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Sperm Whale Allocare

June 3, 2009 · Leave a Comment

Sperm Whales

Shane Gero, Dan Engelhaupt, Luke Rendell, and Hal Whitehead (2009) Who Cares? Between-group variation in alloparental caregiving in sperm whales

Abstract:

Although the details of the various systems of allocare in primates, rodents, and carnivores have been well described, little is known about the existence of alloparental care in cetaceans. It is believed that the matrilineal social organization of the sperm whale functions to provide vigilant allomothers for calves at the surface while mothers make deep dives for food. Sperm whale females do have a system of allocare, but details are unknown. This study aimed to elucidate sperm whale allocare, in particular: who escorts whose calf and whether or not calves suckle from nonparent females. Using photo identification and behavioral calf follows, we examined patterns of adult–infant interactions for 23 sperm whale calves in the Sargasso and Caribbean Seas. Although multiple individuals of both sexes escorted the calves, the system of escorting differed between the 2 sites. For all calves studied in the Caribbean, we found that 1 female provided most of the allocare but did not nurse the calf, whereas in the Sargasso, multiple females provided care for, and nursed, the young. We discuss differences between populations that may have resulted in the observed differences in these 2 systems of allocare and how these findings fit with current hypotheses on the roles of kin selection and reciprocal altruism in cooperative care in mammals.

Categories: Animals · Cetaceans
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Saturday at ACS 2008

November 15, 2008 · Leave a Comment

The morning talk was great. Graham Burnett, a historian from Princeton University, took us through the history of cetacean research.

In 1963, major scientists from various fields of cetacean research met together for the first time at the 1st International symposium on cetacean research.

The three fields of cetacean research were stated as:
(1) Hip-Boot Scientists – scientists who worked from whaling stations(and wore hip-boots), like those in Antarctica (RSS Discovery), and collected data from harpooned whales. The discussion of these scientists was conflicted – it seems that the environment was troublesome for some, evidenced by water color and writings depicting the horrendous scene of dead leviathans, but natural for others who saw the whale hunts as very beneficial sources of data.
(2) Bioacousticians – scientists who wanted to understand the sounds produced by dolphins, includes Navy, Schevill, Watkins.
(3) Brain / Behavior / Language – scientists interested in dolphin cognition & social intelligence like Ken Norris, John C. Lilly (yes, in the same breath). The historian reports that the Brain / Behavior / Language scientists have been the most effective group for raising public awareness :)

This meeting was a volatile boiling pot, and resulted in a book edited by Ken Norris, called “Whales, Dolphins, and Porpoises” (1966/1980ish) that includes the discussion at the meeting “verbatium” (though edited…?…)

Burnett spent a good amount of time describing John Lilly’s work. Pre-1964, Lilly was a very respected scientist. He had a lifetime research grant from NSF, as well as major funding from NASA (Lilly:Dolphins ::. Sagan:Aliens). (more maybe later, until then, if you don’t know , the end story is that Lilly gets wiped off science, along with a bunch of future funding, by feeding LSD to dolphins).

The first panel was on whaling, how countries are bypassing whaling restrictions, and what the US can do to decrease whaling internationally.

DJ Schubert spoke about US policy on whaling. The Polly Amendment (citation 22 USC %1978) allows the US to (1) stop trade with countries violating IWC rules, (2) give certificates to countries abiding by IWC rules. In the last 6(+?) years, we have done only #2, which is disregarded by other countries.  Most of US policy on whaling has been maintained by Ted Stevens (the embezzling senator from Alaska) in light of bowhead whale quotas. Needless to say, not very good.

Jonathan Stern & Phil Clapham discussed Japan’s exploitation of article 8 of the IWC rules, which is the article allows nations to continue whaling for scientific purposes.

Jonathan Stern explained that Japan’s science is based on a theory of ecosystem based management. They argue that they are being out-competed by the whales for fish. Because Japan gets most of their protein from the sea, they see the whales as competitors for an essential resource. Stern claimed that the science is fundamentally flawed: removing the top predator in an ecosystem would cause an increase in fish, a decrease in crill, and an increase in plankton (skewing the whole system). Further, Stern reported that fish eat more fish than whales do. Whales aren’t a limiting species, the fish are prey limited, not predator limited, and that the amount of food that the fish have dictates population size.

Phil Clapham investigated the Japan’s claimed science. He said that if competition was the question, Japan’s scientific studies should focus on whale stock size and mortality rates. But, in 18 years, and 1600 dead whales, there has been no scientific advancement. Clapham accused Japanese scientists of “writing their conclusions before starting the study.” The substaintial science that is done was reported by Clapham to be tangental and weird (artificially inseminating whale ovum with cow sperm). Japan’s last IWC report said that the population could be growing, decreasing, or remaining the same, and include no mortality rates.

