Threatened Gulf

Ten years ago, graduate students Octavio Aburto-Oropeza and Gustavo Paredes worked with Scripps Institution of Oceanography at UC San Diego researcher Enric Sala to mount a back-to-basics marine life surveying campaign across the Gulf of California. They packed a van with an inflatable boat, diving gear, and computers and drove hours each day, sometimes navigating through deserts, often to desolate locations. Six- to eight-hour ecological surveys ensued before the days were over. Most nights were spent on a beach or in a boat. The next day they would pack up and drive off to the next location.

After three months they had examined more than 70 sites around the Gulf of California, including mangroves, rocky reefs, seamounts, and other habitats. Their data formed a rich database of Gulf of California coastal ecology and resulted in an important report describing how a network of marine reserves could help protect the Gulf’s sea life for future generations.

Fast forward to the summer of 2009. Aburto-Oropeza and Paredes, now postdoctoral researchers at Scripps Oceanography, returned to the Gulf to conduct a fresh round of surveys at the same sites to evaluate how much has changed in a decade.

This time, however, rather than a nomadic adventure, the researchers conducted the surveys aboard Don Jose, a fully-equipped diving boat based out of La Paz, Mexico. Rather than an ambitious trio, more than 20 marine ecologists with specialties covering both fish and invertebrate (spineless) animals conducted this round of surveys. And rather than an isolated research endeavor, the 2009 expedition was undertaken as part of the newly launched Gulf of California Program, a research coalition based out of Scripps’ Center for Marine Biodiversity and Conversation and led by Aburto-Oropeza, Paredes, UC Riverside Professor Exequiel Ezcurra, Scripps postdoctoral researcher Brad Erisman, and Scripps Professor Phil Hastings, director of the Gulf of California Program.

For Aburto-Oropeza and Paredes, many of the 10-year changes were shocking and discouraging for the long-term health of the Gulf’s marine ecosystems. Sixty percent of the surveyed sites showed signs of degradation, according to Aburto-Oropeza, and many are now missing the top predators normally present in healthy, functioning ecosystems.

 “Ten years later we can actually measure the effects of not putting conservation measures in place,” said Paredes. “Some of us had been conducting surveys in certain sites every year, but until this year we didn’t know the whole story of what was going on.”

Aburto-Oropeza says the changes have occurred at the hands of fishing activities. In a single generation fishing efficiencies have escalated from traditional hook-and-line methods, to more potent gill net fishing, to today’s vastly more destructive “hookah” diving. Proliferating only in the past 10 years, hookah fishermen use crude oxygen delivery methods (industrial generator and tubing) through basic piping that allows them to walk along the seafloor for long periods of time. The technique is typically conducted at night when fish are resting, allowing the hookah fishermen to spear or grab large numbers of vulnerable fish and invertebrates.

“Hookah diving is probably one of the biggest threats to reef fishes in the Gulf,” said Erisman. “From a fishermen’s perspective it’s very efficient, but, obviously, it’s not the most ecologically responsible way to do it.”

Such destructive fishing methods are eliminating the largest members of the Gulf’s habitats, including fish such as sharks, groupers, and snappers. Scientists say  “fishing down the food web” occurs when such key players in healthy functioning ecosystems are replaced by progressively smaller, less valuable species that occupy lower levels of the food web.

“Some species have undoubtedly been driven to commercial, if not ecological extinction,” warns a report released by the Gulf of California program.

In the most dramatic example of fishing impacts observed on the 2009 expedition, Erisman said a survey of San Esteban Island in the northern section of the Gulf revealed reefs devoid of fish and instead covered by mats of cyanobacteria. Similar examples of marine degradation have been described by Scripps Professor Jeremy Jackson as “the rise of slime.” Overfishing, habitat destruction, and ocean warming are transforming intricate marine food webs with large animals into simplistic ecosystems dominated by microbes, toxic algal blooms, jellyfish, and disease, according to Jackson.

“It is disturbing to witness a severely degraded reef, but especially so at such a remote site as Isla San Esteban. It demonstrates that no areas of the Gulf are immune to over-exploitation,” said Hastings.

Backed by new research grants from the Walton Family Foundation and the David and Lucile Packard Foundation, the launch of the Gulf of California Program is a solid step toward reversing the downward trends revealed in the last 10 years by integrating a patchwork of research efforts into one.

“Lately there has been a greater awareness, mainly because of collapsing fisheries, that marine resources in the region are depleted,” said Erisman. “We need a more comprehensive, regulated approach. People are realizing that we need to come together, coordinate efforts, and integrate data to help understand small- and large-scale ecological changes in the Gulf.”

The 2009 ecosystem-monitoring project was supported by the International Community Foundation, an anonymous donor, and a Pew Ocean Fellowship to Exequiel Ezcurra.

—Mario C. Aguilera