Saturday, August 17, 2019

Species Profile: Hector's Dolphin

Hello again, welcome back to animals under threat. Today, we will be covering a species of dolphin that is classed as one of the smallest dolphin species in the world. Please give a warm welcome to Hector's Dolphin (Cephalorhynchus hectori).

Hector’s dolphin belongs to the Genus Cephalorhynchus which consist of four species which are Hector’s dolphin, Heaviside's dolphin, Chilean dolphin and Commerson's dolphin. They have the most restricted distribution of any dolphin, whale or porpoise species and resided in the waters around New Zealand. They are characterized by their colouration with the back/sides been a light grey, dorsal fin/flippers/ and flukes are black, throat and belly are white and black crescent shaped band across the head behind the blowhole (Reeves et al, 2013).
Picture by James Shook and map by Rudolph

Hector’s dolphin has a unique shaped dorsal fin as it is rounded compared to regular dolphin dorsal fin are curved. They feed mostly on fish such as yellow-eyed mullet, sprat and pilchard but also feed on squid if available (Miller et al, 2013). Hector’s dolphins live in small pods that contain 7-8 members (Brager, 1999).
Pictures of Hector’s dolphin with pod mate in background and caught in net by Stephen Dawson / WWF-Canon.

Hector’s dolphin is under threat from gillnets, pollution, collisions with boats, habitat modification and diseases. Majority of the dolphins are dying from drowning by net entanglement as they are unable to free themselves from the nets (Reeves et al, 2013). Coast development, oil/gas exploration and sand mining are causing changes in the dolphin’s habitat leading to pollution entering the water and making the dolphin’s sick (Worldwildlife, 2019). Toxoplasma gondii is a disease that caused by a parasitic one-celled eukaryote which can cause Toxoplasmosis. This can affect the dolphin’s body condition and can lead to death (Roe et al, 2013).

Next time, we will be covering a mouse species from Australia and its species name is Latin for Smoky.

References
Brager, S. 1999, "Association patterns in three populations of Hector's dolphin, Cephalorhynchus hectori", Canadian journal of zoology, vol. 77, no. 1, pp. 13-18.

Miller, E., Lalas, C., Dawson, S., Ratz, H. & Slooten, E. 2013;2012;, "Hector's dolphin diet: The species, sizes and relative importance of prey eaten by Cephalorhynchus hectori, investigated using stomach content analysis", Marine Mammal Science, vol. 29, no. 4, pp. 606-628.

Reeves, R.R., Dawson, S.M., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2013.

Roe, W.D., Howe, L., Baker, E.J., Burrows, L. & Hunter, S.A. 2013, "An atypical genotype of Toxoplasma gondii as a cause of mortality in Hector's dolphins (Cephalorhynchus hectori)", Veterinary Parasitology, vol. 192, no. 1-3, pp. 67-74.

https://www.worldwildlife.org/species/hector-s-dolphin retrieved 17/08/2019

Picture reference
https://www.iucnredlist.org/species/4162/44199757
https://en.wikipedia.org/wiki/Hector%27s_dolphin




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