Pretty trivial to do at both lab and industrial scales. I've no knowledge of the biology, but if bromoform is the active ingredient it could probably be produced at scale for on the order of a few thousand dollars per tonne(governed primarily by Br2 pricing[0]) then fairly easily doped into pellets or feed.

[0] Maybe less using the haloform reaction. I'm not intimately familiar with the best-industrial manufacturing methods.

In a paper on this topic this was tested and pure bromoform doesn't have the same effect, the authors speculate that is due to delayed release from the seaweed structures.

I was reading about it on wikipedia, it used to be produced in large quantities.

Sigma Aldrich sells a kilo of pure bromoform for about $300. I’m sure bulk bromoform is much cheaper.