How to trap a moray
The first afternoon in the field is particularly charged with excitement. Our main task is to prepare the moray traps for their inaugural night of soaking for the season. This is one of my favorite sites to observe-, the first pass at how our team, a conglomerate of newbies and experienced moray wranglers, can work together.
We haul our 16 moray traps out of the boneyard, a storage site on the USC Wrigely Field Station's property, down to the dock. We check to make sure each trap is in working order. After several hundred hours soaking, our wire traps are salty dogs despite the care we take in cleaning them. We tie rope of varying lengths and a red and white buoy onto each trap. Each buoy is labelled "UC Research" and numbered. We then take a dingy to the neighboring harbor to purchase our bait of choice- anchovies. We buy lots of bags, sometimes so many that the cashier at Two Harbor gives us a disapproving look as we pay. But we can't let the cashier get us down- this bait is for science- for the love of morays everywhere!
We quickly motor back to bait our traps. To do this, we use clear plastic drinking bottles that we poked holes into. That way, a moray can see and smell the bait and can be lured into the trap but has a hard time getting a hold of the bait that is in the trap. Essentially, the awkward cylindrical and slippery bottle is less than ideal for a moray to close its jaws around. This is also great for us since we want to look at the diet of morays and do not want to confound what they are eating with how we are baiting the traps. Also, the bait bottles are reusable. Once the traps are baited, they are stacked into a Wrigley boat and driven out to our sites where they get tossed overboard.
When we were first designing our project, we realized that everything hinged on whether we could successfully trap a moray eel. Little did we know we would be examining data for five hundred morays. How do these traps do the job? Given their snake-like bodies, morays tend to feel comfortable moving around in small spaces. Our rectangular wire fish traps are custom-sized for our needs and are very similar to the American eels traps that are used in the Northeast. Our traps are relatively large (48" x 11" x 9") . One side of the trap has a hole onto which we tie a black mesh sleeve. The mesh sleeve facilitates the movement of the moray into the trap but does not easily allow the moray to turn around and find its way out of the trap since the sleeve collapses upon itself. This is presumably why we find such little by-catch in our trap. Although the trap is baited, other fish do not seem to be as attracted to our traps as morays. We think that this is due to the mesh sleeves that are attached to the opening in the trap. Another phenomenon that could be happening is that once a moray gets caught in our trap, it basically deters any other fish from wanting to explore the trap further. From our experience, a single moray does not discourage other morays from entering the trap. We have caught single morays and as many as 12 smaller morays in a single trap. When we pull the traps up the following day, it is like Christmas in August. We never know how many morays we can expect. -RM
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