Dr. Richard M. Starr

CATCH PER UNIT EFFORT (CPUE) PROJECT: 2003 & 2005

Comparing Sampling Methods for Surveying Nearshore Fishes.
A Collaboration between Fishermen, CDFG, and University Scientists

The California Marine Life Management Act and Marine Life Protection Act have created an increased interest in the development of fine-scaled fishery management plans. Currently, however, little information exists with which to manage fisheries in relatively small sections of the coast. One way to gather data appropriate for fine-scale management is to use a variety of information obtained from multiple sampling methods. Yet before information can be combined, it is important to understand how the different sampling methods relate to one another and how they vary in time and space.

Since 2003, we have collaborated with commercial fishermen and scientists from other universities and state agencies to compare methodologies for surveying nearshore fishes in Carmel Bay. The goals of the project were to obtain estimates of relative abundance (CPUE) and population estimates (from tag-recapture ratios) from three surface fishing gears (traps, sticks, and handlines) and from standardized SCUBA surveys. To utilize their expertise, we met with the fishermen before the project began to discuss project objectives and develop standardized sampling procedures.

Our results indicate that surface based sampling and diver surveys each have strengths, weaknesses, and biases for estimating the relative abundance of nearshore fishes, fish sizes, and species compositions. Additionally, we found catch rates of different gear types to be highly variable over small-scale temporal scales, and were significantly affected by habitat and depth. We did not find any statistically significant relationships among methodologies for generating CPUE estimates. However, variation in CPUE, as measured by standard error, leveled after 450 units of sampling (approximately 10 days) for both sticks and traps. Population estimates, generated from tag-recapture ratios, were much more similar among sampling methodologies than were CPUE estimates.

Participating Scientists: Dr. Rick Starr (Sea Grant, MLML), Dr. Mark Carr (UCSC), Ashley Greenley (MLML), Dan Malone (UCSC), Kristen Green (MLML), and Dave Osorio (CDFG)

Funding: Commonweal Ocean Policy Program

Sal Pitruzzello with lingcod.

Ashley Greenley with a lingcod.

Cabezon with an external dart tag.