Short answer, yes. Long answer, it's going to take a lot of work. Alternate answer, just make a shake charger.

According to Wikipedia, electric eels (which aren't actually eels) produce 100-860 V at 1 A for about 2 ms, so between 0.2 and 1.72 J of energy. This is for burst damage mode. The article says they can perform these bursts intermittently for up to an hour, but doesn't say how often, so it's hard to get total energy produced. In fact, I can't find any source off-hand that gives me this value. Either way, it's probably not a huge amount of energy total.

From this random Reddit question, a cell phone holds about 18 kJ of energy when fully charged. This random Android forum thread, a typical phone lasts 5-10 hours, or 300-600 minutes, while actually using it. So 60-30 J per minute. Let's assume you need about 1 minute to relay critical information to the 911 (999/whatever) operator. Let's also assume the latest iPhone is a bit more efficient than the Androids in the above thread (from 2012), and is setup for low-power mode, and further assume that lets it run for 15 J per minute.

It shouldn't be hard to find some electrical wire you can use to transfer energy from the eel to the charger, but you have a couple problems. First, your wall charger is expecting an AC input, not DC. It's hypothetically possible to overcome this with applied science, but I'm not sure exactly how off-hand. Second, you need to know which end of the eel is positive, and which is negative. With a proper converter (ideally, just replace the entire wall charger with a variable-input converter from 100-900 VDC input to 5 VDC output), it won't matter which end is positive, because the diodes will force the current to go the right way.

Of course, the eel isn't going to cooperate, so you probably won't get the full charge each time, so you might use 200 eels or something just to be safe (even at full charge, 200 of the most powerful eels is only 116 J).

At the end of the day, I'd think an entire airplane worth of salvage would make it a lot easier to do this:

TL;DR
Short answer, yes. Long answer, it's going to take a lot of work. Alternate answer, just make a shake charger.

Eel Power
According to Wikipedia, electric eels (which aren't actually eels) produce 100-860 V at 1 A for about 2 ms, so between 0.2 and 1.72 J of energy. This is for burst damage mode. The article says they can perform these bursts intermittently for up to an hour, but doesn't say how often, so it's hard to get total energy produced. In fact, I can't find any source off-hand that gives me this value. Either way, it's probably not a huge amount of energy total.

From this random Reddit question, a cell phone holds about 18 kJ of energy when fully charged. This random Android forum thread says a typical phone lasts 5-10 hours, or 300-600 minutes, while actually using it. So 60-30 J per minute. Let's assume you need about 1 minute to relay critical information to the 911 (999/whatever) operator. Let's also assume the latest iPhone is a bit more efficient than the Androids in the above thread (from 2012), and is setup for low-power mode, and further assume that lets it run for 15 J per minute.

It shouldn't be hard to find some electrical wire you can use to transfer energy from the eel to the charger, but you have a couple problems. First, your wall charger is expecting an AC input, not DC. It's hypothetically possible to overcome this with applied science, but I'm not sure exactly how off-hand. 

Second, you need to know which end of the eel is positive, and which is negative. With a proper converter (ideally, just replace the entire wall charger with a variable-input converter from 100-900 VDC input to 5 VDC output), it won't matter which end is positive, because the diodes will force the current to go the right way.

This random DC-DC converter takes an input of 30-800 V and outputs 24 V, so it's definitely possible. From there, you can find about 37.9 trillion types of 7-35 V input, 5 V output DC-DC regulators. Combine the two and you have an electric eel iPhone charger. I'm fairly confident you can find both of those devices on any reasonably large aircraft without even building it yourself.

Of course, the eel isn't going to cooperate, so you probably won't get the full charge each time, so you might use 200 eels or something just to be safe (even at full charge, 200 of the most powerful eels is only 116 J). If you can get them to repeatedly burst, you could use fewer total eels (just count each burst as one eel).

Shake it, Baby
At the end of the day, I'd think an entire airplane worth of salvage would make it a lot easier to do this: