Our First Line Transect Survey

On Sunday 12th July the Sea Watch team gathered on the pier in anticipation of the day ahead. The previous day all the volunteers had been trained with the new protocol and were eager to put it into practice at sea. We had all been involved in surveys before but line transect surveys would be more scientific than ones previously encountered. With 10 hours planned we all knew that it would be a long day with few breaks to rest, there is always a job to be done on-board.

The weather looked ominous when we first set off with some dark clouds and a sea state 2. We had to head north, just passed Aberaeron to find the edge of the SAC (special area of conservation), the point at which the line transect would begin.

Transect line i1 was chosen at random from a hat, we had no trouble finding the start and set off in a southerly direction zigzagging our way down the coastline following the coordinate waypoints as indicated on the map. Other differences from previous surveys were that two independent observers had to be on look out at the stern of the boat scanning the horizon for dolphins using binoculars. This caused much amusement among a few members of the team as it is much harder than it seems to hold binoculars to your eyes for an hour whilst at sea, regular arm shaking was the first sign of struggling followed by many inventive techniques of holding up the binoculars to stop your arms aching.

Another difference is that when a dolphin was spotted it should be recorded in the usual fashion but no-one else should be notified until they had passed the 90° angle, perpendicular to the boat. At this point the transect line is left and photographic ID of the dolphins follows. After which the survey continues from the point that the boat left the line. When nothing had been spotted for a while one of the volunteers rather over excitedly yelled “Dolphin”, letting everyone know that there has been a sighting, not exactly protocol.

Just as we were passing back by New Quay, Rachel spotted three dolphins in the bay, one of which was Bond but by the time we had positively ID’d him the other two dolphins had disappeared out of sight.

The line that we chose was an inner transect, it meant that we only had to travel out halfway to the outermost boundary of the SAC, still, even this was 5km out from the coastline. We went all the way out and back to the coast without seeing anything until we met a group of three dolphins closely followed by a further two. After these encounters the sun came out and it became a lovely afternoon as we continued on to the most southerly boundary of the SAC south of Cardigan Island.

Overall the survey was a great success leaving everyone on board happy, spotting a group of 5 dolphins on the transit back to New Quay was a great way to end the day. In total 13 dolphins, a harbour porpoise and a few grey seals were seen.