Archive for the 'From the Curator' Category



Sawfish Granted Endangered Species Protection

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Earlier this month, the National Marine Fisheries Services granted sawfish protection under the Endangered Species Act (ESA).

largetooth sawfish

Sawfish are one of the most, if not the most, imperiled groups of cartilaginous fish. Like most sharks and rays,  late maturity and low reproduction rates make these animals vulnerable to over-exploitation. Additionally, their toothed “saw” often gets caught in fishing gear and nets, making them susceptible to bycatch. As a result of these threats, populations of sawfish have reportedly declined by as much as 99 percent in recent decades.

All seven recognized species of sawfish are considered critically endangered by the International Union for Conservation of Nature (IUCN).  Nationally however, earlier petitions to grant sawfish similar protection under the ESA have not been successful. The first listing, of the smalltooth sawfish, occured in April of 2003. The largetooth sawfish was listed under the ESA in August of 2011. With the freshwater and largetooth species recently being synonymized, all are now protected under the ESA, including the two living here at the Aquarium.

largetooth sawfish

One of the largetooth sawfish that live in our Shark Alley exhibit.

The designation to list all species of sawfish is a positive step forward for these animals. The hope is that through collaboration with other aquariums, research biologists, conservation groups and NGOs we can assist in the recovery of sawfish populations worldwide.

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A Blue View: Dolphin Earthquake Study

A Blue View is a weekly perspective on the life aquatic, hosted by National Aquarium CEO John Racanelli.

From the smallest plants and animals invisible to the human eye to entire ecosystems, every living thing depends on and is intricately linked by water.

Tune in to 88.1 WYPR every Tuesday at 5:45 pm as John brings to the surface important issues and fascinating discoveries making waves in the world today.

June 19, 2013: Dolphin Earthquake Study

A Blue View podcast

Click here to listen to Dr. Mark Turner discuss how
our dolphins reacted to last year’s earthquake.

On August 23, 2011, a magnitude 5.8 earthquake occurred with its epicenter approximately 118 miles from the National Aquarium, Baltimore. A short time before the dolphin pavilion started shaking from the earthquake, an Aquarium volunteer logging the activities of four dolphins noticed that they all started to swim very quickly in close formation, something she could not recall ever having seen before. She had enough time to note this behavior in her handwritten log before the building suddenly started shaking. At the same time all this was happening, the underwater sounds in the dolphin pools were being recorded using a pair of hydrophones (i.e., underwater microphones). The combination of the in-person observation and the hydrophone recordings provides valuable insight into dolphin behavior.

When an earthquake occurs, seismic waves radiate out from the focus of the earthquake at different velocities. The fastest of these, called the primary wave or P-wave, can travel at speeds of 15,000 miles per hour. However, although very fast, P-waves often are unnoticed by humans. The S-wave and surface waves, the ones that shake everything and cause the worst destruction, travel at much slower speeds.

Although no humans at the Aquarium that day reported feeling the P-wave, its trace did show up in our hydrophone recordings almost 22 seconds before the arrival of the S and surface waves. In view of the P-wave’s appearance in the recordings and the dolphins’ behavior, marine mammal researcher Mark Turner believes the dolphins felt the P-wave, and the volunteer observed their reaction to it. Listen to the hydrophone’s recording: 

This is a clip of the underwater sounds in the dolphin pools when the August 23, 2011, Virginia earthquake occurred. Two hydrophones were recording at the time. The left stereo channel is the recording from the hydrophone in the front pool where a dolphin presentation was in progress. The right channel is from the back holding pool where fast swimming in an unusual configuration was observed. In the video that accompanies the sound clip, the top two panels show the raw signal picked up by each hydrophone. The top panel is from the front pool and the bottom one is from the holding pool.

The bottom two panels are spectrograms. A spectrogram is a visual representation of sounds in which the x-axis is time and the y-axis is frequency. In a spectrogram a dolphin whistle will appear as a dark, wavy line, and a squawk can sometimes appear as a stack of parallel wavy lines.

The sound clip begins at almost exactly the time the earthquake started in VA. The various seismic waves traveled from the earthquake’s focus to Baltimore at different velocities, with the P-wave arriving first, 27 seconds into the clip. Although the very low frequency vibrations induced by the P-wave are visible in the upper panels, they are inaudible, although you might hear some water splashing. The S and surface waves (the ones that are very loud and shook everything) did not arrive until almost 22 seconds later, 49 seconds after the beginning of the clip.

