Toxin levels in king scallops

Thursday 21 September 2000

The Food Standards Agency (FSA) is responsible for decisions relating to closures of scallop grounds when shellfish toxin levels exceed internationally recognised limits.

Testing is routinely carried out as part of the UK's monitoring and sampling programme by the Fisheries Research Services Marine Laboratory (FRS ML) in Aberdeen, which is also the UK National Reference Laboratory for algal toxins. The Testing method itself is set out in European Legislation to ensure a common approach and standards are adopted by laboratories across the European Community.

Purpose

This comparative analysis was carried out to establish whether toxin levels in commercially processed scallop tissue were significantly reduced when compared to scallop tissue, which had not undergone commercial processing. A summary of the details of the methodology, results and conclusions of the analysis are set out below.

Method

Approximately 300 scallops were collected from three sampling areas in the South Minches (boxes SM 10, 11 and 12) on 11 September 2000. At that time the selected sampling areas were closed to fishing due to high ASP toxin levels. The samples were then landed at Mallaig under the supervision of an Environmental Health Officer (EHO) from where they were then transferred to the Fisheries Research Services Marine Laboratory (FRS ML) in Aberdeen.

At FRS ML, again under the supervision of an EHO, the scallops were separated into batches of 12 animals. Three batches of scallops from each of the three sampling boxes were prepared for testing by FRS ML, and another three batches from each box were processed commercially before being returned to the ML for testing.

To ensure that the FRS ML toxin analyst could not differentiate between samples prepared at FRS ML and those processed commercially, each was coded. The concentration of domoic acid (the cause of Amnesic Shellfish Poisoning) was then determined for each of the 18 samples using the standard EU testing method. The resulting data were grouped according to the sampling area of origin and whether it had been prepared by the FRS ML or the Commercial Processor. An average concentration of domoic acid was then determined from each group, (see attached table).

All the results were greater than the action limit of 20 micrograms of domoic acid per gram of gonad, the level at which scallop fishing must be banned. The average results for commercially processed shellfish were slightly higher than those prepared by FRS ML for areas SM 10 and SM 12, and lower than those prepared by FRS ML for area SM 11.

Conclusion

There was no significant difference in the toxin levels detected in king scallops prepared by a commercial processor and those prepared by FRS ML.

Summary of Results

Average domoic acid (DA) concentrations found in king scallop gonads. The data are grouped according to the origin of the sample, both in terms of its location and where it was prepared.

SM Scallop Box	Sample Source	Average Toxin Level DA [μg/g]
10	Commercial	36.4
10	FRS ML	31.3
11	Commercial	29.4
11	FRS ML	37.2
12	Commercial	37.1
12	FRS ML	26.1