HICEAS 2017, Leg 1: Surveying Whales and Dolphins Across Hawaiʻi’s Waters

The Hawaiian Islands Cetacean and Ecosystem Assessment Survey (HICEAS) of 2017 set out to cover Hawaiʻi's entire Exclusive Economic Zone, more than 1.8 million square nautical miles from Hawaiʻi Island to Kure Atoll. That took two NOAA ships, the Oscar Elton Sette and the Reuben Lasker, 187 days at sea over five months, in seven trips. The first leg, on the Sette, ran from 6 July to 2 August.

The survey is funded by agencies with a stake in Hawaiʻi's whales and dolphins: NOAA Fisheries, responsible for assessing them under the Marine Mammal Protection Act and the Endangered Species Act, and the U.S. Navy and the Bureau of Ocean Energy Management, which must judge whether their own or regulated activities affect them.

A day at sea

• Before dawn, a CTD rosette goes down to 1,000 meters to measure salinity and temperature, and the acoustics team puts out the towed hydrophone array.
• From sunrise, when distant groups can be seen reliably, visual teams for marine mammals and seabirds search along the planned tracklines. When a group is seen or heard, the teams identify the species, estimate group size and, when conditions and animals allow, take photographs and tissue samples to study population structure.
• At sunset searching stops. The survey technician casts another CTD while the teams check the day's data, archive photos and prepare gear; acoustics drops sonobuoys to listen for baleen whales, then puts the array back out for the night, when many whales and dolphins call more as they feed on plankton rising from the depths and on the fish and squid that follow.

All hands on the flying bridge to count sperm whales; counts run 90 minutes to cover their long, deep dives. NOAA Fisheries.

Focus on the main islands

The main Hawaiian Islands got extra effort, on standard tracklines running from east-southeast to west-northwest across the archipelago and on random fine-scale lines starting or ending at drifting recorders. The area holds several island-associated populations of whales and dolphins and many human activities that could affect them.

In the first 12 days the team deployed 8 Drifting Acoustic Spar Buoy Recorders (DASBRs), which record for four weeks and give a finer picture of distribution and density than the ship alone. They are especially good at finding beaked whales, deep divers that are hard to see in Hawaiʻi's usual weather and may be vulnerable to human-made noise. The team also serviced a High-frequency Acoustic Recording Package off Kona, continuing a record of nearly 11 years, and the Sette's crew recovered and redeployed an Ocean Noise Reference Station north of Oʻahu, bringing back two years of low-frequency noise and whale data for NOAA's national ocean-noise network.

Drones

Two days of calm water off Kona went to shake-down flights for the program's new hexacopter pilots. Aerial images show a group's make-up (adults, juveniles, mothers with calves) and each animal's size and shape, a measure of health. The team made 14 successful flights, over spinner dolphins and short-finned pilot whales among others, learning to fly over a group from a distance, judge image quality on a small screen and keep track of which animals were already photographed. After Kona the weather never suited flying when target species were found; pilot whales, sperm whales, false killer whales and Bryde's whales remained on the wish list.

Leg 1 by the numbers

In 28 days, the Sette surveyed 2,330 nmi of daytime trackline from east of Hawaiʻi Island to south of Lisianski.

Feeding flocks are an indicator of ocean productivity. A few recorders went missing when their satellite transmitters stopped reporting, probably because water leaked into the buoys. The Sette also stopped at French Frigate Shoals to deliver fuel and supplies to the monk seal and turtle field teams.

The HICEAS study area: the whole Hawaiʻi EEZ, with the monument and its expansion in green and the main-islands focus area in red; Leg 1’s track and sightings in white. NOAA Fisheries.

Cetacean sightings on Leg 1. NOAA Fisheries.

Some of the animals

Melon-headed whales. NOAA Fisheries (Permit #20311).

False killer whales. NOAA Fisheries (Permit #20311).

Killer whales. NOAA Fisheries (Permit #20311).

A bottlenose dolphin. NOAA Fisheries (Permit #20311).

A red-tailed tropicbird. NOAA Fisheries (Permit #MB033305-0).

Leg 2 began on 8 August, and on 17 August the Lasker headed west to join, both ships surveying until 5 September before a short break.

Sources

• NOAA Fisheries, "Off to a Great Start: The First Leg of HICEAS is Complete"; rewritten in hubnx's own words. Photographs and maps: NOAA Fisheries. Two photographs credited partly to people outside NOAA are not reproduced here.