Acording to a recent report in Nature, both Thermo Fisher and Millipore Sigma have stopped selling pure stand alone bacteriological agar in order to conserve supplies for their more popular product lines where it's in combination with growth nutrients.

The reason is that poor growth of the seaweed Gelidium has led to harvesting restrictions being imposed in order to conserve stocks and what agar that is produced mostly goes to the food industry as a thickening agent so the media manufacturers have to compete for supplies.

Read the nature article here: www.nature.com/news/lab-staple-agar-hit-by-seaweed-shortage-1.18970#/graphic