They are old exchanges. If you want some action on altcoin better check those top exchanges such as Binance, Kucoin, Okex, Houbi and Bithumb. These exchanges has more concrete volume of new altcoins and even those major coins like ethereum, neo and ripple.

Poloniex just recently launched their IEO of JUST but I am not sure if its succesful Im hearing its below its IEO price, looks like they not yet ready for a good strategy for this.

Even bittrex IEOs before are also not succesful. Maybe traders doesnt really like the way they handled it. In terms of volumes to those I already mentioned they were lower if you are going to compared altcoin volumes. They were gonna be silent but due to traders not by them. They prefer new exchanges now than these two.