Counting Grunion a year after the spill

Last year’s Refugio Oil Spill came at a time when grunion were spawning on the oil-covered sand. Now, scientists are looking at this year’s fish to see if there’s been any lasting effect

On a recent starry midnight, David Witting, a fish biologist at the National Oceanographic and Atmospheric Administration, was out counting grunion on Santa Barbara’s East Beach.

KCRW: Why are you out at Santa Barbara’s East Beach on a Sunday at midnight?

Grunion Run Refugio May 2015 Credit - David Witting
The “Grunion Run” at Refugio Beach, May 2015. Photo: David Witting

Witting: We’re out here to look for Grunion spawning activity. They spawn at the beach during high tides at night. During the oil spill last year, grunion were spawning. The timing of the spill was unfortunate because they were swimming up while the beaches were being exposed to the oil. So, we’re particularly interested in understanding how the oil affected the grunion. A year ago, we were out at midnight looking for grunion spawning and collecting eggs to look at quality and the condition of those eggs, and now a year later we’re doing the same thing at East Beach and Refugio Beach.

East Beach is 25 miles east of Refugio Beach. What data is important here?

This beach was not exposed to oil last year. We’re interested in seeing whether or not there’s a difference between this beach and Refugio beach in terms of the survival and hatchability of the eggs that we collect, and the level of spawning we see.

What did you see tonight?

Tonight we saw quite a lot of grunion spawning. The grunion surf up on the incoming tide and stay on the beach as the tide recedes. The females bury into the sand. The males then surround the female and release their sperm, which percolates into the sand and fertilizes the eggs. Then, the eggs actually sit high and dry on the beach for about two weeks until the next spring tide. When the water comes up, they hatch and the larvae move out into the ocean.

So in two weeks, biologists from the different agencies will come back to these beaches to find those eggs?

Yes, in two weeks we’ll go the areas where we saw spawning, collect clutches of eggs from the beach and bring them back to the lab. When it’s time for them to hatch we’ll  immerse them in water to make them believe the tide is coming in, and then count how many hatchlings we get from a given number of eggs. That’s a mark for the quality of the eggs and how well they survived.

Grunion egg sampling Refugio 2015 Credit - Karen Martin
Biologists collect Grunion egg samples at Refugio Beach in 2015, just after the oil spill. Photo: Karen Martin

 

All this data you’re compiling is going into a Natural Resource Damage Assessment (NRDA), which began after the oil spill. How will the grunion data be incorporated into the NRDA?

We hope to come up with an estimate of how much loss occurred: how many animals were killed, how many eggs were killed, how many hundred yards of grunion habitat were affected… some kind of metric we can use to measure the injury against a restoration project that would recover those injuries in the future. We can also use that data as a proxy for how the oil affects hatch rates in fish in general.

To learn more about the NRDA, click here.

KCRW wants to answer your questions about the oil spill

One year later, are there still things you want to know about the oil spill? Ask your questions here. We’ll investigate.