[intro].

June was a really bad month for North Atlantic right whales. Of the remaining 411 individuals, 6 died.

That's almost one and a half percent of the entire population gone in a month, which is…. Alarming. And mostly our fault.

If we can't fix what we're breaking, we're looking at the functional extinction of these whales in just a few years— and their total disappearance not long after. That would make them the first whale to go extinct as a result of commercial whaling. North Atlantic right whales are already one of the most endangered whale species in the world.

That's because they used to be incredibly popular with commercial whalers. Hence the name—they were considered the “right” whales to target—so they were hunted to near-extinction. But then, governments stepped in to protect them, and things started to look up.

In fact, in the early part of this century, their numbers seemed to be climbing. But that all changed around 2010. And the reason why is pretty clear.

Research published last month found that we've lost an average of 5.3 whales per year since 2009— and that's not counting 2019 and June's Unusual Mortality Event. While researchers can't always tell the cause of death, most of the documented cases have been caused by humans: the whales either were hit by boats or caught in a fishing lines. Of course, we'd like to see less whales die by our hands, but accidents do happen.

So it's important to have an idea of how many human-caused deaths a population can withstand and still be sustainable. That's a value called the potential biological removal or PBR. And researchers have calculated it for North Atlantic Right Whales , taking into account things like how many healthy whales are still around, their reproductive habits, and the availability of their prey.

The problem is, that number is estimated to be 0.9 whales a year— so, in the last decade or so, we've killed more than five times that number. And there's a lot we still don't know— like, how many of them die outside of monitored areas, or how many already have human-induced injuries that will lead to their death later on. For instance, there was one female that died fourteen years after being scarred by a propeller because her scars were re-opened by pregnancy and became infected.

Plus, the numbers are a bit skewed because we're more likely to find carcasses that have been struck by ships — those whales tend to be a little bulkier, so they float. The whales that get tangled in fishing lines tend to sink, so their bodies are never found. And not only are the whales dying too often, they're just not replacing their numbers.

There's only 90-100 adult females out there right now, and last year, they gave birth to 7 new calves— and that was considered a good year. Researchers think they're struggling to reproduce because our changing climate is messing with their usual feeding and pupping grounds, making conditions less favorable for the whale moms. So basically, we've got a small population of whales that aren't making babies, and we're not-so-slowly killing them off.

Both the US and Canada have implemented new laws in recent years to try to lower the number of human-caused deaths. Some have helped, but clearly, there's more work to do. Because ultimately, if we can't stop these losses from happening, it won't be long before these majestic animals disappear entirely.

And other whales similarly decimating by hunting will probably suffer the same fate. In other news—and really, there's no good way to make this transition— research published in the Proceedings of the National Academy of Sciences this week showed how bed bugs keep themselves from getting sexually transmitted infections. And the findings might just help us keep these pests from infiltrating our bedrooms.

Now, these STIs aren't like insect chlamydia — we're talking about infections that result from how these bugs have sex. Bed bugs reproduce through traumatic insemination. The male literally stabs his reproductive organ through the female's abdomen and deposits sperm into her body.

This process can happen every week if the female has access to a blood meal. You see, males generally target well-fed females because they usually lay the most eggs. But that's a lot of stab wounds to deal with, which means a lot of opportunities for infection.

But sort of luckily I guess -female bed bugs are able to buff up their immune systems right before mating. What the researchers wanted to figure out was what triggers them to do this. Turns out, it wasn't what they expected.

They thought the females might learn to ramp up their immune defenses after repeated stabbings. But the team took two groups of adult virgin female bed bugs and fed them as much as they wanted once a week for three weeks. And in the end, the ones stabbed by a glass needle to mimic traumatic insemination didn't have a greater immune response.

Instead, every bug beefed up their immune system after eating. That suggested the injuries the females receive aren't the driving factor—instead, the bugs just have this built in immune response to food. But, the researchers still wondered if it was the act of eating itself, or something else.

So they took immature bed bugs and fed some of them on a consistent weekly schedule. The others were fed at 5, 7, and 9 day intervals so their meals were inconsistent but averaged out to the same once-per-week frequency. Intriguingly, the group that ate every week ramped up their immune system way more after eating than the group with the varied eating schedule.

And this made a big difference when they stabbed the bugs with bacteria-coated glass needles to mimic the wounds inflicted by male bugs— those that were on a predictable feeding schedule had better survival rates. So, it's not the food itself or a full belly, but the animals' anticipating that they'll get food that triggers their immunological preparation for mating. And that knowledge could help scientists find better pest control strategies.

They might be able to target female bed bugs when they're most vulnerable, for example, or uncover ways to make the bugs more prone to infection. And the researchers think that other insects might regulate their immune systems in similar ways, too so the more scientists learn about bed bugs, the better equipped they may be to fight all sorts of pests. Thanks for watching this episode of SciShow News!

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And if you join our patron community, you can get all kinds of exclusive rewards while supporting this free, educational channel. You can find out more at Patreon.com/SciShow. [ outro ].