You may hear some of the presentation music, a bit louder in the left channel. If you listen carefully you will also hear (and see in the spectrograms) dolphin clicks, squawks and whistles. And, of course, you will hear the loud noises made by the earthquake surface waves as they sounded underwater.

An excellent overview of the different seismic waves with animations can be found by clicking here.

All signal displays were generated using Raven Pro, Interactive Sound Analysis Software, Bioacoustic Research Program at the Cornell Lab of Ornithology.

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How the Global Pet Trade is Impacting the Survival of Many Exotic Species

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When it comes to pets, most people are content keeping traditional cats and dogs while others desire animals with a more exotic flair. Pet stores and online vendors offer the potential exotic pet owner an abundance of wildlife, ranging from parrots and marmosets to cobras and scorpions. Sadly, many recipients of exotic wildlife are unaware that their purchases may support a trade that is often illegal, inhumane, or detrimental to wild populations.

It may come as a surprise to many that the United States is one of the largest importers of live animals in the world with over one billion live animals imported since the year 2000. Various regulatory agencies strive to control this trade. The US Fish and Wildlife Service is responsible for enforcing not only its own internal regulations but also those regulations that fall under the auspices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

In addition, the U.S. Public Health Service and the U.S. Department of Agriculture enforce various aspects of live animal importations that seek to prevent the introduction and spread of emerging diseases that affect the health of both humans and domestic livestock. Imports of pet Bell’s Hingeback Tortoise’s were banned when tortoise borne ticks were found to contain Heartwater Disease, a serious threat for wild and domestic ruminants.

In 2003 African Monkey Pox was introduced when shipments of Gambian Pouched Rats, destined for the pet trade, were imported into this country. The scale of the global wildlife trade, both legal and illegal is staggering. It has been estimated that the illegal wildlife trade ranks just behind the trade in illegal arms and narcotics in terms of scope and finances. Earlier this year, 54 critically endangered Madagascar Plowshare tortoises were confiscated by authorities in Thailand. Destined for the high-end illegal pet trade, an adult tortoise of this species might sell for $50,000 – this one shipment represented approximately 10 percent of the world’s remaining population of plowshare tortoises.

plowshare tortoise

A plowshare tortoise.

For those who still wish to maintain non-traditional pets, know that these non-traditional pets require a substantial commitment. The desire to own an exotic pet often clouds ones judgment. Rescue groups are overflowing with unwanted parrots and other exotic animals, relinquished because former owners underestimated the time, money, and commitment it requires to adequately maintain these animals within their homes. In many cases exotic pet owners, ignorant of state or local laws that prohibit the keeping of certain species, have had their animals seized by law enforcement or been forced to surrender them. Responsible and successful maintenance of an exotic pet requires careful sourcing along with substantial research, finances, time commitment, and an honest discussion as to one’s ability to meet the requirements, both physical and psychological, of the species in question.

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A Blue View: Explore A Shore Responsibly

A Blue View is a weekly perspective on the life aquatic, hosted by National Aquarium CEO John Racanelli.

From the smallest plants and animals invisible to the human eye to entire ecosystems, every living thing depends on and is intricately linked by water.

Tune in to 88.1 WYPR every Tuesday at 5:45 pm as John brings to the surface important issues and fascinating discoveries making waves in the world today.

June 12, 2013: Explore the Shore

A Blue View podcast

Click here to listen to John discuss the importance
of responsibly enjoying the shore!

Whether boating, fishing, or just walking along the sandy shore, spending time on the water is a classic summer pastime. For many of us, these visits are an opportunity to explore. From birds, crabs, and fish, to the occasional dolphin and seal sighting, an amazing diversity of life lives in harmony along the shore. It is critical, though, as many of us make our way to the water, that we take responsibility for the ways that our actions impact the environment.

When we get too close to certain wildlife, for example, we can unintentionally cause a nest failure or force an animal to flee, putting its survival at risk. Never feed wildlife, not even the bread scraps from your beach picnic, and avoid sensitive sand dunes by sticking to walkways. And when boating, obey posted speed limits and slow down while motoring through shallow waterways. Respect these natural habitats by observing wildlife from a distance—close enough to appreciate the beauty of these incredible ecosystems but far enough away to leave wildlife and plants undisturbed.

