What is with the killer baby boom?!

Granted you may have been expecting some Wallace and Gromit Were-rabbit inspired tale, but in fact, it’s a post about the scenario that’s causing researchers to be filled with both amazement and unease.

Having been a member of WDC since I was 8, I’ve been immersed into the world of killer whale familial hierarchy, but to break it down, there are three pods, J, K and L (catchy, I know… this coming from the girl that named her first three hamsters Jenny 1, Jenny 2 and Jenny 3) that frequent Puget Sound and are one of the most well-studied groups of marine mammals in the world. And recently, 9 new healthy calves have been identified between December 2014 and January 2016. Sound amazing right, nine new adorably cute calves to frolick about amongst the waves.

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Photo credit: NOAA Fisheries Fervice, Candice Emmons

bb705fa9402b9189b2a12c8690a10e52But something weird is happening, there is a ratio imbalance. Now it’s tricky identifying their sex, you have to catch a glimpse of the underside which means trying to get a clear photo, not the easiest for a creature pretty-much continually submersed. So far, there are definitely four males, and possibly four more! Leaving just one female at the moment. If there turns out to be as many as 8 males and 1 female, we have a problem. Now I don’t need to go into the birds and the bees, but females are the ones doing the birthing. Fewer females, fewer babies= less stability in the population.

One theory is the effect of toxins in the water. POPS, PCBs, even dreaded DDT, have made science new recently – the ZSL published a paper revealing dangerously high levels of PCBS in Europe’s cetaceans. Back in 2009, when doing my A-Levels, I did my extended project on the buildup of PCBs in orcas, and even then, the signs were worrying. Seven years later, and though many of these pollutants have been banned for decades, they may still turn out to be the reason for a gender imbalance in these whales and it’s still really poorly understood why!

In this article by WBUR’s the Wild Life, they interview Carl Safina, who puts it so well:

“They are living in an incredible soup of various kinds of industrial and agricultural toxins”

There is so much to learn about the various effects of these chemicals on the hormones of these organisms – take a look at what it is doing to fish!

But given orcas are top dog, in a long, long food chain, they are also getting the most concentrated doses.

 

“Killerwhales are very polluted animals, and that’s the incredible tragedy of it” Safina says, and all the while they have to deal with prey depletion, avoid being captured and put in a glass shoebox at SeaWorld, put up with excessive noise, side-step being collided with, and of course deal with the holy grail: a changing climate. Top predators? Famed for their savage stardom on nature documentaries?

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Life for them is not as easy as you think. Bioaccumulation and the increasing level of concentration within their blubber is a serious problem, and even with the ban for almost a decade, if PCBs are so persistent and toxic, how can we limit the exposure to such iconic creatures such as orcas?

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