First Catch Your Crayfish

After the efforts of some members to catch scallops during the Weymouth dives earlier this year, I thought the rest of you might be interested in a dive near Buckingham where we were attempting to catch Crayfish. At the time, I was Diving Officer of Stowe SAC and we were invited by Buckingham University to help take part in a survey of Crayfish in the river at Thornborough Mill. The plot was to dive the river every four hours throughout a twenty-four hour period and collect data on the number, size and sex of the Crayfish on each dive. The eventual aim of the survey was to find better ways of killing the little B*****S off since the American Crayfish were taking over the river, but that’s another story. Acting on the principle of "never ask someone else to do something you won’t do yourself", I volunteered to take the midnight to 2AM shift.

Oh well I thought, I and my buddy are both experienced divers, a short night dive to catch a few Crayfish could be quite fun! The briefing was straightforward, collect as many Crayfish as you can in your goody bag, when you have a dozen or so come and hand them to the shore party over by the weir. Do that a couple of times and we can all go home. This is what really happened....

First the entry. When they said go down the ladder, I didn't realise that they meant an aluminium ladder arranged almost horizontally from a nettle infested riverbank into a few inches of water. Not even got wet yet and I already wish I had worn gloves. Still at least the bottom is fairly solid while I put my fins on. Now all we have to do is catch some Crayfish....

There were lots of Crayfish of all sizes and catching the first one was easy. Open the bag behind a Crayfish, disturb the Crayfish slightly and it shoots inside. Close bag and we have one. Easy. Now for the second one. Bag behind Crayfish, open bag and.... the first one shoots out knocking the second one aside! I reach to grab one of the Crayfish and drop my torch. This could be a long night! I now switch to plan B. Catch your first Crayfish as described above. Now before catching your second, shake the bag to make sure the first one is down the bottom somewhere. This is slightly more successful except that shaking the bag tends to scare away the Crayfish you were about to catch! After I have collected four Crayfish I proceed over to the weir to find how my buddy (who I haven't seen for some time) is getting on. We happen to surface together somewhere near the weir and I reluctantly admit to only four Crayfish. I am much cheered to find my buddy has only caught three! Right, lets get on with the job.

I mentioned that the collection point was near the weir. This caused no problem as long as you were upright in the water. When you assumed a horizontal position to resume diving, the current tries to sweep you over the edge. A drift dive with a difference? A hasty duck dive and we can resume our search. The second part of the dive was much like the first. Then I had (what seemed) a bright idea. If I disturb the Crayfish enough, it will swim for some distance in mid-water. While it is doing that I can use the goody bag like a butterfly net to catch it while keeping other Crayfish at the bottom of the bag. This is where I found that Crayfish swim faster than divers! In desperation I resorted to picking the Crayfish up and just stuffing it in the bag. I then found their claws are more than just decoration although I can't say whether I was attacked by the one I had just captured or by one of his mates making a break for freedom!

We finished the dive at 1:30 having started at 11:45 (the maximum depth was just 3.5 meters). The memory of this dive will be with me for a long time, not just because of its length but because of the fight to get a few small creatures into a bag. I'm sorry chaps, they may taste delicious with garlic butter but if it takes that long to catch them you can get your own!

Adrian