Yesterday I had some time to kill before getting a COVID test, and, as usual, wandered down to the ocean. This time I was at Seacliff State Beach. It was pretty crowded, so I walked onto the pier to see if the fishermen were having any luck. They weren't, really. One man kept catching jack silversides (Atherinopsis californiensis) that were too small to keep. There was a lot of banter about sharks and bait and crabs, but what I witnessed yesterday confirms my hypothesis that a lot of what people call "fishing" is merely an excuse to get outside for a few hours. And there is absolutely nothing wrong with that.
As for me, I have nowhere near enough patience to make a decent fisherman. I did, however keep myself amused by eavesdropping on their conversations and writing snippets in my nature journal. I did also find myself mesmerized by the anchovies. Watch for yourself.
Like sardines, anchovies are planktivorous filter feeders. If you watch the video again and can focus on an individual fish for a while, you'll see that as it swims forward, the front end becomes white and bulbous for a few seconds. That's sunlight reflecting off the fish's jaws. Anchovies have metallic silver coloring, which is a defense against predators. For fish that live in surface waters that are brightly lit, all of those glinting flashes of light make it difficult for a predator to zero in on a single fish to pursue. There is safety in numbers, and for anchovies the silvery coloring combined with schooling behavior means that if a predator manages to catch some of the fish in the baitball, most will avoid being eaten. This works against predators such as larger fish, squid, and birds, which generally capture one or a few fish at a time. But if the predator happens to be a humpback whale, which is capable of engulfing the entire school, then the anchovies are SOL. Think about it, though. For any anchovy, the probability of encountering a larger fish, squid, or bird is much higher than encountering a humpback or blue whale. Thus the selective advantage of schooling!
Okay, now back to the feeding. Anchovies have really long jaws for their size and can, like snakes, open their mouths very wide. This allows them to filter as much water as possible as they swim. Food, mostly plankton, is caught on the gill rakers, which are bony or cartilaginous structures projecting forward (i.e., towards the mouth) from the gill arches. Some fishes' gill rakers are nothing more than short nubs. Filter feeding fishes such as anchovies have long thin gill rakers. Water enters the mouth as the fish swims forward, and plankton is caught on the array of gill rakers. The water then passes over the gill filaments, where respiratory exchange occurs, and then out from underneath the operculum. Anchovies cannot suck water into their mouths, and thus can feed only while swimming forward, or ramming water into the mouth. This is a type of feeding called ram feeding.
These anchovies were very close to shore. They were feeding, so obviously there was plankton in the water. I haven't done a plankton tow in a while, as I generally assume that fall/winter plankton isn't as interesting as spring/summer plankton. However, given the presence of feeding anchovies inshore, it might be time to test that assumption.
Sometimes even a well-known site can present a surprise. Here's an example. Yesterday I went up to Davenport to scope things out and see how the algae were doing. This is the time of year that they start growing back after the winter senescence. I also took my nature journal along, hoping to find a spot to sit and draw for a while.
The first thing I noticed was the amount of sand on the beach. Strong winter storms usually carve sand off the beaches, making them steeper. And during the calmer months of summer the beaches are flatter and less steep. Yesterday the beach was very thick and flat. It makes trudging across the sand in hip boots much easier!
The accumulation of sand meant that I could walk around the first point. Unless the tide is extremely low, such as we see around the solstices, the water is too deep for that. But yesterday I walked around it, and it wasn't until I got to the other side that it occurred to me that: (1) hey, I walked around the point; and (2) I could do that only because there was so much sand. See, a thick beach with a lot of sand makes a mediocre low tide feel lower because the water isn't as deep as it would be if the beach were thinner. When the tide isn't low enough for me to walk around the point, I have to clamber down a cliff. The cliff height varies depending on how much sand has built up, obviously, but is about head height for me. Getting down usually involves scooting on my butt and hoping my feet land on something that isn't slippery. As with most climbing, up is easier and less scary than down.
It's hard to imagine the amount of sand there was yesterday. Look at this picture.
See how the rocks in the foreground end? Usually that's the edge of the cliff. Yesterday I could have just taken a tiny step off the top of the cliff onto sand. That's over 1.5 meters of sand in that one spot! If the couple in the background were visiting this area for the first time, they'd have no idea of the conditions that made it so easy for them to get out onto the reef.
There was a lot of sand in the channels between rocks, too.
Normally those channels are deeper. You can see that some anemones were able to reach to the surface of the sand, but many more are buried, along with any other critters and algae unfortunate enough to be attached to the lower vertical surfaces. And while some of them will either suffocate or be scoured off as the sand washes away, many will survive and be ready to get on with life.
