A massive flood last spring that closed the road to Haena State Park for over a year not only affected tourism numbers, but the very makeup of fish, coral and other marine life on the northwest coast of Kauai.

Directly following the April 2018 flood, fishermen and locals were optimistic — they were seeing an abundance of fish in shallow water. Some attributed the increase to the lack of tourists who were unable to reach one of Kauai’s most popular beaches while Kuhio Highway was repaired.

But a report by the state Department of Land and Natural Resources, presented last week at the 26th Hawaii Conservation Conference, found the flood hurt coral reefs and reduced the abundance and weight of certain species of fish.

Cyril Fluck/Flickr

The study looked at the Haena Community-Based Subsistence Fishing Area, an area off the coast where commercial fishing is banned and the community manages the area for subsistence, religious and cultural practices.

It was the first such collaboration in the state, established after elders and researchers discovered signs of fish population declines. The new data does show the area continues to be a success.

Samples taken from inside and outside the area show a wider diversity of species and more fish overall in the community-managed area.

Fish species that feed families in the area were also more plentiful and heavier than those outside the boundaries.

It continues a trend identified during surveys over the years – which is good news for the fishermen and the nonprofit Hui Makaʻainana o Makana, a group of longtime local residents and environmental and cultural stewards that aim to restore Native Hawaiian subsistence fishing practices.

However the negative effects of the April 2018 flood were “highly apparent” in this year’s data, said Ku‘ulei Rodgers, principal investigator for the Coral Reef Ecology Lab.

More coral bleaching was recorded in shallow waters, which the report attributes to the influx of fresh water.

The number of fish, number of different species and number of sea urchins in the community fishing area all dropped from 2017 to 2018.

Almost 50 inches of rain fell in a 24-hour-period during the 2018 storm and the subsequent flood washed thousands of gallons of freshwater into the ocean.

“The freshwater makes a big change in the environment,” Rodgers said. “It brings nutrients, sediments, things that will increase plankton, algae … so you get shifts in fish populations.”

The influx of fresh water was good for certain fish species – those that feed on plankton and other resources that increased following the flood.

Keli’i Alapai, a longtime local fisherman in the area, said he was shocked to see the abundance of fish following the flood.

“The fish were a little skinny, yeah, but there were a lot of fish around,” he said. “Fish were coming right up to the shore.”

He attributes that to the lack of tourists on the once-crowded beach.

“You could walk right up to the shore and they wouldn’t run away because they weren’t harassed by people … no sunscreen in the water either,” he said.

He was also encouraged by the return of the ohiki — small crabs that makes piles of sand on the beach.

“My uncle actually pointed it out to me … he told me ‘man the ohiki is coming back and that’s a good sign,’” Alapai said.

More Studies In The Works

The state is currently collecting data on fish behavior before the flood, during the road closure and after re-opening the road.

“It’s certainly possible that less swimmers meant fish were coming closer to the shore and bigger fish were coming closer to the shore,” said Rodgers.

But she said it was at the expense of other species and – most importantly – the underlying coral reef.

More coral bleaching was recorded in shallow waters, which the report attributes to the influx of fresh water.

The massive coral bleaching event in 2014-2015 wiped out more than 35% of all coral in the Hawaiian Islands, and research suggests that colonies previously affected by bleaching are less resilient.

Anthony Quintano/Civil Beat

“Already we’re seeing paling of corals in many areas,” Rodgers said. “And of course, the corals have a strong relationship with fish populations.”

Alapai said he was also worried about the reef after he saw all the dirty water the flood washed into the ocean.

Climate change will make storms fiercer and more frequent, and Rodgers said this flood gives us a preview into how the ecology off the northwestern coast of Kauai could change if storms and floods become more prevalent.

Rodgers said the biggest threat to coral, and the fisheries they support, is the amount of carbon in the ocean.