A warning against a fish-suffocating red tide was issued Monday along parts of South Korea's southern coast, a state fisheries institute said.

The National Fisheries Research and Development Institute issued the warning, the first so far this year, at 6 p.m. on waters off southern coastal areas from Namhae to Geoje.

Up to 1,500 cochlodinium, or red-tide-causing algae, were found in 1 milliliter of saltwater in the sea, the institute said, adding that this summer's high level of sunlight and higher-than-average water temperatures in the ocean provided an environment conducive for the growth of the algae.  

A red tide is a natural phenomenon believed to be caused by a combination of high temperatures, salinity and nutrients. Some experts believe that when these conditions meet low wind and certain rain levels, a toxic bacteria, called gymnodinium breve algae, multiplies rapidly.

South Korea has suffered from red tides almost every August along its southern coast amid rising sea water temperatures. But over the past several years, no massive harmful red tide has occurred. Red tides kill fish and cause respiratory irritation in humans.

The institute forecast that the red tide will spread wider and faster all summer long. (Yonhap News)