Thursday, June 18, 2015

Fish on the sand

In the eelgrass beds at the bottom of the intertidal zone, fish dart through the thickets, usually visible only as a flash of movement, a streaking silver shape dashing from shadow to shadow, or a panicked thrash to escape my clumsy foot. They're usually not the fish I see in the upper zones, the sculpins and the flatfish, but they speed away so fast that I haven't been able to recognize any.

This last trip to the low tide line, though, the shallows were littered with dead and dying small fish; I was able to identify three species.

Another Pacific sand lance, Ammodytes hexapterus. These grow to about 11 inches long, so this is a youngster.

In one small area, I counted over 50 of these, all dead, but still fresh, surprisingly still untouched by gulls or crabs. They were all young; the adults spawn and die in mid-winter here. I am wondering what caused this die-off.

A larger sand lance, still alive, but barely. The back is a glittery blue-green, which should help with camouflage in the eelgrass beds, at least from above. At night, they burrow into the sand, to hide from predators.

Mixed with the sand lances, a few darker, larger fish stood out.

Pacific snake prickleback, Lumpenus sagitta. About 8 inches long.

Another. This was still alive, but not able to swim away.

Again, these were young fish; the adults grow to 20 inches long and spawn in the winter.

One more; a beautiful singing midshipman, no longer able to sing.

A steampunk fish, looking as if he were made of riveted plates. Plainfin midshipman, Porichthys notatus, about 8 inches long.

These are night-swimming fish; during the day, they hide under rocks. I found a male, guarding eggs, about this same time three years ago, under a rock at the boat launch. He was fatter and longer than this one.

The "rivets" are lines of photopores, cells that emit light. They may help to attract prey at night. (Although we don't really know that; it's human speculation. We do like to imagine that we understand Ma Nature.)

Belly up, showing the pattern of photopores, and his delicate colouring.

Zooming in to the tail end, to show the little lights, and - look closely - tiny waving three-fingered hands, all in a row.

I didn't pick this one up; some midshipmen have poisonous spines. I'm not sure if this species does, but I'm not risking it.

And I'm left wondering why all these suddenly showed up dead, all at once. The water was clear, it smelled fresh, there was no scum or oil sheen. There is construction going on 'way back at the shore, but that's a full kilometre away. Worrisome.

6 comments:

  1. That does seem odd, Susannah. I wonder if there has been any dynamiting in the area? Many years ago, when my family had a cottage on the upper Ottawa River, a local marina had some dynamiting done to deepen the harbour. About a day later, all sorts of fish floated up on the beach in front of our cottage - probably killed by the shock waves from the explosions.

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  2. Meant to say that I love your close-ups of the photopores on the Toadfish. Great camera work as always!

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  3. there is a massive domoic acid bloom along the west coast that has all the beaches closed. Could this be a sign?

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  4. Bev, I don't know about any dynamiting; it's flat land, silty, not rocky all around here, so I don't think there would be need for it.

    The red tide could be a cause. Thanks, Upupaepops; I had forgotten about that. I think, though, that it is supposed to only harm mammals. Maybe fish as well, and we haven't been paying attention?

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  5. The Seattle Times has an article on the bloom. It is not only domoic acid, but also high levels of DSP (Diarrhetic Shellfish Poisoning) and PSP (Paralytic shellfish poisoning). And higher than normal temperatures. "... offshore waters are still about two degrees warmer than normal, said University of Washington climate scientist Nick Bond,..."

    Interesting point to remember: "Also, harmful algal blooms usually don’t color the water."

    http://www.seattletimes.com/seattle-news/health/toxic-algae-bloom-might-be-largest-ever/

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  6. It does look steampunked.

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