piezo sirens

i recently made fishing alarms . the circuit is 9volt battery to on off switch to snapaction switch to piezo siren (with operating range 6 to 12 volts) back to battery. the siren is very loud, i got the loud one because im not always at my rods and i like to hear them from afar but when i am at my rods they’re too loud. right now all i can do is tape over siren to control volume is there a way to control volume ideally id like to find volume control with on off built in like they used to use on old audio equipment. any help with type and ohm rating would be great, along with where to find them thanks ken

No idea what you are talking about (by which I mean you haven’t provided any
detail as to which siren you have, such as datasheet or even a part number).
If you want more than a guess, provide more information please.

heres a link to the one i got one line: http://www.radioshack.com/product/index.jsp?productId=2062405

only specs i saw were:

Add some sound with our Piezo buzzer siren! This buzzer may be used whenever an attention-getting audible warning is needed. The siren is perfect for security systems, over and under-limit indicators and power failure alerts. Operates on 6-14 VDC, with 150mA Current at 12V. Buzzer Tone rated at 2,000-4,500Hz

Ah, that's encouraging - the wide voltage range suggests you will get a reasonable amount of volume control by changing the supply voltage, and perhaps you can get away with taking it even lower than 6V experimentally.

It may be possible to simply add some series resistance to reduce the voltage/current it gets/consumes, and could add a switch to bypass this for full volume. There is a risk that is won't reliably start oscillating though, if "throttled" in this way.

I'd measure its current consumption at 9V in normal use, call it I, then try series resistor roughly equal to 9/I - for instance if I = 0.1A try a 90 ohm (approx) resistor.

If it works reliably at 5V you could use a 5V regulator to power it, and have a SPDT switch to change over to 9V for loud.