Double-netting: an alternative approach for the recovery of parasitic copepods from finfishes

Abstract

An alternative approach for the recovery of parasitic copepods from finfishes is proposed herein by applying double-netting (DN) after visual scanning (VS). Double-netting consists of double-filtering the dislodged debris after washing and shaking all dissected parts visually scanned previously. During DN, two different sized hand-nets (≤200 μm in mesh size) are used simultaneously. The debris entangled in the first net is recovered by washing the first net in the second one. A total of 1448 copepods were recovered from nine sparid finfish species by applying DN, accounting for 25% of the total. The most abundantly recovered copepods were bomolochids and philichthyids. Our double-sieving method is efficient in recovering overlooked copepods by VS, providing more accurate results in diversity and quantitative studies. Additional advantages of DN include its simplicity (small size and weight), low price (less than US$ 3), and convenience (easy to transport and apply directly in the field).

Keywords:

• double-netting
• methodology
• overlooked copepods
• quantitative parasitology

Acknowledgements

We are deeply thankful to Dr Danny Tang for his suggestions. The present study was partially supported by Grants-in-Aid for Scientific Research (Nos. 18380116 to KN and 228247 to IM) from the Japan Society for the Promotion of Science.