. Commercial fisheries review. Fisheries; Fish trade. 31 60°N. SOON. 40'' 60°N, 50°N. 40°N I40''E. ISCE. leO'E. I70''E 180 ircw. lecw. iso'w. kcw. iscw. izo'w. Fig, 3 - Schematic diagram of the depth of 34 %o isohaline, showing area of minimum depth (shaded) south of Alaska PeninsiHa and Aleutian Islands. That other properties are also advected with the dilute runoff is not extensively docu- mented because most of the elements amen- able to analysis at sea arenonconservative-- in other words, they are modified by other processes. These properties are primarily nutrients such as phosphate, s
. Commercial fisheries review. Fisheries; Fish trade. 31 60°N. SOON. 40'' 60°N, 50°N. 40°N I40''E. ISCE. leO'E. I70''E 180 ircw. lecw. iso'w. kcw. iscw. izo'w. Fig, 3 - Schematic diagram of the depth of 34 %o isohaline, showing area of minimum depth (shaded) south of Alaska PeninsiHa and Aleutian Islands. That other properties are also advected with the dilute runoff is not extensively docu- mented because most of the elements amen- able to analysis at sea arenonconservative-- in other words, they are modified by other processes. These properties are primarily nutrients such as phosphate, silicate, or nitrate, which may be consumed by living plants--or replenished by decaying plants and animals as the plume moves seaward. Improvements in chemical analytical tech- niques for accurate determination of trace elements and other chemical constituents of sea water are sorely needed; such improve- ments will greatly aid in determining where in the ocean a homing salmon first chemically detects its natal stream, if indeed it ever loses contact. Surface temperature was not discussed in the previous article because the so-called latitudinal "march" of isotherms, northward in spring and southward in summer as a re- sult of the increasing and decreasing latitude of the sun, is well documented. From ships and satellites, we now obtain data at 5-day intervals on distributions of surface temper- ature, but no data on distributions of surface salinity. This is unfortunate because the salinities would be more useful than the tem- peratures in determining flow. Such obser- vations are not made aboard "Ships of Op- portunity" (merchant vessels), and remote sensing of salinity is not possible. Equilibra- tion of heat at the sea-air interface and other processes tend to mask advective tempera- ture anomalies, but salinity anomalies in some areas can be traced for great distances. Surface salinity across the North Pacific Ocean above lat. 45° N is about 33 %o.
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