SCIENTIFIC COUNCIL MEETING – OCTOBER/NOVEMBER 2005 Testing OGMAP as a Tool for Estimating Biomass and Abundance of Northern Shrimp by

• Main Authors: Katherine R. Skanes, Geoffrey T. Evans
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: northern shrimp
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.496.1975; http://archive.nafo.int/open/sc/2005/scr05-095.pdf

The OGive MAPping (OGMAP) method for estimating biomass (with confidence intervals) from surveys was tested on simulated northern shrimp populations designed to have statistical properties similar to those of autumn shrimp surveys in NAFO Divisions 3L, 3N and 3O. A variety of years of surveys were used both to create reference populations and to simulate samples from them. Proposed OGMAP confidence intervals (CIs) contained the reference biomass slightly less often than they should have (57 % of the time for 60 % CIs; 91 % for 95 % CIs), but were still usefully close. The CIs are also usefully narrower than those produced from stratified aerial expansion which has the false assumption of Gaussian distributions within a stratum.