Rockhoppers ply the frigid waters using narrow, sharp, flipper-like wings for thrust. They typically stick to the shallows, however, are capable of diving up to 330ft in pursuit of finding their food such as the small crustaceans, fish, squid, and krill.
They are very opportunistic when it comes to food. The Rockhopper penguin feeds on krill, octopus, fish, myctophid fish, squid, mollusks, cuttlefish, plankton and crustaceans. Based on their location, season, migration and the time of the year the primary source of food may vary. These penguins swallow all food so it must be small enough to do so. They rely on the spiny barbs in the mouth and on the tongue to give them some traction with the food.
The rockhopper penguin like all other penguin species survives on a diet that is only comprised of marine animals. Small crustaceans and Krill make up the bulk of the rockhopper penguins diet regimen along with larger animals which include squid and numerous species of fish. Rockhopper penguins may be at sea for many days at a time while hunting and catching their prey.
Crustaceans which include cephalopods, krill, and fish are the most common prey for southern rockhopper penguins, while those from the north pick squid. They adapt to the converting conditions of the region they inhabit, just like the depth of the sea or the prey available with this manages that manages their energy in their body.
A Final Word
Rockhopper penguins spend many hours in a day foraging for food. They need to consume enough food for not only their daily survival but to build up layers of fat too. During molting and mating, they will stay on land, and they need these reserves while fasting. Most of the time these penguins, stick to the shallow area of the sea to find their diet. However, Rockhopper penguins can dive up to 100 meters when necessary to catch their food.
Reference:
https://a-z-animals.com/animals/rockhopper-penguin/
https://www.bioexpedition.com/rockhopper-penguin/
https://en.wikipedia.org/wiki/Rockhopper_penguin