Sequencing success for different ages of specimens included in this study. Specimens were grouped in five categories: 1966–1980, 1981–1990, 1991–2000, 2001–2010, 2011–2020. In the graph, stalked columns show successful samples (sequence generated for the target species) in dark grey and unsuccessful samples (no sequence generated or generated sequences not from the target species) in light grey. The total number of samples (N) is indicated below each corresponding column.