World Aquaculture March 2019

WWW.WA S.ORG • WORLD AQUACULTURE • MARCH 2019 39 ( C O N T I N U E D O N P A G E 4 0 ) the gate changed the activity from catching to farming fish. The location of an ancient Hawaiian fishpond always included a source of freshwater, a purposeful design feature. Dissolved nutrients in the freshwater were vital to stimulate primary productivity and the major reason how these fishponds functioned and why pond culture favored herbivores. This practice of using freshwater resources was very similar to how they were used to produce rice in Bali (Lansing 1987). The inclusion of a second moveable gate (Fig. 2) coincided with immigration of the Chinese and Japanese that began during the 1800s. By 1900, three-fourths of Hawaiian fishponds were being operated by Asians (Costa-Pierce 1987) and that also resulted in making harvesting more efficient. The economy of the Hawaiian Islands was also changing from subsistence to a market economy. Many external forces were driving the changes taking place in Hawaii. Tidal exchanges were the main way water circulation occurred and this caused adult fish to congregate in the sluice canals. This occurred at different times of the day and year and also coincided with different phases of the moon. The use of the moon is not restricted to Hawaiians as changes observed have been assigned certain attributes since the dawn of time and by various cultures around the world (Sharp et al . 2015). The collection of milkfish in Hawaii and Bali could be planned and executed based on the tidal calendar, greatly simplifying travel planning and collection of broodstock on both islands. Often not appreciated is the indigenous knowledge of ancient Hawaiians as they already had a good sense of the peak spawning periods for a variety of fish and invertebrate species. One example is a form of fisheries management called the kapu system, an ancient Hawaiian code of conduct, with infractions punishable by death. In Hawaii, the current seasonal restriction of catching striped mullet adults from the wild extends fromDecember through March (Hawaii Revised Statutes, 188-44) and is based on an ancient kapu that covers the period when striped mullet are sexually mature (Anonymous 2013). Traditional fishermen and pond operators have always had a wide knowledge of oceanography, fish biology, behavior, conservation and management practices that preserved the biological integrity of fish stocks for generations before the advent of modern gear or methods. In Hawaii, the Pleiades star cluster rising above the horizon at sunset in late October or early November marks the beginning of the Makahiki festival (Hawaiian NewYear). Seasonal migrations of animals such as humpback whales and Pacific golden plovers were also used to mark seasonal changes. These activities were not restricted to ancient Hawaiians and examples can be found around the world. Because Indonesia straddles the equator, such seasonal changes are much more subtle, and natural phenomena like the monsoons are used to mark the dry and wet seasons. Traditional fishing and agricultural societies should be termed ecologically advanced rather than technologically backward and such traditional knowledge should be preserved (Costa-Pierce 1987, Sato and Lee 1987). Traditional knowledge aided the working group, which could anticipate when milkfish and mullet broodstock were sexually mature, during the summer and winter months, respectively. The working group in Hawaii relied on ancient knowledge as well as developing new technologies for the completion of their research tasks. ModernMilkfish Culture in Hawaii Initial efforts at the Oceanic Institute in Hawaii began between 1976 and 1979, when researchers worked on the artificial propagation of striped mullet Mugil cephalus and initiated work on milkfish. Two Hawaiian fishponds located on different islands in Hawaii were the sources of the milkfish broodstock used for the work done at the Oceanic Institute. There was no success in the artificial propagation of milkfish in Hawaii at that time, although the first successful spawning of captive broodstock and production of milkfish fry in the Philippines had been reported (Vanstone et al . 1977). Sufficient juveniles were collected from an ancient Hawaiian fishpond and were stocked into natural ponds on the Kona coast of Hawaii island. The milkfish industry was still heavily dependent on wild-caught fry so efforts on artificial propagation continued. An examination of the economics of milkfish culture in the three major producing countries revealed that dependence on wild-caught fry was the main impediment to continued growth of the industry (Shang LEFT, FIGURE 3. Statistical model of oocyte growth in milkfish. (Source: Tamaru et al. 1988) RIGHT, FIGURE 4. Serum steroid profiles accompanying maturation of female milkfish. (Source: Tamaru et al. 1988).