Mackerel, bonito, tuna, sardines and anchovies have muscle rich in histidine. When the fish waits without chilling, bacteria on it turn histidine into histamine, and the histamine that forms is not removed by cooking, canning or freezing.
That makes the first hours decisive. The FDA guidance asks for fish to go into ice, ice slurry or chilled brine at 4.4 °C or below within 6 hours of death when the air is above 28.3 °C, and within 9 hours in cooler conditions; ice alone chills more slowly than slurry because less surface touches the fish.
Ashore the target is a temperature near freezing point. Fresh fish that has not been frozen should spend no more than 8 hours in total above 4.4 °C, or 4 hours if the ambient air went above 21.1 °C. Turkish regulation also bans carrying landed fish in open vehicles (Article 46).
Fish spoiled at high temperature may not smell spoiled, so a smell check is not enough. Two questions to the supplier are enough: how many minutes after the catch was it iced, and what temperature did it keep until landing. The lab criterion is a mean of 100 mg/kg across nine samples and no sample above 200 mg/kg.