There has, in fact, been an increase in pirate sightings and attacks in the past few weeks. Part of this is because of the ravages of the plague; quite a few pirate crews have learned to leave ashore their sick (or, on some of the more brutal vessels, to simply throw them overboard) whereas the army and merchant vessels have not been willing to operate on a lean crew--leading to a situation where pirate ships are comparatively "well" while their prey are staffed by larger-but-sickly crews. Quite a few ships have recently surrendered after only token resistance, and their goods seized.
Of the most "known" pirates and their recent activity, Korogur Redfang is definitely one who has been active in the recent sacking of ships. Thea Starguide, Kelpyr Corcane, and Damarfore Windward have also been sighted in the area, taking on army and merchant ships with impunity and stealing their stores. There are also several new players making names for themselves among the sailors and pirates who dock at Redport: Tree Heartstrong, Graves Kair, and Radicel Northborn are names which have been floating around.
The recent attacks do not seem to correlate strongly to any particular family or goods, although it is noted that several of the targeted merchant ships were carrying spell components and rare curative ingredients which had been intended for the Feytower as part of Laerdya Siannodel's cure research. This could be a coincidence, though; at this point, almost all the merchant vessels are carrying something for the Feytower to try against the cure--but it is noteworthy that the pirates seized the goods rather than allowing the packages to continue on to the city, where a cure would surely help them as much as the city residents.
Korogur Redfang has not been seen in port recently, and it is believed that his ship is at sea at the moment. The Redfang family itself is not a strong player in the pirate world; their influence is largely city-based, although they do profit from being the merchant face for many of Korogur's thefts (he funnels much of his stolen goods into Redfang shops) and some of the Redfangs serve as crew on his ship. Korogur does not have any enemies as such--the man is brutal and efficient, but well-liked among Nightdock populace--but he has something of a friendly professional rivalry with Thea and Kelpyr and is openly disliked by Damarfore.
As for lairs of operation, Korogur is said to port among the sea caves south of Brilight whenever his ship needs repairs. Pirate lairs tend to be well-kept secrets among their crew--and the sea caves are a veritable maze if you don't know the lay of the area--but if Jarek were dead-set on going exploring, a way could be found to get him and a small crew there. After that, however, they'd be on their own.