Opercular bones and scales, on the other hand, can be used for both. Take into consideration the fate of the fish at the time of sampling. Otoliths and bones such as cleithra and opercles are not an option for those fish that are to be live released. If the program is on a tight budget then consider the time it takes to prepare the structures before they are aged. Otoliths take considerably less time to crack and burn than do spines and fins that have to be epoxied and sectioned.
Preparation time is reflected in the cost.
Before going out into the field and collecting samples, decide how many samples should be taken. Taking too many samples will waste time and resources, both in collection and data analysis. In the table below is a list of the common target species in Northern Ontario and the appropriate structure to collect, listed in the order of reliability of age assessment. To protect the fragile structure from being broken or lost, place the dried otolith into a 1.5 ml centrifuge tube. The tubes can be stored two ways.