Category: kachemak bay

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AD34 Nanwalek had a new calf in 2018, and it is exceptionally cute. Definitely a highlight of year for me!

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AS41 and another member of AS30 pod goofing around.

The AS33 Matriline

The AS33 Matriline

This matriline of killer whales belongs to AS30 pod, a pod of about 20 or so whales. The matriarch, AS33, has 5 known offspring: AS41, AS43, AS47, AS48, and AS63. I documented all known members of this group this year, and possibly a newborn calf for AS33 as well. Here are their photos, left to right: 

#1: AS33 and potentially a new 2017-2018 calf! This was the only photo I was able to snap of them so I can’t be 100% sure it was hers (her daughter AS47 is close to breeding age) but it seems likely. 

#2: AS63 (6 years old) and mother AS33.

#3: Adult male AS41. There is no age estimate for him but he is at minimum 17-20. 

#4: AS43 (15 years old) and sister AS47 (12 years old)

#5: AS49 (9 years old) and sex unknown. 

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Killer cuddles.

Like many species of dolphin, killer whales are very tactile creatures. They often rub up against each other during periods of socialization. There are times when they are so physically close to one another it can be hard to tell where one whale ends and another begins!

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A male sea otter (I like to call them sea grizzlies) patrolling his territory, keeping an eye out for females or other males.

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I love the feeling of excitement when you make important matches!

As many of you know, I have been trying for the last year to identify and study a mysterious pod of killer whales that has shown up in Kachemak Bay. While I’ve been able to consistently identify one large male across all encounters with these whales, I have not been able to cross match other members of the pod until now.

Because they have always been seen in the company of identified but poorly known pods, it has made identifying individual members of this mystery pod a nightmare. They associate with whales whose ID photos are often not updated, so it was hard to know if the unidentifiable whales I was seeing in my photos were truly members of this new pod or just poor quality photos of whales from other pods that have already been documented.

However, I recently made a successful match between encounters of one member of the mystery pod! This female was seen on two occasions with the large male from the mystery pod and does not match any other known Alaskan resident killer whale, so I can be confident that this female belongs to this mystery pod. It will take many more encounters with these whales to fully understand pod composition and structure.

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The large dorsal fin of AD27 Angiak. At 22 years old, he has reached physical and sexual maturity. Though he will not grow any larger, his dorsal fin may become more wavy and ruffled as he ages.

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Check out that difference in dorsal fin size—an adult male killer whale’s dorsal fin can be up to 6 feet in height, while a female’s dorsal fin be half as tall at around 3 feet.

Surprisingly, we still do not know why this difference in fin size exists. Sexual selection is probably involved—females prefer to mate with large males over smaller ones. But is the tall dorsal fin a byproduct of increasing selection for larger overall body size? Or are females specifically choosing taller dorsal fins? If so, are there beneficial genes associated with a larger dorsal fin that a female might want for her offspring?

On the other hand, perhaps sexual selection isn’t involved at all—sexual dimorphism can be caused by differences in behavior or ecology among the sexes in species. Dorsal fins are used for balance, and in marine mammals, they are also used for thermoregulation. Any differences in behaviors or ecology relating to these factors in males and females could potentially drive changes in fin morphology.

Even seemingly simple questions like “Why is a male killer whale’s dorsal fin larger than a female’s?” can be surprisingly challenging to answer!

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I am roughly 5 feet and 6 inches in height (~167 cm). If I stood on this male killer whale’s back, his dorsal fin would be taller than I am. Their size is often hard to grasp; even when you see them in person, it’s still difficult to gauge how large they are until they make close approaches. Even after dozens of hours spent in their presence, I am still humbled by their size.

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AP4 (back) and AP8 (front).

Are they sisters? Mother and daughter? Aunt and niece? It’s hard to know. Both are adult females and AP4 has a calf of her own (who is hiding behind her mother in this photo). I have suspicions that AP8 may be the matriarch of AP pod; she does not have any young calves but does usually travel with adult males—AP11 is particularly close to her and is probably her son. Her movements also appear to dictate the movements of the other whales. If she makes a sudden turn, the others usually follow.