Is Guam a regional source, destination, or stepping-stone for larvae of three fisheries species?

The pelagic larval duration (PLD) period of fish can influence dispersal, recruitment, and population connectivity, thereby potentially informing best strategies for fisheries management. Computer models were used to simulate the dispersal of larvae of three species, representing a range of PLDs, from the Pacific island of Guam and neighboring islands for a 9-year period (2004-2012) to gain insight into the best management strategies for these species. The species included two springtime spawners with shorter and longer PLDs, scribbled rabbitfish (Siganus spinus; 33 days) and yellowfin goatfish (Mulloidichthys flavolineatus; similar to 90 days maximum), and a fall spawner with a similarly long PLD, bluespine unicornfish (Naso unicornis; similar to 94 days maximum). An ocean circulation model coupled with a particle dispersal model provided simulated numbers of larvae settling at each island in relation to the island where they were spawned. Graph analysis was used to examine generational connections between islands. For S. spinus, self-seeding was the dominant means of replenishment at Guam. Local management actions to maintain adequate spawning stock may be a primary control on long-term sustainability for that fishery. In contrast, N. unicornis and M. flavolineatus populations at Guam were reliant on outside sources for 92%-98% of larval supply. For them, identifying and negotiating the preservation of upstream spawning potential in the Marshall Islands and Federated States of Micronesia will be needed. Guam played a relatively minor role in generational connectivity across the region. Shortest paths spanning the region often did not pass through Guam, or there were equally short paths through other islands.