Peanut Bunker Can’t Hang: Exploring What Causes a Fish KillSeptember 5, 2016
September 6, 2016
As summer halts to a close, we would like to reflect on the major water quality events of the summer. July was Earth's warmest month on record dating to the late 1800s. With the heat came clinging jellyfish in our Harbor waters and thousands of stinging nettles (jellyfish) who thrive in warm, calm waters. Our water quality monitoring team, affectionately known as team fecal (we're discussing t-shirts), saw fecal bacteria readings off the charts in Perth Amboy after heavy rain. Although the water might look clean after rain, we're working on notifying folks of the health hazards of combined sewer overflow (CSO) discharge.
However, most visible of all this summer was the Raritan Bay fish kill, the largest kill anyone here at NY/NJ Baykeeper has ever experienced. Hundreds of thousands of dead peanut bunker washed into Luntze Marina in Keansburg, Pederson's and Brown's Point Marina in Keyport, Natco Lake, and Atlantic Highlands Marina. At Luntze Marina, in particular, the fish covered every inch of water so severely that from a far onlookers thought they were gravel! Peanut bunker are primarily used as bait fish and are overabundant in our bay. It's not unusual for us to be out on the water and see the the surface come alive, as if the water is boiling, with splashing blue fish chasing bunker.
While fish kills are a natural phenomenon, after testing water levels, we can point to low dissolved oxygen (DO) as the cause of death for the fish, the most common cause. Fish need oxygen to breathe and if oxygen levels are too low, the fish suffocate and die. Low dissolved oxygen is the result of the warm water temperatures we've been experiencing, along with nutrients and organic material in the water. The problem can be worsened by polluted stormwater runoff that can contain nutrients from common lawn fertilizers. What can you do? Every little effort counts to improving our water quality. Plant a tree, install a rain cistern, or plant a rain garden to absorb more stormater, use environmentally-safe fertilizers (if you're using them at all), and always pick up after your pets. Nutrients from stormwater runoff and animal waste translates into growing algae that absorbs oxygen in the water and can harm aquatic life below the surface.
Here's to cleaner waterways and a fabulous fall season!
Communications and Outreach Associate