Reeve Net Protocol

We have requested tows with a large-cod end ("Reeve") net to be made on Broad Scale cruises starting in February. The object is to try to sample larger gelatinous predators that are destroyed in the MOCNESS tows. I suggest the following protocol for these tows:
  1. Tows to be made at all Priority 1 stations, as far as possible.

  2. At Priority 1 stations where a 10 m MOCNESS trawl is not made because of weather conditions, I would especially like the Reeve net tow to be made, since it would then be the only sample for large jellies.

  3. Both a 1 m and a 2 m diameter net are on board Oceanus. I would like the Chief scientist to try both and determine which is the more practical to use under BS cruise conditions.

  4. Tow are vertical, made to the depth of the shallowest MOC-10 net, (usually 0-15 m). Ideally, the net bridle is fastened to the end of the wire, so that it hangs below it. In this case the cod end may need to be weighted separately to sink properly. If the net cannot be attached to the end of the wire, it can be fastened with a book clamp near the end. The large, solid cod-end needs to be filled with water before lowering. It is not necessary to use a flowmeter with these tows; we will calculate volume filtered from mouth diameter and depth. The net should be hauled up at about 5 m/min, and carefully retrieved over the side. Probably the entire operation won't take more than 15 min.

  5. Since much of the catch may be fragile (large ctenophores etc) it needs to be examined immediately, before preservation. At a minimum, I would like a count of large jellies, particularly lobate ctenophores, and if possible measurement (oral-aboral length) of a representative subsample. The catch should then be preserved in 5% buffered formalin.

  6. After the February cruise, Erich and I will revise this protocol as experience suggests, and it can then be added to the Chief Scientist's package.

Last modified: February 7, 1997 (Larry Madin)