Urbanization correlates with altered growth and reduced survival of a small‐bodied, imperilled freshwater fish

Abstract

Abstract Life‐history and other vital rate information is important for effective species conservation by informing demographic trends and aspects of population viability. However, species‐specific information is lacking for many small‐bodied freshwater fishes, which can make it difficult to relate demographic trends to threats or recovery actions. Silver Shiner ( Notropis photogenis ), a small‐bodied species listed as Threatened under Canada's Species at Risk Act , lacks well‐informed age and vital rate information. We aged 254 Silver Shiner using opercular and otolith structures and determined that Silver Shiner is short‐lived, with a probable maximum age of 4. Three years of field collections (2017–2019) were used to parameterize growth models and to estimate adult (age 1–3+) mortality rates. Silver Shiner captured in urban reaches exhibited altered growth and higher mortality compared to non‐urban reaches, indicating that urbanization may have demographic impacts on the species. Results highlight the importance of detailed age and vital rate information for assessing threats and informing effective conservation approaches for imperilled fishes. Furthermore, the potential negative impact of urbanization on the growth and survival of this species highlights the urgency of better understanding the influence of urbanization on small‐bodied freshwater fishes in general.