By Tom Kutcher, BayKeeper
So, I hate to report that it’s happening again this year. And it’s bigger and earlier this time. It’s another fish kill of adult menhaden (locally known as pogies) in the Seekonk River. According to local fishermen hanging out at the new DEM boat ramp up near the Pawtucket Falls, dribs and drabs of dead and dying fish have been showing up there for about a week. But today there were hundreds or even thousands of dead fish in the water and on shore, and many more were gulping for air and doing their sad, telltale “death spirals” at the surface, indicating severe stress from oxygen deprivation.
When the water is warm, tides are weak, and weather is dry, the Seekonk River grows stagnant. These are the unfortunate conditions that allow algae to change from fish food to part of a harmful cycle of pollution. Excessive nutrients, stemming mostly from insufficiently-treated wastewater and untreated street runoff from towns and cities along the river (in both Rhode Island and Massachusetts), cause algae to grow rampant and clog the water column. As these algae blooms decompose, oxygen in the water column is consumed and, particularly under stagnant conditions, depleted.
If pogies are chased by predator fish, such as striped bass (stripers) or bluefish, into water where the oxygen is depleted, they can die. That seems to be what has happened this week. The fishermen reported a great run of stripers in the Seekonk River last week, chasing abundant pogies. While stripers are accustomed to dealing with lower oxygen found in upper estuaries, where they breed and overwinter, open-water-loving pogies are not. So apparently, when the stripers chased the pogies up into the river, the pogies could not breathe.
The ironic piece to this story is that abundant pogies and bass in the river is a great sign of recovery, in contrast to past decades of fishless water. But, as the Seekonk River recovers from centuries of abuse and becomes more habitable for fish and other critters, low oxygen events resulting from excess nutrient loads become more visible as those fish are killed. The take-home is that although the Seekonk River and the entire Upper Bay are recovering in grand fashion, there is still a lot of work to do.
Read Tracee Herbaugh's ProJo Article on the subject as well.