Thursday, June 12, 2014

One Fish, Two Fish, Dead Fish, Blue Fish

On the morning of May 12, thousands of dead menhaden or “bunker” fish washed from the Shark River as the tide went out, and littered nearby beaches.  Throughout the day, fish continued to drift from the inlet and wash-up on the shore, primarily in Avon and Belmar.   Early in the day, fishermen and local businesses reported the event, and the New Jersey Department of Environmental Protection and the Monmouth County Health Department collected water quality and fish tissue samples for examination.   

Though it is challenging to diagnose an issue after it actually occurs, scientific consensus is that the kill was a naturally occurring event.  Some thought that the warming temperatures and heavy rains throughout the week stirred up nutrients in the water, causing small algae to bloom.  When the algae dies, bacteria break it down, and this uses up much of the oxygen in the water, which can stress fish and shellfish.  High levels of algae were not found in the water column hours after the event, so others focused on the large size of the bunker school, and how they were chased into the shallows of the Shark River, where oxygen was likely lower than out in the ocean. The sheer number of skittish bunker moving around in a small area could have used up much of the oxygen through the overnight hours. Both of these situations are plausible explanations for a late spring fish kill, and both focus on the fish not being able to survive low oxygen levels.  

The public is often on the front line for spotting and reporting environmental health issues, whether dead fish, discolored water, algae blooms, or debris and medical waste. If you see anything unusual along a river, bay, beach, or in the ocean, call the NJ DEP hotline at 1-888-WARN-DEP. You should write down the report number, take photos of what you observe, and note the day, time, and water conditions.  

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