Publication Abstract

Lipofuscin Age Pigment in the Brain of the European Lobster, Homarus gammarus (L.)

M.R.J. Sheehy and J.F. Wickins

The European lobster, Homarus gammarus (L.), supports fisheries of considerable socio-economic importance which provide major sources of income for many European coastal fishing communities. At least 13 countries fish the lobster, the United Kingdom being among the top producers with 1330 tonnes landed in 1990, worth over £11 million. Management of the fisheries has-been hindered by the difficulty in determining accurately the most basic variables for maximum sustainable yield models, namely the number and size of individuals in particular age groups.

As for other Crustacea, H. gammarus has no permanent hard parts from which age can be determined. Traditional methods for age estimation have been fraught with difficulties. There is considerable individual variation in moult frequency, moult increment and, therefore, size at age, as demonstrated in laboratory rearing studies and from recaptures of tagged lobsters. Consequently, modes in size frequency histograms are often indistinguishable, or, when they do occur, are not reliable indicators of year class. Alternative approaches to age determination of H. gammarus have been attempted including examination of the number of eye facets and the number of antennule segments, in relation to moult stage and age. However, these meristic characteristics have been found to be correlated primarily with the individual's size rather than its age. Measurement of the decay of the radionuclide 228thorium to 228radium was shown to be worthwhile for determination of the time elapsed since the previous moult in H. gammarus, but the method does not give the total age of the individual. As these authors have stressed, it is important to develop some new approaches to crustacean age determination.

Recent studies have indicated that the quantity of granular lipofuscin, a ubiquitously occurring lysosomal degradation product found in the brains of many crustaceans, has potential as an index of age. Preliminary investigations are currently under way to determine the usefulness of lipofuscin for determining the age of some important fisheries species. This article reports the finding of lipofuscin age pigment in the brain of H. gammarus.

Reference:

M.R.J. Sheehy and J.F. Wickins, 1994.Lipofuscin Age Pigment in the Brain of the European Lobster, Homarus gammarus (L.) Microscopy and Analysis, 40: 23-25