Early data suggests CNMI waters may support larger, older reef fish

Preliminary research presented at the 8th Marianas Islands Coastal Conference suggests reef fish in the Northern Mariana Islands may be larger and older on average compared to those in Guam, pointing to possible differences in fishing pressure and ecosystem conditions across the region.

The findings come from a fisheries study examining bluefin trevally, or tarakitu, using data collected in both Guam and the CNMI, particularly from less-populated northern islands, presented during the fifth day of the MICC 2026 virtual event.

“For [the] CNMI, we have fisheries-independent data… from 2014 to 2019… all the uninhabited islands north of Saipan,” said Erin Reed, a fish life history biologist at the NOAA Pacific Islands Fisheries Science Center.

The study found clear differences in fish size between the two areas.

“Fish in the CNMI are about eight centimeters larger on average compared to Guam.”

Age analysis also showed a similar trend.

“Fish in the CNMI are older on average compared to those from Guam.”

Reed said the results are preliminary but may reflect lower fishing pressure or healthier reef conditions in CNMI waters, especially in remote areas with limited human activity.

Separate findings, presented by Ashton Williams and Riley Clevin of the Guam Department of Agriculture’s coral reef programs, at the conference highlighted a different challenge in Guam, where long-term land-based pollution—not isolated events—is the primary driver of reef stress.

“The bigger problem is that this area has been suffering from water quality impacts for a long time.”

While a recent landslide in East Hagåtña Bay drew concern, researchers said its direct impact on nearby reefs was limited.

“Overall, when we look at the whole picture, we've determined that the landslide did not have a significant impact on the corals or seagrasses nearby,” they said.

Instead, Williams and Clevin pointed to decades of degraded water quality, supported by long-term observations showing persistent sediment and pollution in coastal waters.

“We can see all the way through the past 20 years… this kind of dead zone… has been there the entire time.”

They said runoff, nutrient pollution, and other land-based sources continue to affect reef health, underscoring the need for watershed-level management across the region.