Movement and retention of derelict fishing nets in Northwestern Hawaiian Island reefs.

Derelict fishing nets pose hazards to marine systems as they travel through the ocean or become ensnared on coral reefs. Understanding of the movement of nets within shallow atolls can help to optimize operations to protect these shallow reefs. In 2018, six derelict fishing nets at Manawai (Pearl and Hermes Reef) in the Northwestern Hawaiian Islands were tagged with satellite-transmitting buoys and tracked for three years. This study reveals that nets that enter the atoll from the northeast travel southwest towards the center of the atoll, and nets in the center can remain ensnared on the same reef for at least three years. This study shows that satellite buoys are a successful approach to tracking derelict net movement, and can inform future debris removal missions.

Estimating nearshore coral reef-associated fisheries production from the main Hawaiian Islands.

Currently, information on nearshore reef-associated fisheries is frequently disparate or incomplete, creating a challenge for effective management. This study utilized an existing non-commercial fishery dataset from Hawai'i, covering the period 2004-13, to estimate a variety of fundamental fishery parameters, including participation, effort, gear use, and catch per unit effort. We then used those data to reconstruct total catches per island. Non-commercial fisheries in this case comprise recreational, subsistence, and cultural harvest, which may be exchanged, but are not sold. By combining those data with reported commercial catch data, we estimated annual catch of nearshore reef-associated fisheries in the main Hawaiian Islands over the study period to be 1,167,758 ± 43,059 kg year-1 (mean ± standard error). Average annual commercial reef fish catch over the same time period-184,911 kg year-1-was 16% of the total catch, but that proportion varied greatly among islands, ranging from 23% on O'ahu to 5% on Moloka'i. These results emphasize the importance of reef fishing in Hawai'i for reasons beyond commerce, such as food security and cultural practice, and highlight the large differences in fishing practices across the Hawaiian Islands.