Magnificent Animals: Why Sharks are Good for the Ocean and For Us

Dovi Kacev at work. Courtesy: Dovi Kacev.

Dovi Kacev grew up in South Africa and San Diego. A longtime La Jolla surfer, Dovi is finishing up a joint SDSU-UC-Davis Ph.D. in Ecology. For the past 11 years he has carried out research on shark ecology and conservation which has allowed him to study sharks in the wild in San Diego, Baja California, and the Caribbean.

Serge Dedina: As a surfer who grew up in South Africa where there are a lot of sharks, why did you choose to make your life’s work the study of the ocean’s apex predators?

Dovi Kacev: From as early as I can remember I have been interested in sharks, but I did not think of becoming a shark biologist until I was in college. Learning about how important their roles are to maintaining balanced ecosystems, how little we know about their biology, and how much trouble they face due to human pressures, led me to realize that there is a lot that we need to understand better about sharks.  This led me to a career in shark biology.

Dedina: On Tuesday, surfers and a photographer spotted what appears to be shark in Imperial Beach. What is the typical migratory pattern of these animals and what is their conservation status?

Kacev: We have many different species of shark in Southern Californian waters and each species has different migratory behavior and habitat preferences. The shark in the photograph in question looks like it is either a white shark or a basking shark, both of which are known to use local waters and both are protected species due to conservation concerns. Recent tagging studies have shown that adult white sharks tend to come to California in the fall but migrate offshore to an area in the middle of the Pacific Ocean for much of the year. Juvenile white sharks are known to spend more time in the the Southern California Bight. Much less is known about the behavior of basking sharks, but scientists are trying to learn more about them with a new tagging study. Much like it is difficult to identify the species from the photo, it is not possible to estimate the size without some sort of reference.

Dedina: Is it likely the shark is still hanging out in Imperial Beach? Is there enough food locally to sustain them? And what are they typically feeding on?

Kacev: This all depends on the size and species. Last year basking sharks were sighted spending time off of Imperial Beach. They primarily filter feed on small copepods in the water column. Juvenile white sharks seem to take up residency in Southern Californian waters. As juveniles, they are fish feeders, and pose little risk to people. Adult white sharks are known to be seasonal residents in certain locations in central California and Mexico, but to the best of our knowledge tend to be just transient in our waters. If that was an adult white shark, there is no reason to expect that it is still in the area.

Dedina: How many white sharks are out there along our coast?

Kacev: This is a difficult question to answer as sightings are so rare and therefore data on white shark abundance is hard to come by. The most recent study of adult white shark abundance in Northern Californian waters estimated that there are between 200 and 300 adult individuals, which is a pretty small population. Another recent study suggests that the population size may be growing, but growth of shark populations happens at such a slow rate because they take a long time to mature and reproduce at a slow rate. The simplest answer to this question is that the population is likely quite small and that they are more threatened by people than they are a threat to us.

Dedina: Are there any locations in Southern California and especially in San Diego County that you have identified as having larger numbers of sharks?

Kacev: There are areas of seasonal aggregations of leopard sharks and smoothhounds, but none for the larger, more pelagic sharks.

Photo courtesy Dovi Kacev.

Dedina: You have been carrying out research outside of Black’s Beach. What are you and your colleagues observing there?

Kacev: The area off of Black’s Beach is interesting because of a large submarine canyon. We see a lot of leopard sharks, guitarfish, and bat rays. We occasionally catch juvenile thresher sharks in the area, which we tag and track.  In all of my time surfing, diving and fishing in that area, I have yet to see any large, potentially dangerous sharks.  This is not to say they do not exist there, but not in particularly high densities.

Dedina: What is the role of sharks in maintaining the balance of the ocean? Do we really need sharks?

