Guy Harvey Magazine

SUM 2018

Guy Harvey Magazine is focused on fishing, boating, scuba diving, and marine conservation. Portfolios from the world's best fishing photographers, articles on gear, travel, tournaments, apparel, lifestyle, seafood recipes, sustainable fisheries.

Issue link:

Contents of this Issue


Page 40 of 83 | 41 explained Stanford University Oceanographer Dr. Jan Witting, "it is not visible to satellites, leading us to believe this was an ocean desert." To their surprise, the team observed a surprisingly diverse animal community that included deep-sea fish, tuna, other shark species, squids and jellies. Along with the Slocum Glider, two wind-powered Saildrones were employed to expand the study area and simultaneously conduct oceanographic and biological surveys of the environment. The autonomous Saildrones were deployed prior to the expedition and surveyed the White Shark Café ahead of the ship's arrival. The researchers originally tracked the sharks to the Café using pop-up satellite archival tags (PSATs). These sophisticated biologging instruments were attached externally to 20 white sharks off the coast of central California in fall and winter, when the white sharks were feeding in nearshore waters. The tags were programmed to pop off the sharks while Falkor was in the Café area in May, in hopes that they would help guide the researchers' shipboard investigations. Once the tags surfaced and transmitted their position to Earth-orbiting satellites, the team recovered 10 tags released from the sharks. Six more tags transmitted their data sets and two popped off outside the Café area. There were also 18 positional-only satellite tags attached to white sharks and 50% reported from areas in or close by the Café. "It was a white shark treasure hunt assisted by the captain, the first officer and the white shark ecologists on board," said Dr. Sal Jorgensen of the Monterey Bay Aquarium. The satellite archival tags log the depth and temperature of the water around the sharks every few seconds, and these high-resolution data enable a much better understanding of the dive patterns of individual sharks in these deep oceanic waters, providing new insights into their behaviors. The tags also provided the focal points for Falkor's oceanographic surveys, which probed Café waters below the surface of the ocean where satellites cannot observe. "We compared a wide array of biological ocean-observing tools to investigate how to census ocean ecosystems rapidly," Block said. "We found a high diversity of deep sea fish and squids (over 100 species), which in combination with observations made by the ROV and DNA sequencing, demonstrate a viable trophic pathway to support large pelagic organisms such as sharks and tunas." Right: Dr. Salvador Jorgensen and PhD candidate Elan Portner examine a cookiecutter shark specimen, collected through a net tow deployment Below: A screenshot from showing the travel patterns of nine separate white sharks off the west coast of the United States and Mexico.

Articles in this issue

Links on this page

Archives of this issue

view archives of Guy Harvey Magazine - SUM 2018