. Commercial fisheries review. Fisheries; Fish trade. Fig. 2 - Fan aftaoore surveys by John R. Mamung and Charles H. Gilbert. weather permitted, gill nets were set at night. If the weather was too bad for gill-netting, the ves- sels either jogged or reduced their speed at night to avoid large gaps in the trolling coverage. Albacore were taken in significant numbers over a wide area extending from the western bor- der of the survey to the west coast a few miles north of San Francisco. The results are particu- larly gratifying because the distribution of albacore can be rather logically associat
. Commercial fisheries review. Fisheries; Fish trade. Fig. 2 - Fan aftaoore surveys by John R. Mamung and Charles H. Gilbert. weather permitted, gill nets were set at night. If the weather was too bad for gill-netting, the ves- sels either jogged or reduced their speed at night to avoid large gaps in the trolling coverage. Albacore were taken in significant numbers over a wide area extending from the western bor- der of the survey to the west coast a few miles north of San Francisco. The results are particu- larly gratifying because the distribution of albacore can be rather logically associated with the distri- bution of environmental properties. All catches were made in an area with well-defined limits. To the north and east catches were confined by the 57° F. surface isotherm. The southern limit was the northern boundary of the barren, blue, central, northeastern Pacific water as indicated on the chart. This boundary could be readily determined from the bathythermograph sections and also from the clartty of the water. In the barren central water the color was an intense blue, and the Secchi disc could be seen to a depth of 18 fathoms. In the more productive transition zone where albacore were caught the transparency as measured by the Secchi disc was reduced to 10 or 12 fathoms and the color became blue-green. In the coastal water, which did not contain albacore, the Secchi disc could be seen only to depths of 7 to 9 fathoms and the color was green. The fall distribution of albacore, extending from the coast to well offshore in a fairly continu- ous band, suggests that a migration away from the coast is taking place and that it is a gradual ex- odus rather than a rapid, purposeful migration as may have occurred when the albacore were ap- proaching the coast in the spring. cides in time with the formation of the well-devel- oped thermocline in the central North Pacific and the associated high concentrations of surface alba- core as shown in figure 1. In the easte
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