If you hold a stock for at least 61 days of the 121 day period starting 60 days before the dividend and ending 60 days after, then it is taxed like a long term capital gain, or 15%. In other words, you can pay just 15% on the Euroseas dividend gains without actually having to hold it a whole year. Very nice. You'll probably want to do some searches on google about this.
Actually ESEA is incorporated in the Marshall Island. Most of the Shippers are incorporated in tax havens (Bermuda, Bahamas...), where there is absolutely no corporate tax. Another way they get to keep paying high dividends.