Willis, Mel

English

Aquatic Commons

State of Califof!1ld" The Resources Agency
 
Department of Fish and Game
 
Marine Resources Operations
 
California State Fisheries Laboratory
 
Terminal Island~ California
 
CRUISE REPORT 66-S-7 CRAB 
Prepared by Mel Willis 
Vessel: 
Dates:	 Depart San Pedro~ November 10~ 1966 
Return San Pedro~ December 10~ 1966 
Areas:	 Coastal waters from False Cape to Crescent City. 
Purpose: L	 To determine pre-season abundance and condition of 
legal~ 159 mm or greater shoulder width (6 1/4 inches) 
and sub-legal, less than 159 mm shoulder width, mar­
ket crabs~ Cancer magister~ in the Eureka-Crescent 
City area for predicting the 1966-67 season. 
2. To tag sub-legal male crabs for growth studies. 
Operations:	 Ten commercial crab traps were fished at 40 randomly se~ 
lected stations between False Cape and Crescent City 
(Figures l~ 2 9 and 3). Two stations were fished for four 
nights, ten for two nights~ and 28 for one night. Incle­
ment weather prevented us from sampling north of Crescent 
City. 
Thirty stations were sampled for incoming year class 
strengths by	 a gulf shrimp trawl with a 41 foot head 
rope. These	 tows were 1/2 mile in length and adjacent 
to the trapping stations. 
Shoulder width of crabs was recorded for the entire catch. 
Shell condition determinations were made for all male 
crabs. Male	 crabs~ less than 6 1/4 inches shoulder width, 
were tagged with	 suture tags and released at one of three 
locations~ Humboldt Bar 9 Trinidad Head, or Crescent City 
Harbor. 
Results:	 Three of the 400 traps set were lost. The rema1n1ng 397 
traps caught 8~727 crabs (Table 1). The adjusted average 
catch per trap per day was 16 0 3 and 4.3 legal and sub­
legal male crabs respectively (Table 2). The highest 
station catch (34.4 legals per trap) was recorded south 
of Redding Rock. 
The thirty trawls produced approximately 9,100 crabs of 
the 1966 year class (21-58 mm)~ 224 males (88-158 mm), 
five females 9 and 86 commercial sized males (159-210 mm). 
-2­
Marketable sized crabs were in better condition this year 
than last. Overall, 7.1 percent of these were soft com­
pared with last year's 20.5 percent. 
The modal length for commercial size crabs was 185 mm 
shoulder width compared to 170 mm last year. Sixty percent 
of these were 180 mm or larger, compared to 25 percent last 
year. 
Mating marks were noted on 15.3 percent and 2.0 percent of 
the sub-legal and legal males, respectively. 
Based on pre-season surveys and season catches for the 
past 3 years and this year's survey, the total crab catch 
for	 the Fort Bragg-Eureka-Crescent City area should fall 
between 6.8 and 8.9 million pounds. This would exceed the 
20 year average of 6.1 million pounds for the second con­
secutive year	 since 1961. 
We tagged and released 718 male crabs ranging in size from 
95 mm to 159 mm. Two-hunqred twenty-eight were released in 
Crescent City Harbor, 71 at Trinidad Head, and 419 at the 
Humbold~ Bay entrance. 
Personnel: R.	 B. Mitchell, Vessel Captain 
D.	 Gotshall, Biologist-in-charge, November 22-29 
Decembe~ 1-4. 
M. Willis, Biologist, November 22-29, December 1-4. 
Biologist-in-charge,	 November 14-21, 30, 
December 5. 
M. Stuart, Seasonal Aid, November 14 - December 5. 
J.	 Ni~lson, Biologist, Oregon Fish Commission, 
November 17-25. 
S. Taylor, Biologist, MRO, November 17-18, 24. 
G. Merriman, Reporter, Crescent City American, 
November 25. 
Dr. J. DeMartini, Humboldt State College, December 3. 
Dr. J. Pierce, Humboldt State College, December 3. 
T. Chess, Humboldt State College, December 3. 
1-11-67/125 
MRO-TI/fk 
)
; 
-3­
, 
TABLE 1 
TOTAL CRAB CATCH
 
Leg,al Sub-legal Female Total 
False Cape 3986 1191 4 5181 
to Trinidad 
Pat ricks Point 2943 599 4 3546 
to Crescent City 
Total 6929 1790 8 8727 
TABLE 2 
ADJUSTED CATCH PER TRAP PER DAY 
Legal Sub-legal 
False Cape 
to Trinidad 18.,8 5.7 
Patricks Point 
to Crescent City 13,,8 2.9, ' 
Average 16.3 4.3 
Location of Sampling 1,18.5 , ,' Had 
1 , RiverStations for Crab 2i!.9 - : 19.1 ,Cruise 66-s-7 ~ 28.7 1 :
 
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Location of Sampling 
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Figure 3 


Cruise Report 66-S-7 Crab

http://aquaticcommons.org/2372/1/CR_66-S-7.pdf

Cruise Report 66-S-7 Crab

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