# Bikar and Bokak atolls, Marshall Islands: survey records 266 reef fish taxa and 17 seabird species

- Published: 2026-11-11 17:05 UTC
- Section: Planet › Ecology & recycling
- Tags: Bikar atoll, Bokak atoll, Marshall Islands marine sanctuary, intact coral reefs, reef fish biomass, shark biomass, deep-sea fish records, Frontiers in Marine Science, Alan Friedlander, Polynesian rat
- URL: https://realtech.media/news/rt-29affac8fdbf3b60c10b3f4a_bikar_and_bokak/

**A 2023 expedition surveyed two remote Pacific atolls now protected as a marine sanctuary, describing them as relatively intact reef ecosystems, not pristine ones.**

![Bikar and Bokak atolls, Marshall Islands: survey records 266 reef fish taxa and 17 seabird species](https://realtech.media/media/2026/11/03947fedae6eeb5b.webp)
*sciencealert.com*

Scientists have described the Bikar and Bokak coral atolls in the Marshall Islands as relatively intact marine ecosystems, according to sciencealert.com's report on a study in Frontiers in Marine Science [1]. The data come from a 2023 research expedition. Both atolls were declared the first national marine sanctuary in the Marshall Islands [1]. Bikar lies more than 100 kilometers (62 miles) from the nearest inhabited atoll, and Bokak almost 400 kilometers from people [1].

## Reef fish and sharks

The field surveys observed 266 reef fish taxa from 38 families, with greater fish biomass at Bokak [1]. Sharks were the largest individual component of fore-reef biomass: 26.8 percent at Bikar and 33.9 percent at Bokak [1]. Marine ecologist Alan Friedlander of the University of Hawai'i said the atolls have high reef-fish biomass, large predators and, at Bokak, coral-dominated reefs [1].

## Deep water, birds, turtles and limits of intactness

Using submersibles, the team documented 138 fish taxa at depths of up to 275 meters. According to the researchers, 14 of these groups appear to be previously unreported records for the Marshall Islands [1]. Deep-sea cameras recorded another 79 groups of fishes at greater depths [1].

On land, the researchers documented 17 seabird species. They also recorded 71 turtle crawls and 132 turtle nest pits, concentrated largely at Bikar [1]. The authors also describe mature native vegetation and extensive seabird colonies [1].

The authors stress that "relatively intact" is a comparative description, not a claim that the reefs are pristine [1]. At the time of the 2023 surveys, both atolls hosted introduced Polynesian rats (Rattus exulans). The reefs are also exposed to warming waters, coral bleaching and ocean acidification [1]. In the authors' words, ecological condition should be judged from observed ecosystem attributes rather than remoteness alone [1].

For contrast, days after surveying Bokak the expedition moved on to Bikini Atoll, where mid-20th-century nuclear tests left radioactive contamination. An expedition member wrote in a field diary that the first dives found some fish and a few spots of live coral, but also a lot of pulverized, dead reef with little living on it [1].

## Sources

1. [sciencealert.com](https://www.sciencealert.com/scientists-discover-two-remarkably-untouched-worlds-hidden-in-the-pacific)
2. [ua.news](https://ua.news/en/dovkolo-svitu/naukovtsi-opisali-vidnosno-zberezheni-rifi-dvokh-atoliv-marshallovikh-ostroviv-sciencealert)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-29affac8fdbf3b60c10b3f4a_bikar_and_bokak/