MEPS 151:191-203 (1997)  -  doi:10.3354/meps151191

Fluctuating asymmetry in the otoliths of larval anchovy Engraulis encrasicolus and the use of developmental instability as an indicator of condition in larval fish

Somarakis S, Kostikas I, Peristeraki N, Tsimenides N

Developmental instability, measured as fluctuating asymmetry (FA; i.e. deviations from perfect bilateral symmetry), was studied using 2 otolith traits (maximum radius and perimeter) in larval anchovies collected during June 1994 and June 1995 in the northern Aegean Sea (eastern Mediterranean). There was a substantial between-year difference, FA being greater in 1995 than in 1994: mean absolute asymmetry in otolith perimeter was 265% higher in 1995 than in 1994. Similarly, 3 'growth' relationships (standard length, SL, anal body depth, ABD, and recent otolith growth, ROG, on age, A) and 2 'allometric' ones (ABD and ROG on SL) were significantly different between the 2 years and indicated that anchovy larvae collected during 1994 were in better condition than those collected in 1995. These between-year differences could be explained in terms of Lasker's 'stable-ocean hypothesis'. Stability of the upper water column was higher in 1994 than in 1995. Subsequently, we examined asymmetry at the level of the individual: using the residuals of the 5 models as indices of condition, cases of significant negative correlation between asymmetry and the residual-based indices were found, a fact which seemed to depend mainly on the otolith trait and the residual variance of the model used to derive the index of condition. These field results suggest that developmental instability, as measured by bilateral asymmetry of the otoliths, can be used as an indicator of condition in larval fish.

Engraulis encrasicolus · Larvae · Fluctuating asymmetry · Condition · Otoliths · Northern Aegean Sea

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