California fishing blocks

Here, I provide maps and data for California’s commercial fishing blocks.

In 1933, the California Department of Fish & Wildlife (CDFW) established a  gridded data collection system defined by 554 blocks at a 10 minute resolution (~18. 5 km, ~11.5 mi).  The delineation of the commercial fishing blocks is summarized here:

  • CDFW (1935) The commercial fish catch of California for the years 1930–1934, inclusive. Fish Bulletin 44: 124p. Bureau of Commercial Fisheries.

The commercial fishing block system has since been extended northward into Oregon and Washington and southward into Central and South America. I created the US portion of the block system from official CDFW shapefiles. I created the international portion of the block system from old CDFW reports. This shapefile is not official, but it is awfully close.

1. U.S. portion of the block system

This US shapefile was created by combining information from four different sources:

  1. California (most blocks): The majority of California blocks came from a shapefile on the CDFW Marine Region GIS website (Commercial_Fishingblocks.shp).
  2. California (Sacramento Delta): However, this shapefile did not include six blocks in the Sacramento Delta (302, 303, 304, 305, 306, 308). These blocks were digitized from a map printed in Hill & Schnieder (1999). See bottom of website for this map.
  3. Oregon & Washington: The blocks for Oregon and Washington were shared directly from the CDFW GIS team (MAN_Westcoast_OrWaFishingBlocks.shp).
  4. Mexico (blocks 901-904): These blocks also had to be provided from CDFW directly (MAN_CA_CalTrawl_220907.shp).

These were merged and modified to include the following attributes:

  • block_id: unique identifier
  • block_type: inshore, midshore, offshore
  • block_lat_dd: block centroid latitude (decimal degrees)
  • block_long_dd:  block centroid longitude (decimal degrees)
  • block_sqkm: block area (sq. km)

The formatted data are available in the following formats:

Please also see the ‘wcfish’ R package to access the data directly from an R package.

A map of just the blocks in California state waters (plus 901-904 and 916 in Mexico’s waters) is below. These are the blocks principally used in California’s fisheries data.

2. International portion of the block system

I digitized a shapefile delineating the international blocks referred to in CDFW fisheries-dependent data using the images below (provided by the CDFW GIS team).

The following blocks are nested within larger blocks:

  • 911 = 912, 913, 914
  • 921 = 922, 923, 924
  • 931 = 932, 933, 934
  • 941 = 942, 943, 944
  • 951 = 952, 953, 954, 955
  • 961 =962, 963, 964, 965
  • 967 = 966, 968, 969
  • 910 = all international blocks north of 27.5°N
  • 920 = all international blocks north of 22.0°N
  • 930 = all international blocks north of 16.25°N
  • 940 = all international blocks north of 7.5°N
  • 950 = all international blocks north of 2°S
  • 960 = all international blocks south of 2°S

In the international block system, the following blocks reflect areas around islands:

  • 917 – Guadalupe island
  • 926 – Alijos Rocks (Rocas Alijos)
  • 936 – Revilla Gigolo Islands
  • 946 – Clipperton Island
  • 955 – Malpelo Island
  • 956 – Cocos Island
  • 957 – Galapagos Islands

I am still perfecting the digitization of these data but a beta version is available here:

Original map
The figure below shows the basis for the digitized international blocks.

Digitized map
This figure shows the results of the block digitization (grey points show island blocks):

This shapefile could be considered official if the vertices printed in the following maps were confirmed by CDFW (I visually estimated them to create the shapefile):

 

Appendix

The figure below illustrates Figure 12 from Hill and Schneider (1999) which shows the existence of blocks in the Sacramento Delta that are not commonly plotted in CDFW’s reference materials on the block system. However, these blocks are occasionally referred to by fishermen, and are thus included in my master shapefile.