Urchins and Kelp


Urchins and Kelp
Chris Nelson via Urchinomics

California’s kelp forests are currently facing a major threat: deforestation.

The root of this issue can be attributed to small, spiny invertebrates – purple sea urchins (Strongylocentrotus purpuratus). When urchins do not face predation pressures, their populations multiply, and they devour the foundation of kelp forests. When too many urchins are present, they prevent growth of canopy forming kelp, turning a beautiful and diverse kelp forest into a wasteland – also known as an urchin barren. These barrens don’t provide any of the benefits of a kelp forest, such as harboring endangered or commercially important species, sequestering carbon, preventing shoreline erosion, and oxygen production.

This video from the BBC documentary "Our Planet" shows the problem in stunning detail (starting at 20m 46s)

It is possible for humans to reverse these barrens, by removing sea urchins and contributing to a thriving urchin fishery. While “gonad” is not a particularly appetizing word, sea urchin gonads (referred to as “roe” or “uni”) are highly desirable in the global seafood market. The problem is that urchins collected directly from the barrens are essentially worthless.

Sea urchin gonads serve as their nutrient storage, so when there is little food, gonad production decreases. One solution is roe enhancement, or the collection of wild, mature urchins of non-marketable quality and developing the roe via aquaculture. Researchers are interested in creating formulated food for the urchins specifically to enhance their roe to a market size within a few months. This framework would incentivize people to collect urchins from barrens and culture them, producing sustainable seafood and allowing kelp forests to recover.

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