The second surprise of the day was a bright orange object. What I could see of it was about as big as my thumb, and at first I thought it was a nudibranch. Then when I crept closer for a better look, what popped into my head was "snailfish". Which was an odd thing, because I'd never seen a snailfish before. But something about the creature's posture looked somehow familiar.
Fortunately I had the presence of mind to take photos before trying to draw this little fish, because this is all I had time to get:
When I spooked the critter it took off really fast, confirming that it was no nudibranch. It was, indeed, a snailfish! It came to rest in a small hole in a rock, from where it looked out at me.
The snailfishes are a very poorly studied group. As a group they are related to the sculpins. There are snailfishes throughout the northern temperate and polar regions, from the intertidal to the deep sea. iNaturalist shows 43 observations of L. florae, eight of which are in California. Before yesterday, none had been recorded at Davenport Landing.
So there you have it, a snailfish! We don't know much about any of the snailfish species, even the intertidal ones. They apparently have pelvic fins modified to from a sucker, similar to the clingfishes, but I didn't have a chance to examine this specimen closely enough to confirm that. I don't know why they are called snailfishes, either. They're not snail-shaped at all.
Now, about that thing up there where I said "snailfish" came to mind even though I'd never seen one before. That happens quite a bit—a name will jump into my head before I've had a chance to think about it. Sometimes I'm wrong, but often I'm right. I know I hadn't seen a live snailfish before, but obviously I'd seen photos of them or I wouldn't have been able to recognize this orange creature as being one. It's fascinating how the brain forms search images, isn't it?
The intertidal sculpins are delightful little fish with lots of personality. They're really fun to watch, if you have the patience to sit still for a while and let them do their thing. A sculpin's best defense is to not be seen, so their first instinct is to freeze where they are. Then, if a perceived threat proves to be truly frightening, they'll scoot off into hiding. They can also change the color of their skin, either to enhance camouflage or communicate with each other.
Around here we have a handful of sculpin species flitting around in our tidepools. Sculpins can be tricky to identify even if you have the fish in hand--many of the meristics (things you count, such as hard spines and soft rays in the dorsal fin, or the number of scales in the lateral line) used to distinguish species actually overlap quite a lot between species. The fishes' ability to change color means that skin coloration isn't a very reliable trait. When I was in grad school there was another student in my department who was studying the intertidal sculpins, and she told me that most of the ones we see commonly are either woolly sculpins (Clinocottus analis) or fluffy sculpins (Oligocottus snyderi). I've developed a sort of gut feeling for the gestalt of these species, but I'm not always 100% certain of my identifications.
Anyway, back to the camouflaged sculpins. The ability to change the color of the skin means that sculpins can match their backgrounds, which comes in very handy when there isn't anything to hide behind. Since the environment is rarely uniformly colored, sculpins tend to have mottled skin. Some can be banded, looking like Oreo cookies. The fish in this photo lives in a pool with a granite bottom. The rock contains large quartz crystals and is colonized by tufty bits of mostly red algae. There is enough wave surge for these fist-sized rocks to get tumbled about, which prevents larger macroalgae from colonizing them.
Other shallow pools higher up in the intertidal at Asilomar have a different type of rocky bottom. The rocks lining the bottom of these pools are whitish pebbles that are small enough to be tossed up higher onto the beach. I don't know whether or not these pebbles have the same mineral content as the larger rocks lower in the intertidal, but they do have quartz crystals. The pebbles are white. So, as you may have guessed, are the sculpins!
Other intertidal locations have different color schemes. On the reef to the south of Davenport Landing Beach, you will see a lot of coralline algae. Some pools are overwhelmingly pink because of these algae. Bossiella sp. is a common coralline alga at this location.
What color do you think the sculpins are in these pools?
Give yourself a congratulatory pat on the back if you said "pink"!
Sculpins aren't the only animals to blend in with coralline algae. Some crustaceans are remarkably adept at hiding in plain sight by merging into the background. Unlike the various decorator crabs, which tuck bits and pieces of the environment onto their exoskeletons, isopods hide by matching color.
Turning over algae and finding hidden creatures like these is always fun. For example, I saw these isopods at Pescadero this past summer. See how beautifully camouflaged they are?
Sometimes, when you're not looking for anything in particular, you end up finding something really cool. Last weekend I met up with students in the Cabrillo College Natural History Club for a tidepool excursion up at Pigeon Point. We were south of the point at Whaler's Cove, where a staircase makes for comparatively easy access to the intertidal.
