Has anyone any information on the arc of radio equipped Japanese trawlers that were set up to detect USN movements near Japan in 1942?
Were they naval manned?
The late actor Rod Steiger,17 at the time,served on one of the US destroyers escorting the Doolittle Raid carrier.He mentioned in a TV interview a few years ago before he died that his deepest regret from WW2 was being involved in the machine-gunning of one of these trawlers---he stated that it was just a civilian fishing vessel,equipped with a radio,and as was the custom at the time the fishermen had their wives and children onboard with them.
Japanese screening trawlers--Doolittle Raid
This maybe of some interest, though other parts within the piece state that the cruiser Nashville sunk the Patrol craft and not a destroyer 
The numerous enemy contacts may give the impression that the Task Force unfortunately encountered an isolated patrol. No such assumption should be made. On the contrary, the variety and the number of patrol craft seen is a strong indication that a heavy patrol in depth is general, at least to the east of Honshu and the Kurils. This patrol probably utilizes hundreds of small craft of various types and extends 700-800 miles offshore. All y surface patrol craft are undoubtedly equipped with effective radio and apparently all are armed with machine guns. Some are camouflaged with two-tone mottled coloring. Evidence supports the belief that they are not equipped with radar
http://www.ibiblio.org/hyperwar/USN/shi ... Tokyo.htmlThe Japanese surface patrol is particularly suited to their eastern sea frontier and is unquestionably effective. Were it equipped with radar, it could be made almost impenetrable with fewer units
From the same siteAt 0310 radar disclosed two enemy surface craft bearing 255°T., distance 21,000 yards, and at 0312 a light was seen approximately on that bearing. Ship went to General Quarters, set Material Condition Afirm and energized the degaussing gear. Course of the Force was changed to 350°T., and at 0341 the two enemy vessels went off the screen bearing 201°T., distance 27,00 yards. Our presence was apparently unnoticed by the enemy and a westerly course was resumed at 0415.
At 05008 fighter patrol and search flight were launched. At 0715 one search plane returned and, by message drop, reported sighting an enemy patrol vessel in Latitude 36° 04' North and Longitude 153° 10' East at 0558 and that he believed he had been seen. later developments indicate that this vessel made the original contact report.
At 0744 an enemy patrol vessel was sighted bearing 221°T., distance approximately 10,000 yards. There was no doubt now that our force had been detected and almost certainly had been reported. Nashville was ordered to sink the patrol vessel by gunfire as the carriers turned into the wind (320°T., 26 knots); Hornet to launch Army B-25's for attack and Enterprise to relieve patrols. The first Army bomber was launched at 0820 approximately 650 miles from Tokyo, a last one was off at 0921. At 0927 the Force commenced retirement on course 090°T., speed 25 knots.
At 1214 radar reported enemy patrol plane bearing 0207deg;T., distance 70,000 yards. This plane came within 64,000 yards of our force but passed off the screen at 1228 bearing 314°T., distance 83,000 yards.
At 1400 two enemy patrol vessels were sighted and attacked by Enterprise planes returning from search. One was sunk and the other damaged. By 1413 the enemy ship still afloat was in sight of our surface forces and Nashville was ordered to attack and sink her. A white flag was broken in the enemy ship and after taking 5 prisoners, Nashville sank her by gunfire. Apparently these two vessels were the same ones reported by radar 0310.
Andy H
pictures of the 90-ton "23rd Nittou Maru"
It was requested by IJN on Dec 1 1941, equipped some MGs, half of the sailors were IJN serviceman. The trowler was commanded by Yokosuka Naval Station.
On Feb 1 1942, the 23rd Nittou Maru was grouped withother 76 former trawlers and auxiliary cruisers "Asaka Maru", "Awata Maru" and "Akagi Maru", as the 22nd Squardon of the 5th Fleet.
Awata Maru
regards