"Fish to disappear by 2050?"

"Fish to disappear by 2050?" HT: Spacedaily.

"An end to seafood by 2050?" "Fish to disappear by 2050?" These sensational media Are Fish Near Extinction?s were the result of a 2010 report by the United Nations Environment Program, declaring that over-fishing and pollution had nearly emptied the world's fish stocks.

That scarcity portends disaster for over a billion people around the world who are dependent on fish for their main source of protein.

Now, a new study by Dr. Roi Holzman and Victor China of the Department of Zoology at Tel Aviv University's George S. Wise Faculty of Life Sciences has uncovered the reason why 90% fish larvae are biologically doomed to die mere days after hatching.

With this understanding of the mechanism that kills off the majority of the world's fish larvae, leaving only a marginal proportion to populate the world's oceans, "We can help find a solution to the looming fish crisis in the world," said Dr. Holzman.

The research, published in PNAS and conducted at the Inter-University Institute for Marine Sciences in Eilat, Israel, suggests that "hydrodynamic starvation," or the physical inability to feed due to environmental incompatibility, is the reason so many fish larvae perish.

The physical structure of the larvae and their flawed interaction with the physical environment provided the answer Dr. Holzman was looking for. Over the course of two years, he and doctoral student Victor China observed fish larvae at three significant points in their development (at the beginning, middle, and end of that "critical period" - eight, 13, and 23 days old).

They found that the "stickiness" of the water - the viscosity of the surrounding ocean water - was hampering the larvae's attempts to feed.

"All that determines the larvae's feeding ability is viscosity - not age, not development. Only their interaction with the surrounding water," said Dr. Holzman.

"Because the water molecules around you have weak electrical bonds, only a thin layer sticks to your skin - a mere millimeter thick. If you're a large organism, you hardly feel it. But if you're a three-millimeter-sized larva, dragging a millimeter of water across your body will prevent you from propelling forward to feed. So really, it's all about larval size, and its ability to grow fast and escape the size where it feels the water as viscous fluid."

The researchers found that in less viscous water, the larvae improved their feeding ability. In theory, they can be expected to increase their survival rate. "We conclude that hydrodynamic starvation is the reason for their dying," said Dr. Holzman.

"Imagine eating soup with a fork - that's what it's like for these larvae. They're not developed enough at the critical point to adopt the constrained feeding strategy of adult-sized, better-developed fish."

Armed with this knowledge of the larvae's biological flaw, the researchers are currently patenting a solution to maintain higher survival rates among fish larvae populations.