It's fun taking students to the intertidal because I enjoy helping them develop search images for things they've never seen before. There really is so much to see, and most of it goes unnoticed by the casual visitor. Often we are reminded to "reach for the stars," when it is equally important to examine what's going on at the level of your feet. That's the only way you can see things like this chiton:
Mopalia muscosa is one of my favorite chitons. It is pretty common up and down the California coast. However, like most chitons it is not very conspicuous--it tends to be encrusted with algae! This individual is exuberantly covered with coralline and other red algae and has itself become a (slowly) walking bit of intertidal habitat. It is not unusual to see small snails, crustaceans, and worms living among the foliage carried around by a chiton. Other species can carry around some algae, but M. muscosa seems to be the most highly decorated chiton around here. I showed this one to some of the students, who then proceeded to find several others. A search image is a great thing to carry around!
Compared to the rocky intertidal, a sandy habitat can be a difficult place to live. Sand is inherently unstable, getting sloshed to and fro with the tides. Because of this instability there is nothing for holdfasts to grab, so there are many fewer algae for animals to eat and hide in. Most of the life at a sandy beach occurs below the surface of the sand, and is thus invisible to anyone who doesn't want to dig. There's a beach at Whaler's Cove where I've found burrowing olive snails (Olivella biplicata) plowing along just below the surface. I wanted to show them to the students, so I waded in and rooted around. I did find Olivella, but I also found a burrowing shrimp. I think it's a species of Crangon.
Now that is some damn fine camouflage! If the shrimp didn't cast its own shadow, it would be invisible. Even so, it was clearly uneasy sitting on the surface like that. I had only a few seconds to shove the camera in the water and snap a quick photo before the shrimp wriggled its way beneath the sand again.
As I've said before, observation takes practice and patience. To look at something doesn't mean you truly see it. That's why it is so important to slow down and let your attention progress at the pace of the phenomenon you're observing. If the only things that catch your eye are the ones that flit about, then I can guarantee you will never find a chiton in the intertidal. And wouldn't that be a sad thing?
We usually think of sea stars as the colorful animals that stick to rocks in the intertidal. You know, animals like Pisaster ochraceus (ochre star) and Patiria miniata (bat star). I see these animals all the time in the intertidal, and if you're a regular reader of this blog you've probably seen the photos that I post here. Given how prominent P. ochraceus and P. miniata can be in the rocky intertidal, it may be a bit of a surprise to learn that not all sea stars live on rocks. In fact, some can't even really stick to a rock.
This morning I was meandering through the Seymour Center when I stopped at a recently refurbished tank. The new inhabitants are a couple of curlfin sole (Pleuronichthyes decurrens) and their secretive and strange roommate. Here's one of the flat fish:
The other fish was hiding up against the wall in one of the back corners and didn't come down until it was feeding time.
The secretive roommate was all but invisible. Here's a photo. Ignore the fish's tail. Do you see anybody else?
Fortunately for all of the tank's inhabitants, feeding time was just around the corner. I knew what would happen, so I stuck my phone on the glass and recorded some video. Keep an eye on the upper left-hand corner. Watching the fish eat is entertaining, too. Just how do they manage with those tiny sideways mouths?
It's not the greatest bit of video, but did you see what happened? That creature emerging from the sand is Astropecten armatus, a sea star that lives in sand. And did you notice how fast it moves? Most of the time it is buried under the sand and usually comes out only to grab food. Every once in a while I'll find it on one of the walls but most of the time it is essentially invisible to human viewers on the other side of the glass.
All spread out, this Astropecten is probably a little smaller than my hand. It has a smooth-ish aboral (i.e., top) surface, lacking the spiny protuberances that Pisaster has. The texture of the aboral surface is similar to that of the bat star, Patiria miniata. The species epithet, armatus, means 'armored' and refers to the row of marginal plates along the perimeter of the body. These plates bear a row of spines that point up and another row that point down. Astropecten is unusual among sea stars for having suckerless tube feet. Its tube feet are pointed, and instead of being super grippy, work to push sand around so the animal can sort of bulldoze its way along. As always, form follows function!
