Channel Islands: Unhealthy environment

[Jak Crow]

I dived the Channel Islands last weekend, and while it was great to dive a different location, it's clear that the massive sea urchin infestation is a bad situation for the islands. The biggest thing I saw was almost a complete lack of vegetation, there was almost no kelp, and the rocks were bare of even algae. The urchins have stripped all the plant life. There's hardly any large invertebrates. It was all urchins, brittle stars, and hand sized anemones. The only lobsters I saw turned out to be stuck in an abandoned trap. The environment seems completely out of whack.

 

[TSandM]

It depends on the parts of the islands where the boat drops you. On Anacapa, there are sections that have been marine preserves for over 20 years, and they are incredibly lush. Beautiful stands of kelp shelter hundreds of fish, and the holdfasts provide habitat for many nudibranchs and other creatures. On the sides of the islands where fishing is allowed, the fish that eat the urchins have been decimated, and the urchins eat the kelp holdfasts . . . so you end up with bare rock and urchins. Seeing the contrast between the two areas was the first time that the concept of marine damage from human activity really hit me.

 

[Jak Crow]

We dove one spot at Anacapa where there's a sea lion colony and some arch swim thru, and Hungry Man's cove at Santa Cruz. While Anacapa had more fish, both locations were stripped bare

 

[fisheater]

Overfishing has led to those urchin barrens. Without predation, the urchins eat up all the kelp holdfasts. When we kill / pollute the predators, the system goes out of whack.


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[Jak Crow]

I know what causing this. I'm making an observation. The urchins are stripping the plantlife bare, there's not enough predators to eat them, thus the urchin population has exploded.

 

[bperc]

You should go on a trip to Santa Rosa or San Miguel. You will see a marked difference between these islands and Anacapa. At Anacapa, if you had dove the landing or the far west end, you would have seen lots of healthy kelp.

 

[Jak Crow]

Hopefully that will be the case in June.

 

[drbill]

As TSandM and others have pointed out, what you see is highly dependent on where in the "Channel Islands" you dive. By the way, there are eight of them separated by distances as large as 100 miles. The removal of sea otters by the mid 1800s is a major factor why sea urchins are thriving. Add to that the harvest of sheephead and lobster, predators on the sea urchin, and you have a recipe for eco-disaster. Here on Catalina, at least in the protected areas, you have fairly abundant lobster and sheephead that keep the urchins hiding in their holes and feeding only on drift kelp.

 

[Jeff Shaw]

Otters have been sighted at point Fermin and Vincente.

They are back!!!!!

 

[H2Ocean]

Over fished? This being semi close range for line fishermen, and spearfishermen, and mollusc, crustacean collecting divers isn't difficult to predict. However many years of closures taking place on the front side of Anacapa has pushed all the pressure to the backside. There's the front side and the backside. According to MPA's success in seeding areas this close together, doesn't seem to be working at all. The backside may get pelagics cruising by at seasonal cycles following what they feed on, sardines, mackerel ect., but residential species are way far and few between. Like the new MPA's in Palos Verdes, Point Dume, yea sure they're going to slowly develop while the neighboring shorelines get double pressure.