The Fish and Wildlife Division says the boat reported it released an estimated 30,000 to 40,000 pounds of menhaden when its net broke.
Most of the fish washed up along Hereford Inlet in North Wildwood over the weekend. Some fish were reported scattered on North Wildwood beaches from the inlet south to 18th Street.
Menhaden are a small bait fish and is a member of the herring family.
Officials initially suspected low oxygen levels were to blame.
The vessel works out of Lund's Fisheries in Cape May. The division says Lund's has accepted responsibility and will remove the fish.