Geographic and seasonal distributions of the vaquita, Phocoena sinus

Abstract

A TOTAL OF 980KM OF AERIAL SURVEYS WERE FLOWN IN SEARCH OF THE VAQUITA, PHOCOENA SINUS IN THE NORTHERN GULF OF CALIFORNIA IN SEPTEMBER 1989. IN ADITTION, FOUR WHOLE VAQUITA SPECIMENS WERE COLLECTED IN 1987 AND 1988 VAQUITA WERE SEEN FROM THE AIRCRAFT ON SEVEN OCCASIONS (14 INDIVIDUALS). MEAN GROUP SIZE WAS 2.0 INDIVIDUALS, AND ALL SIGHTINGS OCURRED IN WATER DEPTHS UTILIZED BU THE VAQUITA OBTAINED DURING FALL SURVEYS WERE SIMILAR TO THOSE PREVIOUSLY OBTAINED IN SPRING SURVEYS. OUR SIGHTINGS OBTAINED IN FALL (WHEN SEA SURFACE TEMPERATURE MAXIMA OCCUR) SUGGEST VAQUITA OCCUPY THE NORTHERN GULF YEAR - ROUND AND THE SPECIES EXHIBITS ADAPTATIONS THAT ENABLE IT TO WITHSTAND GREAT WATER TEMPERATURE RANGES IN THE NORTHERN GULF.