It’s also essential to dispose of trash properly. Every summer, people leave their footprints—and a whole lot of trash—along our coasts. From fishing line to plastic bags, our throwaways can throw our oceans into turmoil if we don’t dispose of these materials responsibly.

Fishing line is particularly dangerous to animals. Wildlife often eat or become entangled in monofilament line, which is practically invisible. One unfortunate sea turtle was found with an astounding 590 feet of fishing line in his gut. One study showed that more than 50 percent of sea turtles stranded on a beach contained traces of debris in their digestive tracts. Sixty-five percent of those animals had ingested plastic bags, and it’s no wonder: the U.S. International Trade Commission reported that 102 billion plastic bags were used in the United States in 2008 alone—that’s a bag a day for every woman, man and child.

Though there are many statistics citing the numbers of animals that die as a result of marine debris each year—one estimate in fact is 100,000 marine mammals and millions of birds and fishes—this area of study is evolving. The National Oceanic and Atmospheric Administration’s Marine Debris Program is taking essential strides in supporting efforts to research, prevent, and reduce the impacts of marine debris, but it’s clear that we can’t afford to wait to take action. The bottom line is that even one piece of garbage on the beach is one too many.

This year, think about your impacts as you pack for your day at the beach. A great place to start is reusable goods. It’s often windy by the shore, so keep your trash and belongings from blowing into the ocean. Some popular fishing areas provide safe recycling containers for monofilament line. You can also ship monofilament to the Berkley Recycling Center in Iowa. This company will use your line to create Fish-Habs, which are four-foot underwater habitat structures made from recycled fishing line, milk cartons, and soft drink bottles. These cubes attract fish and encourage plant growth, providing natural cover necessary to maintain healthy habitats.

Whatever you do, follow this one essential rule when you’re at the shore this summer: When it’s time to go home, leave nothing but your footprints!

Diane Rehm’s Environmental Outlook: Jellyfish And The Health Of The Ocean

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Earlier today, I spoke to NPR’s Diane Rehm about jellies and the impact that jellyfish population increases and expansion of some species’ geographic ranges are having on the health of our oceans.

Jack Cover at Diane Rehm show

With Bill Dennison and Diane Rehm at NPR.

Jellyfish first appeared around 560 million years ago (long before the time of dinosaurs). They’re 95 percent water, have no brains and no bones and no heart or blood, yet these gelatinous animals are among the worlds’ most resilient organisms.

The jellies simple body plan has remained relatively unchanged. But lately some scientists are concerned the animals are thriving too well – overrunning marine ecosystems, forcing nuclear power plants to shut down and filling the nets of commercial fisherman and shutting down fisheries around the world.

Some of the jellyfish species on exhibit here at the Aquarium.

Jellyfish species from top left (clockwise): blue blubber jelly, upside down jelly, spotted lagoon jelly, Leidy’s comb jelly

There are both ecological human-related issues causing an “explosion” of jellyfish populations around the world.

  • Over the years, climate change has raised the average temperature of the ocean. While this rise has negatively impacted organisms like coral, warm season jellies start breeding earlier and have longer active seasons.
  • Human activities, such as the over-fertilization of our lawns and farms, results in a runoff of excesses of nutrients into the Chesapeake Bay and ocean. This results in what’s known as an algal bloom. When the algae absorbs all of this nutrient run-off, it dies. Bacteria then feeds on the dead algae and removes all dissolved oxygen from the water – this process is called eutrophication and produces “dead zones.” Fish and crabs perish in these dead zones, but not the resilient jelly. Jellyfish can survive with low oxygen levels!
  • Jellyfish are opportunistic feeders. When food, like zooplankton, is abundant, they will grow rapidly and reproduce at a rapid rate. Excessively large jellyfish populations can out compete young fishes that also feed on zooplankton.
  • Some scientists speculate that the reproduction of jellyfish predators may also be giving jelly populations a boost. For example, all seven species of sea turtle will opportunistically feed on jellyfish when they are encountered. The largest species of sea turtle, the leatherback, feeds almost exclusively on jellies. Pacific populations of leatherbacks are currently at about 7 percent of their historic population levels. Human activities are the cause of sea turtle population declines. Overfishing has reduced fish populations that also feed on jellies.

To listen the full “Environmental Outlook” segment on Diane Rehm’s show, click here

Jack Cover


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