Temporal variations of condition and prey-predator status for two Halfbeaks (<i>Hemiramphus archipelagicus</i> and <i>H. lutkei</i>) in the Karachi Coast of Pakistan through multi-model inference

Abstract

The present study focuses on the temporal variations of condition through multiple functions (allometric, <i>K_A</i>; Fulton's, <i>K_F</i>; relative, <i>K_R</i>) and prey-predator status through relative weight (<i>W_R</i>) for two halfbeaks, <i>Hemiramphus archipelagicus</i> (Collette & Parin, 1978) and <i>Hemiramphus lutkei </i> (Valenciennes, 1847) using the monthly samples from the Karachi Coast of Pakistan during January to December 2014. The smallest individual was 14.0 cm in TL for both species, but the largest individuals were 23.5 in TL for <i>H. archipelagicus</i> and 27.8 cm in TL for <i>H. lutkei</i>. The BW ranged from 8.0-27.4 g for <i>H. archipelagicus</i> and 7.0-37.4 g for <i>H. lutkei</i>. There was significant differences in length-frequency distributions (LFDs) between two species (<i>P</i><0.001). The <i>K_F</i> was highly correlated with TL for both species (Spearman rank test, <i>P</i><0.001). Therefore, it is suggested that <i>K_F</i> is the best condition factor for assessing the wellbeing of this two Halfbeaks in the Karachi Coast of Pakistan. There was no significant relationships between TL <i>vs. K_A</i>(<i>r_s</i>=-0.0264,<i> P</i>=0.056 for <i>H. archipelagicus</i> and <i>r_s</i>=-0.0883, <i>P</i>=0.855), TL <i>vs. K_R</i> (<i>r_s</i>=-0.0108, <i>P</i>=0.813 for <i>H. archipelagicus</i> and <i>r_s</i>= 0.0235,<i> P</i>=0.608) and TL <i>vs. W_R</i> (<i>r_s</i>=-0.0099, <i>P</i>=0.828 for <i>H. archipelagicus</i> and <i>r_s</i>=0.0235,<i> P</i>=0.608 for <i>H. lutkei</i>), but significant relationships were found in TL <i>vs. K_F</i>, BW <i>vs. K_A</i>,BW <i>vs. K_F</i>, BW <i>vs. K_R</i> and BW <i>vs. W_R</i> (<i>P</i><0.001) for both species. In addition, the <i>W_R</i> was not significantly different from 100 (Wilcoxon signed rank test <i>, P</i>=0.654 for <i>H. archipelagicus</i> and <i>P</i>=0.405 for <i>H. lutkei</i>) for both Halfbeaks in the Karachi Coast of Pakistan, indicating the habitat is still in balance condition with the good combination of prey and predators.