Factors that affect Vaquita Mortality

Parasites
Parasites have been found on the flukes of some Vaquita found entangled in nets. Three types of trematodes have been found in the intestines of dead Vaquitas. It is not known to what degree parasites affects Vaquita´s health.

Predation

Various fishermen from El Golfo de Santa Clara who caught Vaquitas in their nets notified researchers that between February and May of 1990 and 1991 they found parts of Vaquita in the stomachs of several species of large sharks, including some species of sharks: the white shark (Carcharodon carcharias), the shortfin mako (Isurus oxyrinchus), the lemon shark (Negaprion brevirostris), the blacktip shark (Carcharhinus limbatus), two species of thresher shark (Alopias superciliosus and Alopias vulpinus), and the broadnose sevengill shark (Notorynchus cepedianus). Some vaquita tangled in nets showed scars on their flukes from teeth that could be shark or killer whale, and there have been sightings of killer whales and also of other species of sharks, like the tiger shark (Galeocerdo cuvier), scalloped hammerhead sharks (Sphyrna spp.) and bull shark (Charcharhinus leucas), among others. However there have been no direct reports of attacks on vaquita by these species of sharks or by killer whales.

Mexican waters become a giant whale sanctuary

Hermosillo, Mexico.- Mexican seas and its exclusive economic zone (200 miles from the coastline), became a giant sanctuary and refuge for whales since past 24th of May, acording to announcement published in the Mexican Official Gazzete, thanks to the efforts of WWF Mexico by lobbying, and Greenpeace with the proposal.

The mexican whales will have guaranteed its reproduction circle, borning, growing, learning, feeding and migrating, important phases for this cetaceans, also their habitat won´t be exposed to human explotation.

The Vaquita is a cetacean

Cetaceans are a subgroup of mammals, mostly marine, distinguished among other things, for living their entire life in water. Adaptations for a totally aquatic life include changes in external body form to subtle physiological changes that allow for life in salt water.

Threats to Vaquita’s habitat that could affect recuperation

Given the limited geographic distribution of Vaquita, the condition of that habitat plays an important role in determining the status of the population. Any change in the habitat could affect the well being and recovery of the Vaquita.

Reduction in Colorado River flow
The flow of water from the Colorado River has been greatly reduced by dams and other water projects in Southwestern U.S. and to a lesser extent, in Northwestern Mexico. Today freshwater flows from the Colorado River reach the Delta only in years of heavy precipitation. Some investigators assume that this reduced flow has caused a drastic change in the ecosystem. For example, the low salinity estuarine conditions that prevailed prior to these flow reductions have been replaced by negative hypersaline estuarine conditions in the Delta, and these changes could have caused alterations in the food web and in biological diversity. However, there isn’t sufficient information to confirm this hypothesis. The available evidence suggests that the Colorado River Delta acts like a very fertile coastal lagoon, maintaining abundant populations of crustaceans and mollusks, and other species use this habitat for feeding and as a refuge.

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