SLOW MUSCLE POWER OUTPUT OF YELLOW- AND SILVER-PHASE EUROPEAN EELS (ANGUILLA ANGUILLA L.): CHANGES IN MUSCLE PERFORMANCE PRIOR TO MIGRATION

• Main Authors: D. J. Ellerby, I. L. Y. Spierts, Leeds Ls Jt
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: Key words; European eel; Anguilla anguilla; work loop technique
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.318.1635; http://www.wellesley.edu/Biology/Faculty/dellerby/Ellerby et al 2001a.pdf

Eels swim in the anguilliform mode in which the majority of the body axis undulates to generate thrust. For this reason, muscle function has been hypothesised to be relatively uniform along the body axis relative to some other teleosts in which the caudal fin is the main site of thrust production. The European eel (Anguilla anguilla L.) has a complex life cycle involving a lengthy spawning migration. Prior to migration, there is a metamorphosis from a yellow (non-migratory) to a silver (migratory) lifehistory phase. The work loop technique was used to determine slow muscle power outputs in yellow- and silver-phase eels. Differences in muscle properties and power outputs were apparent between yellow- and silverphase eels. The mass-specific power output of silver-phase slow muscle was greater than that of yellow-phase slow muscle. Maximum slow muscle power outputs under approximated in vivo conditions were 0.24 W kg−1 in Summary yellow-phase eel and 0.74 W kg−1 in silver-phase eel. Power output peaked at cycle frequencies of 0.3–0.5 Hz in yellow-phase slow muscle and at 0.5–0.8 Hz in silverphase slow muscle. The time from stimulus offset to 90 % relaxation was significantly greater in yellow- than in silver-phase eels. The time from stimulus onset to peak force was not significantly different between life-history stages or axial locations. Yellow-phase eels shifted to intermittent bursts of higher-frequency tailbeats at a lower swimming speed than silver-phase eels. This may indicate recruitment of fast muscle at low speeds in yellow-phase eels to compensate for a relatively lower slow muscle power output and operating frequency.