Population Characteristics of a Closed Northern Pike (Esox lucius) Catch-and-Release Population in Minnesota

Author

John Kempe

Date of Award

5-2018

Document Type

Thesis

Department

Biology

First Advisor

Andrew Hafs

Abstract

Literature regarding catch-and-release populations of Northern Pike are rare and provide a unique perspective on their population dynamics. Shingobee Lake is a 64- ha mesotrophic lake with a maximum depth of 12.2 m located in northern Minnesota. Northern Pike fishing has been catch-and-release only since 2005, and there are no public accesses on the lake. Annual ice-out trap-netting occurred from 2009-2017, and a sizable amount of the Northern Pike recaptured via trapnet or angling had been previously tagged (37-59%). The lack of exploitation and high tagging percentage provided a unique opportunity to study the population dynamics of Northern Pike. Shinogbee’s population of Northern Pike is female dominated and consists of old, slow growing, large individuals. The overall capture ratio of female:male fish was 1.75:1. Only 2.1% of the sampled males were over 600 mm, compared to 37.2% of the female population. Abundance estimates throughout the study period remained stable (21 to 33 fish/ha) and a catch curve indicated an overall mortality rate of 31%. Female Northern Pike grew faster than males in Shingobee Lake, however both sexes lagged behind an international growth standard. Weisberg’s mixed effect growth model showed little year-to-year (environmental) or cohort base variation in growth. Proportional size distribution ranged from 42-56, indicating a stable size structure throughout the study period. The results of this study support the argument that restricting harvest can improve the size structure of a Northern Pike population. Management aimed at improving pike size structure must take into account the importance of protecting large, older individuals.

Recommended Citation

Kempe, John, "Population Characteristics of a Closed Northern Pike (Esox lucius) Catch-and-Release Population in Minnesota" (2018). Biology Graduate Theses. 14.
https://pines.bemidjistate.edu/thesis-biol/14