Saturday, December 3, 2016
Right Whales and Ship Strikes
Note: This program first aired on December 3, 2016.
If you wanted to design an ocean animal that is perfectly constructed to get hit by ships, what characteristics would you include? It should probably be big, and slow moving. Make it dark so it is hard to see. If it is a mammal, it will need to spend time at the surface, so it can breath. It should have to spend long amounts of time feeding on very small food items, again, often at the surface, at night. Make it easily stressed by noise, which decreases its ability to communicate with others of its kind. Put its range right near shore, in major shipping lanes near highly populated areas.
This isn’t just a hypothetical exercise, this animal actually exists. It is called the Eubalaena glacialis, North Atlantic Right Whale, and it is one of the most endangered large whales in the world.
Many people have heard the story of the Right Whale, so called because they were the “right” whale to hunt especially in the early days of whaling. As a species evolved to feed in relatively shallow productive water of the continental shelf, they stay close to shore, which made them accessible to land based hunters in small boats. They could be brought to shore and processed on land, and were an important part of the land based whaling industry, before the more ocean going sperm whale was discovered and chased all over the global ocean on multi year whaling expeditions. Right whales also have enough blubber, or body fat, to lower their overall density enough that they will float when killed, again, making them easier to manage from a small boat. It is hard to know how many Right Whales were around before commercial whaling began, but they received internationally recognized protection starting in 1935, after having been harvested consistently in the northwest Atlantic since the 1500’s, and most likely earlier in European waters. Researchers estimate that there were less than 100 North Atlantic Right whales left in the western Atlantic in 1935. Since that time the population has rebounded, but very very slowly. The most current published population estimate puts the number around 476 individuals, based on direct observation. Though they are no longer hunted, they are still highly endangered.
Why are they still endangered? If we return to our list of characteristics of our vulnerable ocean animal, we can start to see why. They like to hang out where we spend most of our time in the ocean too. They fish where we fish. They travel where we travel. The two big reasons that Right whales die as a result of human activity are 1. They get tangled in fishing gear and 2. They get struck by ships.
The fishing gear entanglement issue is complicated, and unfortunately seems to be a fact of life for North Atlantic Right Whales. Researchers have observed that 83% of these whales have scarring consistent with entanglement, and around half show signs of multiple entanglements. Changes to fishing gear are a start at preventing this problem, but there is further work to do.
On the ship strike side, and because I work at a maritime college I focus more on this end of things, some very positive strides have been taken. In areas where these whales are known to congregate at certain times of the year, speed limits have been imposed for vessels over 65 feet. These zones are called seasonal management areas or SMAs and came into effect in 2008. Compliance on the part of industry has slowly but surely increased since that time. Speed makes a huge difference. If a whale is struck by a ship traveling at 20 knots, mortality is 100%. When ship speed is reduced to 9 knots, mortality is around 20%. And it has had an impact. Before 2008, 87% of the ship strike mortality occurred within or just outside the SMAs, because that is where most of the whales were. Since these slow zones were established, all of the documented ship strike mortality events, averaging 1 per year, occurred outside of the SMAs. So just getting ships to slow down where the concentration of whales is highest has worked to decrease our impact on this population. Not that we should stop and pat ourselves on the back, there is certainly more to do. These whales continue to face the threats of ship strike outside of the SMAs, entanglement in fishing gear, increased stress from noise pollution, and the likelihood of a genetic bottle neck stemming from such low population numbers in the early 20th century. We’ll learn more about what is being done on a future show.
There is a ton of info out there on these whales, including many federal websites, due to the federal regulations stemming from the protections encumbered by the Endangered Species Act.
The study that documented the positive impact of the speed reduction zones: http://www.int-res.com/articles/esr_oa/n023p133.pdf
From the federal government: http://www.nefsc.noaa.gov/publications/tm/tm219/8_NARW.pdf