INFORMATION BULLETIN (98-83)          August 31, 1998         
 Sustainable Fisheries Division        10:35 a.m.               
 907-586-7228


                              
      NOTIFICATION OF STANDARD POLLOCK DENSITY FACTOR USED 
                   IN THE POLLOCK FISHERIES 

The National Marine Fisheries Service (NMFS) is providing
notification of the standard pollock density factors being used 
by observers to derive volumetric catch weight estimates in the
pollock fisheries, according to Steven Pennoyer, Administrator,
Alaska Region, NMFS.

Observers have been instructed to use a fixed density factor of
0.98 t/m3 to convert pollock bin volumes to catch weight, and a
fixed density factor of 1.02 t/m3 to convert pollock codend
volumes to catch weight.  These fixed density factors were
derived from extensive at-sea research aboard a commercial
factory trawler between September 1996 and March 1997.  This
research is summarized in the Alaska Fisheries Science Center
(AFSC) Processed Report 97-07, "Evaluation of haul weight
estimation procedures used by at-sea observers in pollock
fisheries off Alaska" (available through the AFSC).  

Accuracy of volumetric measurements by observers will be improved
if vessel operators and crew cooperate with observers to (1)
minimize the amount of water in bins prior to observers'
volumetric measurements, (2) improve visibility into bins, and
(3) provide observers with adequate time, assistance and safe
conditions to measure all dimensions of a codend with a measuring
tape.

Questions regarding observer catch weight measurements may be
directed to the North Pacific Groundfish Observer Program at 
206-526-4078.
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