While I was seining with the LAIP interns this past summer, we came across some interesting fish living near the mangroves. While some of the fish and nearly all the invertebrates we've seen are species that may spend their entire lives in the pond (the half-spotted goby, for example, or Podopthalmus vigil, the Hawai'ian swimming crab), others are transient. Many Hawai'ian fishponds are strategically placed at the mouths of streams because highly productive, protected estuaries are important nursing grounds. As the fishpond wisdom goes, tiny fish and food go in, larger fish can't escape, and voilà: a productive and low-impact fishery. Fishponds like He'eia can attract juvenile reef fish in addition to traditional food fish, making for a diverse and colorful community of juveniles. Above is a juvenile to'au (Lutjanus fulvus) we caught in the mangroves by one of the river makaha. To'au are an alien snapper species found in abundance on Hawai'ian reefs. They are efficient at colonizing new areas (genetic evidence here) though they are not necessarily invasive; more on this important distinction later.Mahalo nui to Jack Randall, Senior Ichthyologist at the Bishop Museum for help with the ID.
More on L. fulvus and its range in the Indo-Pacific:
Gaither, M., Toonen, R., Robertson, D., Planes, S., & Bowen, B. (2009). Genetic evaluation of marine biogeographical barriers: perspectives from two widespread Indo-Pacific snappers (Lutjanus kasmira and Lutjanus fulvus) Journal of Biogeography, 37 (1), 133-147 DOI: 10.1111/j.1365-2699.2009.02188.x
