N

number of fish studied; n is often used

the letter represents a wriggling eel and in Phoenician and Hebrew is called nun (a fish)

1) annual mortality rate (the ratio between the number of fish which die during a year from causes other than fishing and the number alive at the beginning of that year. Also called annual natural mortality rate, conditional natural mortality rate, seasonal natural mortality rate)

2) number of fish studied; N is often used