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Tracking Spiny Lobsters in San Diego Bay

Audio

Aired 8/13/09

A research team led by a marine ecologist at San Diego State University is studying spiny lobsters in San Diego Bay. They're trying to determine how many live there. I joined the team as they checked metal traps in the bay.

A research team led by a marine ecologist at San Diego State University is studying spiny lobsters in San Diego Bay. They're trying to determine how many live there. I joined the team as they checked metal traps in the bay.

We meet SDSU professor Kevin Hovel and California Fish and Game marine biologist Doug Neilson at a Shelter Island boat ramp.

Hovel, also a marine biologist, says the California Spiny Lobster does not have claws, otherwise it looks no different from other lobsters. But much is unknown about the creatures.

"Well, when I arrived at SDSU in 2001, I learned that very little research had ever been done on California Spiny Lobster," Hovel said. "And we lacked basic information about population size, where lobsters come from, ultimately where they recruit from, the habitats that they prefer, different parts of their life history."

So, he set up a research program to answer those questions. The two year project is funded by the Port of San Diego.

Marine biologist Doug Neilson explained the state Fish and Game Department's role in the study.

"The lobster's been identified as an important species by the department," Neilson said. "And this research is actually been put together to help us develop a stock assessment."

Travis Buck (left) and Kevin Hovel (right) measure lobsters from one of 20 traps in San Diego Bay.
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Above: Travis Buck (left) and Kevin Hovel (right) measure lobsters from one of 20 traps in San Diego Bay.

He said the Spiny Lobster's range on the west coast stretches from Central Mexico to Monterey Bay. But commercial fishing in this country is only allowed from the Mexican border to Point Conception.

Neilson said one area in San Diego, Point Loma, makes up about 20 percent of the total catch.

He said during the 2007-2008 season the spiny lobsters caught around Point Loma had a value of $1.58 million.

"From the viewpoint of the commercial fishery, San Diego is very important," Neilson said. "We also tend to have some of the highest, if not the highest, recreational catch here as well."

Unfortunately, Neilson has a broken foot and won't be joining us on the trip to check the 20 traps scattered throughout the bay. So, Hovel, and two other Fish and Game Department employees, Travis Buck and Bob Reed, climb into the small boat.

One of 20 traps in San Diego Bay used for spiny lobster research.
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Above: One of 20 traps in San Diego Bay used for spiny lobster research.

The first couple of stops no buoys are spotted. High tide has put them too deep underwater to find or the lines might have been severed by one of the hundreds of boats that traverse the bay each day.

While we head west to the next site, toward the mouth of the bay, Hovel tells us he's using sound to track the lobsters.

"So we have, actually underwater right now on heavy anchors, receivers or hydrophones that pick up signals from lobsters we've tagged and store that in memory," Hovel said. "So we come out about once a month, we retrieve our stations underwater, download the data and we can look and see where these lobsters are moving throughout the bay."

He said some lobsters hang around the same underwater neighborhood. The Coronado Bridge area is one example. But Hovel said in areas closer to the mouth of the bay, lobsters journey to the Point Loma kelp forest and back to the bay.

"We don't have enough data yet to talk about exactly how much exchange we think there is between the two places, Point Loma and the Bay," Hovel said. "But we're starting to see data that suggests that there is quite a lot of movement between the two areas."

Hovel said it's not known whether the Bay is the source of lobsters for the kelp forest population. He hopes the acoustic tracking can provide an answer.

We've reached our first trap, a bit southwest of Shelter Island.

"So we pull up a trap, the first thing we look for fish is bycatch, which is if we caught some other species in the traps and sometimes we catch some rock crabs, stingrays, some fish like bass," Hovel said. "Those are put over the side alive. Then we look at our lobsters, we process them one by one. We record the sex of the lobster, the length of the lobster, the size."

Travis Buck measured the lobsters and describes their characteristics, "female, unplastered, new hard shell..."

Plastered, unplastered? Hovel said during mating the male deposits a sperm pack on the underside of the female. If that's present they call it "plastered."

This female spiny lobster is carrying eggs (bright orange).
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Above: This female spiny lobster is carrying eggs (bright orange).

This female spiny lobster is carrying eggs, which he says is not typical for this time of year.

Hovel said his findings about lobster behavior and habitat use can help in future marine reserve planning.

He'll continue the trapping and search for recaptures - lobsters they've tagged - until the commercial lobster season begins.

Hovel wants commercial or recreational fishermen who find some of the tagged lobsters to contact him. He says the information will help figure out lobster movements.

He hopes to continue the research on a smaller scale next summer. Hovel says there are more mysteries to solve, including finding out more about the spiny lobster's nocturnal movements in the bay.

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