Dolphin Conservation
Overfishing Pollution and Military Sonar Harm Cetaceans
International cooperation is necessary to save whales.
All whales, dolphins and porpoises are suffering from human activities.
Fishing
- Overfishing - Modern fishing techniques are very efficient and allow stocks to be exploited with unprecedented success. Bigger and better nets, powerful large boats, echo-location and even spotter-planes and satellites allow fish shoals to be located and caught anywhere in the oceans. Fish stocks have been reduced to such low levels that dolphins find it hard to get enough food in some places.
- Collateral damage - Some of the nets designed to catch fish can also catch dolphins trying to feed on the same shoals. This is especially true of Tuna fishing. Serious concern over declining dolphin populations led to the adoption of ‘dolphin-safe’ fishing practices some years ago, but it is still not clear how effective this has been (see ‘The Dolphin-Tuna Controversy’).
Pollution
PCBs (Polychlorinated biphenyls) are among the most notorious of the persistent organic pollutants. Although most uses of PCBs were banned in the seventies they are still affecting some dolphin populations (Ref: ‘Environmental Model Developed by Trent University Researcher Shows That Killer Whales Retain High Concentrations of PCBs - Dr. Brendan Hickie Predicts Ongoing Health Risks to Orcas in the Pacific Northwest). Other pollutants have adverse effects on fish populations, making it harder for dolphins to find their food.
Noise
Cetaceans communicate by sound (Killer Whale Calls) and also use echo-location to find their way about and locate fish shoals. Noise generated by engines and propellers is a nuisance, but military sonar can be lethal (See ‘Whales, Dolphins and Ocean Noise’ and ‘Protecting Whales from Dangerous Sonar’).
Mediterranean Dolphin Populations
The Whale and Dolphin Conservation Society (WDCS) is very concerned about the common dolphin's disappearance from the Mediterranean – a short video can be watched here.
Common Dolphins (Delphinus delphis) were once common in the Mediterranean, but their numbers have declined dramatically. They are no longer intentionally hunted, but they are suffering from the effects of overfishing (of their preferred prey – sardines and anchovies) and thousands still get caught in nets. The population is endangered and only urgent action can save them.
Whale-watching
More and more people are becoming interested in whales, the fact that they need to surface in order to breathe means that they can be watched from boats in suitable locations. ‘Whale-watching’ is becoming a popular leisure activity, and as the general public learns more about the problems whales are facing there is growing pressure for legislation to protect them. This is a complex issue since many cetacean species have a worldwide distribution and international cooperation is necessary if effective measures are to be put in place.
(See also:'Protecting Irrawaddy Dolphin')
Other articles by John Blatchford
