[MARMAM] New paper on the vaquita just published

Thomas Jefferson sclymene at aol.com
Wed Jun 2 14:01:55 PDT 2021


Dear MARMAM,

The vaquita, Gulf of California harbor porpoise (Phocoena sinus), is highly endangered. We present a synopsis of the situation, with a summary of earliest "scientific" discovery of the species. As an appendix, we are also fortunate to have a lovely retrospective by the great marine mammal biologist Kenneth S. Norris, of describing the species from several skulls found in the 1950's. Let us hope that vaquita may survive.
Vaquita: beleaguered porpoise of the Gulf of California, México
Bernd Würsig, Thomas A. Jefferson, Gregory K. Silber and Randall S. Wells

The vaquita (Phocoena sinus), an endemic porpoise of the Gulf of California, México, was first described scientifically in 1958, from three
skulls. It is considered a sister taxon of an ancestor of the Southern Hemisphere Burmeister’s porpoise (P. spinipinnis) and spectacled porpoise
(P. dioptrica), a case of antitropical distribution and speciation. Vaquita in modern times seem to have existed largely in waters 10 to 30 m deep
of the very northern Gulf of California, and may have already existed in relatively low numbers by the 1950s and 1960s. The external appearance
of the vaquita was not described until the late 1970s, and not until the 1980s and 1990s did additional information about ecology and
biology emerge. Those studies and more recent shipboard and aerial visual line transect surveys, as well as stationary and boat-towed acoustic
arrays, mapped occurrence patterns and approximate numbers in greater detail than before. The first credible estimates of abundance appeared
in the 1990s, with numbers in the mid-hundreds and declining. While several reasons for the decline were originally postulated, mortality
due to entanglement in nets has been established as the only known cause of decline, especially due to bycatch in large-mesh gillnets set for
the endangered croaker fish totoaba (Totoaba macdonaldi). This fish is prized in China for human consumption of its swim bladder, generally
ground up for purported therapeutic purposes. An extensive, lucrative fishery for totoaba, now illegal for many decades, has existed since at
least the 1920s, and has recently increased. Although there have been laudable attempts to stem or halt totoaba fishing, these have largely
been unsuccessful, and as of this writing the vaquita is on the brink of extinction. However, rapid concentrated action against illegal fishing
with gillnets may yet save the species, and hope (with attendant action) must be kept alive. This overview is followed by an appendix of a previously
unpublished popular essay by K.S. Norris describing when, where, and how he first discovered the species, and subsequent early work
relative to this newly-described porpoise.

The PDF is available for free download at this link:  https://www.revistas-conacyt.unam.mx/therya/index.php/THERYA/article/view/1109/pdf_342
Bernd Würsig and co-authors
  
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