In the wild, A. armatus lives on sandy flats, rarely exposed even at low tide. One of its favorite prey items is the olive snail, Olivella biplicata. Imagine this life-and-death encounter taking place below the surface of the sand: Olivella is burrowing through the sand, minding its own business and unaware that Astropecten is following the slime trail it (Olivella) left behind. Astropecten catches up to Olivella, shoves a couple of arms into the sand around Olivella, engulfs the snail, and swallows it whole. Eventually an empty Olivella shell is spat out. Incidentally, many small hermit crabs, especially Pagurus hirsutiusculus and juveniles of other Pagurus species, live in Olivella shells. I've often wondered why there are so many empty but intact olive snail shells for the hermit crabs to find, and now suppose that Astropecten's method of feeding might have something to do with it.
Interesting star, this Astropecten. I'm really happy that it is on exhibit again, because even most visitors will never see it, watching it come out to feed is always fun.
Professor Emeritus John Pearse has been monitoring intertidal areas in the Monterey Bay region since the early 1970s. Here on the north end of Monterey Bay, he set up two research sites: Opal Cliffs in 1972 and Soquel Point in 1970. These sites are separated by about 975 meters (3200 feet) as the gull flies. My understanding is that the original motivation for studying these sites was to compare the biota at Soquel Point, which had a sewage outfall at the time, with that at Opal Cliffs, which did not. The sewer discharge was relocated in 1976, and the project has now morphed into a study of long-term recovery at the two sites. In the decades since, John has led students, former students, and community members to conduct Critter Counts at these sites during one of the mid-year low tides. Soquel Point is visited on the first day, and Opal Cliffs is visited the following day. When John founded the LiMPETS rocky intertidal monitoring program for teachers and students in the 1990s, the Soquel Point and Opal Cliffs locations were incorporated into the LiMPETS regime.
I have participated in the annual Critter Counts off and on through the years--around here, one takes any chance one gets to venture into the intertidal with John Pearse! I usually have my own plans for this series of low tides, but try to make at least one of the Critter Count mornings. This year (2019) the first 16 days of June have been designated the official time frame for Snapshot Cal Coast, giving marine biologists and marine aficionados an excuse to go to the ocean and make observations for iNaturalist. I had set myself the goal of submitting observations for every day of Snapshot Cal Coast, knowing that every day this week would be devoted to morning low tides. That's the easy part. Next week, when we lose the minus tides, I'll do other things, like look at plankton or photograph seabirds. My plans for this week included a trip to Franklin Point on Wednesday and doing the Critter Count at Opal Cliffs on Thursday. John asked me if I could also do the Wednesday Critter Count. As I alluded above, I'm not going to say "No" to an invitation like that! So I didn't make it out to Franklin Point to document the staurozoans for Snapshot Cal Coast, but that's okay. Some plans are meant to be changed.
Day 1- Soquel Point
Both the Soquel Point and Opal Cliffs sites are flat benches with little vertical topography. The benches are separated by channels that retain water as the tide recedes. The Soquel Point site has deeper channels that make the benches more like islands than connected platforms.
The benches are pretty easy to get around on, as long as you remember that surfgrass (Phyllospadix spp.) is treacherous stuff. The long leaves are slippery and tend to cover pitfalls like unexpected deepish holes. The difficulty at this site is that it takes very little rise in the tide for water in the channels to get deep. You can be working along for a while, then get up to leave and realize that you're surrounded by water. Keeping that caveat in mind, we worked fast.
For the Critter Count we keep tabs on only a subset of the organisms in the intertidal. The quadrat defines our sample; we put it down at randomly determined coordinates within a permanent study area. Some animals, such as anemones, turban snails, and hermit crabs, are counted individually. For other organisms (surfgrass, algae, Phragmatopoma) we count how many of the 25 small squares they appear in. Some quadrats are pretty easy and take little time; others, such as ones that are placed over channels or pools, are more difficult and take much longer.
Because of the rising tide I didn't have a lot of time to look around and take photos of the critters we were counting. Linda and I were worried about finishing our quadrats before the channels got deep enough to flood our boots. But here are two of the things that caught my eye:
Day 2 - Opal Cliffs
The next day we met a half hour later and a few blocks down the road. The Opal Cliffs site is a popular spot with surfers: If you've ever heard of the surf spot Pleasure Point or seen the movie Chasing Mavericks, you know about this location. As far as the intertidal goes, it's an easy site to study. The channels aren't as deep as those at Soquel Point so we could work at a more leisurely pace. As the rest of the group hauled up all the gear and left to get on with their day, I stayed behind to take pictures for my iNaturalist observations. The sky was overcast, making for good picture-taking conditions. I'll just add a gallery of photos to share with you.
There is one critter that deserve more attention here, because I'd never seen one in the intertidal before. Two of the guys finished their quadrats early and started flipping over rocks to look for an octopus. To my knowledge they didn't find any octopuses, but they did find a bizarre fish. At first it didn't look like much:
Hannah, the LiMPETS coordinator for Monterey and Santa Cruz Counties, recognized the fish right away and grabbed it by the body. She held it up so we could see the ventral surface.
This is a plainfin midshipman. These are nearshore fish found in the Eastern Pacific from Alaska to southern Baja. Clearly, I need to spend more time flipping over big rocks! The midshipman is a noctural fish, resting in the sand during the day and venturing out to feed at night. Like many nocturnal animals, it is bioluminescent--those white dots on the fish's belly in the photo above are photophores. Midshipmen are heavily decorated with photophores all over the body. This bioluminescence is used both for predator avoidance and mate choice.
The lives of plainfin midshipmen and human beings intersect in the wee hours of the morning. During breeding season these fish sing or grunt. They breed in intertidal areas, where females lay eggs in nests that are subsequently guarded by males. Both sexes make noise, but it's the breeding males that are the noisiest. They grunt and growl at each other when fighting for territory, but hum when courting females. Females typically grunt only when in conflict with others. People who live in houseboats on the water in Sausalito have reported strange sounds emanating from the water beneath them, only to learn that what they hear are the love and fight songs of fish!
I've always been a fan of the intertidal fishes. They seem to have a lot of personality. Plus, any aquatic animal that lives where the water could dry up once or twice a day deserves my admiration. Of course, all of the invertebrates also fall into this category, which may explain why I find them so fascinating.
After we admired the midshipman's photophores and impressive teeth, we put it back in the sand and replaced the rock on top of it. It was probably happy to get back to snoozing away the next few hours before the tide returned. I don't know how I never realized the midshipmen were in the intertidal. I think I just assumed that they were in deeper water. Now that I know where to find them, I will spend more time flipping over rocks. And who knows, maybe I'll even find an octopus!
I don't remember what I expected from my first view of Death Valley. I knew it to contain the lowest elevation (Badwater Basin, 282 feet below sea level) in North America and that it was really hot in the summer, but beyond that I had no clue. [Aside: the marine biologist in me wondered which metric 'sea level' refers to, and decided that it was probably mean low low water] I certainly wasn't prepared for the spectacular geology, although in retrospect I shouldn't have been so surprised. We didn't see much in the way of wildflowers, for one reason that I didn't anticipate but which makes perfect sense: although Death Valley received enough winter rain to form a temporary lake in the valley, there hadn't been enough rain in the autumn to trigger a superbloom. That was fine by me, as I'd already seen many wildflowers on the trip and was happy to be fascinated by the geology.
There are at least two small waterways in Death Valley National Park that are called Salt Creek. The first one we encountered was in the hills above the valley, and is a rare desert riparian area.
This Salt Creek is fed by several small natural springs and runoff from the scant winter rains. As you can imagine, this oasis is a vital necessity for wildlife. Animals as large as desert bighorn sheep and as small as quail depend on this water source, which may contain the only somewhat reliable drinking water for 15 square miles.
As I mentioned, for me, Death Valley ended up being all about geology. I knew the valley floor was where we would find the lowest elevation in North America: Badwater Basin, 282 feet (86 m) below sea level. And now I can say that I've seen it, but there isn't much to see except the line of other tourists hiking out across the salt flats to take photos of the sign. So as a must-see destination, Badwater was interesting but not compelling. We skipped it.
But the rocks! The hills surrounding the valley, especially those on the eastern side, are spectacular. My favorite area was a range of hills called Artists Palette, viewable from a gorgeous 1-way loop drive off of Highway 190. When I saw the name on the map I thought it must be a place either a location where painters found minerals they could use to make paint, or a scene they liked to paint. Fortunately we decided to take the detour that meanders through the formations, so we could get off the main road and just gawk. I had never seen anything like this scenery. I know enough geology to understand that minerals come in all sorts of colors, but had not seen them together like this in a natural state. My eye is always drawn to colors, and I couldn't stop goggling at the variety of umbers, ochres, greens, and pinks, all jumbled together like some giant's ice cream sundae.
It's impossible to capture the grandeur of this landscape in a photograph. You really have to see Artists Palette in person to appreciate the vibrant colors of these hills. If you ever go to Death Valley , take the time to drive this little loop. You won't regret it!
Across the valley to the west, are the Panamint mountains. Beyond them, the Owens Valley and the mighty Sierra Nevada!
So those are the rocks. The fish were in the second Salt Creek that we encountered, about 20 miles north of the Artists Drive loop. This Salt Creek is one of the remnant small bodies of water left after Lake Manly dries up. Lake Manly is a temporary lake that occasionally forms in Badwater Basin after unusual heavy rains. Most of the time, though, Badwater Basin is dry except for some small creeks. Salt Creek generally flows from north to south down the valley and eventually disappears into the sand.
Salt Creek is inhabited by a little pupfish, Cyprinidon salinus salinus, that looks like and is about the size of a guppy. Well, maybe it's a little bigger than a guppy. Populations of pupfish inhabit several creeks scattered over the desert across California and Nevada. Over time they have evolved into 10 genetically distinct species and subspecies, each adapted to the nuances of its particular stream. Two of the 10 have gone extinct in historic times. The Salt Creek pupfish, C. salinus salinus, is endangered, due to the ephemeral nature and fragility of its environment.
They are called 'pupfish' because they appear to be playing like puppies. Plus, they are very cute. But life as a fish in one of the driest places on the planet is a tough gig. Pupfish live short, intense lives, growing to adulthood and breeding in the span of a single year.
Salt Creek pupfish (Cyprinidon salinus salinus) in Death Valley
As you can see, the creek is hardly deep enough for these little fish to swim. Pupfish exhibit the sexual dimorphism common in fishes--females are rather drab and nondescript, while males are more colorful. The behavior that was described as playful, earning the fish the moniker 'pupfish', is really all about the business of living. Males are territorial, defending a spot against other males. When a female chooses to spawn with a male, she enters his territory. Then the two of them perform a short, wiggling dance, and spawn together.
From the perspective of an evolutionary biologist, the isolated pupfish populations are fascinating. Each waterway inhabited by pupfish is an independent 'island' in a very real sense of the word. The fish cannot migrate between streams, and thus populations evolve independently of each other. This is called allopatric speciation, from the Greek roots 'allo-' meaning 'other' and '-patry' meaning 'country'. Over time, each population becomes reproductively isolated from the others, so that even if Manly Lake were to become once again a permanent body of water, the fish from different streams would be unable to mate with each other.
Of all the things that manage to eke out a living in what is arguably one of the most inhospitable places in the world, these little fish are my favorite. Major props to them, for surviving where they do and making it look like fun!
About a year and a half ago I wrote about salmonids and beavers in the Lake Tahoe-Taylor Creek region, specifically about the non-native kokanee salmon (Oncorhynchus nerka) that were introduced into the region in the 1930s and 1940s as a game fish. Since then the kokanee has displaced the only salmonid native to the Tahoe basin, the Lahontan cutthroat trout (Oncorhynchus clarkii henshawi), to the point that the latter was thought to be extinct.
Fast forward several decades, and Professor Mary Peacock of the University of Nevada, Reno, has found some long-forgotten Lahontan cutthroats in tiny streams in eastern Nevada near the Utah border. This is Professor Peacock's story to tell, not mine, and you can read about it in this newspaper article. The article has a link to the actual scientific paper, published in an open-source avenue of the Royal Society. This truly is a resurrection story!
How does a group of people go about trying to save a federally endangered species? The answer, of course, depends on the species. However, you can bet your bottom dollar that it takes a tremendous effort over many years by many dedicated and talented people, all of whom know that in the end their work may not succeed. Ultimately it is society who decides whether or not such efforts, costly in both person hours and dollars, are worthwhile. After all, we are the people who vote elect the legislators to decide how our tax monies are spent. Not only that, but which of the many endangered species should we try to save? Can we save them all? Should we try to anyway? If not, then how do we decide which species are worth the effort? And what should we do about the species that are deemed unworthy?
Today I took my Ecology students to locations on Scott Creek and Big Creek in northern Santa Cruz County, where biologists are working on saving the coho salmon, Onchorhynchus kisutch. Our guide for the day was Erick, a fisheries biologist with the National Marine Fisheries Service (NMFS), a division of the National Oceanographic and Atmospheric Administration (NOAA). Erick's job is to maintain the genetic diversity of this population, which occupies the southernmost part of the coho's range in North America. The coho is a federally endangered species in California, and this southern population represents the species' best chance for surviving and adapting to the ocean and river conditions that are predicted due to climate change.
