SOME ECONOMIC ASPECTS OF SHORE LIFE 289 



importance by reason of their use as bait by fishermen. 

 Foremost among these is the Lug- worm {Arenicola marina), 

 whose " casts " are so marked a feature of tidal mud flats, 

 or of sands with an underlying layer containing vegetable 

 detritus. From these situations they are dug in quantity 

 and used as bait for the capture of flat fish, whiting, cod, 

 haddock, etc. In some estuarine and similar sheltered 

 areas this worm occurs in immense numbers, varying with 

 the amount of food available (see Plate VI). Davison (1891) 

 at Holy Island found their numbers to vary from 8'2 to 42 

 per sq. yd. in 19 measured areas. At Musselburgh, Firth of 

 Forth, in January, 12 to 15 casts occurred per sq. yd. and 

 many of the worms were 13 inches in length. From these 

 sands about 1000 were dug daily (Ashworth, 1904). 



Aberdeen is an area unfavourable to lug- worms, and 

 they are (or were) imported from the Moray Firth, and sent 

 100 miles by rail prior to use. They weigh, on average, 

 half an ounce each, which is equivalent to 400 worms per 

 stone of 14 lbs. The cost was given by Ashworth at los. per 

 stone, and the railway charges at i^. 2d. per stone ; this 

 transport was only possible in cool weather. 



M'Intosh states that a single worm may bait from four 

 to six hooks, but that breaking up the worm causes the 

 fingers to suflFer from friction and the worm's secretions : 

 the fingers are dipped in a solution of alum to avoid this. 



In Guernsey, Nereis cultrifera is used as bait for whiting, 

 conger, etc. Mussels are of importance as a bait, as are 

 also the sand eels {Ammodytes spp.) ; of lesser value are 

 " soft " specimens of the green shore crab {Carcinus moenas), 

 limpets, cockles, and others. 



Adverse Factors. — Certain animals and birds may at times 

 exercise a distinctly adverse influence upon the shore 

 forms that are of economic value. 



Shore-haunting sea-gulls are chiefly scavengers, but 

 on occasions have been accused of destroying cockles. 

 Scott (19 1 6), however, considers that it is difficult to say 

 whether undisturbed cockles can be reached by them. 

 Fishermen state that they have seen gulls " tread " cockles 



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