Christopher Faist: Dolphins and Crossbows, July 24, 2011

NOAA Teacher at Sea
Chris Faist
Aboard NOAA Ship Henry B. Bigelow
July 20 — August 1, 2011

Mission: Cetacean and Seabird Abundance Survey
Geographical Area: North Atlantic
Date: July 24, 2011

Weather Data
Air Temp:  23 ºC
Water Temp: 21 ºC
Wind Speed: 11 knots
Water Depth: 35 meters

Science and Technology Log

Bottlenose Dolphin bowriding
Bottlenose Dolphin bowriding

Continuing our quest to count mammals and seabirds has brought us to shallower waters.  Currently we are moving in an area south of Martha’s Vineyard.  In this area we have had better visibility allowing us to sight species like the south polar skua and bottlenose dolphin.  Increased sightings bring new equipment and tools utilized by scientists to give a clearer picture of the diversity of animals in our survey area.

South Polar Skua
South Polar Skua

In addition to seeing animals through binoculars, scientists also want to learn about animal genetics and vocalizations.  Specialized equipment like a crossbow loaded with a biopsy dart or a towed hydrophone array can give scientists greater insight into the animals they are trying to study.

Pete ready to take a biopsy sample
Pete ready to take a biopsy sample

Pete, one of the marine mammal observers is also tasked with using a crossbow and biopsy dart to take a small sample of whale or dolphin tissue.  When the visual sighting team (using binoculars) spots an animal, they direct the bridge (where the ship is controlled) to steer the ship toward the animal or group of animals.  At this point, Pete begins to prepare his genetic sampling equipment.  On the bow of the ship are two raised platforms, one on each side.  With his crossbow in hand Pete harnesses himself to the ship, climbs on a platform and loads a biopsy dart.  If the animals are close enough he will then fire the dart, which is tethered to the ship, and collect a very, small piece of skin and blubber from the animal.  This tissue sample can be used by scientists to study the animal’s DNA, sex, health, diet, pollution levels and in females, check for pregnancy.

Crossbow loaded with biopsy dart
Crossbow loaded with biopsy dart

Another tool used to deepen a scientist’s understanding of marine mammals is a towed hydrophone array.  Included in a thin tube towed behind the ship are underwater microphones or hydrophones.  These are used to listen to noises in the ocean but for this cruise, the hydrophones are tuned to pick up sounds made by marine mammals.

One of the problems associated with using visual sightings to count marine mammals is they only spend a short period at the surface where they can be visually observed.  To ensure that all animals are counted, scientists like Rob and Sandra listen for animals that may be underwater when the ship passes.  Using multiple hydrophones they can use computer software to locate the noises and note the presence of animals that may be missed by visual observers.

Personal Log

Today was our first day of good weather that lasted all day.  What that means is 12 hours on deck looking for animals.  Even though I can take a break whenever I need it, I am worried that if I leave the deck I will miss something interesting.  After that many hours on deck it is great to get some dinner and head for bed.  I have been sleeping really well, making  getting up at 6am to start surveying almost enjoyable.

Next posting I will talk about the CTD/Bongo sampling device that I am helping to deploy every day at lunch.