Our first stop was at the weir and fish trap on Scott Creek. There are actually two fish traps in this location: one to catch adult salmon swimming upstream and one to catch smolts migrating downstream (more about that in a bit). Adult salmon returning to spawn come into the trap and end up in the box to Erick's right. Every day during the spawning season at least two people come down to the weir to count, measure, sex, and weigh each fish in the trap. Then the salmon are trucked up to the hatchery, where they will be used for spawning under controlled conditions. The stretch of creek behind Erick is located between the fish traps; there are no salmon in it because the adults are all captured by the large trap, and the outgoing smolts are caught in the upstream trap.
At this point the entire creek passes through those screened panels, and the fish are directed into this box:
The smolts are netted out, put into buckets, and carried downstream past the adult fish trap. From there they migrate out to the ocean, and if all goes well they will spend the next two years feeding and growing before they return to the creek as adults.
Adult coho salmon caught in the trap are trucked up to the hatchery, which is located on Big Creek. There has been a hatchery on this site since the early 1940s. The current installation is operated by the Monterey Salmon and Trout Project, with permission of the landowners and from the state. Erick and his fellow fisheries biologists are charged with maintaining the genetic diversity within this small population of fish. They do so by keeping track of who mates with whom and making sure that closely related individuals do not mate. Each female salmon's eggs are divided into separate batches to be fertilized with as many as four males. Each male's sperm can be used to fertilize up to four females' eggs.
Fertilized eggs are incubated in a chamber set at 11°C and 100% humidity; in other words, they are not incubated in water. Once they hatch they are transferred to trays of water, where they remain until they have used up their entire yolk sac and need to be fed. Each of these trays contains one family of fry; in other words, all of the babies from one female-male mating.
From these trays the fishlets move into indoor tanks and then outdoor tanks. They are fed, and this is when they develop one of the bad habits of all hatchery fish: they get used to food coming from above and drifting down. In the wild, a juvenile salmon in a stream feeds on aquatic insects, small crustaceans, and the like. Many of their favored prey items are benthic, but they will also feed on insects at the surface. To do so, they have to spend time going up and down in the water column, when they are at risk of being eaten themselves. Hatchery-reared juveniles don't have predators to deal with and have learned that food lands on the surface of the water. They don't understand the need to remain hidden, and many of them get picked off by birds and other fish.
As a safeguard against an extremely poor return of spawning adults, each year some portion of the juveniles are kept at the hatchery and grown to adulthood on-site. This means that even if very few fish return to the river, or if there aren't enough females, the captive breeders can be used to make up the difference. This year, the 2017-2018 spawning season has so far been successful. As a result there were adult salmon that, for whatever reason, were not used as breeders. Today just happened to be the day that they would be returned to the creeks, where they may go ahead and spawn, and we got to watch part of it.
Returning to the story of the outmigrating juveniles, one of their biggest challenges is smoltification (my new favorite word), the process of altering their physiology in response to increasing salinity as they move towards the ocean. This is a unidirectional change in physiology for salmon; once they have fully acclimated to life in the ocean they cannot re-acclimate to the freshwater stream where they were born. Smoltification takes place over a few to several days. The hatchery has several year-old fish ready to smoltify (I think that's the verb form of the word) and will be releasing them in several batches at approximately two-week intervals starting later in March. The outgoing fish are tagged so that when they return in two years the hatchery staff will be able to determine which batch they came from, helping them understand what release conditions resulted in the greatest survival and return of adults. Kinda cool, isn't it?
The bad news is that as of right now any baby fish released into the creek won't be able to get to the ocean. We haven't had enough rain recently to break through the sand bar that develops on the beach where Scott Creek runs into the sea.
It will take some decent rainfall to generate enough runoff to breach the sand bar. A good strong spring tide series would help, if it coincides with a big runoff event. We are supposed to get some rain this weekend and into early next week. I hope it's enough to open the door to the ocean for the smolts. In the meantime, they will hang out on the other side of the highway in the marsh.
They'll have to wait until the ocean becomes available to them, and in the meantime will be vulnerable to predators, especially piscivorous birds. Hopefully the rains in the near forecast will be heavy enough to open up the sand bar and the smolts will be able to continue their journey out to sea. Good luck, little guys!
My bald sculpins have begun hatching! Their egg mass has been disintegrating over the past few days and I couldn't tell if that was because they were dying or hatching. Yesterday I was able to spend some time looking at them and was surprised to see that a few little pink blobs had wiggled their way out of the egg mass while I was manipulating it. Baby fishies! Well, they're still mostly yolk, but each yolk has a baby fish attached to it. They flit around quite a lot and are difficult to photograph. I had to put this trio in a depression slide, the macro photographer's trick of making the universe smaller so the creature can't swim too far away.
