The Department of Environmental Protection plans to take more water samples today as part of an investigation into the massive die-off of menhaden in Delaware Bay. In addition, fish tissue samples will be collected and sent to a laboratory for analysis.
“Right now we do not have any indication that pollution or a toxic algae bloom such as red tide caused this large die-off,” said Bob Van Fossen, the DEP’s Manager for Emergency Management. “We also do not believe that this resulted from the breaking of a commercial fishing net. Low dissolved oxygen levels in the water may be a factor, but this may be difficult to confirm.”
One possibility the DEP is exploring is that large schools of menhaden, perhaps driven by predators, massed close to shallows along the shore or in the creeks and rapidly depleted the available supply of dissolved oxygen. The DEP plans to send teams into creek areas to today to investigate, but these efforts are being hampered by bad weather.
Initial water samples indicated that dissolved oxygen levels at the time the samples were taken during the day Wednesday were acceptable. But it appears that the die-off occurred during the nighttime, when dissolved oxygen levels tend to drop because aquatic plants stop the process of photosynthesis.
Water temperatures measured during the day Wednesday were very high, nearly 85 degrees. Extremely warm water holds less oxygen than cooler water.
“While this appears to have been a natural event, we are continuing to work with the Cape May County in trying to come up with a definitive cause and will be offering direction to local officials regarding the disposal of the fish,” Van Fossen said.
The wash-up of menhaden in the Delaware Bay appears to encompass about seven to eight miles of shoreline stretching from Kimbles Beach in Middle Township south to the Villas in Lower Township. Additional shoreline assessments are being done today.
The heaviest concentration of dead fish appears to be at High’s Beach in Middle Township, about halfway between the northern and southern extents of the washed up fish. The fish appear to be exclusively small menhaden, also known as peanut bunker. Most are about 3.5 to 4 inches in length.
The DEP will continue to provide the public and media with updates as they become available.