Predicting larval metamorphosis of Pacific lamprey Entosphenus tridentatus through measurements of length and mass

Abstract

The utility of length and mass measurements to predict the larval metamorphosis of Pacific lamprey Entosphenus tridentatus was evaluated. During 2004–2008, larval E. tridentatus were collected from Cedar Creek (Washington, USA) in either the spring or autumn, measured for total length and total mass, reared in captivity and monitored for metamorphosis. The minimum total length, total mass and condition factor of larvae that were observed to go through metamorphosis were 102 mm, 2.0 g and 1.52, respectively. Logistic models indicated that total length and condition factor in both spring and autumn were the most significant variables for predicting metamorphosis of Pacific lamprey during the subsequent summer. Mass in the autumn also appeared important to predict whether metamorphosis occurred in the subsequent summer. Collectively, all models using specific minimums of total length, total mass or condition factor of larvae as criteria for them to metamorphose were sometimes (5 of 14 cases) able to predict the percentage of larvae that would metamorphose but rarely (1 of 12 cases) able to predict which individual larvae would metamorphose. Similar to other anadromous species of lampreys, the size and condition of larval E. tridentatus have utility for predicting metamorphic fate.

The decline of the ecosystem services generated by anadromous fish in the Iberian Peninsula

“…The effects of environmental change on wild populations of Atlantic salmon, both in abundance (Ozgul et al, 2010;Lane et al, 2012) and in dynamics (Cornulier et al, 2013;Nelson & Yamanaka, 2013), have become increasingly documented over the years (Hittle et al, 2021). A recent study (Wang et al, 2021) reviewed the impacts of a changing climate on several lamprey species, from physiology (e.g., Baer et al, 2018;Whitesel et al, 2020), phenology (Kirillova et al, 2016;Wang et al, 2021), shifts in distribution range (Lassalle et al, 2008;Elliott et al, 2021), genetic adaptation (Close et al, 2002) to changes in species interactions and community structure (e.g., Boeker & Giest, 2016). In Central Portugal, it has been observed a clear effect of drought in the abundance of sea lamprey using the fish pass located at the Coimbra Dam (Fig.…”