Dive 7: Caja de Muertos Island

Date: November 7, 2018
Location: Lat: 17.82438°, Lon: -66.56745°
Dive Depth Range: 401-539 meters (1,315-1,770 feet)

Several queen snappers (Etelis oculatus) were seen during Dive 7, including one individual recorded at a depth of 539 meters, thus extending the previous depth record (450 meters) of this species by a substantial margin. Queen snapper is an important fishery species throughout the Caribbean. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.2 MB).
Crinoids and brittle stars attached to the glass sponge Farrea occa. These echinoderms were frequently observed attached to glass sponges, black corals, stylasterids, and octocorals during the dive. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.4 MB).
Two hermit crabs were seen using hollowed pieces of wood during Dive 7. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.1 MB).
Several species or urchins were seen during Dive 7, including this distinctive species (Cidaris blakei) with fan-like spines. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.1 MB).

During today’s remotely operated vehicle dive, we explored seafloor habitats at depths between 401-539 meters (1,315-1,770 feet) to the south of Caja de Muertos Island off the south shore of Puerto Rico. The dive started in a habitat dominated by soft sediments with a few large boulders and then transitioned into hard ground with smaller boulders. We documented at least 10 different fish species during the dive. Particularly noteworthy was the sighting of the queen snapper (Etelis oculatus) at a depth of 539 meters (1,770 feet), thus extending the previous depth record of this species (450 meters or 1,475 feet) by a substantial margin.

Sponge abundance and diversity was low and consisted mostly of encrusting glass sponges and demosponges. In contrast, echinoderm diversity was high and included various species of urchins, sea stars, crinoids, and brittle stars, the latter two of which were frequently attached to stylasterids, black corals, octocorals, and glass sponges. Other noteworthy invertebrates seen during the dive included hermit crabs using hollowed wood pieces as shells.

The vast majority of snappers targeted by recreational and commercial fishers are located in deep waters off the west and east coast of Puerto Rico. There are about 70-80 fishermen licensed to fish deep-sea snappers in Puerto Rico. The snapper shown in this video is the queen snapper Etelis oculatus, which is one of the main deepwater species targeted by the fishery.

Very little is known about the life history, habitat preferences, feeding habits, and population dynamics of queen snappers. Prior to this expedition, fishers and scientists reported this species from depths as deep as 450 meters (1,476 feet). During the Océano Profundo 2018 expedition we observed a queen snapper at a depth of 539 meters (1,768 feet) at a site located southwest of Isla Caja de Muertos near Ponce, Puerto Rico, thereby extending the known depth range of this species.

Video courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (mp4, 69.2 MB).

Location of Dive 7 on November 7, 2018. Download larger version (jpg, 2.3 MB).

The remotely operated vehicle track for Dive 7, shown as a white line. Scale is water depth in meters. Download larger version (jpg, 312 KB).