Publications: Peer-reviewed journal articles (by staff)

Facilitation of upstream passage for juveniles of a weakly-swimming migratory galaxiid

  • Doehring KAM,
  • Young RG,
  • and McIntosh AR
1 January, 2012
CITATION

Doehring K, Young RG, McIntosh AR 2012. Facilitation of upstream passage for juveniles of a weakly-swimming migratory galaxiid. New Zealand Journal of Marine and Freshwater Research 46(3): 303-313.

ABSTRACT

The mitigating effects of fish passes to aid fish dispersal are well recognised; however, non-sports fish species, juveniles and weak swimmers have mostly been neglected when developing solutions to fish passage issues. We studied the juvenile (fork length, FL < 60 mm) swimming ability of a weakly swimming fish species, inanga (Galaxias maculatus), up an artificial ramp to evaluate the effects of fish size, ramp slope (5 degrees, 15 degrees, 25 degrees), water velocity and the potential need for resting opportunities (pools) for a successful ascent. Water velocity significantly increased and fish passage success significantly decreased with ramp angle, with only one fish passing the 25 degrees ramp. On average, fish had to be 10 mm larger to ascend a 15 degrees ramp angle than at 5 degrees. Pools did not enhance passage success in this study. To facilitate fish passage at barriers for weakly swimming fish species like juvenile inanga, ramps should provide a rough surface substrate and have an optimal angle of 5 degrees for a 3-m ramp.