Argulus Project Update

Argulus egg collection update to end May 2023.

 Norfolk Flyfishers Club lake, Swanton Morley, Norfolk.

Sixteen pipes for egg collection were put over the posts in the lake on 30th March and one more (pipe 4) added on 4th April. Water temperature at that time was 10°C when argulus were expected to begin laying. Three inspections and eggs removed have been carried out.

DateApproximate No. stringsApproximate No. eggsWater temp    °CWater Clarity cms.
26th April74029,50012.5120
14th May62536,20014.8300
 30th May1799,60016.7300+
Totals1,54475,300  

Water temperature is measured by first platform on south bank below haul road. Significant numbers of caddis larvae were found on the pipes yesterday. These do predate on the argulus eggs. Large numbers of snails eggs are amongst others on the pipes.

The photo shows the longest string found so far this year. There are 400 eggs in this string. The small green ‘blobs’ remain unidentified to me. Whilst somewhat time consuming the individual strings are removed by a scalpel so the pipes are returned with most of the other invertebrates left to develop.

Dennis Willis   1st June 2023
Argulus-egg-update-to-end-May-2023.docx