Pilot Whales in Steadfast Family Groups Strand on the Sandy Shoals of Tasmania
Recently, nearly five hundred long-finned pilot whales have stranded themselves on sand spits in the waters off of Macquarie Heads on Tasmania’s west coast. A place much like Wellfleet in Massachusetts Bay, this is a tidal area with shallow shoals of sand and mudflats. Marquarie Heads is a known hotspot for pilot whale stranding. More than 80% of Australian whale strandings are reported to happen in Tasmania with 200 pilot whales in 2009 and 294 pilot whales in 1935.
More than sixty people turned out to rescue the whales. Working twelve-hour days beneath gray rainy skies, often standing waste deep in the water, they used slings, trucks and small boats with outboard engines to pull surviving whales to deeper waters. They managed to save about 94 of the 470 stranded whales.
Pilot whales are in the dolphin family of toothed whales. These mostly black or gray whales have a length up to 21 feet. Pilots are second only to Orca whales in size. Males are a few feet longer than females. These whales are more robust and recognized by a large melon above the jaw on their foreheads. The scientific name is Globicephala melas, which is from the Latin for globe and the Greek for head. Locally, they are called potheads for this reason.
They are called pilot whales because a group of whales (pod) is believed to be led by a leader. However, whenever I’ve seen pilot whales, they break the wave in a line with no clear leader. Observers tell of individual whales taking turns leading.
Pilot whales are arguably the most social of all whales which is probably why pilot whales more than any other whale die in large strandings. The whales stay in family groups. The young and adolescent whales stay with parents. Pilot whales co-mingle with other pods to reproduce. They then separate and leave mates in respective family pods. The interval for pilot whales giving birth is one of the longest, once every three to five years.
Pilot whales have extraordinary mother-calf bonds. The calf nurses for 36–42 months. Young whales will continue to take milk for years, until 13–15 years old. Female pilot whales will go through menopause and continue to lactate and nurse for years after they stop reproducing. Pilot whales have in their flippers the greatest number of finger bones (hyperphalangy) of any whale, thirteen as compared to our three. Of all the mammals, only Cetaceans have evolved more than five phalanges per digit.
The black kettle pot on the whale’s head is a melon filled with an acoustical oil. The area is muscled to shape the melon and tune the direction of sound. Like us, the whale once had two nostrils. Today only the left trachea reaches the blowhole. The right trachea circles within the head. It has “monkey lips” that creates the sound used for navigation and ranging.
The lower jaw also contains acoustical oil and may be used much like a long-range microphone to pin point the direction of sound’s echo.
The sonar trap between melon and lower jaw is astoundingly efficient. A squid one mile away may be located and swiftly swallowed. To do so is all the more remarkable because the density of the squid’s body is not very different from the density of the water around it, except for the squid’s beak. For a number of whales to all dive and strike a squad of squid requires excellent communication as to who is targeting which squid.
Pilot whales are cosmopolitan, found in all oceans. They are more adaptive to new prey than are Orca whales where some eat only fish and others eat only seals. Pilot whales followed tuna fishermen for the squid they used for bait. Frozen blocks of bait were thawed then put on hooks. After setting their lines, rather than refreezing bait, the left-over thawed squid were thrown overboard. The pilot whales were there sweeping up squid chum.
The longline fishermen found traditional hooks, swallowed by tuna, tore up the insides. When the three-mile-long line was hauled in many tunas were no longer marketable. Circle hooks replaced traditional hooks. The new hooks have a gate that completes the circle. These hooks dug into the lip or gill plates of the tuna and could be more easily removed after the catch. Caught tuna, tethered to the longline, swam back and forth. Pilot whales discovered they had a taste for tuna when the taking was easy.
Pilots whales care for their young. About sixty miles off of Oregon Inlet (NC) a pilot whale was observed pushing a dead young calf for four days. Over the course of three weeks, other researchers saw the whale pushing her deceased calf. The pod of whales kept slow pace with the female whale. The pod remained close together.
Whales, like humans, suffer from the accumulation of heavy metals and other toxins that bind to lipids and fat cells. Bluefin tuna have the greatest amount of toxins because they are long-lived and feed on fish at the seventh trophic level where each predator concentrates in their body the toxic load from prey. One pound of bluefin has the toxicity of an enormous volume of diatoms at the bottom of the food chain, about four New York City dump trucks full. Yellow fin has one thousandths of the toxicity of blue because it is one trophic level down and does not live as long.
Females whales are found to have lower levels of toxins than males. This is because the females pass toxins in their milk to calves. Bottle-nosed dolphins in Florida’s Indian River Lagoon, where waters are particularly toxic due in part to harmful algal blooms, are experiencing a first born survival rate of only thirty percent. Second born whales have a better survival rate but caregiving by the female seems to have diminished after the loss of the first born. Signs of nurturing dementia have been observed with pilot whales.
The North Atlantic Right Whale is the species of whale most likely to go extinct because in 2018 no calves were born. With toxins bio-accumulating in bodies, and toxins passed down the generations, it is only a matter of time before all fertility is lost. That time will come for more populations of whales, including the pilot whale, unless we stop polluting.
When we restore the health of pilot whales, we restore our health as well. It is time to vote the ocean. Elect or return to office legislators who will advance policies and enact legislations (practices, rules and regulations) that stop polluting and establishes better management along with more responsible stewardship of the ocean. Vote the Ocean.
Originally published at https://www.oceanriver.org on October 4, 2020.