Sentence:  ... And fish the knolls on the North Sea Holes/ And try your luck at the North Shields Gut/ With a catch of a hundred <WSD>cran</WSD>. 
Meaning of the word marked with <WSD> tags:  A measure of herrings, either imprecise or sometimes legally specified. It has sometimes been about 37½ imperial gallons, or 750 herring on average.