10 
PACIFIC SCIENCE, Vol. XX, January 1966 
DEPTH IN METERS 
90 
80 
70 
60 * 
2 
-n 
50 m 
</> 
40 
30 
20 
10 
Fig. 1. Curves showing: dash line, correlation between mean width of Stage V crabs and depth of water 
from which their host mussels were collected; solid line, correlation between per cent of infestation of host 
mussels and depth of water from which they were removed. 
maturity in relatively shallow waters were, larger 
on an average, than crabs which have developed 
and are collected from deeper waters (Fig. 1). 
This relationship was noted to exist throughout 
the entire one and one-half years that the crabs 
were studied. A further discussion of these cor- 
relations is deferred to another part of this 
paper. 
The highly colored eggs contained in the 
gonads show clearly through the thin mem- 
branous exoskeleton. The color varies during de- 
velopment; initially appearing chrome yellow, 
they appear coffee brown immediately prior to 
their deposition (see Maerz and Paul, plate 9, 
K-2 and plate 15, A-ll). Unless a crab has just 
become ovigerous, eggs are almost always pres- 
ent in some stage of development. It has been 
observed that within a week after egg deposition 
new eggs begin to form and become visible in 
the gonadal tissues. 
While the gonads of Stage IV crabs occa- 
sionally contain developing eggs no Stage IV 
ovigers have been found. It is not until the adult 
Stage V instar is reached that egg deposition oc- 
curs. The smallest oviger found measured 5 mm 
in carapace width; the largest was 13.4 mm. The 
largest crabs collected (i.e., those 14 mm in cara- 
pace width ) , were not ovigerous. However, their 
gonads did contain large numbers of well de- 
veloped eggs and it appeared that these were 
about to be spawned. 
The average carapace width of 187 ovigers 
collected from two depths off Mineral Point (55 
and 130 m) was 8.5 mm. These crabs were re- 
moved from mussels collected during a period 
(November, 1959) when the ovigerous females 
constituted almost 60% of the total population. 
These ovigers were, on the average, 1 mm less 
in carapace width than the average of all the 
Stage V crabs collected during the period of 
study. This is undoubtedly due to the fact that 
many of these crabs were still in their first year 
and had not attained full adult size. In addition, 
part of this sample was taken, as noted, from 
relatively deeper waters where the average size 
of the Stage V is smaller. 
