Murraykelleher5639

© 2020 London School of Economics and Political Science.Plasma concentrations of progesterone (P4 ) and 17β-oestradiol (E2 ) in juvenile, pre-ovulatory, early, mid- or late pregnancy stages of female blue sharks Prionace glauca were analysed. Concentrations of P4 were significantly higher in pregnant than in non-pregnant individuals, whereas E2 concentrations increased with embryonic and follicular development. A highly accurate (86.1%) random forest classification model was developed to predict shark pregnancy. It is proposed that hormone concentrations could be used for the subsequent non-lethal determination of female P. glauca reproductive state. © 2020 The Fisheries Society of the British Isles.We hypothesized that oxygen uptake (ṀO2 ) measured with a novel protocol of chasing rainbow trout Oncorhynchus mykiss to exhaustion inside a static respirometer while simultaneously monitoring ṀO2 (ṀO2chase ) would generate the same and repeatable peak value as when peak active ṀO2 (ṀO2active ) is measured in a critical swimming speed protocol. To reliably determine peak ṀO2chase , and the peak during recovery of ṀO2 following a conventional chase protocol outside the respirometer (ṀO2rec ), we applied an iterative algorithm and a minimum sampling window duration (i.e., 1 min based on an analysis of the variance in background and exercise ṀO2 ) to account for ṀO2 dynamics. In support of our hypothesis, peak ṀO2active (707 ± 33 mg O2 h-1  kg-1 ) and peak ṀO2chase (663 ± 43 mg O2 h-1  kg-1 ) were similar (P = 0.49) and repeatable (Pearson's and Spearman's correlation test; r ≥ 0.77; P  less then  0.05) when measured in the same fish. Therefore, we conclude that estimates of ṀO2max can be independent of whether a fish is exhaustively chased inside a respirometer or swum to fatigue in a swim tunnel, provided ṀO2 is analyzed with an iterative algorithm and a minimum but reliable sampling window. The importance of using this analytical approach was illustrated by peak ṀO2chase being 23% higher (P  less then  0.05) when compared to a conventional sequential interval regression analysis, while using the conventional chase protocol (1-min window) outside the respirometer increased this difference to 31% (P  less then  0.01). Moreover, because peak ṀO2chase was 18% higher (P  less then  0.05) than peak ṀO2rec , chasing a fish inside a static respirometer may be a better protocol for obtaining maximum ṀO2 . This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.Coping style is defined as a set of individual physiological and behavioural characteristics consistent across time and context. In the zebrafish Danio rerio, as well as in many other animals, several covariations have been established between behavioural, physiological, and molecular responses. However, not many studies have addressed the consistency of behavioural responses over time starting at the larval stage. Therefore, we aimed to improve our understanding of behavioural consistency across context and over time in zebrafish from the larval to juvenile stages. We conducted two distinct experiments a larval stage experiment (from 8 to 21 days post fertilization, dpf) and a juvenile stage experiment (from 21 to 60 dpf). On one hand, the larval experiment allows to focus on the transition between 8 and 21 dpf, marked by significant morphological changes related to the end of larval stage and initiation of metamorphosis. On the other hand, the juvenile experiment allows to properly cover the period extendinuct this experiment provides new perspectives for the further study of the longitudinal evolution of various traits, including behaviour, over life stages in fish. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.The European weather loach (Misgurnus fossilis) is a cryptic and poorly known fish species of high conservation concern. The species is experiencing dramatic population collapses across its native range to the point of regional extinction. Although environmental DNA (eDNA)-based approaches offer clear advantages over conventional field methods for monitoring rare and endangered species, accurate detection and quantification remain difficult and quality assessment is often poorly incorporated. In this study, we developed and validated a novel digital droplet PCR (ddPCR) eDNA-based method for reliable detection and quantification, which allows accurate monitoring of M. fossilis across a number of habitat types. A dilution experiment under laboratory conditions allowed the definition of the limit of detection (LOD) and the limit of quantification (LOQ), which were set at concentrations of 0.07 and 0.14 copies μl-1 , respectively. A series of aquarium experiments revealed a significant and positive relationship bn target DNA concentrations are critically low, which could be attributed to a reduced sensitivity of ddPCR to inhibition effects, higher sample concentrations being accommodated and higher sensitivity obtained. © 2020 The Fisheries Society of the British Isles.This study investigates the effect of water temperature on the development rate of eggs and larvae, the duration of the endogeneous feeding period and its consequences for recruitment of smelt (Osmerus eperlanus) in Dutch lakes IJsselmeer and Markermeer. We measured temperature-dependent egg and larval development rates as well as mortality rates from fertilization till the moment of absorption of the yolk-sac and from yolk-sac depletion onwards in temperature controlled indoor experiments. Using multinomial modelling we found significant differences in development time of egg development stages under different temperature regimes. Based on historic water temperatures, the model predicted that the larval endogenous feeding period has advanced at a rate of about 2.9 days/decade in a more than 50 year period since 1961, yet there was no change in endogenous feeding period duration. JG98 As zooplankton is more responsive to daylight than water temperature cues, a mismatch of the peak of the onset of exogenous feeding of smelt and the peak of zooplankton blooms could lead to high mortality and therefore low recruitment of smelt.