Nontraditional Measurement Devices

September 15, 2016

Question: I am aware that a person must be able to judge the size of their take, but are there any regulations saying what types of devices the person must carry? For example, I recently observed a group that were crabbing and their only means of measurement was a cut zip tie, but it was indeed the correct minimum length. (Katlyn G., Sausalito)

Answer: It varies, but for crab, the only requirement is that the device be capable of accurately measuring the minimum size of the species (California Code of Regulations Title 14, section 29.05(c)). But, sometimes the regulations are very specific about the type of measuring device that is required. Persons taking abalone, for example, “shall carry a fixed-caliper measuring gauge capable of accurately measuring seven inches. The measuring device shall have fixed opposing arms of sufficient length to measure the abalone by placing the gauge over the shell” (CCR Title 14, section 29.15(f)).

An object such as a ruler is capable of accurately measuring rock crab because size limits are “measured by the shortest distance through the body, from edge of shell to edge of shell at the widest part.” For Dungeness crab though, the measurement is “five and three-quarter inches 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).” Because of the curvature of the Dungeness carapace, and the need to measure the straight line distance across a curved surface between the points, a measuring device such as a ruler or zip tie is not accurate. CDFW recommends using a fixed or adjustable caliper for Dungeness crab. It does not have to be commercially purchased and we have seen devices cut out of wood or plastic that work fine.