49 



THE LAMPREYS OF THE TYNE. 



By a. meek. 



This investigation began at Houxty, Wark, on the North 

 TjTie, on May 20th, 1916. On that occasion our first sample of 

 larval lam^Dreys was obtained in the sandy mud at the side of 

 the river, and as all present were concerned, 1 here append the 

 names of Abel Chapman, W. F. Henderson and George Bolam 

 and thank all for their help on that and at the next visit mentioned 

 below. 



It was continued at Bellingham further up North Tjnie in 

 the last fortnight of August, when a large collection was made 

 at various places in the Tjne, in the neighbourhood of Bellingham, 

 and also in the Reed. The collecting at Houxty was continued 

 in September by Mr. Chapman, and at Bellingham and in the 

 Reed in September, October and November by Mr. J. Allen, 

 Bellingham. This year in May another visit to Houxty gave us 

 a further sample at the end of a year. The general details of 

 the captures are indicated in the following table. 



From this it will be seen that the larvae are very common, 

 and it is evident also that three or four generations are included 

 in the captures. So far, however, no trace of mature lampreys 

 has been found. Mature lampreys have been seen in the Tjne ; 

 I have heard of them in the neighbourhood of Bellingham and 

 opposite Hesleyside. It appears from the table that spawning 

 takes place in June, for the young lamprej^s obtained in August, 

 measuring about 1*5 cm., are more than probably the product 

 of the year. The larvae grow rapidly after hatching, as has been 

 shown in the case of Planer's lamprey by Goette. They measure 

 on hatching about 2-8 mm., reach 4-5 mm. in four days, and 6-5 

 mm. in eleven days. The youngest lampreys we got measured 

 12 mm., and would onlj^ therefore have been about one month 

 old at the most. If the incubation period be one of about three 

 weeks the spawning would appear to take place in May and June. 



