Tagging and mark-recapture experiments are quite typical methods to monitor size and phenotypic diversity of natural populations, especially those of particular conservation or scientific interest. In the present paper we applied a Bayesian hierarchical model on pike mark-recapture data collected by experimental fishing over four years. The pike monitoring belongs to KESKALA research project and using a range of fishing methods the aim of the data collection was to observe all pikes in the study lakes. Thus, it becomes an interesting question to ask, how well this goal is reached.
The modeling suggested that despite intensive fishing over several years with a large variety of methods, a good fraction of pikes are likely to go unnoticed. From a life-history monitoring perspective, the results thus suggest that it is very difficult to reliably monitor all life-histories in the targeted populations. If unnoticed fish differ from those observed via fishing, then inference made about phenotypic trends based on observed fish are likely to be biased.
From a more applied perspective, the model presented in the study provides a method to do stock assessment in small populations targeted e.g. by recreations fishing. While from a fisheries research perspective these populations would be of small interest, from a conservation perspective small isolated populations are often quite important, not to mention economic and societal values associated to recreational fishing.
Kuparinen A, Alho J, Olin M, Lehtonen H. Estimation of northern pike population sizes via mark recapture monitoring. Fisheries Management and Ecology (in press)
