SS1.09 Fisheries Population Linkage Spatial and Temporal Variation in Zooplankton
Date: Wednesday, June 12, 2002
Time: 10:00:00 AM
Location: Carson C
 
MyersRA, Dalhousie University, Halifax, Canada, myers@mscs.dal.ca
 
THE RESOLUTION OF HJORT'S CRITICAL PERIOD HYPOTHESIS
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MUCH OF FISHERIES RESEARCH CENTERS AROUND HJORT'S CRITICAL PERIOD HYPOTHESIS WHICH STATES ``THE NUMERICAL VALUE OF A YEAR CLASS IS APPARENTLY STATED AT A VERY EARLY AGE, AND CONTINUES IN APPROXIMATELY THE SAME RELATION TO THAT OF OTHER YEAR CLASSES THROUGHOUT THE LIFE OF THE INDIVIDUALS''. HERE I TRANSLATE THIS HYPOTHESIS INTO TWO ALTERNATIVE QUANTITATIVE MODELS, AND DEVELOP THE STATISTICAL METHODS THAT ALLOW THE CRITICAL PERIOD HYPOTHESIS TO BE FORMALLY TESTED BOTH. THESE RESULTS ARE THEN COMBINED USING A RANDOM EFFECTS META -ANALYSIS THAT EXPLICITLY MODELS THAT SPATIAL CORRELATIONS IN RECRUITMENT AMONG POPULATIONS. THESE METHODS ARE APPLIED TO POPULATIONS OF MARINE, ANADROMOUS, AND FRESHWATER POPULATIONS WHERE THERE ARE SURVEYS AT DIFFERENT AGES, AND FOR WHICH THE VARIANCE OF THE ESTIMATION ERROR CAN BE ESTIMATED. WE FIND NO SUPPORT FOR THE STRONG VERSION OF HJORT'S HYPOTHESIS, BUT THAT A WEAKER VERSION OF THE CRITICAL PERIOD HYPOTHESIS APPEARS TO APPLY TO MANY MARINE DEMERSAL SPECIES.