SAGIP SARIHAY #18
Carcharhinus longimanus (Oceanic whitetip shark)
Words by Alyssa Rae Suyo
Artwork by Patricia Ysabel Tolosa
Description
Carcharhinus longimanus is commonly known as the oceanic whitetip shark with a wide range of surface water preference, including tropical and temperate seas. It is observed to be an active and fearless shark species, and is measured approximately 350 cm in length (Rigby et al., 2019). Among the marine animals, C. longimanus is included in one of the largest and most abundant shark species with an average longevity of 15 years (NOAA, 2014). This species is mostly solitary, however, tends to aggregate during their hunt around food sources (Babcock et al., 2008).
Locality
C. longimanus is listed as a high migratory species in the United Nations Law of the Sea, as cited in Burgess et al. (2009). According to Young & Carlson (2020), it is a ubiquitous pelagic shark in a global range of tropical seas that are most commonly found in the Pacific Ocean within the 100N and 10oS coordinates. It is native to a lot of countries, including the Philippines (Rigby et al., 2019). Interestingly, the distribution of this species demonstrates a geographic sexual segregation, wherein lagoons and fore-reefs are prefered by females and males, respectively (Mourier & Planes, 2013).
Threats
Data recorded in the period of 1992–2000 in the US pelagic long line logbook demonstrated that approximately 70% of the C. longimanus population has declined within the waters of the central and western regions of the Atlantic Ocean, wherein it has been classified as a critically endangered species as published by IUCN (Rigby et al., 2019). One of the factors that contributed to this include its high catchability caused by its inquisitive nature and surface water preference. In addition, it is also globally targeted and bycaught for its meat, liver oil, skin, and fins in gillnet fisheries, small and large scale long lines, and purse seines (Dulvy et al., 2014). Other threats are caused by cage diving in ecotourism, climate change, and habitat modification such as ocean acidification and temperature fluctuation.
How can we help this endangered species?
In Australian waters, the population status of this C. longimanus is managed through research analysts to stop the population decline by ensuring that the recovery plan and conservation status will not be hindered by anthropogenic activities. With this, the general recovery plan involves the implementation of prohibiting oceanic white shark transhipment and storage in international wildlife and fisheries treaties to prevent its capture. This recovery system also minimizes the mortality rate in bycatching and promotes its safety release. Lastly, the amount reduction of allowed berleying in ecotourism activities is also recommended to minimize the behavioral impacts of C. longimanus that affects their survival (Bruce & Bradford, 2011).
References
Babcock E. A., Camhi M. D., & Pikitch E. K. (2008), Sharks of the Open Ocean: Biology, Fisheries and Conservation, United Kingdom: Blackwell Publishing Ltd.
Bruce, B., & Bradford, R. (2011). The effects of berleying on the distribution and behaviour of white sharks, Carcharodon carcharias, at the Neptune Islands, South Australia. CSIRO. doi.org/10.5072/83/5849a259282fc
Burgess G., Carvalho F., Coelho R., Hazin F. H.V., Rego M., Oliveira P., Tambourgi M. and Travassos P. (2009). Notes on the reproduction of the oceanic whitetip shark, Carcharhinus longimanus, in the southwestern equatorial Atlantic Ocean. Col. Vol. Sci. Pap. ICCAT: 64–69.
Dulvy, N. K., Fowler, S. L., Musick, J. A., Cavanagh, R. D., Kyne, P. M., Harrison, L. R., … & White, W. T. (2014). Extinction risk and conservation of the world’s sharks and rays. elife, 3, e00590.
Mourier, J., Mills, S. C., & Planes, S. (2013). Population structure, spatial distribution and life‐history traits of blacktip reef sharks Carcharhinus melanopterus. Journal of fish biology, 82(3), 979–993.
NOAA (2014). Oceanic Whitetip Shark Charcharhinus longimnus. National Oceanic and Atmospheric Administration. Retrieved from http://www.nmfs.noaa.gov/pr/species/fish/oceanicwhitetipshark.htm on 6 Jun 2021.
Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Pacoureau, N., Romanov, E., Sherley, R.B. & Winker, H. 2019. Carcharhinus longimanus. The IUCN Red List of Threatened Species 2019: e.T39374A2911619. Retrieved from https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T39374A2911619.en. On 6 Jun 2021
Young, C. N., & Carlson, J. K. (2020). The biology and conservation status of the oceanic whitetip shark (Carcharhinus longimanus) and future directions for recovery. Reviews in Fish Biology and Fisheries, 30(2), 293–312.
