Self-sampling by fishers works!

Gepubliceerd op
31 januari 2014

During 2012, catches in the Dutch pulse fishery were sampled by fishers (self-sampling) and independent observers. The results show that self-sampling by fishers is a valuable research method, comparable to the traditional sampling by observers. The research also shows that the pulse gear catches less benthic organisms and more marketable sole in comparison with the conventional bottom trawl fishery.

Less benthos and more marketable sole in the Dutch pulse fishery

The report ‘Monitoring catches in the pulse fishery’ from IMARES (2013)1 confirms that self-sampling is a valuable research method and comparable to the sampling by independent observers. It’s the first time that at this scale pulse fishers sampled their catches themselves. The self-sampling was carried out by 25 vessels, which in total sorted 578 samples. The ten observer trips were performed on different vessels during the course of 2012.

Small differences


The results show only 3 significant differences between the two research methods: catches of benthic organisms (benthos) and debris (plants, stones, dead material), sole discards and cod landings were found to be lower in the observer program. A possible explanation for these differences is that the observer trips were carried out in a limited fishing area and a limited time-frame. Figure 1 shows the average catch composition of both the self-sampling and observer program. 

Pulse fishery catches more marketable sole and less plaice

The results of the pulse monitoring program were also compared with data on the traditional bottom trawl fishery in the same period (report 'Discard sampling of Dutch bottom trawl and seine fisheries in 2012'. The comparison showed that the pulse fishery catches more marketable sole and less plaice (see table 1). The number of benthos caught per hour in the pulse fishery is much lower than in the traditional bottom trawl fishery: pulse fishers caught 84% less starfish and 58% less crabs. Cod catches were low in both fisheries. 

Table 1 Comparison of plaice and sole catches in the pulse trawl fishery and the bottom trawl fishery.jpg

Pulse fishery is becoming more popular

A number of Dutch fishermen have changed to the pulse fishery, because of low fuel costs and higher economic viability. The pulse trawl is a relatively new gear and because of high commitment towards research, more and more knowledge is becoming available on this fishing technique. ‘Monitoring catches in the pulse fishery’, commissioned by the Cooperative Fisheries Organisation 3 and executed by IMARES 4, contributes to the available knowledge on catch composition of the pulse trawl.