Sarasota Dolphin Research Program

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Human-related problems affecting wild dolphin populations along the Pacific coast of Guatemala
By Ester Quintana-Rizzo, PhD, Fundación Defensores de la Naturaleza, Guatemala and Universidad del Valle de Guatemala de Guatema

Metal harpoon used to kill dolphins for shark bait along the Pacific coast of Guatemala (person is included for scale).

Many cetacean species are found along coastal areas and thus are vulnerable to a variety of human activities. As part of a study examining the diversity, abundance, and distribution of coastal cetacean species along the Pacific coast of Guatemala, I have been able to identify two problems affecting small cetaceans’ populations in the country: entanglement of dolphins in fishing nets and dolphin harpooning. Dolphins are harpooned to use their meat as shark bait. Interviews with fishermen indicate that the harpooning is a relatively common practice, which is used in two situations: 1) when fishermen do not have enough bait to catch sharks and 2) when sharks do not seem to like the non-dolphin bait provided by fishermen. Shark fishing, one of the main practices in some coastal towns, uses a technique called “cimbra”, a pelagic longline that can be up to 10-15 km long and have a variable number of hooks. A cimbra can use a combination of bait. When only dolphin meat is used, this requires the killing of three dolphins. A cimbra that uses a combination of non-dolphin meat and dolphin meat requires killing one dolphin. Harpoons used to kill dolphins are long metal bars approximately 2 m long (see photo) with a detachable sharpened head. In 2005, 353 fishermen along approximately 255 km of coastline were registered to have at least one cimbra. It is estimated that approximately 468,735 pounds of sharks are caught annually.

Another problem faced by small cetaceans in Guatemala includes their incidental entanglement in fishing nets. In the spring of 2009, three dead dolphins were entangled in a ghost fishing net approximately 200 m long. According to the fisherman who works on the project, this type of net is used illegally to capture swordfish (Istiophorus platyperus) in offshore waters. The net probably floated with the currents close to shore as it was found at 3.5 nautical miles from the coast. Two of the dolphins, a male and a female, were in advanced stages of decomposition and were tentatively identified as bottlenose dolphins. Based on their size, they were probably adults. The third dolphin was a fresh carcass that probably got entangled that day. A necropsy revealed that this dolphin was a juvenile female bottlenose dolphin in good health. A few days after the incident, a local fisherman reported to have seen at least 10 more dead dolphins in another location. Those animals were not entangled but were just floating in the water at approximately 10 miles from shore. The fisherman who saw them said that they were in an advanced stage of decomposition and thus, their identification was not possible. Since it is uncommon to see these high numbers of dead dolphins in an area, it seems likely that their death was human related. One fisherman reported that around 20 dolphins get entangled in his net on a monthly basis. Mortality rates due to entanglement or harpooning have not been quantified or even studied in the country. Thus, their effects on local cetacean populations are unknown, but these preliminary reports indicate that the problems are potentially serious and should be studied. The documentation of the problems can help to raise awareness because the government has not taken any actions to try to resolve them.

In another development, I am pleased to report that our report “Primer studio sobre la diversitad, distribucion, y abundancia de cetaceos en la zona economica exclusive del Oceano Pacifico de Guatemala,” a first description of the diversity, abundance, and distribution of cetaceans along Guatemala’s Pacific coast, supported by a Chicago Board of Trade grant and based on data collected by NOAA, has now been distributed to all Guatemalan government agencies dealing with the protection and conservation of wildlife and marine resources. Copies of the report were also sent to the universities having Biology as a subject area and to conservation NGOs. The response to the report has been very positive. The main comment so far is that people are happy that the information is available and that the information is in Spanish. I received a letter from the National Commission of Protected Areas, which says that the information will be of great use to their agency.