Juvenile and young fish communities are stated to be rapidly entering waters among new reforested mangroves. What is the best way to observe and describe sightings qualitatively (via census) ?
Thank you for your infos and help! @Simon: I really would try to work non-invasive, since major focus of my work is the assessment of reforestation and recovery of important ecosystem functions of respective mangroves, such as fishery nursery and supply. I don't want to destroy these rehabilitated functions by measurments immediately.
@ Dan Gwinn: Your ideas of baited fish traps are nice! Of course you're right, water clarity has to be somehow appropriate to be able to film trapped fish. But I'm optimistic! Will try to find more about fish traps! Thank you a lot!
DIDSON acoustic camera systems have been used succesfully in mangroves. Video like sonar signal and species IDs are possible as well as lengths for nursery function data. Expensive gear so you may want to arrange rental or loan.
http://www.soundmetrics.com/products/didson-sonars
Thank you Michael Travers! Unfortunately budget is pretty low, but nice to know existing possibilities for the future!
@Dawn Gwinn: Thought more about the traps.. Baiting would mean experimental manipulation, and could lead to the assumption fish were just entering mangroves because of the baits. I'm thinking about unbaited traps, the ones that are constructed in a certain size or shape, that make fish easily enter them, but not let them get out anymore. Probably local fishermen know some tricks..!
We use to use unbaited traps for monitoring juvenile fish in the Colorado River Grand Canyon. Baitless traps did not catch as many fish as unbaited ones, but they still caught a resonable number of fish. The following link is to a paper on this work. If you cant access the pdf and would like a copy I can email it too you.
http://www.fwspubs.org/doi/pdf/10.3996/082012-JFWM-071
I have also recently coauthored a paper that is in the revision process in PLOS One. Its on the use of a camera trap/baited trap gear combination for monitoring reef fish. I could also email you a copy of that manuscript if you like. Just let me know.
Hi Dan, I would also be keen to get a copy of your PLOS One MS. I am currently exploring fish monitoring methods for turbid and high current waters in north-western Australia and baited BRUVs and traps are a couple of methods used ith some success during neeap tides.
Thank you very much, Dan Gwinn! I'll read into it and contact you for further infos !
Verena and Michael, my email is [email protected]. Shoot me an email and I will send you the manuscript. Incidentally, I will be in Perth for the last week in September and three weeks of Oct. Would love to chat more about monitoring methods. Cheers
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