91 



Ansell, Alan D. 1964. 



Some parameters of growth of mature Venus mercenaria L. J. Cons. 29(2): 

 214-220. 



Most of the data reported in this paper were based on hard clams from the 

 area of the outfall of Marchwood generating station in Southampton Water in 

 southern England. Relationship between length and total weight was deter- 

 mined separately for adults and for laboratory-reared juveniles: adults, 

 log W = 2.8838 log L - 3.2869; juveniles, log W = 3.1422 log L - 3.6185. 

 For wet and dry flesh weight it was assumed that regression lines for all 

 W/L relationships should be parallel, and in the form log W = 2.8838 log 

 L - X, where X was calculated for upper and lower limits of possible values 

 from X = - 3.2869 (for total weight) using upper and lower of other weights 

 as percentages of total weight. When wet flesh W was 8% of total W, log F w 

 = 2.8838 log L - 4.3838; at 25% of total W, log F w = 2.8838 log L - 3.8890. 

 Dry flesh weight varied between 1.5% and 5.5% of total weight, and the 

 appropriate equations were: log F^ = 2.8838 log L - 4.5465; and log F<3 = 

 2.8838 log L - 5.1108. Exact relationships depended largely on state of 

 gonads, which affected wet and dry flesh weights. Percentage wet flesh 

 weight increased progressively with increase in size of clam from Jan to 

 Mar 1962, but from June onwards percentage wet flesh weight was more or 

 less the same for clams of all sizes. The same variations applied to dry 

 flesh weights. Limits of total body nitrogen in relation to length were: 

 log N = 2.8838 log L - 5.6434, and log N = 2.8838 log L - 6.1108; limits of 

 total carbohydrate were log C = 2.8838 log L - 5.0917, and log C = 2.8838 

 log L - 5.964 7. Relationships between length and total volume, and length 

 and shell cavity volume, respectively were: log Vt = 3.0497 log L - 3.7867, 

 and log V sc = 3.1653 log L - 4.2652. The wide variation found demonstrates 

 the dangers of using such transformations unless the "condition" of the 

 animals is well known, in preparing the regression line and in the actual 

 experiments. Where only length is known for a given group of clams, the 

 only accurate transformations are to total weight, total volume, and shell 

 cavity volume. Position of the regression line within limits given here 

 depends on "condition", slope depends on relative condition of animals of 

 different sizes. - J.L.M. 



92 



Ansell, Alan D. 1964. 



The clam and industry in Britain. Sea Frontiers 10(1): 48-55. 



Venus mercenaria has become naturalized after accidental introduction in 

 some European areas, notably in Southampton Water, England. Although the 

 clam is localized within the single estuarine system it has become the 

 dominant bivalve on many shores. History of the species in England began 

 with several accidental and deliberate introductions in the 19th century. 

 Live specimens were recovered from the estuary of the Humber in 1864 and 

 clams were taken at intervals until 1907. It is unlikely that it bred 

 there, and the colony was supported only by continued introductions from 

 the U.S. In 1869 clams were imported and planted at Reculver in Kent and 

 at the mouth of the Mersey. These clams did not survive. In 1883 another 

 attempt to introduce hard clams near Liverpool, this time in waters of 

 lower salinity, also failed. Other attempts in northern waters of Britain, 

 although clams survived for a while, did not develop breeding stocks. In 

 the early 1860s similar introductions were made in French waters. These 

 clams did not reproduce. Some 50 yrs later, however, successful intro- 

 duction was made at Charente-Maritime, which now supports the only hard 

 clam fishery in Europe. The colony in Southampton Water may have originated 

 from clams accidentally introduced with American oysters, or as some have 

 suggested, larvae may have drifted across from Brittany. The most likely 

 explanation is that clams may have been discarded from the galley of a 

 transatlantic liner, for which Southampton is a major port. There is some 

 evidence that the original introduction occurred prior to 19 36 and that the 

 population remained at a low level for a time. Southampton Water is 

 moderately polluted, and the pollution-tolerant hard clam may have thus 

 been able to occupy the niche vacated by the less tolerant soft clam. At 

 Marchwood, near where the Test River enters Southampton Water, an electric 



25 



