Is a Tape Measure Good Enough?

January 30, 2020

Question: I’ve heard folks say you need a crab gauge to measure crab. Would a tape measure be sufficient? (Benson)

Answer: Although not prohibited by law, a tape measure is not recommended. The minimum legal size of crab is five and three-quarters inches for a Dungeness crab measured by the shortest distance through the body from edge of shell to edge of shell directly in front of and excluding the points (lateral spines), as per California Code of Regulations (CCR) Title 14, section 29.85.

There is simply too much room for human error in using a tape measure compared to a crab gauge. For instance, the natural swell in the crab’s body could lead one to believe a crab is of legal size if a tape measure is extended directly over the body when, in fact, the crab is undersized. Crab gauges are inexpensive and readily available at bait and tackle shops in areas where crabbing is popular. There’s no reason to risk a citation by using a tape measure.

And since we’re on the subject, one of the more common violations our wildlife officers encounter in the field is the take of undersized Dungeness crabs by new recreational crabbers who measure their crabs incorrectly. The regulations cited above state the measurement cannot include the lateral spines or points that extend from the crab’s body. Many inexperienced crabbers, however, incorrectly include the spines in measuring their crabs, leading to the illegal take of undersized crabs.

Here’s the illustration from the reg book on crab measuring: