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toward the telltale gas bladders on the surface near the
shoreline. “We restored that one in 2006 and the ones
adjacent to it in 2007 and 2008. That one around the
corner was done in 2009.”
Looking at the large swath of affected coastline
(nearly 4 linear miles), we are stunned. This is bigger
than we could have imagined.
Although it’s pretty well known that the beauty
of kelp forests can match that of the most exotic
warm-water destinations, underneath the superlatives
is a less well-known similarity: These temperate
ecosystems are in just as much peril as coral reefs.
The nearshore kelp forests in some parts of southern
California have experienced up to 75-percent declines
in the last century, a multifactorial crisis brought about
by storms, the El Niño phenomenon, pollution, urban
water runoff in populous areas and predation.
Key among kelp predators is the purple sea urchin
(Strongylocentrotus purpuratus). While larger urchins such
as the red sea urchin (Strongylocentrotus franciscanus) are
valuable to commercial fishermen because of their large
gonads (the edible portion of the urchin), the far smaller
purple sea urchins have miniscule gonads and are not
harvested commercially. This combined with the hunting-
and fishing-related declines of natural urchin predators
such as sea otters, spiny lobsters and California sheepheads
set the stage for disaster. Purple sea urchins, which number
approximately two per square meter in healthy kelp
ecosystems, have overpopulated the kelp forests in some
areas, devouring the kelp holdfasts and creating bleak
urchin barrens in their wake.
The terminology is absolutely accurate: Urchin
barrens can hold as many as 70 purple urchins per
square meter — and little else. Red sea urchins in such
areas are much smaller than those in healthier marine
environments, producing gonads that are approximately
one-fifth the normal size. The barrens are valuable to
no one: Divers don’t have kelp forests, fishermen can’t
find robust urchins to harvest, and the other marine life
that normally populates kelp ecosystems is pushed out.
Even in places where water quality has improved, the
barrens remain, which indicates that once purple urchins
overpopulate an area, the kelp is doomed.
Academic researchers and conservation organizations
have been grappling with this issue for decades. Urchin
removal and relocation showed promise in small areas,
demonstrating that the kelp could replenish rapidly if
the purple urchin numbers were diminished. However,
the process was laborious and dangerous for divers,
and the weight limits of the boats restricted daily yields.
Leaders ultimately decided to cull rather than remove
the purple urchins in badly affected areas. The culling
method is unsophisticated, using simple geologists’
picks to crush the urchins’ endoskeletons, but the
results are undeniable. In recent years the effort has
forged unlikely close partnerships among conservation
organizations, divers and commercial fishermen, all
united toward the goal of rebuilding the kelp forests.
Ultimately, The Bay Foundation hopes to restore 150
acres, an area the size of a small college campus.
As we pull up to the dive site, we count four boats
nearby, all owned by commercial fishermen working
to help cull the purple urchins. Ford waves to the
fishermen and talks to us about some of the recent
successes. “For a long time people thought that
smashing urchins would induce a spawning event, but
research has never supported the theory — it’s just a
myth. And do you see that?” he asks, gesturing to some
kelp at the surface. “We just cleared that area of purple
urchins four months ago, and the kelp is already
starting to come back. It’s incredible to see. It grows so
fast that in a few areas the fishermen have even been
able to harvest red urchins again.”
He explains to us the goals for today, which include
evaluating the perimeter of the new kelp growth and
counting the urchins in the barrens. On the bottom, we
slowly examine the edge of the kelp forest, noting clusters
of large red urchins and sea stars on the rocks. Delicate
strands of new kelp have taken hold on the sea floor, and
garibaldi and surfperch weave lazily through the leaves.
Only 40 feet away kelp is absent, and the pale rocks
are covered with purple urchins. The difference is
frightening. We watch in gratified awe as the divers
begin moving in an automated and perfectly tuned
fashion. They set a central marker line, then each diver
runs a 100-foot-long perpendicular transect line. Once
the lines are set the divers begin counting the purple sea
urchins in their area, then they pull up their line and
run a new transect. When we have reached our agreed-
upon bottom time, we ascend, and Ford collects the
divers’ urchin survey numbers so they can determine
which areas are most appropriate for culling.
Our work for the day complete, the captain starts
the motor, and we head back to the harbor, examining
the nearshore water for areas that appear to lack kelp
growth. There are many, but the mood is optimistic as
the divers excitedly compare the marine life they saw in
the areas of newly reestablished kelp. As we pull up to
the dock, Ford turns to us and says, “I have seen some
incredible life come back to these areas: giant black sea
bass, harbor seals and even a school of baby molas once;
an excellent reforestation effort, I think.”
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