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Yaquina Bay Crab Research
Yaquina Bay Crab Research
Crab Research Results



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Dungeness crab abundance

In this figure, the total number of Dungeness crab that we capture in our research project varies depending on the season.  The numbers represent the average number of crab of all sizes that are found in each pot when they are pulled.  This a reflection of total abundance, which is greatest in the fall and least in the spring.  The number of crab per pull in Yaquina Bay and Alsea Bay is very similar to each other, and follows the same seasonal patterns.  Since the beginning of this research in May 2007, over 36,000 crab have been captured and measured in Yaquina and Alsea bays.

 

Number of crabs

Species composition

In Yaquina Bay, red rock crab and Pacific rock crab are captured along with Dungeness crab during our research sampling.  Dungeness are usually the most abundant crab captured in the pots, but in the spring red rock crab comprise a significant portion of the catch.  This is primarily due to the reduced abundance of Dungeness crab during the spring.  In Alsea Bay, our research sampling has never caught a red rock or Pacific rock crab, probably due to the lack of rocky habitat which rock crab prefer.
Proportion of Yaquina bay total catch by species

Sex ratio

The crab research conducted by ODFW has revealed that males and female Dungeness crabs are not caught in equal numbers.  Overall, most of the Dungeness crab we catch are males, This is especially true in the winter.  In the late summer-early fall, the male/female ratio is closer to 50/50.  Possible reasons for these proportions varying throughout the season include the timing of various life history events, including molting, mating, egg extrusion, movements, etc.

 

 

Yaquina bay crab sex ratio from research pots

Legal sized Dungeness crab

Of particular interest to anyone wanting to catch Dungeness crab in Oregon’s bays is the best time of year to try bay crabbing.  The ODFW crab research has found that in Yaquina and Alsea the best time to go bay crabbing is in the late summer through fall.  This time of year has the greatest availability of male crabs over the legal size limit (5 3/4” across the back NOT including the spines) because the annual summer molt has replenished the supply of legal-sized crab.  Additionally, during this time male crabs from the ocean move into the bays.  Male Dungeness crab in summer are typically soft because most have recently molted, but by the fall most of the legal-sized crab are firm and are filling out with meat.

 

number of legal Dungeness crab per pull

Research vs recreational catch

Coinciding with the crab research sampling, ODFW conducts a survey of recreational crabbers in Yaquina Bay and Alsea Bay.  The Catch per Unit Effort (CPUE) is a measure of success in the recreational fishery, often expressed as the average crabs per person interviewed during the survey.  The ODFW research success rates were standardized to make them comparable to the recreational fishery, and the results show that the recreational and research crabbing success rates follow the same seasonal pattern: more legal-sized male Dungeness crab are captured in the late summer and fall than any other time of the year.

 

 
Sport versus research catch

 

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