This is a fascinating subject, but will all due respect, Moose, you've got one of your basic facts wrong:
Full moon and new moon tides, collectively known as Spring Tides (a term which has nothing to do with the season), are both higher than tides at the quarter moon (neap tide), but full moon tides are generally the highest. This is due to the fact that the moon is closest to the earth when it's full. Like you said, when the moon is full, it's on the opposite side of the earth from the sun. So the gravitational pull of the sun and earth are combined, and the moon is at its perigee (point in its orbit closest to the earth). Since, as you said, "The sun being bigger but farther away will not have as much pull as the smaller moon which is much closer," this results in generally the highest tides of the cycle. I say "generally" because other things, most notably wind and currents, also influence tides, so this doesn't
always hold true. There's a good quick explanation of how it all works at http://astroprofspage.com/archives/247
On this I totally agree. I've never put much stock in solunar tables, though. I just think they overstate the case. But I do believe that the moon has a direct effect on living things. There was a really interesting study done that, I think, scientifically proves this. It's discussed at a website devoted to solunar theory: http://www.solunar.com/the_solunar_theory.aspx
but the gist of it is, Dr. Frank A. Brown, a biologist at Northwestern University, had some live oysters flown in from the east coast to his lab near Chicago. Oysters open their shells with each high tide, and Dr. Brown wanted to see if this was due to the change in ocean levels or to a force from the moon itself. He put them in water and removed them from all sunlight. For the first week they continued to open their shells with the high tides from their ocean home. But by the second week, they had adjusted their shell-openings to when the moon was directly overhead or underfoot in Chicago.
Exactly how this applies to freshwater fish, I don't think anybody knows. But many species do time their spawning around full moons, and I don't think that's just because moonlight makes for a romantic ambiance.
