Coral reef fishes represent a highly diverse and economically important component of tropical marine fauna globally. Coral reef fisheries support coastal communities and island nations across the Indo-Pacific, including US jurisdictions in the Central, Western and South Pacific. Species on coral reefs live in the shallow coastal environment and have a wide range of body sizes, color patterns, life spans and reproductive strategies. Understanding the life history strategies of harvested species is very important for enhancing our ability to sustainably manage coral reef fisheries. Several decades ago, it was commonly believed that most coral reef fish species were short-lived (lifespans of only a few years) because there were so many conspicuous species competing for similar resources. However, once scientists started using otoliths to age tropical fishes, we learned that many families lived unexpectedly long lives, up to 30 years or more. Even more surprising has been the more recent investigation of changes in lifespan and maximum body size across different areas. Investigating spatial variation in life history traits of harvested coral reef fishes is a major objective of the Samoa Archipelago Fisheries Research Cruise.
Fish life history strategies change across space as a response to changes in the environment (for example: ocean temperature, primary productivity, habitat distribution and availability, level of competition with other species for resources). Hence, fish from low latitudes with warm ocean temperatures will often be short-lived and smaller-bodied on average, whereas the same species from a slightly higher latitude (colder ocean temperatures generally) will be longer-lived and reach a larger body size. These metabolic changes to growth rate and life span are important to fisheries yields, and scientists onboard the Samoan Archipelago Fisheries Research Cruise are working to better understand these changes.
During this research cruise aboard the NOAA Ship Oscar Elton Sette, we are targeting several species of coral reef fish for life history research. Among these is the bullethead parrotfish Chlorurus spilurus. This species, with its similar sister species Chlorurus sordidus, spans from the Northern Red Sea to the Hawaiian Islands to French Polynesia to southern Africa and is among of the most common parrotfish species in the world. Collections of these species have been undertaken at 30 locations across their entire range spanning from highly populated areas to remote uninhabited islands (for example, Rose Atoll) to better understand the magnitude and influence of certain environmental drivers of life history variation. So far we’ve learned that maximum age and maximum body size can more than double from one location to another. That means that a particular species might reach over twice as big and twice as old as the same species in a different location!
For a cruise overview, click here.
To read about the SE16-01 Blog 2 – Secretary of the Office of Samoan Affairs, District Governor of Manu’a, and District Governor of American Samoa East District visit the NOAA Ship Oscar Elton Sette in Pago Pago, American Samoa, click here.
To read about the SE16-01 Blog 3 – Nightlight fishing for atule in American Samoa, click here.
To read about the SE16-01 Blog 4 – Bottomfishing for samples, click here.