#14: The Basking Shark of Lubec

On the morning of September 2, we received a few calls from our colleague Chris, relaying information from members of the community about a live animal that had stranded far out on Mowry Beach in the Lubec channel, just a couple of miles from our field station. Chris and a local marine patrol officer went to the shoreline and used binoculars to identify the animal as a basking shark.

Marks in the ground show the shark had been thrashing.

We piled into our truck around 8 AM with a few buckets, tools and a measuring tape. When we arrived, the tide was still going out, and we walked about half a mile out on the mud flats to get to the shark. The shark was on firm ground consisting of mud, sand and rocks. The claspers (identifying the animal as a male) were a bit bloodied, and indentations in the ground showed where the caudal fin (tail) had been sweeping back and forth. Towing the animal to water at this point was out of the question, as it would have done more damage than good to its body.

Looking into the gills.

There were a few locals toting buckets of water from a large pool of sea water to the shark. The idea behind this was to try to keep the shark wet, since it was already a warm morning, and to try to provide oxygen by forcing water over the gills. Since the shark had been stranded for hours already and high tide wasn't until noon, we knew the likelihood of the shark surviving was slim, but we figured we might as well try to do what we could to keep him alive. Our team joined in the line to pass full buckets to dump on the shark, which measured about 24 feet long.

Taking measurements.

The tides in this region are known to be the largest in the world, and they move very rapidly. Eventually, we had to clear the area as the water started rising. Two of the Aquarium boats and the marine patrol boat arrived on scene, and tied line around the caudal keel (tail stock) of the shark.

It was difficult to leave when the tide started coming in. Photo: Marianna Hagbloom

Finally, there was enough water around the body to cause less damage when moving him, and the teams were able to get the shark to the deeper part of the channel. Though they "walked" him around to get water flowing through the gills, he never started moving and was eventually declared dead. He was tied up to a nearby beach for necropsy.

Working to move the shark to deeper water.

Early the following day, five researchers from the Grand Manan Whale & Seabird Research Station (GMWSRS) arrived in Lubec to perfom the necropsy. Though these researchers study this species, very few necropsies have ever been performed on basking sharks since they don't typically strand or wash ashore, let alone in great condition. This necropsy would be taking place on a specimen less than 24 hours after death! The examination was going to provide a goldmine of information and allow the team to learn things that have never been documented before.

The necropsy team makes preparations to begin.

Chris and Marianna met the GMWSRS team and led them to the location of the shark. After doing a visual inspection of the external body, accurate measurements were taken. The first cut was made at the caudal keel (tail stock), and the team worked their way forward. The shark had beautiful red and white muscles, and many samples and photographs were taken to study their structures.

Collecting samples.

The body cavity was cut open to sample the internal organs, and we learned just how large a basking shark liver can be (VERY LARGE!)! A few of the gill rakers, reminiscent of whale baleen in appearance and function, were removed, along with the eyes. A representative from a museum near Bangor was onsite and will be creating a display using these parts, along with the skin from the large pectoral fin.

Gill rakers.

The shark appeared to be healthy, but histology will be run on the collected samples to see if anything unusual was going on internally (toxins, pathogens, etc) that may have contributed to the shark's stranding and/or death. It's possible that what ultimately killed this animal, though, was a lack of oxygen and a lethal quantity of lactic acid, which builds up when a shark becomes stressed, particularly if it is oxygen deprived. With no skeletal structure either, the weight of its own body may have been a contributor. Though it was tough to watch such an amazing creature die like this, we are assured that the body was not wasted; instead, scientists learned so much from this necropsy that this single animal has propelled their knowledge onto an entirely different level.

Basking sharks have very tiny teeth!

Thanks to all the members of the community for their efforts to help this animal when it was stranded, and for their support and interest during the necropsy!


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