Not sure what this means, but it struck me that these search locations fall into two sweeping categories:
1. Places that LE has thoroughly searched (Rockridge, Coyote Hills, Don Edwards)
2. Bodies of water that are heavily populated (where a body would likely have shown up due to heavy perimeter traffic unless a boat was used).
They checked the perimeter of Lake Elizabeth by feel, but if I recall correctly, that's it. Also, Berkeley Marina, Lake Temescal and especially Lake Merritt are all heavily trafficked around the perimeter.
Some info on these places of the next search:
Berkeley Marina (which has restaurants, trails, facilities and plenty of hikers/bikers, especially with Cal students returning in August):
http://www.ci.berkeley.ca.us/ContentDisplay.aspx?id=8634
Lake Merritt (with lots of dwellings and businesses surrounding as well as people walking around the lake and people boating and giving gondola rides):
http://www.oaklandnet.com/parks/parks/lakemerritt.asp
Lake Temescal (very popular, especially on the weekends):
http://www.ebparks.org/node/1170
http://z.about.com/d/geology/1/0/i/8/lake-temescal.jpg
http://www.yelp.com/biz/lake-temescal-oakland