CONTENTS 



Introduction 1 



Methods 1 



Results 6 



Catch 6 



Catch composition 8 



Abundance indices 8 



Fishing mortality 9 



Recruitment 10 



Partial recruitment 10 



Stock size 11 



Catch and stock size projections 11 



Discussion 12 



Literature cited 12 



Figures 



1. Northwest Atlantic from North Carolina to Labrador showing ICNAF Subareas 3, 4, and 5 and 

 Statistical Area 6 2 



2. Northwest Atlantic off the U.S. coast showing bottom trawl survey sampling strata and ICNAF 

 Subarea 5 and Statistical Area 6 3 



3. Stratified mean catch (kilograms) per tow of Atlantic mackerel from the U.S. spring (1968-77) and 

 autumn (1963-76) bottom trawl surveys 4 



4. Exponential curve calculated through 1968-77 time-series (1969 point omitted from calculation of 

 curve) of spring survey catch-per-tow (kilogram) indices for Atlantic mackerel 4 



5. Relationship between fishing mortality for Atlantic mackerel from cohort analysis and fishing 



effort derived from spring survey catch per tow and total catch 5 



6. Power curve relationship between Atlantic mackerel year-class size at age 1 from cohort analysis 



and autumn survey catch per tow at age 5 



7. Power curve relationship between Atlantic mackerel year-class size at age 1 from cohort analysis 



and spring survey catch per tow at age 1 6 



8. Power curve relationship between Atlantic mackerel year-class size at age 2 from cohort analysis 



and spring survey catch per tow at age 2 6 



9. Atlantic mackerel spawning stock biomass (metric tons) in 1962-77 and abundance at age 1 of the 

 1961-77 year classes from cohort analysis 10 



Tables 



1. Mean weights at age (kilograms) for Atlantic mackerel (ICNAF 1974) 



2. Estimation of fishing mortality (F) in 1977 for the ICNAF Subareas 3, 4, and 5 and Statistical Area 

 6 Atlantic mackerel fishery 



3. Fishing mortality rates (F) for Atlantic mackerel in ICNAF Subareas 3, 4, and 5 and Statistical 

 Area 6 derived from cohort analysis with natural mortality (M) = 0.30 



4. Catch per tow (number) of age Atlantic mackerel from the U.S. autumn bottom trawl surveys 

 (strata 1-2, 5-6, 9-10, 13, 16, 19-21, 23, 25-26) and year-class size (millions of fish) at age 1 from 

 cohort analysis 



5. Catch per tow (number) of ages 1 and 2 Atlantic mackerel from the U.S. spring bottom trawl surveys 

 (strata 1-25, 61-76) and year-class size (millions of fish) at ages 1 and 2 from cohort analysis . . . . 



6. Atlantic mackerel catch (metric tons) from ICNAF Subareas 3, 4, and 5 and Statistical Area 6 

 during 1961-77 



7. Estimated Atlantic mackerel catches (metric tons) in 1977 by country from ICNAF Subareas 3, 4, 

 and 5 and Statistical Area 6 



8. Atlantic mackerel catch (commercial and recreational) (millions of fish) from ICNAF Subareas 3, 

 4, and 5 and Statistical Area 6 during 1962-77 



9. Stratified mean catch (kilograms) per tow (In and retransformed) of Atlantic mackerel from the 

 U.S. bottom trawl surveys in the spring (strata 1-25, 61-76) and autumn (strata 1-2, 5-6, 9-10, 13, 

 16,19-21,23,25-26) 



iii 



