Thanks to those that have offered comments on my original post about
Cichlasoma tuba fry. I realize now that I didn't explain the situation
quite clearly enough.
First, the current velocity I was reporting (60 cm/s) was measured
within about 6 inches of the fry (i.e., not an average stream
Second, this isn't burst swimming. The kids had to maintain this
velocity for around 3 days! (or else be swept away).
To be sure they were trying to use the ground to some extent, but
I'm not sure how much less the velocity was right against the gravel.
I was measuring the velocity with a propellor-type (General Oceanics)
current meter and the fin diameter of 6 inches only allowed me to
get that close to the substrate.
Is there another type of device that would allow me to measure the
current profile in say 1 inch increments from the substrate -- that
would be truly ideal?
Thanks for your input.
-- Ron Coleman
[log in to unmask]
On Tue, 24 Dec 1996, Neal R. Foster wrote:
> Fuiman and Magurran (1994. Development of predator defenses in fishes.
> Rev. Fish Biol. Fish. 4:145-183.) found that length-specific burst
> swimming speeds of freely swimming early life stages of fishes are
> proportionately higher than in yearling, subadult, or adult fish--
> typically about 15 body lengths per second but ranging as high as 60 body
> lengths per second. I assume that the young Cichlasoma were only
> maintaining such speeds for brief periods of time--20 seconds, usually
> less--the "standard length" of a "burst." Generally speaking, burst speeds
> are independent of temperature (Beamish, 1978. Swimming capacity. in Fish
> Physiology, Volume 7), but the warmer water there in Costa Rica might have
> enhanced the swimming ability of the young cichlids even further.
> Neal R. Foster, U.S. Department of Interior, USGS-Biological Resources
> Division, Great Lakes Science Center, 1451 Green Road, Ann Arbor, Michigan
> 48105-2807; Phone [+voicemail]: (313)994-3331-x264; FAX: (313)994-8780;
> e-mail: [log in to unmask]
> > ----------------------------------------------------------------------
> > Date: Mon, 23 Dec 1996 02:40:05 -0800
> > From: Ron Coleman <[log in to unmask]>
> > Subject: Fast Swimming Fry
> > Hi,
> > I was recently working up some data I collected last year in Costa Rica
> > and was wondering if someone more knowledgeable in the "swimming"
> > literature, particularly larval swimming could comment.
> > Water velocities in this river change rapidly with precipitation, but at
> > some places and times I recorded velocities of around 60 cm/sec.
> > Free-swimming young of the species I study (Cichlasoma tuba, TL = roughly
> > 1 cm to 1.5cm) were maintaining position in these currents (with some
> > difficulty). This comes out to 40 to 60 body lengths per second of
> > sustained swimming (for at least a few days before the water slowed down).
> > This seems pretty high to me in comparison to the values I seem to be
> > encountering in the literature.
> > My question: is this unusually athletic or are there other fish doing
> > similar things? Any pointers would be gratefully received.
> > Thanks,
> > Ron Coleman
> > [log in to unmask]
> > ----------