Date Awarded


Document Type


Degree Name

Master of Arts (M.A.)


Virginia Institute of Marine Science


Spanish mackerel were purchased from commercial fisheries in the Chesapeake Bay in the period 1993-1994 and processed for biological data to describe reproductive biology. Spanish mackerel are multiple spawners with asynchronous oocyte development and indeterminate fecundity. They spawn in the Chesapeake Bay area from June through August, June being the peak spawning month. Individuals, however, vary greatly in when they begin and end spawning. The presence of Gravid and Running Ripe females indicates spawning inside the Chesapeake Bay, and the capture of small juveniles suggests the region may be used as a nursery grounds. Sex ratios vary greatly, females generally dominating at larger sizes. Length at first maturity (L50 ) was 230 mm FL in females and 232 mm FL in males; all females are mature at 330 mm FL and all males at 340 mm FL. Mean batch fecundity is 74,077 eggs, increasing with length and somatic weight. Average relative fecundity is 143 eggs/g female(± 10 SE). Spanish mackerel are .sometimes infected with a live-bearing nematode that reduces fecundity.



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