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Ocean Research

2017:  JAN | FEB

January 2016 Issue

Study of Fishing Gear
Drag on Whales

Entanglement in fishing gear is the leading cause of death for North Atlantic right whales, one of the most endangered of all the large whale species. A research team led by the Woods Hole Oceanographic Institution (WHOI) has for the first time quantified the amount of drag on entangled whales that is created by towing fishing gear, such as rope, buoys, and lobster and crab traps.

A tensiometer measured the drag forces on various types of fishing gear collected from past right whale entanglements. The team tested 16 sets of gear—five sets that included floats or buoys, one that included a two—brick lobster trap and 10 that were line only—towing them behind a vessel across a range of speeds and depths.

The team found considerable variation in drag created by the different sets of gear, with the presence of floats and buoys having a significant effect on the overall drag created for the entangled animal. On average, the team found that entanglement increases the total body drag to 1.5 times that of a nonentangled whale. They also calculated the additional energy costs to the animal.

By reducing trailing line length by 75 percent, drag on the animal can be decreased by 85 percent.

Teledyne Sonar Supports
Sub Investigation

The Ocean X Team found a Russian submarine on the bottom of the Baltic Sea, 2,750 m outside the Swedish coast, in July 2015 during a large area search using side scan sonar, with equipment from Teledyne BlueView.

Due to its dual-frequency technology, the pilot was able to navigate the sonar installed on an ROV efficiently to the target while collecting sonar recordings, taking accurate measurements and keeping aware of the surroundings.

The Ocean X dive team conducted hands-on inspection of the submarine. Using a diver handheld imaging sonar device that contains a 2D forward-looking sonar, the divers were able to locate the submarine quickly after descending 87 m to the bottom, making efficient use of their short bottom time to investigate the submarine for identifying markings and evidence of damage that led to the sub’s sinking.

MacArtney ROV Winch
For Antarctic Research

An icebreaking polar supply and research vessel will map out Antarctic subsurface and marine life with the help of an ROV winch supplied by MacArtney Underwater Technology. The winch system, acquired through Swedish SubSea Solutions on the part of University of Gothenburg, will be used to support South African research stations in Antarctica.

A MERMAC R10 AHC ROV winch with active heave compensation (AHC) has been installed to safely control the launch, operation and recovery of work-class and inspection ROV systems.

Whale Shark Project
Yields New Insights

Rolex Laureates Brad Norman and Rory Wilson, via Norman’s conservation group ECOCEAN Inc., have enlisted the aid of students and teachers from 16 schools in Western Australia to study whale shark movement and activities.

In ECOCEAN’s Whale Shark Race Around the World, the schools raised sufficient funds to equip 12 whale sharks off the town of Ningaloo with satellite tags, enabling both students and scientists to study the sharks’ migration in real time.

This project springs out of two science projects that won separate Rolex Awards for Norman and Wilson in 2006. Norman pioneered a way to identify individual whale sharks from the spots on their skin, while Wilson developed a smart device that records the activities of wild animals when unobserved by humans.

The project has thus far discovered that sharks use similar locomotion tricks to small birds, which fly in undulating flight, powering up and gliding down. This is an energy-saving measure, and whale sharks do the exact same thing; the difference being that, as they are much bigger, they do it much more slowly. This may help them cover greater distances in the ocean.

The whale shark tracks can be seen at www.whaleshark.org.au/satellite-tracking.

AutoNaut for Plymouth
University Research, Teaching

Researchers and students at Plymouth University will have the chance to use an advanced autonomous wave-propelled surface vessel from MOST (Autonomous Vessels) Ltd., which will provide an AutoNaut craft after entering into a license agreement with the university, including access to a 3.5-m preproduction model.

AutoNaut can operate autonomously or via a pilot using a laptop and Internet and satellite communication.

Mercury Toxicity Moves
Up Food Chain

FAU Harbor Branch researchers have, for the first time, closed the loop between marine mammal and human health, by taking findings from their research and applying them to explore the potential risks facing humans living in the same region.

The most toxic form of mercury, methylmercury, builds up in fish, shellfish and animals that eat fish, and are the main sources of mercury exposure in humans.

The study centers on dolphins living in the Indian River Lagoon (IRL), Florida, and humans who live along the estuary and consume much of the same seafood as the dolphins.

Initial studies of IRL dolphins showed high levels of mercury. The cross-section of people tested also had high levels of mercury, much of which was due to consumption of locally obtained fish and shellfish. More than half the participants in the study had a concentration of mercury in their hair greater than the guideline for exposure defined by the U.S. Environmental Protection Agency.

The major human health risk results from high mercury exposure during pregnancy, since the developing nervous system of a fetus is highly vulnerable to environmental inputs.

2017:  JAN | FEB

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Sea Technology is read worldwide in more than 110 countries by management, engineers, scientists and technical personnel working in industry, government and educational research institutions. Readers are involved with oceanographic research, fisheries management, offshore oil and gas exploration and production, undersea defense including antisubmarine warfare, ocean mining and commercial diving.