Analysing tropical elasmobranch blood samples in the field: blood stability during storage and validation of the HemoCue® haemoglobin analyser

Gail D Schwieterman; Ian A Bouyoucos; Kristy Potgieter; Colin A Simpfendorfer; Richard W Brill; Jodie L Rummer

doi:10.1093/conphys/coz081

Analysing tropical elasmobranch blood samples in the field: blood stability during storage and validation of the HemoCue® haemoglobin analyser

Conserv Physiol. 2019 Nov 29;7(1):coz081. doi: 10.1093/conphys/coz081. eCollection 2019.

Authors

Gail D Schwieterman¹, Ian A Bouyoucos^{2

3}, Kristy Potgieter⁴, Colin A Simpfendorfer⁵, Richard W Brill¹, Jodie L Rummer²

Affiliations

¹ Department of Fisheries Science, Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA.
² Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia.
³ PSL Research University, EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, 58 Avenue Paul Alduy, Perpignan Cedex 66860, France.
⁴ College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia.
⁵ Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia.

Abstract

Blood samples collected from wild-caught fishes can provide important information regarding the effects of capture (and thus post-release survival) as well as other stressors. Unfortunately, blood samples often cannot be analysed immediately upon sampling, and blood parameters (e.g. blood oxygen levels and acid-base parameters) are known to change with storage duration due to the metabolic activity of the red blood cells. We obtained blood samples from both untreated and stressed individuals of both blacktip reef shark (Carcharhinus melanopterus) and sicklefin lemon shark (Negaprion acutidens) to determine the effects of storage duration on blood pH, haematocrit and haemoglobin concentration ([Hb]). We found no significant effects after storage on ice for up to 180 minutes. Moreover, to validate the usability of a HemoCue haemoglobin analyser (a point-of-care device), we compared data from this device to [Hb] determined using the cyanomethaemoglobin method with blood samples from 10 individuals from each of the aforementioned species as well as epaulette shark (Hemiscyllium ocellatum). Values from the HemoCue consistently overestimated [Hb], and we therefore developed the necessary correction equations. The correction equations were not statistically different among the three elasmobranch species within the biologically relevant range but did differ from published corrections developed using blood from temperate teleost fishes. Although the HemoCue is useful in field situations, development of species-specific calibration equations may be necessary to ensure the reliability of inter-species comparisons of blood [Hb]. Together, these data should increase confidence in haematological stress indicators in elasmobranch fishes, measurements of which are critical for understanding the impact of anthropogenic stressors on these ecologically important species.

Keywords: HemoCue; blood; elasmobranch; haematocrit; haemoglobin concentration; storage duration.