MIGRATORY CONTINGENTS ASSESSMENT OF GREY MULLET MUGIL CEPHALUS AS INFERRED BY OTOLITH MICROCHEMISTRY
Date Issued
2009
Date
2009
Author(s)
Rosel, Rodolph Charles Nacpil
Abstract
To understand the habitat use and life history strategies of the grey mullet Mugil cephalus, a total of 578 and 9 individuals were collected respectively from Kao Ping River in southwest Taiwan and from Abulog River, northwest Philippines in November 2007 to February 2009. Among them 136 individuals were aged by reading the annulus in the whole otoliths and 42 individuals were analyzed for otolith strontium to calcium ratios by electron probe microanalyzer. The mean (±SE) fork length (FL) of the grey mullet collected from Kao Ping River estuary was 420.47 mm ± 2.43, corresponding to an age of 2+ years. The relative growth of weight on length of the grey mullet was isometric. The length at first maturity was estimated to be 315.00 mm in fork length. Growth parameters of the mullet was fitted by von Bertalanffy growth equation as: asymptotic length (L∞) = 568.40 mm FL an growth coefficient (K) of 0.22. Gonadosomatic indices indicated that the mullet spawned during the winter season around December. The temporal change of Sr:Ca ratios in otolith indicated that most of the mullet from Kao Ping River was estuarine contingent. However, the Mugil cephalus from northern Philippines stayed longer in freshwater. These results indicated that the habitat use of the grey mullet is facultative, which depends on the environmental availability.
Subjects
migratory history
grey mullet
Kao Ping River
otolith microchemistry
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