The Threats to the Common Dolphin population
The common dolphin (Delphinus delphis) is about to get extinct and this is due to a number of reasons. Firstly, all the changes happening to the environment such as temperature affect the amount of prey in the water and makes them disperse to other locations (Bearzi, 2003). Because of this, the population of dolphins is affected due to a drop or disruption in the food web.
Illegal Fishing with Drift Nets
Another factor is illegal fishing with drift nets. This illegal activity has resulted in ether unintentional or intentional catching of dolphins (Mussi, 2002). Overfishing cases and destruction of the habitat of the fish causes extinction of the dolphins' prey as well.
Predation Perception and Catching
One of the main reasons for catching dolphins is because they were perceived as the predators to fish. This is why more common dolphins were caught more than the bottlenose dolphin.
Catastrophic Effect of Toxic Compounds
The third reason is the catastrophic effect of xenobiotic toxic compounds in the sea water (Fossi, 2000). Remarkably, the population of common dolphins was almost completely wiped out due to toxicity. Basically, higher toxicity levels might have increased the frequency of common dolphins' death cases.
Incidental Mortality from Collision with Fishing Boats
Fourth on the list is the incidental mortality brought about by collision with fishing boats. This was caused by busy tourism seasons accompanied by traveling cruise ships and sails.
The Need for Conservation Measures
To conclude, the significant threat to common dolphin population is overfishing. It is also explained by an exploitative competition for prey fish between fishermen and the dolphins. The European Commission reports the decline in demersal and pelagic resources of the Ionian Sea. To prevent them from disappearing, conservation measures should be undertaken. Finally, driftnet fishing should be prohibited if we want common dolphins to survive.
References
Bearzi, G., Reeves, R. R., NOTARBARTOLO-DI-SCIARA, G. I. U. S. E. P. P. E., Politi, E., Canadas, A. N. A., Frantzis, A., & Mussi, B. (2003). Ecology, status and conservation of short-beaked common dolphins Delphinus delphis in the Mediterranean Sea. Mammal Review, 33(3-4), 224-252.
Fossi, M. C., Marsili, L., Neri, G., Casini, S., Bearzi, G., Politi, E., & Panigada, S. (2000). Skin biopsy of Mediterranean cetaceans for the investigation of interspecies susceptibility to xenobiotic contaminants. Marine Environmental Research, 50(1), 517-521.
Mussi, B., Miragliuolo, A., & Bearzi, G. (2002). Short-beaked common dolphins around the island of Ischia, Italy (southern Tyrrhenian Sea). European Research on Cetaceans, 16, 15.
