Eilat mariculture researchers work to increase fish supply for dinner table

Researchers at the National Center for Mariculture in Eilat are developing new means to propagate the region’s sought after fish species.

November 4, 2014 01:38
4 minute read.
AN EMPLOYEE of the National Center for Mariculture

AN EMPLOYEE of the National Center for Mariculture checks the condition of a fish as part of the center’s research into increasing stocks in the country’s waters. (photo credit: NATIONAL CENTER FOR MARICULTURE)

As global food demand continues to explode and governments grapple with how to satisfy an increasingly hungry world, researchers at the National Center for Mariculture in Eilat are developing new means to propagate the region’s sought after fish species.

“Despite the fact that we improve fishery means and increase fishery efforts, the demand is higher, and within less than 50 years it is anticipated that over 90 percent of edible fish will be gone,” said Dr. Hanna Rosenfeld, acting director of the National Center for Mariculture in Eilat, a unit of the Israel Oceanographic and Limnological Research Institute.

Rosenfeld was addressing a group of journalists on Thursday, on a tour organized by the Government Press Office in conjunction with the Agricultural Research Organization’s Volcani Institute. While sea bass and sea bream are the prime fish domesticated in Israel, scientists at the National Center for Mariculture recently “made a breakthrough in closing the whole life cycle activity of the gray mullet” and are now able to induce spawning of the fish in their lab’s hatchery, Rosenfeld explained.

Consumption of fish in general has become increasingly popular as both public awareness toward eating healthily and buying power have grown, Rosenfeld explained.

With these trends, aquaculture has likewise seen a sharp rise, supporting about 50% of the fish consumption around the world and with an estimated value of $150b., she added.

“It is clear now that if we are all going to live in this crowded world we need to cultivate the sea just as we do the land,” Rosenfeld said.

Unlike developing mammalian livestock, however, fish domestication poses additional challenges due to the diversified nature of many fish types that people consume, she explained.

As far as the gray mullet is concerned, Lake Kinneret (Sea of Galilee) has been stocked with fingerlings yearly for some time – yet these have traditionally been caught in the wild from the sea, explained Dr. Amos Tandler, a senior scientist at the National Center for Mariculture.

“The bottom line of the achievement you see here is that you produce in captivity what was captured in the past in the wild,” Tandler said.

To spawn the fingerlings, the researchers maintain a broodstock – a stock of sexually mature fish – whose reproductive potential they follow closely, Rosenfeld explained.

Because mullet face reproductive dysfunction in captivity, they provide the brooders with hormonal fertility treatment and they go on to produce millions of eggs.

Rosenfeld emphasized, however, that these are individual hormone treatments to the brooders alone, and that the resultant progeny are entirely hormone free. The fingerlings are moved to the hatchery and are reared in normal conditions, she said.

Now that the scientists are able to spawn the fingerlings themselves in the lab, rather than catch them at sea, they would like to see an industry develop that generates and mass reproduces the fingerlings, explained Dr. Ariel Diamant, a professor of marine science at the center.

The gray mullet fingerlings have already been commercially produced for three years at Kibbutz Ma’agan Michael, near Zichron Ya’acov, which is in the process of scaling up its efforts, as well as at the Ardag marine agriculture company in Eilat, Rosenfeld said.

After successfully spawning the gray mullet fingerlings, the scientists at the National Center for Mariculture are focusing on doing the same for white grouper. The grouper “spontaneously spawns,” meaning that the scientists do not need to provide fertility treatments, but viral diseases remain a barrier toward progressing to a commercial stage with this species, Rosenfeld explained. She and her colleagues are trying to develop vaccines for the diseases, which cause loss of life at all stages.

The grouper fingerlings may not yet be prepared for commercial production, but Diamant said that Ma’agan Michael has expressed interest in taking on a commercial effort once the time is right.

“These are one of the important fish of the future,” he said.

Like Rosenfeld, Diamant emphasized that “the global fish tray is worth billions of dollars” but still faces many constraints due to production costs as well as still mysterious factors like diseases in marine species.

Nonetheless, with the oceans “unable to supply the world demand for protein from the sea,” scientists are working to fill in the gap, he explained. Diamant stressed that each fish species has its own unique properties, and aquaculture researchers therefore must gain expertise in their individual reproduction routines, nutritional quality, food and other details, to bring the products to the marketing stage.

“If we learn everything about the gray mullet and we know everything very well, when we start a new fish like tuna, it’s a whole new world,” he said. “Every fish has its own problems and demands.”

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