Fishing in the deep: observations of a deep-sea anglerfish

Uploaded by MBARIvideo on 22.08.2012

This small deep-sea anglerfish, Chaunacops coloratus, was first observed at Davidson
Seamount in 2002 by scientists from the Monterey Bay Aquarium Research Institute, the Monterey
Bay National Marine Sanctuary, and Moss Landing Marine Laboratories. Although it was first
described from a single specimen collected off Panama in 1899, we had no idea that these
fish existed in our waters off California, far to the north. In fact, it took us a while
to figure out exactly what species this fish was and to do so we needed help from several
ichthyologists. In 2010 we observed 6 more at Taney Seamounts, also off California. We
were able to collect specimens and make observations about behavior which had never been done before.
We realized immediately that not all of these were red or rose colored as we had previously
thought they should be; some were actually blue. We believe the larger, mature looking
fish are red while the smaller, immature fish are blue and we propose that this notable
color change is associated with age and a transition from a drifting juvenile phase
to a benthic adult phase. Often, when startled by our remotely operated vehicle, an escape
response was elicited and the fish bolted from the seafloor, straight up in a great
burst of speed. We timed one of these ascents and found that this little fish could travel
as fast as 7 feet per minute! We also observed a maneuvering behavior akin to walking, which
is quite common among its shallow-water siblings, the frogfish. Scientists think that 'walking'
is more energy efficient than swimming and that it also disturbs the surrounding seawater
less, reducing the chances of startling nearby prey. One of the remarkable traits that all
of the anglerfish have in common is the ability to 'fish' for prey. The anglerfish deploys
a lure, called an esca, which it dangles from the end of a modified dorsal fin ray, called
an illicium. We observed one of these anglerfish deploying its shaggy, mop-like lure just above
its mouth. It deployed its lure for about 25 seconds and then stowed it in its illicial
cavity after an unsuccessful attempt at attracting prey. We also used traditional measurements
and modern molecular tools to verify that this species was what we thought it was and
to verify its relationship to the other fishes within its family. These 7 observations by
MBARI are the first and only time this species has ever been observed alive, in its natural
habitat at depths of 7,500 – nearly 18,000 ft below the oceans surface. We used these
modern tools to show that the scientist who originally described this species way back
in 1899 got it right! For MBARI, this is Lonny Lundsten.