Kacev: Sharks often act as apex predators and as such they are important for controlling the population sizes and behaviors of the species they feed upon.  Research on the East Coast has shown that in certain areas where sharks have been over fished, populations of rays have blossomed leading to the collapse of shell fish fisheries, because the rays feed on the shell fish. Healthy ecosystems need to be in balance and this requires maintenance of all the levels of the food web.

Shark carcasses in Mexico. Courtesy Dovi Kacev

Dedina: You have been traveling down the coast of Baja California to carry out shark research. What have you found there?

Kacev: We have found that in Baja there are a lot of fishing camps that catch a lot of sharks and rays, particularly juveniles. These fisheries are likely to have a large impact in the shark populations in the region. We have also found that in general the fishermen in Baja understand the importance of sustainable fisheries because their livelihoods depend on there being healthy populations of these fish. As a result, most of the fishing camps have been very accommodating to our research.

Dedina: There seems to be a lot of documentation and reporting now about shark sightings along the California coast. Is the population of sharks increasing?

Photo courtesy of Dovi Kacev.

Kacev: It is difficult to say whether shark populations are increasing, the population of ocean users is increasing, or the likelihood of people reporting sightings is increasing. It may also be a combination of all three factors. It is important to note that most shark populations are low relative to historical abundances, so even if their populations are increasing they are still of conservation concern. Even if shark populations are increasing, they do so at a very slow rate. Also, since sharks play such an important role in our coastal ecosystems and many species are of conservation concern, we should be celebrating if their population are indeed increasing. I hope that with continued increase in public curiosity and education, people will realize that sharks are a welcome part of our ocean system.  Instead of fearing them, we should respect them.

Dedina: California just passed a ban on the sale of shark fins. Why should we care about the plight of these animals?

Kacev: We should care about the plight of sharks because they are magnificent animals and our ocean ecosystems rely on them. Beyond just the value of sharks for their ecosystem services, it is important to remember that many people’s livelihoods revolve around the oceans and fisheries. Any disturbance that effects the balance of the ecosystem could eventually lead to the collapse of various fisheries.

Photo courtesy of Dovi Kacev.

The Mexico Shark Fishing Moratorium Fiasco

Great white shark. Photo by Terry Goss, copyri...

White shark near Mexico's Isla Guadalupe.

In the early 1990s I spent a lot of time around shark fishermen and observing the slaughter of sharks in Baja California Sur. At that time, fishermen had moved over from  the Sea of Cortez where shark populations had collapsed, to focus on an intensive long-line and gill net fishery along the Pacific, concentrating on the offshore fishing grounds of Magdalena Bay, San Ignacio Lagoon, the Vizcaino Peninsula and finally the area north of Guerrero Negro (Los Cirios Coast). At that time rays were also fished intensively due to to the collapse of other fisheries.

Shark dump near La Bocana in BCS, Mexico.

Most of the shark meat and ray meat (used to make machaca) were considered second or third-class fish, which meant a lower price. For sharks obviously it was the trade in fins that drove fishermen to go out 20-60 miles from shore to set long-lines or gill nets. At that time I had not realized that this type of fishing activity was being carried out all over the world and was causing the collapse of shark populations.

I had not also realized the extent to which the obsession with shark fin soup in Taiwan, Hong Kong and China was driving the extinction of the ocean’s most feared, beautiful and interesting animals.

Shark fin soup

Shark fin soup.

WiLDCOAST has been working with Defenders of Wildlife-Mexico and Iemanya Oceanica to curtail the excessive shark fishery in Mexico and to educate the general public through media campaigns of the impact the shark fishery was having on Mexico’s ocean health.

When sharks unfortunately attacked and killed two surfers a few years ago just north of Zihuatanejo (and attacked another surfer who survived) we carried out a successful effort to stop a government sanctioned revenge shark slaughter.

We also worked with organizations like WildAid, Oceana, NRDC, Ocean Conservancy and Heal the Bay to advocate for the ban on the sale of shark fins in California. Our wrestling superhero El Hijo del Santo has been a tireless advocate for sharks and reached more than 30 million people through appearances on news and talk shows on the Telemundo networks to call for the California ban on shark fins.

