Traditionally, Fishery industry has been one of the most important industries in Canadian economy.In the past decade, responsible fishing operation has been becoming the main concern at various levels, including the government, industry groups, scientific institutions, and environmental organizations.The fundamental objective of any responsible fishing operation is to maximize returns to the operation with minimum effects on fish populations and environment.Research in fishing gear selectivity is a very important area for fishery management.While commercial fishing activities are carried out at sea, fishing gears should be designed to allow small fish to escape as large fish are retained.In this presentation, a probabilistic model design for estimating selection curves of trawl fishing gear will be studied.We shall introduce here is the so called Modified Alternate Haul Model Design which can be used in Trawl Experiments.In this model design, the control gear involved in the traditional alternate haul experiments will be eliminated.This model design will enable the experiment data to be collected only on gears to be evaluated to produce corresponding selection curves of those gears simultaneously.This model will significantly reduce monetary costs, increase experimental efficiency, and keep the waste of undersized fish at minimal level.