Tom Helser
NOAA Northwest Fisheries Science Center
April 13, 2005

A generalized linear mixed model (GLMM) that treats year and spatial cell as fixed effects while treating vessel as a random effect is used to estimate biomass and variances for 11 slope species in the NMFS bottom trawl surveys on the upper continental slope of U.S. West coast. A Bernoulli distribution is used to model the probability of a non-zero haul and we examine alternative error distributions from the exponential family using AIC to model the non-zero catch rates.