My aquatic research runs the gambit from macroinvertebrates to fisheries. Most of my work in fisheries has focused on fish movement and population dynamics. For Example using otolith chemistry to identify source and sink habitat. Otoliths can be absolutely gorgeous when prepared correctly.
In this lab some of the common research that is conducted includes age and growth modeling and otolith chemistry. The age of fish can be determined using bony structures such as the otoliths, the ear bones. The otoliths must be prepared to reveal growth rings by cautiously cutting, sanding, and polishing them until the rings can be counted in days, months, years, or a combination of these. The bony structures are used in conjunction with length and weights of fish to determine the growth rate.
Age and growth rates are essential to elucidate the population dynamics and structure. Some of the population dynamics that can be denoted from age and growth research are age class fluctuations, lifespan, and birth/death rates. For example, using the Von Bertalanffy growth model will indicate growth trends of specific fish species that are crucial to biologists that manage fisheries. Furthermore, age and growth research techniques can be considered the bread and butter to aquatic research and the core to management strategies.
Otoliths can be useful for much more than age indicators. The chemical make-up of otoliths can also indicate the origin of fish populations. Different freshwater systems have slightly different amounts of chemicals that are imprinted into the otoliths core. These chemicals can be a range of elements such as calcium and strontium. The different concentrations can indicate where an individual originated. The outer rings can give clues to the different locations an individual has inhabited or if they stayed in the same location for the duration of their life.
Determining origin of naturally reproducing rainbow trout in the Arkansas River using otolith chemistry below the Pueblo Reservoir. Youth trout have been found in the Arkansas River in close vicinity to the Pueblo Hatchery. This research is multi-level. The origin of the youth rainbow trout must be determined through otolith chemistry to indicate if the population originated from the Pueblo Hatchery, Shavano Hatchery, or if they were born in the Arkansas river through natural reproduction. If the research concludes that there is natural reproduction, the size of the naturally reproducing population will be estimated. This research will allow Colorado Parks and Wildlife to make crucial management decisions.