20 
PACIFIC SCIENCE, Vol. XVIII, January 1964 
ranged from 10,000 to 33,000. For 17 indivi- 
duals counted, the average productivity per 
brood was 20,540 eggs per female. Usually there 
is only one brood per year and those females 
producing a second brood or, perhaps more 
correctly, a late brood, are rare. Thus, the average 
of 20,540 represents the seasonal productivity 
for this species. 
Cancer productus 
HABITAT: Geographically, C. productus is 
found from Alaska to Magdalena Bay, Baja 
California, in two major types of habitats. Pri- 
marily it is found in bays and estuaries, such 
as Puget Sound, Grays Harbor, Willapa Bay, 
and other similar areas in the state of Washing- 
ton and up and down the coast. The second type 
of habitat is that classified as a "protected rocky 
coast,” which could be characterized by any of 
the small rocky bays or inlets along the open 
ocean front where rocky headlands or other 
rocky obstructions cause wave refraction and 
thus create a zone of less violent action. This 
second type of habitat is perhaps a minor one. 
C. productus is fo $n d under these conditions at 
the Tacoma Narrows in Puget Sound. 
The writer considers the primary habitat of 
this species to be that of the large bay or sound. 
Schmitt (1921:222) notes that C. productus is 
remarkably absent from fine sand and mud sub- 
strates in San Francisco Bay. Rather, he lists 
this species as being found largely upon sand, 
gravel, or rock substrates. Cleaver (1949:70) 
mentions that C. magister remains generally in 
areas with sand or mud bottoms in the bays 
along the Washington coast. He states that while 
this species may occasionally be found on rock 
or gravel, it is, as a rule, replaced by C. pro- 
ductus, which is predominant in such situations. 
Weymouth (1914:124) suggests that C. pro- 
ductus lacks a straining apparatus to prevent 
fine particles of mud and sand from entering the 
gill chamber. Thus, this species is restricted to 
those zones which will allow it to bury itself 
in the substrate without clogging the gill 
chambers. Our own observations in Puget Sound 
coincide with those of Schmitt and other work- 
ers, for this species is frequently found around 
the Point Defiance boathouse, under the dock 
at Titlow Beach, and in many similar areas in 
which the substrate consists of hard packed sand, 
gravel, or broken shell fragments. 
Our observations suggest that this species is 
equally active at night or in the daytime. Due to 
its large size C. productus has few enemies 
within the zone of its normal activity. While 
many of the very large rock fishes, octopi, or 
other marine animals will prey upon this species, 
and other crabs as well, these predators are 
normally absent in the most favored micro- 
habitat of C. productus. When inactive this 
species may be found hiding at the base of ; 
pilings, where it buries itself beneath gravel | 
or shell fragments, or else hides beneath sunken i 
logs or rocks which loosely cover the substrate. 
Extremely rarely does one find this species hid- 
ing in hydrogen-sulfide mud. 
The time and place of activity or inactivity 
of C. productus seems to be governed mainly by 
the "choice” of the individual, its age or sex, 
or the particular phase of reproductive activity 
or molting activity carried on. A survey of our 
bimonthly reports for 2 years of collecting 
shows that from January through May males are 
predominant in the intertidal zone, while fe- 
males are almost totally lacking. Those few fe- 
males encountered during this time were, with 
one exception, without eggs. From the end of 
May on into June the sexes are almost equally 
distributed in numbers, while the females pre- 
dominate throughout the summer months up 
into early October. Then the males and females 
are almost proportional in numbers throughout 
November and December. Males were never 
totally wanting in our field collecting at any 
time of the year, as were female specimens. As 
will be noted under Reproduction, presence or 
absence coincides well with the period of egg 
development, molting of the males, and the 
times of copulation. Juvenile specimens were 
abundant only in areas adjacent to those occu- 
pied by the adult individuals. These observa- 
tions suggest that males and females may have a 
horizontal migration to the deeper water during 
periods of the year, or they may become inactive 
and extremely secretive and thus remain care- 
fully hidden within the habitat area. Cleaver 
(1949:70) reports for C. magister that: 
An interesting feature of this species is the tendency 
to aggregate by size and sex. Until a width of two or 
three inches is reached, crabs of both sexes are found 
