---
title: "A new abundance estimate for vaquitas: first step for recovery"
canonical: https://vaquita.mx/library/jaramillo-legorreta-1999
updated: 2026-10-16T18:27:32Z
source: Generated from vaquita.mx
---

# A new abundance estimate for vaquitas: first step for recovery

- Type: Research paper, peer reviewed
- Authors: Armando M. Jaramillo-Legorreta, Lorenzo Rojas-Bracho and Tim Gerrodette
- Published: 1999
- Journal: Marine Mammal Science 15(4):957-973
- Language: English
- Licence: Unknown
- DOI: [10.1111/j.1748-7692.1999.tb00872.x](https://doi.org/10.1111/j.1748-7692.1999.tb00872.x)
- Source: [https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-7692.1999.tb00872.x](https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-7692.1999.tb00872.x)
- Page: https://vaquita.mx/library/jaramillo-legorreta-1999
- Topics: Population & surveys

## Summary

A three-boat line-transect survey in summer 1997 was the first designed to estimate vaquita abundance over the whole range. It recorded 125 sightings of vaquita groups and estimated a total population of 567 animals (95% CI 177 to 1,073). The authors say this is better than earlier estimates, but that it should not be compared directly with the 1993 figure.

## Why it matters

It is the first complete estimate of the vaquita population, and later surveys use it as the reference point for measuring decline.

## Key findings

- Total population estimated at 567 animals, 95% CI 177 to 1,073.
- 125 sightings of vaquita groups, mainly because large binoculars were seven times more effective than hand-held binoculars.
- The vaquita's range is restricted to the northwestern corner of the Gulf of California.
- The boundaries of the Upper Gulf of California and Colorado River Delta Biosphere Reserve do not match the vaquita's distribution well.
- The shallow area north of San Felipe held a higher density of animals than earlier surveys indicated.

## Caveats

The 1997 estimate was more than twice the 1993 estimate, but the authors state that several reasons prevent a direct comparison and that it should not be concluded the population is increasing. The confidence interval is wide, spanning 177 to 1,073.