Hammerhead in the La Bocana shark dump. In some areas, schools of hammerheads are caught in gill nets that also annually drown thousands of loggerhead sea turtles.

Since then we have attempted to work to have Mexico include endangered hammerheads on the CITES list. That effort was squashed by the Mexican government.

So last week, conservationists were surprised and happy to learn that Mexico had proposed a moratorium on fishing all species of sharks and rays. And from this story that appeared on the New York Times blog it seemed very clear that the moratorium would be real:

Mexico announced here plans yesterday to ban shark and stingray fishing starting next year, creating what would be the largest initiative by one nation to protect shark species.

The temporary moratorium is part of a burgeoning global movement against the trade of shark fins used as an ingredient in an Asian delicacy. Mexican authorities said they were inspired by the “shark sanctuary” declared two years ago by Pacific nation of Palau.

“Mexico wishes to share with the international community our intention to declare next year a moratorium on shark and stingray fishing,” said Yanerit Morgan, Mexico’s deputy permanent representative to the United Nations on the side of a General Assembly meeting yesterday.

Joined by leaders of a small-island nations and other Latin American states, Morgan said the fishing ban would encompass Mexico’s territorial seas and expansive exclusive economic zone (EEZ) in the Pacific Ocean, Caribbean Sea and Gulf of Mexico.

The goal, she said, was to protect “pregnant female specimen and newborns of the main shark and stingray species.”

Morgan at the Mexican U.N. mission said her country’s decision to establish a moratorium is strictly a domestic initiative and not part of a regional North American or Latin American conservation effort.

“Our decision is a national policy,” Morgan said. “We hope that others can join us.”

Seemed pretty clear. Except it wasn’t. According to my inside sources in the Mexican government there was no plan to have a moratorium. The statement at the U.N. was a “mistake.” One source informed me that here was another proposal for a 3-month moratorium that they were confused about. Another source informed me that the proposal was actually real, but was only a foil in an attempt to pressure Mexican fishery officials (rabidly anti-conservation) to actually enact the 3-month moratorium.

Both sources assured me that a statement from the Mexican government clarifying the situation would be forthcoming.

It has been more than a week and no statement has been issued clarifying anything. Leading shark conservationists in the U.S. I spoke with continue to believe that Mexico is serious about conserving shark populations and the moratorium.

And this morning the New York Times, in an editorial, “A Growing Movement to Save Sharks”, lauded Mexico for its shark  and ray conservation initiative:

Last month, Mexico announced that it would ban shark and stingray fishing beginning next year. This would affect Mexico’s exclusive fishing zones in the Pacific Ocean and in the Gulf of Mexico. Several island nations — Micronesia, the Maldives, Palau, and the Marshall Islands — have already created shark sanctuaries. There is hope that Honduras and Colombia will follow suit, perhaps creating a protective corridor reaching to the Galapagos Islands.

So is the shark moratorium truth of fiction?

These types of policy “wars” in Mexico over proposals used to be carried out domestically in the state-run media. Different newspapers would publish policy proposals by competing factions in a government agency (the Mexican government under the PRI essentially bankrolled the press).

You would always know an article was a political message because it would appear without a byline with a very forceful and badly written statement about a very obscure policy. Another newspaper would carry the same type of article from a competing faction of technocrats calling for a different obscure policy.

Then the issue would vanish from the public spotlight.

What is unfortunate is that in the past, Mexico used to pass far-reaching conservation initiatives because it was worth the positive international media exposure it received–and then those plans would be implemented (to some degree).

Now let’s hope that the Calderon administration is not cynical enough to have carried out a policy war internationally and use the international press to argue over competing proposals–one of which-the year-long moratorium–the government never intended to ever happen.

That would be a shame for sharks and for ocean health.

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