SPLASH

The second panel was about the program SPLASH, which documents the “Structure of Populations, Levels of Abundance, and Status of Humpbacks” in the North Pacific ocean.

In this project, (1) abundance is documented using photo ID, as well as mark & recapture; (2) Population stock structure using photo ID and genetic markers; and (3) Status, or anthropogenic effects, by analyzing skin cells for biological contaminants.

John Calambokidis and his research study abundance and population stock structure using photo ID. The dorsal fin of whales are captured on film, then compared to other pictures taken down the coast of North America. Calambokidis et  al. report that in the summer, humpbacks are found in multiple sites scattered along the northern coast of North America, from California to the Aleutian Islands. These whales all meet up at the winter breeding grounds, but, save 1 or 2 whales, go back to their same individual group site for summer feeding.  They estimate a population size of 20,000 Humpbacks, a 7% increase since 1966 (after the international moratorium on whaling in 1973).

David Mattila spoke about health of, and human impacts on, humpback whales. He estimates that  >300,000 whales die in entanglements from fishing gear each year, and suggested that populations where no scars are observed may mean populations that die immediately when entangled, or come into contact with larger & lethal equipment (rather than assuming that since there is no visual evidence, it doesn’t happen). As alluded to, he and his team analyze entanglements by looking at the scarring patterns on humpback whale tails. If a whale has a scar across each fluke, is considered evidence that that whale had escaped from entanglement. In the Southeast Alaska population, Mattila estimates 50% of the whales show signs of entanglement. At least 30% of the humpbacks seen off the coast of Hawaii show signs of entanglement.  Many whales arrive to the annual breeding grounds in Hawaii having towed fishing equipment from fisheries in Alaska and Canada. Matilla asked the audience to consider how many whales were dying if 50% showed scarring.

There are two main types of gear that harm cetaceans: small, light, near shore gear such as ropes and lines; and large offshore gear, such as large crab cages. The larger the gear, the more lethal to the whale who comes into contact with it.

Scott Baker heads the genetic analysis studies conducted by SPLASH. His results mirrored those of Calambokidis very accurately. Baker et al. reported that there are 3 pure stocks of humpback whales: (1) those that migrate from Alaska/Canada to Hawaii (2) those that migrate from southern Baja California & Mexico, and (3) populations that migrate from China, Japan, and the Philippines.

Baker reports that for these three populations, there is “strong maternal fidelity that goes back to the ice age.” He made this discovery by analyzing samples of mitochondrial DNA (mtDNA), obtained from bits of skin and bone. mtDNA is passed down through females to their offspring (in all mammals). A geneticist can use mtDNA to create family trees, tracking populations through similarities in the mtDNA gene structure. Baker also pointed out that whaling can cause the demise of an entire population, eradicating the “cultural memory” of a location, or a migration path. This is likely the case, e.g., in the Mediterranean Sea where before there was a population of Sperm Whales, and after heavy whaling, the population no longer exists, and hasn’t returned since the 1973 moratorium.

Killer Whales (Orcinus orca) (& Monterey Bay population)

The last talk of the afternoon was given by Nancy Black, who has conducted a 20+ year study on the killer whale population in Monterey Bay. After a fascinating overview of killer whales (found all over the world, sexually diamorphic, 5-9 year inter-birth-interval, sexually mature at 12-17, populations include post-reproductive females, residents are nice, transients are mean), spoke about the different hunting behavior employed by killer whales.

Transient killer whales hunt a wide variety of other mammals, including seals, sea otters, dall’s porpoise, Risso’s dolphins, pacific white sided dolphins, humpback calves, grey whale calves, blue whale calves (etc.). They employ three different tactics, based on their type of prey.

Seals and sea otters are the easiest targets, since they don’t start to swim away from the killer whales until it’s too late. Orcas use their strong flukes to slap the pinniped out of the water, which sends them flying in the air and kills them. Black reports that mother orcas will sometimes spend a longer amount of time hunting these animals when there is a calf nearby.

Dolphins are harder to catch: the killer whale must first sneak up on the dolphin, then beat them at a chase that ends when the orca moves its body under the dolphin and bucks it until it dies.

Mysticete whale calves (humpbacks, grey, blue, etc.) are generally hunted when they “swim through the wrong part of town.” That is, when they go through the bay, instead of around it in the open sea. Mysticete calves are larger than orcas, creating a different challenge for the orca. The calves meet their end when orcas team up, sometimes adopting roles, to drown them. The tongue and blubber are eaten first.

I had hoped to ask Dr. Black about her provokativ use of words (learning, cultural transmission, etc.) but had only a chance to clarify the reproductive age (12-17), and how post-reproductive females were determined (lots of years of watching them). Perhaps I’ll find her tomorrow.

