Will the Shrewsbury Dolphins Survive the Winter?
Dolphins feeding in the Shrewsbury, Credit: NOAA
Two juveniles died of common, but different causes, one on September 24th and one on October 8th. Necropsies revealed that one had chronic fungal pneumonia and the other had parasites. The records show that both dolphins deaths occurred during water temperatures above 15 C so the pneumonia could not be related to the cold.
A third death was reported on Christmas. A pregnant female was found near the Route 36 bridge construction connecting Sea Bright and Highlands. Tests showed no signs of pneumonia but revealed that there was no fresh food in her stomach meaning she hadn’t had anything to eat recently. Perhaps the water isn’t too cold for the dolphins themselves, but if it is too cold for their prey then they are in danger of not surviving the winter.
“Food may be plentiful now, but it won’t be plentiful in February,” said Andrew Mencinsky, executive director of the Surfers’ Environmental Alliance, who watches the dolphins on his own almost every day.
There is still much disagreement between some environmental groups and NOAA when it comes to moving or rescuing the animals. NOAA believes that moving the dolphins “carries a high risk of causing more harm that good, including the risk of killing or stranding animals.” But in four of the last five years the Shrewsbury river has frozen over. If this happens the dolphins will not be able to surface to breathe and it is likely that they will drown.
However, Teri Rowles, lead veterinarian for the Fisheries Service and leader of the National Marine Mammal Health and Stranding Response Program, predicts that the dolphins will be able to keep a portion of the river from freezing over just because of their movement and constant surfacing.
The dolphins are being monitored twice a week by trained biologists who work with coastal bottlenose dolphins. NOAA is also working with Rutgers University to record ambient noise levels so we can learn if the Route 36 bridge construction project is affecting them. The construction will stop if dolphins appear within 500 yards of the site.
Dolphin in the Navesink, Credit: NOAA
Copyright © 2009 by Marine Science Today, a publication of OceanLines LLC
