Since the beginning of July, at least 124 bottlenose dolphins have washed ashore on the east coast of the US, all of them either dead or dying, and wildlife officials say that a fast-spreading infection could be behind the deaths.
While there is no definitive answer to the spike in mortality (up to seven times what is considered average), at least one of the dolphins did test positive for morbillivirus, which is often fatal to dolphins.
The National Marine Fisheries Service is declaring the fatalities to be an "unusual mortality event", and are investigating the potential cause of death, which could also include biotoxins from harmful algae blooms, pollution, ship collisions, or possible acoustic trauma from ships or other ocean infrastructure.
In 1987-88, bottlenose dolphins on the east coast were hit by a morbillivirus epidemic, with a death toll of at least 900 individuals, and there is some concern that this year's event is yet another instance of that disease.
"Because of the sheer number of animals [dying] over multiple states, people are very concerned that this might be a repeat." - Trevor Spradlin, marine mammal biologist for the U.S. NOAA National Marine Fisheries Service
Additional concern was expressed that because these bottlenose dolphins are akin to the the "canary in the coal mine" on the coasts that many humans inhabit and eat from, this event may also be an indicator that something very serious may be happening in the oceans, although at this point, no hard data is available on the cause.
"If it is a virus, then deaths could be tied to weakened immune systems that allowed something else to kill off the animals. Unraveling what is happening can be quite complex." - Barns