7 GEORGE Vv SESSIONAL PAPER No. 38a A. 1917 
: DIATOMS AND LOBSTER REARING. 
By Prof. W. T. MacCiement, M.A., D.Sc., Queen’s University, Kingston. 
- The entirely commendable desire to increase the annual crop of lobsters, and thus 
add to the income of the fishermen as well as to the supply of a delicious sea food, 
has prompted attempts at the semi-domestication of the lobster. A creature may be 
said to be domesticated when it will reach full size, will reproduce freely, and will live 
about the normal life-time of its kind, in the artificial conditions furnished by man. 
We are as yet far from reaching such a desirable state of affairs in our relations with 
the lobster. While mature female lobsters, captured in the sea, will extrude eggs 
freely in captivity, we have not yet, in the few experiments made, so closely approxi- 
mated to the conditions required for the health and growth of young lobsters, as to 
see before us in the near future the prospect of large and successful lobster gardens, 
maintained by the amphibious farmers of the Maritime Provinces. The account of 
the experiments inaugurated by the Biological Board of Canada will be found else- 
where.* With only one factor of the environment of the lobsters has the present 
writer had intimate relations, and it is with that this article deals. 
1. Actions or Lorster Larv#. 
For several days after they are hatched, young lobsters show a desire to occupy 
water that is well lighted. They crowd to the lighted side of a glass vessel, and within 
a few seconds will have deserted the shaded for the sunny portion of the water in 
which they are lying. Otherwise they show little recognition of direction in their 
movements, sinking quietly or jerking themselves apparently aimlessly up or down 
or laterally through the water, often with their backs or heads downward, and with 
their bristly outer leg-branches constantly vibrating. Their spasmodic movements 
are probably the result of various stimuli besides that of light, as is shown by the 
fact that they seize greedily any small object that seems likely to make them a satis- 
factory meal. When the minute lobsters are crowded together, this edible object is 
quite likely to be another lobster of the same brood.’ The stronger of the two 
immediately shows how fond he is of his relative by eating as much as possible of 
kim or her. Cannibalism is one of the factors always to be kept in mind in connec- 
tion with artificial arrangements for rearing the lobster. 
Whether the lobster larve normally seek the lighted surface layers of the sea in 
which they are hatched is unknown, as few of them have been captured in open 
waters, and very little is known of the details of their lives when free. Surface layers 
may or may not be their natural haunts, but all attempts at rearing the young lobsters 
have been made in well-lighted and somewhat shallow enclosures. The idea is 
accepted by the experimenters that the young lobsters are attracted to the bright 
surface waters, that there they are visible to the perpetually hungry larger denizens of 
the ocean, such as the schools of herring and mackerel, and that consequently myriads 
of the lobster larve are devoured before they have learned even the alphabet of self- 
defence. After they have moulted a few times, four or five, they acquire the form and 
features, though minute, of the adult lobster, and show the adult habits of seeking 
concealment, and of using their claws as weapons of defence. Hence it is believed 
*See Professor Knight’s Report on Lobster Sanctuaries and Hatching Ponds. Canadian 
Biology, 1914-1915. Supp. 5th Ann. Rep. Dep. of Naval Service, 1916, pp. 41-54. 
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