Summer growth depression in the striped mullet, Mugil cephalus L.




Cech, J.J., Jr.
Wohlschlag, D.E.

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Growth rates by scale analysis of Mugil cephalus taken from south Texas coastal waters throughout one year showed two major periods of slow growth. The period of slowest growth, followed by annulus formation, occurred during the colder late autumn and winter months. Another major growth depression occurred during the summer when food availability to the mullet should be maximal. Optimal growth rates for Age I and older fish were in spring and briefly in early autumn. Annual growth increments, however, agree well with those for other published Gulf of Mexico mullet studies. Females appear to be slightly, but not significantly, larger and to have somewhat better survival rates. The summer growth rate depression coincides with observations of pronounced summer depression of active and routine respiratory rates observed in earlier studies. This coincidence implies that there may be unknown summertime changes in food assimilation and in biochemical metabolic pathways. The summer growth rate depression would have significant effects on assessments of biological production rates compared to similar assessments conventionally based on yearly increments.


p. 91-100.


marine fish, striped mullet, Mugil cephalus, growth, biological production