Mass marking in European sturgeon: chap. 25
Résumé
When assessing stocking programmes, there needs to be discrimination between stocked fish and wild fish, and between different groups (i.e., cohorts, release sites) within stocked fish. Few methods are available for marking a large number of fish at an early stage with minimum handling. Chemical mass marking matches these prerequisites, and this method has been retained for the European sturgeon. Because the sampling has no adverse effects on individuals, marking efficiency has been checked on the pectoral fin ray. After qualified results were recorded in 2007 and 2008, this led to the testing of the possible effect of chemical or size/age on marking efficiency and mark quality. A tetracycline bath at 600 ppm for 8 h has given satisfactory results in fish not younger than 4 months.