Table 11.— Mean length (nm) of Atlantic menhaden In samples from purse seine 

 catches, by port. 



Table 12. — Mean weight (g) of Atlantic menhaden in samples from purse seine 

 catches, by port. 



age-4 have been too scarce to permit meaningful con- 

 clusions to be drawn. 



Mean lengths for all ages combined also reflect the 

 increased growth rates (Tables 11, 12). There are slight 

 increases for fish in samples at South Atlantic ports, but 

 large increases for fish at Chesapeake Bay, Middle 

 Atlantic, and North Atlantic ports. The largest in- 

 crease in mean lengths is for fish in Chesapeake Bay 

 samples. Mean length offish from North Carolina fall 

 fishery samples generally were smaller from 1965 to 

 1971 than from 1955 to 1962. This change has resulted 

 from the decrease in the average age of fish in the 

 catch. Since weight increases at a much greater rate 

 than length for fish over 200 mm, the length increases 

 for fish caught during the summer north of Cape 

 Hatteras represent a relatively large increase in 

 biomass. 



YEAR CLASS STRENGTH 



Relative strength of year classes can be inferred by 

 following the catch of each year class as it passes 

 through the fishery. Because of the age and size dis- 

 tribution of Atlantic menhaden, variation in fishing 

 effort in different areas can distort the relative impor- 

 tance of different age groups in the catch and make 

 assessments difficult. If only the Chesapeake Bay 

 catch, which has accounted for the major share of the 

 catch since 1964, and the combined catch of ages 0-4 

 from all areas are considered, some meaningful in- 

 ferrences can be drawn. 



The 1951, 1953, 1955, 1956, and 1958 year classes 

 appear to have been strong. Whether they were un- 

 usually stronger than year classes prior to 1951 is not 

 certain. The 1958 year class, however, was certainly 

 the most abundant since 1951 and may have been one 

 of the largest ever produced, although there is no way 

 of knowing. 



Evidence of the strength of the 1959 year class is 

 conflicting. Although the catch of age- 1 fish was poor, 

 the catch of ages 2 to 4 was relatively good. Perhaps 

 the 1959 year class did not appear as abundant at age- 

 1 because the catches were dominated by the age-2 

 fish of the super abundant 1958 year class. Also, 1960 

 was a year of poor market conditions, and Chesapeake 

 Bay plants, which account for most of the age-1 catch, 

 established quota restrictions on the catch. 



All of the year classes from 1960 to 1970 appear to 

 have been smaller than any from 1951 to 1958. 

 Although the total number of fish from the first three 

 age groups after 1959 was not much less than the total 

 number from these age groups prior to 1960, the effort 

 against these age groups was much greater. In 

 Chesapeake Bay, effort nearly doubled from 1955 to 

 1964. 



The 1964, 1966, and 1969 year classes appear to 

 have been the largest produced between 1959 and 

 1970. Since fishing effort in Chesapeake Bay was ex- 

 ceptionally high, particularly from 1964 to 1968, these 

 year classes were smaller than the catches indicate 

 and probably did not equal the abundance of any of 

 the year classes from 1951 to 1959. 



12 



