State and federal agencies are investigating the death of a Hawaiian monk seal on Hawaii Island.
The 10-year-old male seal, known as RB18, was found dead in a submerged fish pen maintained by Blue Ocean Mariculture in nearshore waters near Keahole Point on March 5.
The farm said prior to the seal’s death, it had emptied the pen of most of the fish and removed a large side panel to allow a shark to escape. The seal was found dead the next day.
A necropsy determined he had drowned, as he had no signs of serious injury or disease. Officials say his stomach was full of large fish, suggesting he had foraged very recently prior to his death.
“(The seal) remained submerged, so what we think happened is the seal went in through that hole that was opened up for the shark, maybe caught some fish that was in there, and then when it stopped feeding and realized it had to come up for breath, it wanted to go up and couldn’t,” said David Schofield, NOAA marine mammal response coordinator.
The National Marine Fisheries Service says the net is now out of service and Blue Ocean Mariculture has removed the top of the pen to reduce the risk of further entrapments. The company is also in the process of removing the entire pen from the ocean.
“This is a rare situation and NMFS is investigating the death of the seal,” said Ann Garrett, assistant regional administrator in the NMFS Protected Resources Division.
The Hawaii Department of Land and Natural Resources’ Office of Conservation and Coastal Lands is also conducting an investigation and review to ensure this doesn’t happen again.
DLNR Chair Suzanne Case said, “We are greatly saddened by the death of RB18 but are working together to learn from this tragedy and to minimize any additional impacts to monk seals and other protected marine species that may be associated with offshore aquaculture and the Blue Ocean Mariculture operation.”