LARVAE AT EN 



YEAR (19 ) 



OIJAN OITEB OlMAR OlAPR OlMAY OIJUN OIJUL OlAUG O l SEP OlOCT Ol 



MONTH 



O IDEC O 1 , 



Figure 7. Annual cumulative density (no./500 m ) of sand lance larvae at EN and NB. 



At NB, more than 70% of the 1981 cumulative density was collected on April 15. These patterns could 

 be explained by the finding that larvae that hatch together tend to remain together (Norcross et al. 1961). 



Time-series models of larval density at EN and NB fitted observed data well and had R values of 

 0.74 and 0.92, respectively (Fig. 8; Appendix XIV). These models included periodic components of 4 and 

 6 mo, suggesting that the abundance of sand lance larvae is inherently seasonal within each year. The 

 previously mentioned decline in abundance of sand lance after 1981 has become a feature of the time-series 

 model, which provides an average characterization of the years of high (1977-1981) and low (1982-1985) 

 abundance. Therefore, the measures of variation from the model forecasts (MSE) at EN and NB (Appendix 

 XIV) are presented as a two-unit operational baseline for future assessments. 



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