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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.

Sanctuary staff work with staff from Hawaii's Division of Aquatic Resources to free a humpback off the Big Island.
Humpback whale disentanglement effort
HIHWNMS, MMHSRP Permit #932-1489

Technique

Large, mobile whales are 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.

Justin Viezbicke assesses an entangled humpback whale.
Entangled Humpback Whale
HIHWNMS, MMHSRP Permit #932-1489


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 the Big Island. In addition, two responders kits, representing a subset of the gear, reside on Oahu and the Big Island.

Sanctuary and Hawaii's Div. of Aquatic Resources staff work together to free an entangled humpback off Maui.
Entangled Humpback Whale
HIHWNMS, MMHSRP Permit #932-1489


Technology

In addition to specially designed tools that help us get hold of and cut free large entangled whales, there are transmitters and receivers that allow us to automatically and remotely track an entangled animal over time.  The science is called telemetry and it is an important tool in helping us rescue whales. The Hawaiian Islands Humpback Whale National Marine Sanctuary uses telemetry to track and re-locate entangled whales that cannot 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). 

Response team using VHF telemetry to re-locate an entangled whale.
Rescuers at work on boat
HIHWNMS, MMHSRP Permit #932-1489

In addition, telemetry is useful in those cases where an effort has been initiated, but terminated early due to those same condition considerations or the behavior of the animal has made in dangerous for the rescue team or for the welfare of the animal to proceed.  Thus, in all regards, telemetry increases the safety of disentanglement operations, and may assist in its overall success.  The Network uses both Argo (satellite) and GPS-based transmitters along with VHF radio transmitters. Transmitters are placed on a telemtry 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. 




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