SUMMARY

• Main Authors: G. Walter Ingram, William J. Richards, Clay E. Porch, Victor Restrepo, John T. Lamkin, Joanne Lyczkowski-shultz, Gerald P. Scott, Stephen C. Turner
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: multivariate analysis; fish larvae; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.558.2738; http://www.iccat.int/Documents/Meetings/Docs/SCRS/SCRS-08-086_Ingram_et_al.pdf

Fishery independent indices of spawning biomass of bluefin tuna in western North Atlantic Ocean are presented which utilize NOAA Fisheries ichthyoplankton survey data collected from 1977 through 2007 in the Gulf of Mexico. Indices were developed using similarly standardized data from which previous indices were developed (i.e. abundance of larvae with a first daily otolith increment formed under 100 m2 sea surface sampled with bongo gear). Indices were also developed for the first time from standardized data collected with neuston gear [i.e. abundance of 5-mm larvae (i.e. seven-day-old larvae) per 10 minute tow]. Indices of larval abundance were developed using delta-lognormal models, including following covariates: time of day, time of month, area sampled and year. Due to the large frequency of zero catches during ichthyoplankton surveys, a zero-inflated delta-lognormal approach was also used to develop indices. Finally, a multivariate delta-lognormal approach was employed to develop indices of annual abundance based on both bongo and neuston catches. The results of these approaches were compared with one another and with other indices of larval abundance previously developed for the Gulf of Mexico.