Are 3 minutes good enough for obtaining baseline physiological samples from teleost fish?

Abstract

A prerequisite to studying the physiological status of wild animals is the ability to obtain blood samples that reflect the condition prior to capture or handling. Based on research in avian taxa, it is recommended that such samples be obtained within 3 min of capture; however, this guideline has not been validated in wild teleosts. The present study addresses the time course of physiological changes in a number of blood metrics across six species of freshwater fish. Fishes were caught using a standardized angling protocol and held in a water-filled trough prior to the collection of a blood sample, via caudal phlebotomy, between 0.5 and 11 min after capture. Changes in whole-blood glucose and lactate concentrations, hematocrit, and plasma cortisol concentrations were assessed. Change-point analyses indicated that blood lactate concentrations and hematocrit did not deviate from baseline values until ∼2–5 min of handling for all species, whereas blood glucose concentrations generally did not deviate significantly from baseline over the 11 min test period. In all species, plasma cortisol concentrations began to increase above baseline between ∼4 and 8 min after capture. Thus, to ensure that blood samples are representative of baseline conditions across multiple metrics, we recommend that sampling be limited to less than 2 min in teleost fishes.

Comparing Immobilization, Recovery, and Stress Indicators Associated with Electric Fish Handling Gloves and a Portable Electrosedation System

“…Blood parameters of Bluegills (left) and Largemouth Bass (right) subjected to one of three treatments (control, fish handling gloves [ FHG ], and Portable Electrosedation System [ PES ]) measured during two time periods (0.5 and 4.5 h posttreatment): (A) , (B) mean blood glucose concentration (mmol/L); (C) , (D) mean blood lactate concentration (mmol/L); and (E) , (F) mean plasma cortisol concentration (ng/ mL ). Dotted line denotes the absolute baseline level (Lawrence et al., in press); asterisks denote significant differences between groups (* P < 0.05; *** P < 0.001); and letters ( a P < 0.05; b P < 0.001) denote significant differences within a treatment group.…”

“…; Trushenski et al. ; Lawrence et al., in press). All experimental practices were approved by the Carleton University Animal Care Committee under guidance from the Canadian Council on Animal Care (Number 1082340).…”

“…This first blood sample was extracted closer to the caudal fin to allow room for a second blood sample to be extracted closer to the anal fin. A 0.3‐mL blood sample was drawn from Bluegills, and a 0.5‐mL sample was drawn from Largemouth Bass; each sample was obtained in less than 3 min to avoid the presentation of handling stress in blood parameters (Lawrence et al., in press). The TL of the fish was recorded, and then the fish was returned to its original, uniquely labeled blacked‐out holding cell.…”

Cortisol does not increase risk of mortality to predation in juvenile bluegill sunfish: A manipulative experimental field study

“…A larger size class (size range: 8–10 cm TL) was used here to ensure sufficient volumes of blood for analytical procedures. Blood (~100 µl) was collected via caudal venipuncture (23 G needle on a 1 ml syringe; 10,000 USP units/ml of sodium heparin; Sandoz, Boucherville, Canada) with the procedure taking less than 3 min to ensure that samples were representative of baseline conditions (Lawrence, Jain‐Schlaepfer et al, ). Whole blood was immediately assessed for blood [glucose] using a portable glucose meter (Accu‐Chek Compact Plus; Hoffman‐La Roche Limited, Mississauga, ON, Canada) that has been validated for use in teleost fishes (Serra‐Llinares, & Tveiten, ; Wells & Pankhurst, ; reviewed in Stoot et al, ).…”

Comment: Practices for Drawing Blood Samples from Teleost Fish

“…except in cases where the collection method itself may perturb the parameter of interest (e.g., as in cortisol, glucose, and lactate titers; Lawrence et al. ).…”