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Sunday, April 20, 2014

Study: Landed reef fish shows different positive situation

Micronesian Environmental Services owner and principal John Gourley served as guest speaker in Rotary Club of Saipan’s weekly meeting yesterday at the Hyatt Regency Saipan. (Mark Rabago) Saipan reef fish sold in local markets in 2009 compared to those caught from 2011 to 2013 show a "very different and positive situation," according to Micronesian Environmental Services owner and principal John Gourley.

Speaking at yesterday’s Rotary Club of Saipan meeting at the Hyatt Regency Saipan, Gourley said the most recent study of local reef fish sold in the markets of Saipan generally showed an improvement in the number of fish found above the L50 value on certain species where sizes could be compared with the 2009 study.

For example, quoting the 2009 study, he said hangon (organespine unicornfish) sold "were often being caught" below the size where 50 percent of the females are sexually mature (or L50).

In the 2011-2013 study conducted by his company, only 0.3 percent of hangon were found to be below their L50 (16.5 cm FL) size.

Palakse or laggua (redlip parrotfish) found in fish markets in 2009 were also "very often caught" below their L50 size (36 cm FL), but in the 2011-2013 study only 5 percent of the fish were found to be below the female L50 size (24 cm FL).

The most dramatic change from the 2009 study was for tataga (bluespine unicornfish). Whereas 90 percent of those found in Saipan markets were below their L50 size (36 cm FL) in 2009, the 2011-2013 study showed only 39 percent of tataga that found itself in local markets were below their L50 size.

What’s more encouraging is from the 20-25 cm average length of the 1,180 tataga caught in 2009, the length of the 5,480 tataga caught and sold from 2011 to 2013 increased to an average size of 28.5 cm (FL).

The only species of reef fish sold in local markets that showed a jump in the number of those caught below L50 was the steephead parrotfish. In 2009, only 24 percent of steephead parrotfish in local markets were below the female L50 (32 cm FL) size. However, from 2011 to 2013, approximately 30 percent of steephead parrotfish were below their L50 (31 cm FL) size.

The 2009 study didn’t have any data on hiyok (bluebanded surgeonfish), which is the most dominant reef fish in Saipan markets. The 2011 to 2013 study found very few hiyok in the market that was below the female L50 (16.6 cm FL).

It’s not that the sizes of market reef fish increased from 2009 to present, but that the 2009 market study used L50 values that proved to be inaccurate. This resulted in drawing incorrect conclusions with respect to the percentage of market fish that are considered immature. Using science-based results for sexual maturity, Gourley found that certain dominant market reef fish were not nearly in such poor shape as depicted in 2009.

The 2009 study was conducted over a four-month period and involved measuring 11,500 fish (approximately 7,000 lbs), while the 2011-2013 study was done in a span of 36 months and encompassed a total of 111,893 fish (65,797 lbs).

Micronesian Environmental Services’ bio-sampling data collection program for commercial Saipan landed reef fish was made possible by a 2010 grant from the Pacific Islands Fishery Science Center (NOAA) and is managed in conjunction with the local Division of Fish and Wildlife.

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