Research supports what the gunny said. Larger fish are females.
Mixing milt with eggs
Fig.3 graphic summary of average lengths and weights of striped bass, or rock, at different ages.
This chart highlights two facts. 1) beginning at three years of age, the female is larger than the male at the same age: and 2) males do not live as long as females. In this sample of fish very few males over 8 years old were captured; none were found among fish over 11 years old. Therefore virtually all "jumbo" striped bass appears to be females. These results are based on calculated data derived from the examination of annular rings of scales taken from striped bass in various regions of the Chesapeake bay, during 1957 and 1958. After Mansuetti 1961A
Maryland Dept of Natural Resources