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.
References:
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
