I never dredged in grassy beds or rocky area.
Mud isn't good too - we almost had to go to a quiropratic after trying to
pull a dredge full of mud to the boat...
Of course sandy bottom is much better since the dredge will "filter" the
excess.

Marcus


>From: "Monfils, Paul" <[log in to unmask]>
>Reply-To: Conchologists of America List <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: dredge design
>Date: Mon, 21 Jan 2002 15:34:50 -0500
>
>Dredging on grassy beds with a small, lightweight dredge is not very
>productive, because the dredge simply bends the grass forward and slides
>over it.  The only shells you are likely to get with a dredge on a grass
>bottom are small snails that may cling to the grass blades, well above the
>bottom.  You rarely get a shell that was on the substrate among the bases
>of
>the plants, because the dredge simply can't get down to that level.
>Consequently, the dredge does very little damage to the grass beds.  I
>usually avoid grass beds though, for the reasons already stated, unless I
>am
>specifically after a species that commonly climbs up the grass, or lies on
>top of it, like some Pectens.
>On a rocky bottom, a small dredge is again unlikely to take many mollusks,
>or to do much damage (except to itself).  A small dredge works best on a
>fairly smooth sand or fine gravel bottom, where it does a minimum of
>damage,
>and can take quite a few species.  Muddy bottoms are a bit more difficult
>to
>dredge, but here too a fair number of species can often be taken.
>
>Paul M.




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