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Large Whale Disentanglement

Since the threat of entanglement to large whales is not typically immediate, there is time to cut the animal free. However, disentangling a 45-foot, 40-ton, and typically free-swimming animal is not an easy task and can be quite dangerous for any rescue team as well as the entangled animal.

Trained responders work to free humpback whale off Maui
Humpback whale disentanglement effort
Photo credit: R. Finn/ HIHWNMS/ NOAA Fisheries MMHSRP Permit # 932-1905


Large, mobile whales are generally disentangled by using a modification of an old whaling technique called “kegging”. Historically, kegging involved attaching barrels or kegs to whales by harpooning them. The extra drag and buoyancy of the kegs would tire the whale out and keep it at the surface where it could eventually be lanced to death. For disentanglement purposes, rescuers throw grapples or use hooks on the end of poles to attach to the gear entangling the animal. Instead of barrels, the network uses large polyballs (buoy floats) for buoyancy and drag to keep the whale at the surface, slow it down and generally tire it out. The desired result is a whale that is more approachable, allowing rescuers to safely assess the animal and entanglement, and attempt to free the animal of all entangling gear. Specially designed hooked knives on the end of poles are then used to cut the animal free.

Trained responders assess entangled humpback whale.
Entangled Humpback Whale
Photo credit: C. King/ HIHWNMS/ NOAA Fisheries MMHSRP Permit # 18786-02

Disentanglement Equipment 

The Network has five complete caches of disentanglement equipment. Caches include an inflatable response vessel, outboard, grabbing tools (e.g., grapples and skiff hooks), buoys for kegging, various knives, safety gear, documentation gear, and telemetry (transmitters for tracking entangled whales).

The caches of equipment are located on Kauai, Oahu, Maui, and two on the Big Island. In addition, first responder kits, representing a subset of the gear focused on assessing, documentation, and tagging, reside on Oahu, Maui and the Island of Hawaii.

Trained responders deploy a telemetry package to track an entangled whale off Maui.
Entangled Humpback Whale
Photo credit: J. Moore/ HIHWNMS/ NOAA Fisheries MMHSRP Permit # 18786-02


In addition to specially designed tools that help us get hold of and cut free large entangled whales, there are transmitters, receivers, and remote platforms that allow us to automatically and/or remotely track and monitor an entangled animal over time. The science is called telemetry and it is an important tool in helping to rescue whales.

The Hawaiian Islands Humpback Whale National Marine Sanctuary uses telemetry to track and re-locate entangled whales that cannot otherwise be disentangled during the initial response due to limited resources (experience of on-site personnel, proper equipment), and/or condition restraints (weather, sea state, time of day, remoteness of location).

Ed Lyman of HIHWNMS uses live-stream goggles with camera on the end of a pole to assess an entangled humpback whale.
Rescuers at work on boat
Photo credit: T. Blough/ HIHWNMS/ NOAA Fisheries MMHSRP Permit # 18786-02

Telemetry is useful in those cases where an effort has been initiated, but terminated early due to condition considerations, or the behavior of the animal has made it dangerous for the rescue team or for the welfare of the animal to proceed. As such, telemetry increases the safety of disentanglement operations, and may assist in its overall success. The Network uses Argos (satellite), GPS-based and VHF radio transmitters to track an entangled whale. Transmitters are secured on a telemetry buoy, which is attached to the entangling gear trailing behind the animal. Transmitters, receivers, antennas, and telemetry buoys, like the disentanglement tools, are strategically placed throughout the state with trained personnel.

In addition, when safe and otherwise appropriate, the Hawaiian Islands Humpback Whale National Marine Sanctuary uses suction-cup acoustic tags on entangled whales. These benign tags placed on the animal using suction cups while still entangled, or soon after being freed, may provide information on the animal’s communications, movement patterns, and energetics both during and after being entangled.

The sanctuary has been investigating and/or using small Unmanned Aerial Systems (sUAS)for years to assist in their large whale entanglement response efforts, and in their Humpback Whale Health and Risk Assessment Program. In response, the use of sUAS platforms, or drones, allows remote assessment that reduces any impacts to the animal, and at the same time, minimizes risk to the authorized responders (i.e., reduces the time responders are near the animal). Like any tool, it must be used appropriately and certain requirements from the FAA, permit office, NOAA, and others must be met.

Jason Moore operates a drone to document humpback whales for health and risk assessment studies. Ed Lyman watches the live feed.
Rescuers at work on boat
Photo credit: HIHWNMS/NOAA


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