They decided to bring it on board and easily managed to pluck it from the water, then put it in the bait tank where it remained alive until just before they got back to the dock.
There are differnt kinds of Ratish though we have still not identified exactly which kind this is. Most of the information availalbe refers to the Spotted Ratfish, which this one obviously isn't.
They are found in deep water:
Biology Glossary (e.g. epibenthic)
Bathydemersal to benthopelagic generally between 300 and 500 m depth. Found in the upper continental slope. Usually found in deeper waters in southern latitudes, while making a summer inshore migration up to 40-100 m in the northern areas. Sluggish, usually occurring in small groups. Feeds mainly on bottom-living invertebrates. The single dorsal spine is sharp and pointed, and although only mildly venomous can inflict a painful wound. Oviparous. Males have a clasper on the forehead that is probably used to hold on to the female during copulation. Egg capsules are about 17 cm long; young look alike adults and hatch when 10 cm long. Common by-catch when trawling for shrimps in the North Sea or Skaggerak.