In this study conducted in 2009, we combined catch-based datasets across CNMI, Guam, Yap, and Pohnpei, to evaluate indicators of fishery status. This study is inclusive of over 50,000 fish measurements from the commercial markets and fisher catches, providing an extensive snapshot in time. To our knowledge, this study represents the first peer-reviewed assessment of size and species-based catch data throughout Micronesia, and the Western Pacific, and highlights a need for more robust fishery-dependent data collection and reporting.
Taking a Measure of Saipan’s Fish Stocks
What types of fish make up the majority of market sales?
Are fish being caught before they can reproduce?
How do our markets compare with other islands in Micronesia?
Why Measure Fish in Our Markets?
The reef fish that pass through Saipan’s markets are as important as the money that passes through the economy. They represent a healthy food source, key ecological function, and a wealth of traditional knowledge and education. Financially, they are a source of income for fishermen and businesses.
Clearly the time to improve our understanding of these stocks is now.
Approximately 7,000 lbs of reef fish were measured from 4 prominent markets in 2009. Using these data, we estimate that between 50,000 and 80,000 lbs of fish were commercially caught for Saipan-based markets. Parrotfish and unicornfish (Laggua, Palaksi, Tataga, and Hangon) make up ~70% of the catch, representing algae and detritus eating fish.
Why are big fish so important? Introducing the “L50”
The “L50″ is a scientific term for the size at which 50% of the fish population becomes reproductively mature. This is one common management target. For example, at 13″, most tarakitu begin reproducing. However, the larger the fish gets, the more eggs it is able to produce. You might think that a 26″ tarakitu, being twice the size of a 13” fish, would produce twice the eggs, right? In reality, it would produces 86x the number of eggs! This is one of the reasons why big fish are so important in our marine ecosystems.
One important question to ask is how many of our fish are caught BEFORE they are big enough to reproduce?
Two popular fish, the “Tataga” (Naso unicornis) and “Laggua” (Scarus rubroviolaceus), which together make up around 30% of all of the market catch, are very often caught below their L50 size (likely before they are big enough to reproduce) which decreases the number of fish in future generations. Even very common fish such as “Hangon” are often being caught below their L50. Evidence is mounting to show that high fishing pressure forces fish to start to reproducing earlier in life, however the quality and abundance of eggs is lower.
How does Saipan’s Catch Compare to Other Islands?
Comparisons with Pohnpei show the daily commercial catch to be 75% smaller; a disproportional decrease even considering the greater availability of fish habitat in Pohnpei. Besides volume, Guam and CNMI catches are composed of very different fish groups. Saipan had fewer predator fish (groupers, jacks, snappers) and more algae eating parrotfish and unicornfish. This is termed “fishing down the food chain”.
Key Findings and Recommendations
- Fishermen consistently traveled further (to Tinian/Aguijan/Rota) to generate their profit.
- There is a strong similarity between our market catch and the Guam SCUBA spear catch. Both successfully target lots more parrotfish compared with surgeon and unicornfish that are typically the most dominant in markets. This is an indicator that although illegal, SCUBA fishing feeds a majority of the markets surveyed.
- Data suggests that some fish still have good reproducing populations, however many very desirable fish do not.
Action for Change
Action is needed to increase the sizes and abundances of fish within our waters. Action must be a combined effort between government, public, and private business sectors. Action starts with discussion among the stakeholders; knowledge and solutions lie within each one of us.
In order to get a better estimate of annual market catches we plan to repeat market surveys in future years to understand change over time. It is our goal to continue to provide all available information to you. In addition, public presentations of this information are available upon request to PMRI.