Monitoring fish and coral for marine health

by Sharon Higa | June 26, 2021

Outside of the scientific community and curious snorkelers, few people know that Hawaiian Electric has been quietly surveying coral reef populations and fish communities along the West Oahu coast as part of ongoing marine monitoring of plant operations.* The original researchers have since retired, but we caught up with Derrick Fenske, Hawaiian Electric environmental scientist, and Kuulei Rodgers, marine biologist consultant, to learn about what they do, the importance of these efforts, and its significance to the health of our ocean and, ultimately, our planet.

Underwater maps and dive plan. Check. Oxygen kit and cell phones. Check. It’s a typical dive for Kuulei Rodgers and she knows safety is priority. The Oahu native, who holds a master’s and Ph.D. in marine biology from the University of Hawaii, spent a lifetime in the ocean surfing and she knows the drill.

A descent to depths of 12 meters at 14 ecological survey sites along five miles of Leeward coastline demands that all gear passes inspection and divers complete medical exams and refresher courses on first aid, oxygen and CPR training. Weather, surf and ocean currents are considered. The potential for encounters with small reef sharks, monk seals, spinner dolphins, eagle rays and turtles add cautious excitement as the day unfolds on a Hawaiian Electric vessel equipped with GPS and emergency equipment.

Kuulei has been monitoring coral reefs and fishes since 1992 under the Hawaii Institute of Marine Biology and is currently on the faculty at the University of Hawaii. In 2019, she joined the consultant team on Hawaiian Electric’s coral monitoring program and took over the fish monitoring study when her predecessor retired.

“Hawaiian Electric has the longest running coral monitoring program in the State of Hawaii,” said Kuulei, noting researchers began annual monitoring in 1973. “It employs the same methodology since its inception and returns annually to the same permanent sites.” This consistency is key as scientists can use this baseline data to better understand coral population changes and recovery patterns across different environmental conditions and events, such as storms, hurricanes and coral bleaching.

Kuulei said the data show a major storm in 1980 did extensive damage to shallow water coral sites while Hurricane Iwa in 1982 damaged corals in deeper waters. Bleaching events, such as that in 2014/2015 when warmer-than-average ocean temperatures affected statewide coral mortality, also were documented. The west side, however, was spared the brunt of the bleaching due to open ocean flushing and strong currents. “The healthier the coral populations the higher the fish communities.”

And that’s just what Derrick Fenske, a Hawaiian Electric environmental scientist, wants to see in the data. Derrick, who holds a degree in Geography from UH with an emphasis on the Pacific region, has been involved in scientific monitoring for about 25 years and joined Hawaiian Electric in 2004 to oversee the marine monitoring programs, among other responsibilities. He also was involved in setting up the fish monitoring program in 2007 as part of a commitment to and benefits package for the West Oahu community and continues to oversee it.

“The information from the fish surveys is used to compare the differences (if any) from year to year between the number of fish species, overall fish number and even the size of fish,” said Derrick. “This can tell us a lot about the stability or changes within these survey areas, which spans from Barbers Point to Nanakuli, and can help determine whether our facilities’ operation has any impact on the nearshore waters. The good news is, to date, the surveys have found no significant changes in fish communities that can be attributed to the Kahe or Campbell Industrial Park Generating Station operations.”

A school of weke or Hawaiian goatfish

During the 2020 pandemic when larger fishes and shifts in species composition were reported at areas previously impacted by heavy human use such as Hanauma Bay on Oahu and Molokini Island off Maui, the Hawaiian Electric survey sites remained stable year over year with the usual dominant species — mainly brown surgeonfish (maiii) and saddle wrasse (hinalea lauwili) — in residence.

Quarterly monitoring and long-term consistent methodology addresses data integrity, which is challenged by changing fish populations due to seasonal shifts and differences in water temperature, salinity, clarity, oxygen levels, nutrients and other factors. These influence fish abundance, distribution/migration and species. Calibrating fish counts among different observers also ensures data correlation, so no fish is left behind or double counted.

How many fish can you count?

“The methodology utilized in this type of monitoring is fairly simple, however, the level of experience and knowledge of our consultants conducting the surveys is remarkable,” said Derrick.

Kuulei, who also was a marine mammal trainer before joining UH, and Derrick, an avid fisherman, surfer and diver, are advocates for ocean health and its inhabitants. Healthy coral reefs not only provide habitat for fish and sea life, but also protect the shoreline from wave erosion, support the economy and control the amount of carbon dioxide in the ocean. Both scientists emphasized that decisions made today by individuals, agencies/organizations, businesses and government have an impact on the health of the marine environment now and in the future.

“Many studies indicate ocean warming, unethical overfishing, reef degradation, rising seas, and pollution and water quality issues have an impact on coral reefs and healthy fish populations,” said Derrick, who hopes future generations will still be able to tell stories of spotting big fish and healthy corals.

Kuulei echoed the concern and added, “Sound management strategies based on scientific research will increasingly play a more important role in the future of reefs. It will take a global effort to minimize the effects of climate change, but we can all work together to make a difference. We want to be able to tell the next generation that we were part of the solution, the movement that helped save our coral reefs.”

Kuulei offers these tips to reduce your impact:

  • Reduce your opala and pick up trash on the beach
  • Think of the true cost of everything you buy, the cost to the environment
  • Buy local
  • Try to eat lower on the food chain
  • Develop, advocate for and use earth-friendly technologies

*Underwater photos provided by Derrick and Kuulei.

Sharon Higa is a senior communications consultant at Hawaiian Electric Company.

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