Geographic Variation in the Reproductive Ecology of the Panamic Grunt in the Southeastern Gulf of California

Abstract

AbstractBiological parameters pertaining to the reproductive ecology of the Panamic Grunt Pomadasys panamensis were investigated in 788 individuals sampled from the southeastern Gulf of California between November 2009 and October 2010. Length frequency distributions and mean TLs differed between sampling areas, with organisms from the coastal population exhibiting two clear modes that included most of the organisms (mostly adults; mean TL = 25.7 cm), while the open‐sea population appeared to consist of several cohorts (mean TL = 19.5 cm). Significant differences were recorded in spawning activity, gonadosomatic index (GSI), gonad weight, and size at maturity between fish from the coastal area and specimens from the open sea. The highest gonad weights and GSI values were recorded in the coastal zone during spring, coinciding with a peak in the number of mature females. In the open sea, the mature individuals were reproductively inactive throughout most of the yearlong study period, as individuals in late maturity stages represented a small portion of the sample. Female TL at 50% maturity (i.e., L50) was significantly lower in the coastal zone than in the open sea. The results suggest a differential use of available habitats by Panamic Grunts and highlight a need to consider temporal and geographic differences in reproductive ecology when formulating an adequate management program for this species.