SEA-FISHERIES LABORATORY. 109 



THE MACKEREL FISHERY OFF WALNEY IN 1913. 

 By Andrew Scott, A.L.S. 



Mackerel were extremely abundant and widely distributed 

 in the Irish Sea during the summer of 1913. The fish made 

 their appearance in the area lying of! Walney Island about 

 the middle of June, and were evidently fairly numerous until 

 about the end of the first week in September. The mackerel 

 came quite close to the land on this occasion. Many were 

 caught by line in Barrow Channel, in the vicinity of the ferry 

 pier at Piel, and a few were taken in the stake nets on Roosebeck 

 Scars. Although the fish apparently left the area off Walney 

 early in September, they continued to be caught off Blackpool 

 until late in October. In all probability the abundance of 

 mackerel was largely due to a remarkably extensive invasion 

 of the ctenophore Pleurobrachia, along with numerous small 

 examples of Beroe. The visitation of the ctenophora began 

 early in July and lasted for nearly a month. The swarm 

 reached its maximum about the 10th, and then gradually 

 diminished in numbers. The water of the open sea and in 

 Barrow Channel was so densely populated for a time with 

 Pleurobrachia, that an ordinary coarse tow-net was quickly 

 filled when towed behind a boat. Great numbers were stranded 

 on the shore as the tide receded, which gave it the appearance 

 of being covered with small glass marbles. The local fishermen, 

 with their half-decked fishing boats, caught considerable 

 quantities of mackerel by line during the fishery, but they were 

 frequently prevented from reaching the fishing ground owing 

 to too much or too little wind. Under more favourable con- 

 ditions the fishery would have been very valuable, as the 

 catches were quickly sold at about one shilling per dozen fish. 



