File:Marine biological report for the year ended and the half year ending (1918) (14774524365).jpg

Identifier: marinebiological41918cape (find matches)
Title: Marine biological report for the year ended ... and the half year ending ..
Year: 1913 (1910s)
Authors:
Subjects: Marine biology
Publisher: Cape Town : Cape Times Ltd., Govt. printers
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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s year at least) spawning had not commenced inthe latter half of May, that is there was no extrusion of theeggs though the ovaries were well advanced. Probablytherefore many of these fish would be in the berried con-dition by the end of this temporary close season. It hasbeen accepted that it is very necessary to protect the femalein berry both in the case of the Cape Crawfish here and thelobster in other countries. It follows that a great deal of goodwould result from the further protection of females, whichare about to extrude their eggs and assume the berried con-dition. I have drawn attention to the fact that there are someindications that the female crawfish does not spawn everyyear, but until this is definitely established it may be assumedthat it does so, and, if this be the case, it will be obvious thatnon-berried females in May and the beginning of June requirealmost as much protection as those which have already becomeberried. A close season at this time would therefore seem
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5 to be well worthy of further consideration. From observa-tions of the crawfish in captivity it appears that one malemay attend several females during the season. This hasbeen actually observed, and may further be rendered fairlycertain from the fact that the female has been observed toextrude her ova only two or three days after copulation.It follows therefore that there is a much greater necessity forprotecting the female than the male. (2) Stages in Life History of Crawfish.—It is of importancefrom a practical point of view to ascertain the form andhabits of the young crawfish. We have found that the firststage after hatching is in the form of a small somewhat opaqueform which swims rapidly to the surface of the water by meansof its antennae. It is then transformed into a flat transparentform which swims about by means of special swimming branchesdeveloped on the legs. It apparently then descends to thebottom of the sea and by a series of stages becomes larger.During this procesmarinebiological41918cape

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