The impacts of derelict fishing gear on the NWHI coral reef ecosystem are numerous. A primary effect of reef entanglement is structural damage to the coral substrate that comprises the physical habitat for reef biota. Waves acting on the ensnared nets and lines cause them to break off coral heads. The liberated gear subsequently snags and similarly damages other coral. The process continues until the derelict gear is removed, becomes weighted down with enough coral to sink, or it is fully incorporated into the reef structure.
|Entangled monk seal|
In addition to its direct impact on the coral substrate, derelict fishing gear poses a serious and potentially lethal threat to the highly endangered Hawaiian monk seal, threatened and endangered sea turtles, and other marine life. Because of the extreme difficulty of observing mortality events, the total mortality caused by entanglement has not been reliably estimated. However, survey data show that entanglement in derelict fishing gear is a serious mortality risk for monk seals. All six extant breeding subpopulations of this seal are located in the NWHI, and this species suffers the greatest reported entanglement rates (averaging 15 seals per year) of any pinniped (seal or sea lion). Until derelict fishing gear can be stopped at its source, removal of accumulated debris from the reefs may be the only effective way to reduce its impacts.