Thousands of Dead Fish Removed From New Jersey Lakes After Winter Freeze

Volunteers hauled out about 1.2 tons of dead fish from Lake Appert in Allendale on March 15. The massive die-off struck multiple lakes and ponds statewide, hitting both northern and southern regions.

Teams from the Celery Farm Nature Preserve and the Fyke Nature Association crammed around 80 contractor bags with dead carp, sunnies, bluegills, catfish, and various other species. Each bag weighed 30 pounds. Newton Creek in Camden County experienced its own separate incident.

"The die-off was caused by a lack of dissolved oxygen in the water as a result of the lake being covered with ice, then snow, for many weeks," Jim Wright wrote in his blog, according to Patch "Compounding the disaster were the sudden, drastic spikes between warm and cold temperatures during the previous seven days."

Wright sits on the board for the Fyke Nature Association. He explained that two other winter fish die-offs happened in the past 25 years at the Celery Farm, but nothing came close to this scale.

Scientists call this a "winterkill." It strikes when a pond or lake freezes for weeks on end, and oxygen gets depleted. Once the ice thaws, countless oxygen-starved fish rise to the top.

The wild temperature swings this month made things worse. Warmer weather can spark algal blooms that generate dangerous bacteria, killing aquatic life.

The Newton Creek incident got blamed on quick temperature shifts and bacterial growth, according to the NJ PEN Newsletter. Plants and nutrients below the surface die off fast, the NJ Fish and Wildlife Division reports.

Wright said crews must find and remove these die-offs fast, before decomposition ruins water quality and creates a terrible smell.

Anyone spotting a major fish die-off should call the Department of Environmental Protection through their 24/7 hotline at 877-WARN-DEP. The NJ Fish and Wildlife Division says what people observe during a fish kill matters most when figuring out what caused it.

Residents can write down what they see and email NJFWFish@dep.nj.gov.