California Department of Fish and Wildlife

Comparison of CPUE and Visual Surveys of Nearshore Fishes

Fishermen, CDFW and University Scientists collaborate on nearshore research -- A cooperative research project compares methods of nearshore fish assessment

Principal Investigator:

Dr. Richard M. Starr
University of California
Sea Grant Extension Program
8272 Moss Landing Road
Moss Landing, CA 95039
(831) 771-4442; FAX (831) 632-4441
Starr@mlml.calstate.edu

Co-principal Investigator:

Dr. Mark Carr
University of California Santa Cruz
100 Schaffer Road
University of California
Santa Cruz, CA 95060
(831) 459 3958
carr@biology.ucsc

Affiliated Fishermen and Researchers:

  • David VenTresca, California Department of Fish and Wildlife
  • Dave Osorio, California Department of Fish and Wildlife
  • Mike Ricketts, Commercial Fisherman
  • Sal Pitruzzello, Commercial Fisherman
  • Giovanni Nevoloso, Commercial Fisherman
  • The Alliance of Communities for Sustainable Fisheries

Introduction

The California Marine Life Management Act requires the California Department of Fish and Wildlife to develop management plans for nearshore fisheries that are based on scientific information about stock sizes (Weber and Heneman 2000). The California Marine Life Protection Act also requires that decisions about marine protected areas be based on sound biological information. Typically, fishery managers use fishery-dependent data and/or fishery-independent surveys to estimate population sizes of marine species. Fishery catch and effort data can provide a robust database for use in developing population models and for evaluating changes in abundance indices over time. Fishery-independent information, such as data collected by visual surveys, provides additional information about relative abundance and biological characteristics of fished populations. Currently, however, relatively little fishery-dependent or independent information is available to evaluate nearshore fish populations. The California Department of Fish and Wildlife (CDFW) has collected nearshore landings, some logbook, and other fishery-dependent information. In conjunction with other marine scientists, CDFW coordinated the development of a standardized protocol for visually assessing nearshore fishes and invertebrates.

As fishery-dependent and fishery-independent information are collected, it is important to understand what the data represent, i.e., how the different sampling techniques relate to one another, how they are affected by environmental variation, and how they vary in time and space. With respect to fishery-dependent information, it is important to know the variability in catch patterns between gear type, habitat type, depth range, and oceanographic conditions. With respect to fishery-independent information, it is also important to know the variability in abundance between sites, depth ranges and oceanographic conditions. Finally, to maximize the benefits of both fishery-dependent and independent information, it is important to understand the relationship between the two types of data collection methods- CPUE surveys and visual fish density surveys.

This project brought together a group of fishermen, CDFW staff, and university researchers, who collaborated to investigate relationships between catch-per-unit-effort (CPUE) of typical nearshore commercial fishing operations and estimates of fish density derived from scuba surveys. We also recorded bycatch of different gear types. Information obtained in this study will be used by fishery managers to improve estimates of population abundance of nearshore fishes, and to improve estimates of bycatch in nearshore fisheries. The process of generating this information will help bridge the cultural gap that exists between fishermen and CDFW scientists, relative to understanding the differences between fishery-dependent and fishery-independent data sources.

The study will evaluate differences between CPUE of typical nearshore fishing gear and scuba surveys in the Monterey Bay area. The results should provide useful information with which to understand the relationship between fishery-dependent (catch rates) and fishery-independent (scuba) surveys in different habitat types. The field work for this project took place in Carmel Bay, Monterey Co. and was conducted by Rick Starr (University of California Sea Grant Program) and Mark Carr (University of California Santa Cruz). The study will provide information about relationships between fishery-dependent and independent surveys, and how environmental variation affects estimates of relative abundance in time and space.