[Animals] The mystery of the 137 sea lions that arrived dead on the coast of Baja California

[Draeno]

 

Under the midday sun, a blackish sand beach, soft waves and a rotten smell. There are 137 sea lion carcasses scattered, alone or in groups. Sometimes up to 150 meters separate each other. They are swollen, in an advanced state of decomposition. The most probable thing, observe the scientists present in the place, is that they died in the sea and floated dragged by the currents of the north to this point of the coast of Baja California Sur, the beach of San Lázaro. Pending laboratory analysis, the main hypothesis to explain the largest incident of this type that is remembered in northern Mexico points to poisoning by red tide, a natural phenomenon caused by the proliferation of algae.

The alert jumped on September 3. “Wow”, thought the biologist Aurora Paniagua, president of the Mmares association, when the notice arrived. I had never heard of anything like it in size. Neither she nor any of her colleagues from the Marine Mammal Stranding Network, a collective platform that is in charge of monitoring animals stranded on beaches and trying to save those still alive. Since 2012, almost 300 cases have been reported in the area, from gray whales to common dolphins. “Mostly they are individuals. Sometimes, between two and five and, in rare cases, more than 10. Seeing wolves and I had never touched them in that amount”, explains Paniagua. Before the episode on the beach of San Lázaro, the largest incident of this type on the north coast of Mexico that the consulted associations remember did not reach 100 copies.

The day after the report, Paniagua and a dozen people, including scientists and inspectors from the Federal Attorney for Environmental Protection (Profepa), left La Paz for Magdalena Island, located four hours from the regional capital, at the end of a wide spoon-shaped bay. The fishermen from the coast crossed them by boat. They got into several 4x4s and a four-engine and began to travel the more than 50 kilometers of beach. “It was finding you one corpse after another,” recalls Paniagua, by phone from La Paz.

With a yellow tape, protected with scarves or face masks, they measured the thickness of the neck and the size of each animal, from the nose to the tip of the tail. When they finished with one, they marked it with white spray so as not to repeat themselves. Taking samples to find out what had happened was not easy. Of the 137 dead animals, only four were fresh enough. Those were opened with a scalpel to remove bits of liver, kidney and brain. They were like that for seven hours.

From the outset, the biologists observed that no corpse had marks of fishing nets. Baja California Sur is an area rich in marine fauna and is among the main fish producers in the country. In 2017 it was placed in third place with a production of more than 110,000 tons. It is not strange that sea lions, especially the young ones, approach the nets, attracted by the prospect of easy food, and become trapped. But both the scientists present on the ground and Profepa rule out that possibility. "No marks of anthropogenic origin caused by nets or blows and cuts caused by some type of boat were observed on them," the agency declared in a statement released this Sunday, ten days after the first alert was sent to the associations.

In addition to the absence of marks, neither the number of corpses nor the type of specimen found on the beach of San Lázaro matches this hypothesis. Among the 137, only one female was found. The rest were males between five and nine years old, weighing an average of 200 kilos and measuring around 2.4 meters in length. In addition, they sported the typical crest on their heads. Biologist Fernando Elorriaga, a CICIMAR researcher at the National Polytechnic Institute, points out that this homogeneity reinforces the poisoning hypothesis: “These males feed in certain areas and could have consumed a contaminated resource. There is a segmentation by sex of feeding areas and that is why other groups did not fall”. The only female, the scientist points out, "could have arrived alive and perhaps was not part of the event."

 

https://elpais.com/mexico/sociedad/2020-09-14/el-misterio-de-los-137-lobos-marinos-que-llegaron-muertos-a-las-costas-de-baja-california.html#?rel=mas