2013 Field Research Report Reveals Changes

Key Findings in 2013 Include:

  • Gray Whale Abundance Increases for Third Year
  • Eel Grass and other Algae Declining
  • Female-Calf Pairs Move between LSI and Bahia Magdalena
  • 5-Year Acoustic Baseline Report in Preparation

The 2013 winter season marked the eighth winter field season and year for the Laguna San Ignacio Ecosystem Science Program (LSIESP). Since its beginning in 2006, LSIESP continues to provide information on the biological status of the lagoon and its wildlife, especially the gray whales, to the local community, eco-tourism operators, and government officials. We have been fortunate to work with many university student researchers and their professors, many of which have gone on to pursue additional academic training and to careers in marine wildlife science, management, and conservation.

Seventeen bi-weekly census surveys of gray whales were conducted in the lagoon to monitor abundance, distribution, habitat use. Surveys began on January 19th 2013 and continued until April 8, 2013. The overall number of gray whales was similar to that seen in 2011 and 2012, and greater numbers of gray whale were observed in the lagoon compared to the low numbers observed between 2007 to 2010. The greatest number of adult whales was counted on 16 February 2013 (214 adults and 58 mother-calf pairs).

For the third consecutive winter since 2010, we observed a late season increase in the number of female-calf pairs entering Laguna San Ignacio. This was again a significant increase compared to the low numbers observed1996-2010. Female-calf counts reached a high count of 86 pairs on 2 March and after that averaged 66-pairs until the last survey on 8 April.  This late season increase and photo-id records indicate that mother-calf pairs are entering Laguna San Ignacio from calving areas in Bahia Magdalena to the south, and perhaps from other winter aggregation areas as well.

Rafael Riosmena-Rodríguez, Ph.D. of the Programa de Investigación en Botánica Marina at UABCS and his students monitor and evaluate the decline of eel grass meadows (Zostera marina) that has occurred in the lagoon in the past decade. At this time it is uncertain what factors are contributing to the eel grass decline, but opportunistic brown algae (Gracilaria vermicullophyla) and another unknown and possibly invasive species are displacing eel grass in areas where it used to thrive.

Eel grass and the related invertebrate fauna associated with the sea-grass meadows provide food for a wide range of invertebrates and vertebrates (e.g., sea turtles, Brant geese, marine fish, etc.) in the lagoon, and the loss of eel grass is expected to change the tropic structure of the lagoon significantly.

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