermolt crab. Emergence of this protein appears to co- 
incide with a decrease in He synthesis and increase in 
He degradation. 
In experiment 9, after starvation within a period of 
55 days, a significant increase in mean copper concen- 
tration in the hepatopancreas of southern Tanner crab 
was found. We also observed a significant decrease in 
mean [He] in these crabs, compared with He levels in 
control animals immediately after capture. However, 
in experiments 6 and 7, which involved repeated pot 
hauls at short time intervals, there were no significant 
changes in hepatopancreas copper levels in snow and 
southern Tanner crabs that had reduced [He] (Table 3). 
Therefore, much of the copper that was released during 
He degradation caused by pot hauling did not accumu- 
late in the hepatopancreas and was probably excreted 
from the body. This result may be explained by low lev- 
els of copper-binding proteins in the hepatopancreas 
of adult males of snow and southern Tanner crabs be- 
cause they do not have periods of active synthesis and 
degradation of He associated with molt stage. 
Ionic composition of hemolymph 
Plasma ion (Na + , K + , Cl - , Ca 2+ , Mg 2+ ) concentrations 
were measured to examine ionoregulatory changes 
at the gills of affected crabs. The snow and southern 
Tanner crabs are typical of other stenohaline marine 
crustaceans in that their hemolymph is isosmotic with 
their environmental seawater but the ionic composition 
of their hemolymph can differ considerably from the 
composition of seawater around them (Prosser, 1973). 
In the hemolymph of snow crab and southern Tanner 
crab, [K + ] is considerably higher and [Mg 2+ ] is consid- 
erably lower than concentrations in the surrounding 
seawater. 
Biochemical analysis of stress responses in crusta- 
ceans have shown that various stressors can alter ion 
concentrations in hemolymph and, therefore, that ions 
may be used as indicators of physiological stress (Ston- 
er, 2012; and references therein). However, the exact 
mechanisms and physiological causes of ionic changes 
are usually difficult to explain. Several studies have 
reported increased [Ca 2+ ] and concentration of bicarbon- 
ate ion ( HCO 3 - ) in crustacean hemolymph during aerial 
exposure, which may indicate the mobilization of cal- 
cium carbonate (CaC 03 ) from internal sources, such as 
calcified exoskeleton to compensate for low pH (Taylor 
and Whiteley, 1989; Lorenzon et al., 2007). [Mg 2+ ] can be 
elevated in hemolymph of open-wounded crabs because 
of entry of magnesium-rich seawater (Uhlmann et al., 
2009). Changes in [K + ], [Na + ], and [Cl - ] in hemolymph 
of crustaceans are highly variable with stress (Stoner, 
2012 ; and references therein). 
In experiment 1, which involved repeated pot hauls 
at long time intervals, and in experiment 9, which 
investigated long-term starvation in pots, [K + ] in he- 
molymph of snow crab and southern Tanner crab 
were significantly lower compared with [K + ] in freshly 
caught crabs (Table 4). It should be noted that, in ex- 
periments 1 and 9, mean [He] in hemolymph of snow 
crab and southern Tanner crab were significantly lower 
compared with mean [He] in control crab immediately 
after capture. 
An essential role is played by K + in the mainte- 
nance of the difference in electrical potential across the 
plasma membrane of a cell, typically referred to as the 
“membrane potential.” That physicochemical regula- 
tory function enables normal nerve impulse transmis- 
sion, normal contraction of muscle fibers, and normal 
heart function. Interestingly, changes in the ionic com- 
position of the hemolymph of crabs after repeated pot 
hauls were the same as changes in the ionic composi- 
tion during long-term starvation, when metabolic rate 
and physical activity probably were reduced. However, 
the meaning of these changes needs to be studied. 
Effects of decompression on crab condition 
Changes in ambient pressure during lifts of crabs in 
pots to the water surface are an unavoidable adverse 
factor that affects the crabs. Studies of the blood circu- 
lation of brachyuran crabs, including snow and south- 
ern Tanner crabs, indicate that fluctuations of ambient 
pressure have the greatest effect on the blood flowing 
in the gills (Taylor, 1990). The phyllobranchiate gills of 
brachyuran crabs consist of 2 alternating rows of close- 
ly spaced, flattened lamellae that extend forward and 
backward from a median shaft. Each lamella consists of 
single layer of epithelial cells lining the cuticle. Pillar 
cells, which are located in the cellular layers in oppo- 
