Dr. Lowe –
I wanted to thank you again for your excellent presentation last week at the Joslyn Center in Manhattan Beach. I know it was well received, and the information will help many of us with our “Behavioral modification” as you were saying. I also wanted to point out one other class of “Top predators” that you may have overlooked in your studies: Birds.
The Brown Pelican has made a tremendous comeback in the Southern California area since the 1960’s as well. I’m not sure the numbers, but I would guess there are roughly 100x as many now as there were back then. Cormorants too are quite numerous. The Seagulls are always around, it doesn’t seem to me they’ve changed much over the years. I figured maybe this would be an interesting side note to your studies though.
One other thing I noticed, is that the populations of animals in the bay increased somewhat in the years from the 1940’s to the 1990’s, but the real exponential growth on your charts seemed to happen when gill netting was restricted in the 3-mile coastal areas. Not sure if I remember that correctly or not… Cleaning up the bay has helped tremendously as well, I’m sure. I know the lessons learned in Lake Tahoe and places like that have helped down here as well. Perhaps the Sewage Treatment Engineers share methods and help each other with data and new technology. I think that was one of the largest concerns up around Tahoe in the 1950’s and 1960’s, and much of their technology was groundbreaking stuff designed to protect a precious resource.
The Hyperion plant in El Segundo is a pretty amazing place also. They capture enough natural gas (methane?) to power the City of El Segundo pretty much (via the Scattergood Steam Generating plant). Recently, they put in a new gas line from the Sewage plant to the Scattergood plant, it looks like they’re adding more generators as well. Pretty cool I thought. They also capture most of the solid waste in settling ponds and convert that to fertilizer. It’s not gross, it’s all sterilized and such.
Anyhow, I was also going to mention the reason I figured the Great White Sharks (GWS’s) are coming south towards Manhattan and Hermosa is because of the population growth in general (of the sharks). Overpopulation in one area, probably pushes the juveniles south. If they breed or bear their pups off Anacapa Island, or maybe they come in to the bay to actually pup, but that’s where they hang out off those Channel Islands, then the babies are probably born up that way in the northern part of the Santa Monica Bay (maybe even off Pt. Dume’). Then, they travel southwards looking for space. Just seems reasonable if there are as many up there in the Will Rogers State Beach area as you showed in that one photo.
Oh, and we saw a very small GWS pup on Saturday as well. Our group, since Steve Robles was attacked two weeks prior, had not been back in the water as a group. Several people were very anxious about the whole idea of getting back in, so we agreed not to go by the piers (to avoid the fishing lines) and then to swim in closer to shore, in case something happened. Well, when you swim in 6′ of water instead of 12′ you get to see the bottom the entire time. Every dark patch you see freaks you out, even though it’s just Sand Dollar beds (mainly). We found out about those a couple months back off the MB Pier. It was a very clear day, and we saw dark patches on the bottom and dove down to investigate them. They were beds of thousands upon thousands of Sand Dollars! It was amazing. So now we recognize them when we swim over them, but still, swimming over them again and again, and then sand, and then, somebody saw a very small GWS pup, as I said, a first year, perhaps a newborn, about 3.5′ in length. He swam away very quickly when he saw us, all I saw was sand kicked up from him swimming away very quickly. Definite GWS though – and that was in Hermosa Beach around 28th St.
So, needless to say, several people were freaked out and got out of the water. I just continued swimming after that but kept my eyes shut (mostly) when they were underwater. We all of us know – it was because the shark two weeks ago was on a fishing line and agitated that it attacked Steve – no doubt. But still, seeing another shark so soon after the one that got Steve was too unnerving for some folks. These are people who’ve swum the English Channel, and Steve himself swam the Catalina Channel you know. We’re not talking wimps here. But sharks, for whatever reason, just are too much to deal with. I’m just glad I’ve not seen one close up (yet). I’ve seen plenty of small sand sharks and such, and Sting Rays all over the place. Those are really the key I think, that very dense Sting Ray population out there. My guess is that’s a very staple food source for young GWS’s. They literally can probably gorge themselves on Sting Rays out there, we’ve seen them for years, sometimes whole schools of them swimming along underneath us as we swim from pier to pier.
The sharks? I think those baby sharks are usually much more afraid of us than we are of them. It’s just not normal to have one so agitated. We still aren’t sure whether we’ll be able to get Fish and Game to file charges against the fisherman. We’re trying. The Lifeguards found his tackle (most probably his) floating the next day off Manhattan Beach. Maybe you saw it? The leader line was about 1,500-2,000lb test stainless cable (more than 1/8″ and closer to 3/16″), and the hook was a 5″ hook (big enough gear for Marlin, or larger sharks). The line was supposedly Dyneema, which is very strong, and potentially very abrasive. One of our group swam over the line, I’m kind of surprised he wasn’t hurt by it. Quick reactions I suppose. The kicker is there was a float on the line. Normally you don’t go fishing for rays with a float on your line.
Sting Rays are normally bottom feeders only I thought. Sharks, they’ll attack anything if they’re hungry! And fish, all fish are curious. I was surprised to see the hook had some pink lure material on it. But perhaps he’d found that’s what works best. He is the same guy who caught a GWS off the MB Pier last year supposedly. Last year, he apparently reeled it in all the way to the pier before letting it go. He brings a net with him and everything. I’ve talked with the guy before, I go down to the pier frequently – my wife and I do. We’ve talked with many fishermen down there, except the ones who don’t speak English. But this guy was down there pretty often. My opinion, and generally many agree, is that he purposely went down to catch a GWS that day, and that’s strictly illegal (and now we know it’s very dangerous).
Anyhow, again, we sure appreciated your coming down and giving us that lecture. Is any of that material available online? It’s very interesting stuff, I’d like to take another look (or 3) at it.