The National Oceanic and Atmospheric Administration (NOAA) is investigating an unusually high number of recent humpback whale deaths that occurred last year. Since January of 2016, 41 humpbacks died off the Atlantic coast of the U.S. between Maine and North Carolina, three times more than the average. So what’s killing humpbacks?
NOAA examined 20 of the dead whales and determined that half “had evidence of blunt force trauma or pre-mortem propeller wounds” from apparent encounters with ships. (photo – NOAA)
Researchers are unsure why this is happening, however Greg Silber of NOAA fisheries suggest that, “It’s probably linked to resources,” “Humpback whales follow where the prey is.” Does this indicate that the prey has changed their migratory habits, or is there less prey for the humpbacks to feed upon?
The remaining half of the whales examined, exhibited no sign of propeller injury and fortunately, none showed evidence of infectious disease. See more in EcoWatch and CNN. Plus see our related posts on whales: A Whale of a Tale and Shark-A-Thon: Latest News & Gossip on Sharks.
We Do Know What Killed Lulu
A beloved orca called Lulu that was found on an island off the Scottish coast in January apparently died of drowning after becoming entangled in fishing nets. With Lulu’s death there are only eight remaining individuals in her pod, the only resident population found in Britain’s waters, raising concern for the long-term survivability of killer whales in UK waters. (photto – natureworldnews.com)
Now there is an even sadder twist to Lulu’s story. After a necropsy was performed researchers discovered “shocking levels of PCBs” or polychlorinated biphenyls, a banned but highly pervasive toxic chemical in Lulu’s body.
Dr. Andrew Brownlow from Scotland’s Rural College, told BBC News, that the levels “were 20 times higher than the safe level that we would expect for cetaceans to be able to manage.”
A threshold level might be around 20-40 mg/kg stored in tissues, however Lulu had levels of PCBs approaching 957mg/kg. putting her as “one of the most contaminated animals on the planet in terms of PCB burden,” Brownlow said. Lulu was twenty years old and her long life span may also have contributed to the extreme accumulation of PCBs.
Although the immediate cause of Lulu’s death was entanglement in the fishing net, it is possible that the extreme levels of PCBs might have contributed. It is known that PCB chemicals can affect the brain and may have had a debilitating effect on her. “We very rarely see entanglement in killer whales—actually this is one of the first cases we have documented” said Brownlow.
PCBs can also cause infertility which might explain why Lulu never reproduced. An ominous factor in hopes for the future sustainability of Britain’s orca population. Read more in USA/Today.
Dolphin’s Immune Systems Vulnerable from Ocean Pollution
A first study comparing the health of wild and captive dolphins discovered that captive dolphins living in aquariums are healthier. Researchers at the University of South Carolina compared, two groups of wild bottlenose dolphins living off the Atlantic coast of the US with two groups of bottlenose dolphins living in aquariums.
Ocean pollutants appear to stress the immune systems of the wild dolphins making them more susceptible to bacteria, viruses and parasites. The wild dolphins living off the coast of Charleston, South Carolina were exposed to high levels of industrial pollution and the dolphins in the Indian River lagoon in Florida were exposed to toxic levels of mercury and because dolphins are higher on the food chain these toxins become more concentrated in their tissues. (photo – Getty Images)
The compromised immune systems are “likely a result of encountering and fighting off illness caused by pathogens, parasites and anthropogenic pollutants in the ocean that do not exist in closely managed zoological habitats.”
The researchers suggest that their findings could have health implications for humans living in these same areas, because the residents and fishermen consume the same toxins.
In contrast the dolphins in captivity at the Georgia Aquarium had healthier immune systems, a result of the environmental controls on water and food quality.
“These wild dolphins are trying to tell us something and we are not listening. As a sentinel species, dolphins are an important way to gauge the overall health of our oceans. If wild dolphins aren’t doing well, it could also indicate future impacts to ocean health and even our own health.” Said Dr. Brossart of the Georgia Aquarium. Read more at wwwindependent,.co.uk
A Reprieve from the Battle of the Rays
We reported recently on an annual “sporting event” where cowhead rays are slaughtered in Chesapeake Bay see: Rays Killed for Fun?? In Chesapeake Bay??
The Battle of the Rays occurs as the rays migrate from southern waters to the Bay to give birth. Consequently the victims of the battle are usually pregnant making it a double hit on the future sustainability of the rays
Originally it was thought that the rays competed with local fishermen for fish. When that theory was disproved the event degenerated into a bashing for fun. The rays are shot with crossbows or clubbed with baseball bats and then thrown away. Can’t you see the fun and sport in this? (photo – Shutterstock, the dodo,
The Battle has become a hugely controversial event and now the Maryland governor has signed a moratorium on the killing of cownose rays in contests through July 1, 2019. In this, period the Department of Natural Resources is required to prepare a fisheries management plan for the rays by Dec. 31, 2018.
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