Temperature affects age at maturity, an important life-history metric in fish that strongly impacts population growth rates. In most cases, warmer temperatures lead to faster sexual maturation in fish. This relationship is particularly important in determining invasive species risk; if the temperature is sufficiently warm to allow faster than average maturation of invasive fish, there will be faster than expected population growth.
To determine if there is a significant relationship between temperature and age at maturity in fish, we examined published data regarding invasive Asian carp. This species group includes silver carp (Hypophthalmichthys molitrix), bighead carp (Hypophthalmichthys nobilis), and grass carp (Ctenopharyngodon idella), and are predicted to invade the Great Lakes watershed, despite current preventative efforts. Age at maturity of Asian carp from around the world were obtained through a literature search. For each location, we estimated temperature conditions using the average values in the WorldClim database. Average annual air temperature and average air temperature during the warmest quarter, an approximation of the growing season, were both considered as predictors of age at maturity.
Results/Conclusions
We found a significant linear relationship between air temperature and ages at maturity for Asian carp. Both average annual air temperature (R2 = 0.56, p < 0.001) and average air temperature in the warmest quarter (R2 =0.45, p < 0.001) were significant predictors, though annual air temperature explained more of the variation in the age at maturity of the carp. The interaction between species and temperature was not significant (average annual temperature F = 2.57, df = 2, 43, p>0.05; average temperature in the warmest quarter F = 1.62, df = 2, 43, p>0.05), indicating that the species could be grouped together for analysis. The relatively high explanatory power of these simple relationships imply that air temperature can be used to predict ages at maturity of Asian carp around the world. Incorporating this type of relationship between temperature and life history should help generate more accurate population models, and ultimately help us to assess risk and the need for interventions when managing invasive species.