On Food and Cooking

countries now routinely monitor waters for
the algae and shellfish for the toxins, so the
greatest risk is from shellfish gathered
privately.
There are several distinct types of shellfish
poisoning, each caused by a different toxin
and each with somewhat different symptoms
(see box below), though all but one are
marked by tingling, numbness, and weakness
within minutes to hours after eating.
Dinoflagellate toxins are not destroyed by
ordinary cooking, and some actually become
more toxic when heated. Suspect shellfish
should therefore be avoided altogether.
Finfish generally don’t accumulate toxins
from algae. The exceptions are a group of
tropical reef fish — barracuda, groupers,
jacks, king mackerel, mahimahi, mullets,
porgies, snappers, wahoo — that prey on an
algae-eating snail (cigua) and can cause
ciguatera poisoning.