Categories: Cetaceans · Nature · Uncategorized
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Entangled Humpback “Thanks” Rescuers

February 21, 2008 · Leave a Comment

This article is a bit old, but it’s a favorite…

San Francisco Chronicle

Daring rescue of whale off Farallones

Humpback nuzzled her saviors in thanks after they untangled her from crab lines, diver says

Wednesday, December 14, 2005

A humpback whale freed by divers from a tangle of crab trap lines near the Farallon Islands nudged its rescuers and flapped around in what marine experts said was a rare and remarkable encounter.”It felt to me like it was thanking us, knowing that it was free and that we had helped it,” James Moskito, one of the rescue divers, said Tuesday.Sunday’s daring rescue was the first successful attempt on the West Coast to free an entangled humpback, said Shelbi Stoudt, stranding manager for the Marine Mammal Center in Marin County.The 45- to 50-foot female humpback, estimated to weigh 50 tons, was on the humpbacks’ usual migratory route between the Northern California coast and Baja California when it became entangled in the nylon ropes that link crab pots.

It was spotted by a crab fisherman at 8:30 a.m. Sunday in the open water east of the Farallones, about 18 miles off the coast of San Francisco.

Mick Menigoz of Novato, who organizes whale watching and shark diving expeditions on his boat the New Superfish, got a call for help Sunday morning, alerted the Marine Mammal Center and gathered a team of divers.

By 2:30 p.m., the rescuers had reached the whale and evaluated the situation. Team members realized the only way to save the endangered leviathan was to dive into the water and cut the ropes.

It was a very risky maneuver, Stoudt said, because the mere flip of a humpback’s massive tail can kill a man.

“I was the first diver in the water, and my heart sank when I saw all the lines wrapped around it,” said Moskito, a 40-year-old Pleasanton resident who works with “Great White Adventures,” a cage-diving outfit that contracts with Menigoz. “I really didn’t think we were going to be able to save it.”

Moskito said about 20 crab-pot ropes, which are 240 feet long with weights every 60 feet, were wrapped around the animal. Rope was wrapped at least four times around the tail, the back and the left front flipper, and there was a line in the whale’s mouth.

The crab pot lines were cinched so tight, Moskito said, that the rope was digging into the animal’s blubber and leaving visible cuts.

At least 12 crab traps, weighing 90 pounds each, hung off the whale, the divers said. The combined weight was pulling the whale downward, forcing it to struggle mightily to keep its blow- hole out of the water.

Moskito and three other divers spent about an hour cutting the ropes with a special curved knife. The whale floated passively in the water the whole time, he said, giving off a strange kind of vibration.

“When I was cutting the line going through the mouth, its eye was there winking at me, watching me,” Moskito said. “It was an epic moment of my life.”

When the whale realized it was free, it began swimming around in circles, according to the rescuers. Moskito said it swam to each diver, nuzzled him and then swam to the next one.

“I never felt threatened. It was an amazing, unbelievable experience,”Moskito said.

Humpback whales are known for their complex vocalizations that sound like singing and for their acrobatic breaching, an apparently playful activity in which they lift almost their entire bodies out of the water and splash down.

Before 1900, an estimated 15,000 humpbacks lived in the North Pacific, but the population was severely reduced by commercial whaling. In the 20th century, their numbers dwindled to fewer than 1,000. An international ban on commercial whaling was instituted in 1964, but humpbacks are still endangered. Between 5,000 and 7,500 humpbacks are left in the world’s oceans, and many of those survivors migrate through the Gulf of the Farallones National Marine Sanctuary.

Whale experts say it’s nice to think that the whale was thanking its rescuers, but nobody really knows what was on its mind.

“You hate to anthropomorphize too much, but the whale was doing little dives and the guys were rubbing shoulders with it,” Menigoz said. “I don’t know for sure what it was thinking, but it’s something that I will always remember. It was just too cool.”

Humpback whales hold a special place in the hearts of Bay Area residents ever since one that came to be known as Humphrey journeyed up the Sacramento River in 1985. The wayward creature swam into a slough in Rio Vista, attracting 10,000 people a day as whale experts tried desperately to turn it around. Humphrey went back to sea after 25 days of near-pandemonium and worldwide media attention.

In the fall of 1990, Humphrey turned up again inside the bay in shallow water near the Bayshore Freeway, finally beaching on mud flats near Double Rock, just off the Candlestick parking lot. He remained stuck for 25 hours, until volunteers, helped by a 41-foot Coast Guard boat, pulled him free and sent him back to the ocean. He has not been seen since.

Humpbacks like Humphrey do seem to relate to people more than other whales, according to Stoudt.

“You do hear reports of friendly humpbacks, whales approaching boaters, especially in Baja California,” Stoudt said, “but, for the most part, they don’t like to be interacted with.”

E-mail Peter Fimrite at pfimrite@sfchronicle.com

This article appeared on page A – 1 of the San Francisco Chronicle

Categories: Cetaceans · Favorites · Nature · humans