Factors affecting estimates of year-class strength and growth of muskellunge (Esox masquinongy): A long-lived, low-density, trophy fish species.

摘要

Muskellunge (Esox masquinongy) populations have been infrequently assessed. From an angler-contributed archive of muskellunge biological data and cleithra, samples from 16 populations across the North American range were interpreted for age and growth information using digital data collection. A systematic method was developed to assess age interpretation variance and its impact on year-class analysis. Bias was not present and precision was high (mean CV = 5.35%) for the age interpretations, and no significant effects of variance on year-class strength estimates were found. Year-class strength histories had varying correlations with summer (Lake St. Clair: p = 0.009, r2 = 0.36; Ontario populations: p = 0.044, r2 = 0.13) or spring (Kawartha District populations: p = 0.044, r2 = 0.15) temperatures in the first year of life, but no relationships were observed with water level or changes in minimum size limits. Cleithra size-at-age increased over time in the Lake St. Clair and St. Lawrence River populations, reflecting an increase in size from the 1940s through to the late 1980s (Lake St. Clair: +7.2%; St. Lawrence River: +9.3%). However, temperature did not correlate with mean annual growth. Therefore other factors, particularly competition and predator interactions with the fish community, are hypothesized from circumstantial evidence to be more important than the direct effects of temperature.