With the initial excitement calming down from our new shark visitor (see this post for details), I wanted to take a moment to acknowledge the people behind our Sleeper Shark Project—lead by Dr. Markus Horning and Dr. Chris Lowe. In the past two years, I’ve had the pleasure of working with this amazing team of professionals and scientists as we explore the new horizons of a species that we know very little about. From vessel operations, to logistics of designing equipment for metabolic studies, to shark ecology and physiology, to telemetry design—we all have our own experiences and expertise we can contribute. This is incredibly important when venturing into the unknown because as with any new exploration—there are many things we can plan for and others we have to problem solve and work through together.
Part of this team is also you: resource managers, Alaska residents, visitors to the center, and really anyone who reads these blogs and lives on our Blue Planet. At the ASLC, our research aims to provide a better understanding of our marine ecosystems because oceans are incredibly important to everyone in terms of recreation, food resources, wilderness, adventure, climate and health. Sometimes the research is direct and applied to specific conservation questions, but often, the first step is exploration and understanding.
Exploration is definitely the name of the game for Sleeper Sharks. Many people I talk to: (1) had never heard of Pacific sleeper sharks before and (2) didn’t know they were here in Alaska—so in a way everyone, including you, our readers, have been along for this journey with us every step of the way–asking questions, learning, and helping further our global understanding of the importance of healthy oceans.
For example, there have been many great questions in the changing exhibit room about sleeper sharks:
Devin Asks: What does the Sleeper Shark eat?
Sleeper sharks eat a wide variety of fish and squid, but they also appear to have an interesting appetite for marine mammals. While some diet studies in Alaska found no evidence of sea lion remains in sleeper shark stomachs, data from LHX tags implanted in sea lions suggest that these sharks may in fact have a taste for sea lions.
In 2011, our research team received data from an implanted LHX tag indicating a 4-year old male Steller sea lion had died by predation. The data showed a very quick drop in temperature from normal 37 degrees Celsius to what seemed ambient sea water temperature–however, curiously the tag did not detect light or air as it usually would when a tag emerges from a dead animal and pops to the surface of the water. Even more curious was that the temperature of the tag after the death was much colder than the sea surface temperature where it was transmitting from. Dr. Markus Horning came to the conclusion that most likely, a Pacific Sleeper shark attacked the sea lion and swallowed the LHX tag!
One reason for the difference in results between these two studies could be that in the diet study, they only looked at sharks that ranged in size from 110-250 cm (3.5-8 ft) A recent study on the closely related Greenland shark found that small sharks (<200cm) mainly ate cephalopods like squid; and it was only the large animals (>200cm) or really large animals (>300 cm) that ate marine mammals frequently.
This discovery that sleeper sharks may prey on Steller sea lions led our team to look up what is known about these sharks: very, very little indeed. So we too are thinking of important questions, forming hypotheses and testing them!
Keep submitting your questions and stay curious!
Written by: Dr. Amy Bishop