Haematology and blood chemistry baselines of adult blacktip sharks (Carcharhinus limbatus) from the Galapagos islands

Lucie Arliaud

There has been a rising interest for shark physiology over the last decade as a consequence of the intensification of anthropogenic pressures on the marine environment. Haematology and blood chemistry parameters are an important tool to assess the health and well-being of wildlife and may also be used to assist management for given populations. Recently, research efforts have been conducted to describe health status of different taxa of the Galapagos Marine Reserve (GMR) through blood analysis; however, physiological condition of marine species in this area, including sharks, remains understudied. To assist filling this gap, this study was focused on the analyse description of haematology and blood chemistry parameters of free-living blacktip sharks (Carcharhinus limbatus) from near Santa Cruz Island, Galapagos.  A total of 12 adult female sharks were captured and sampled for blood under a protocol designed to reduce fighting and handling time. Blood chemistry results were obtained with CG4+ i-STAT cartridges but failed with the CHEM8+. Erythrocytes counts were found to be similar than those found in literature for the same species in other locations, whereas leukocytes total counts were lower. Differential counts of white blood cells, lactate, and pH levels were reported in similar ranges to the ones from literature in other populations, even though different dishing methods were employed. Lactate was however lower than the studies using longlines as capture methods. No correlation was observed between blood parameters and fight and handling time, and no conclusion could be drawn regarding stress levels. This study provides some baselines of haematology and blood chemistry parameters for this sample of the population of Santa Cruz Island; however, further research would be needed to provide reference intervals of the population of blacktip sharks found in Galapagos.