1 Meter Mocness Towing Procedure For Globec Broardscale Cruises

  1. The 1-meter MOCNESS (MOC-1) sampler is loaded with ten nets. Nets # 1-4 are 150µm mesh, and nets # 0, 5-9 are 335-µm mesh.
  2. MOC-1 tows are double-double oblique from surface to ~5 meters off bottom. Maximum tow depth of net #0 and #5 is 500 meters. Net #5 net is is brought up from maximum depth to 200 meters whereupon net #5 is closed and net #6 is opened.

    A standard tow is as follows:

    NET  MESH(µm) RATE(m/min) STRATA(m)
     0    335     15m/min     Down - from surf to maximum depth
                                      or 500 meters.
     1    150       "         Up - from max tow depth to 100m.
     2     "        "         UP - from 100m to 40m.
     3     "        "         UP - from 40m to 15m.
     4     "        "         Up - from 15m to surf.
     5    335       "         Down - from surf to maximum depth
                                     or 500 meters.  On stations 
                                     deeper than  200 m, tow 
                                     Net #5 to 500 m and then 
                                     back to 200 m, then open #6.
     6     "      10m/min     Up - from max tow depth to 100m.
                                    (See note for net 5.)
     7     "        "         Up - from 100m to 40m.
     8     "        "         Up - from 40m to 15m.
     9     "        "         Up - from 15m to surf.  This net
                                     remains open at end of tow.   

  3. Winch rates for nets # 0-5 are 15 m/min and for nets #6-9 10m/min.
  4. During the tow, nets are tripped "on the fly" and the computer command is initiated about two meters from the next designated depth stratum to be fished. For example, when a net fishing on the up haul within the 100 to 40-meter stratum reaches 42 meters, trip the next net.
  5. At the end of the first oblique haul (#0-4), when the MOC-1 is at the surface, trip any remaining nets of 150µm mesh (<= #4) so that net #5 (with 335µm mesh)is fished on the down cast of the second oblique cast.
  6. On completion of the second double oblique cast (nets # 5- 9), when the MOC-1 is again at the surface, close the net fished to both minimize surface sampling and to end data acquisition. The exception is if #9 net is the last net fished, it of course cannot be closed (just mouse click "end acquisition" in the program) before the MOC-1 is retrieved back aboard.
  7. At stations where water depth is such that subtraction of the ~5-meter off bottom safety factor results in only a few meters of depth to be sampled, the current protocol is to not fish a net for only one or two meters, but to fish a net for a 3m or greater stratum.
Last modified:
April 1, 1996
January 2, 1996
December 21, 1995

Created: February 2, 1995