This little fish was cooperating with me, so I carefully placed a coverslip on its drop of water and took some video. The first part was shot through the dissecting microscope with epi-illumination from a fiber-optic light, which shows the surface details. The second clip was taken through the compound microscope with trans-illumination; this kind of lighting doesn't show any of the three-dimensional structure of objects but does a wonderful job with transparent objects like larval fish.
I like that the baby fish have spots on their yolk sacs as well as the top of the head. And from the second half of the video it appears that they don't yet have a gut, at least not one that I can see. For the time being they don't need a gut, as they're surviving off the energy stored in the yolk sac, but once the yolk has been absorbed they will have to start feeding. At that point they'll need to have complete guts. I imagine they will be hungry, and hope I have something they'll be able to eat.
How big are these baby fish, you ask? The smallest ones were about 2 mm long, and the biggest one was twice the size, with a correspondingly smaller yolk.
And yesterday I caught some time-lapse video of a baby hatching from its egg. Why have I never played with the time-lapse function on my phone before? It's really cool.
For now I'm keeping the babies in a mesh container, separated from their father so he cannot eat them. I don't think I'll end up with more than a couple dozen hatched larvae, as the egg mass has begun to decompose and many of the embryos have died inside their eggs. And no doubt some of the larvae that I've rescued already will die. I figure I have a few days before I need to worry about feeding the survivors. After that, who knows? Your guess is as good as mine.
Almost a week ago, my sculpin eggs were doing great. The embryos had eyes and beating hearts and were actively squirming around inside their eggs. A few of them had died but overall they seemed to be developing well. I had high hopes that they would continue to do so, and began to think of what I'd need to do once they hatched.
Today the egg mass is 19 days old, and things aren't going so well.
Many of the embryos on the outer edges have died, and all that remains of them are the tattered remnants of their eggs. Those opaque white eggs have been dead for a while and the pale pink shredded eggs died more recently, in the last day or so. I took a quick peek at the egg mass yesterday, and it looked much healthier than it does today. I'd guess that all told about 30% of the embryos have died since development began.
The embryos that are still alive seem to be fine. Their eyes can now move around independently but I still don't know what, if anything, they can see. Their bodies continue to grow and now they have spots on their tails as well. I can make out where the heart is because I can see it beating, but I can't discern any of the other internal organs. If the lighting is just right I think I can see pectoral fins on some of the embryos, which are too faint and indistinct to photograph. The baby fish are still swimming around inside their eggs, too.
Question of the Day: What caused the eggs' condition to deteriorate so rapidly?
Well, I can think of a couple of explanations.
Explanation #1: Not everybody survives long enough to hatch. Sculpins and other fishes that lay large numbers of eggs are generally described as having a Type III survivorship curve (see right). These organisms have lots of babies, few of which survive to adulthood; probability of death is highest in the youngest age classes. Individuals that do make it to adulthood experience much lower mortality and have a decent chance of surviving into old age. In an egg mass like this, each egg has a very small probability of eventual survival to adulthood. To paraphrase an old saying, if they all survived then the world would be covered in bald sculpins. Obviously that's not the case--and that's a good thing!--so most of these eggs are not going to make it in the long run even in the best of circumstances.
Explanation #2: Crappy water quality. A very strong storm blasted through the area yesterday, complete with wind gusts to about 50 m.p.h. and 1-2 inches of rain, depending on location. All of this rain generates a lot of surface runoff, which carries mud and debris (think bushes and trees as well as garbage) into Monterey Bay. Plus, the high winds and turbulent swell stir up the bottom in shallow areas, resulting in brown, turbid water. This is the water that we use in the lab, and it's our only source of seawater. Today the water was visibly cloudy. At least it seems to be just sediment, though, and not another phytoplankton bloom.
Poor water quality could affect the sculpin eggs if the sediment settles out on the surface of the egg mass, impeding gas exchange between the eggs and the surrounding water. In the field these eggs would be subjected to strong turbulence from the bashing waves, which would keep them clean and the water highly oxygenated. Some species of fish guard their egg masses and blow water on them to clear them of both sediment and fouling organisms. I hadn't seen the parents of my sculpin eggs caring for their offspring at all, but I have been rinsing off the egg mass every day. Maybe I haven't been able to keep the eggs clean enough. It does seem to be the eggs on the outside of the mass that are dying, so cruddiness might very well be part of the problem.
I'll look at them again tomorrow and see if anything has changed. The news could be either good or bad, and I honestly don't know what to expect.