California Deep-Sea Trawling Expedition

Deep-Sea Trawling aboard the Research Vessel Robert Gordon Sproul

From 5 August 2010 to 7 August 2010, researchers from The Field Museum led a deep-sea trawling expedition off of San Diego, California. Assistant Curator Leo Smith headed a team of ichthyologists (Chris Jones, Susan Mochel, John Sparks, Kevin Swagel, and H. J. Walker) and Associate Curator Janet Voight headed a team of invertebrate zoologists (Meg Daly and Luciana Gusamaõ) that sampled a diversity of depths and habitats. The round-the-clock cruise was able to make 21 trawls, even though the average depth was over 3,000 feet. We hope that you enjoy our images of the incredible diversity we found off the coast of California. Be sure to check out a movie of one of our Issacs-Kidd Midwater Trawls coming on board.

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Sproul Collecting Party

Deep-sea trawling expedition collecting party (from left to right): John Sparks (American Museum of Natural History), H. J. Walker (Scripps Institution of Oceanography), Leo Smith (Field Museum), Meg Daly (Ohio State University), Janet Voight (Field Museum), Chris Jones (Field Museum), Luciana Gusmaõ (Ohio State University), Susan Mochel (Field Museum), and Kevin Swagel (Field Museum).

Trawling Map

Map of trawling locations off San Diego and in the San Diego Trough that were sampled during the expedition

R/V Robert Gordon Sproul

R/V Robert Gordon Sproul - The ship used during the August 2010 zoology deep-sea trawling expedition.

Attaching the Otter Trawl

Chris Jones and the marine technician attaching the otter trawl for our first collection on the cruise. The wood otter boards in the image are paired, and they are positioned such that the hydrodynamic forces acting on them as the boat moves forward, pushes them outwards; these forces prevent the mouth of the net from closing. They also act like a plough, mucking up the seafloor. This creates a turbid cloud, which scares fishes and other creatures toward the mouth of the net.

Setting the Otter Trawl

Chris Jones and the marine technician releasing the otter trawl.

Sorting the Bottom Trawl

Janet Voight, Kevin Swagel, Chris Jones, and Leo Smith sorting the bottom trawl, which contained mostly flatfishes and sea urchins.

Turbot

Leo Smith holding a Turbot (Pleuronichthys). This one was one of the most common fishes that we collected in the bottom trawls.

Pacific Midshipman

A Pacific Midshipman (Porichthys) collected in a bottom trawl off of San Diego. The white dots on its underbelly are bioluminescent light organs. This fish is called a midshipman because these light organs look like the buttons on a midshipman's uniform. Unlike most fishes, the bioluminescent toadfishes get their chemicals necessary for bioluminescence from their diet.

Benthic Octopus

A small benthic octopus found among the sea urchins.

Brittle Star

A bottom dwelling brittle star. The brittle stars or ophiruoids are similar to the traditional asteroid starfishes, but instead of using tube feet for locomotion, they use their arms directly.

Janet Voight with a Sea Cucumber

Janet Voight holding up one of the many species of Sea Cucumbers we brought up from the sea floor.

Eelpout

An eelpout (Lycodes) that had a tissue sample taken and preserved in liquid nitrogen for future DNA analysis. The orange tag has a unique identifier on it, so we can track the specimen as a voucher for the tissue sample.

Crab with Eggs

A deep-sea bottom crab that is holding eggs on its underside.

King Crab

A king crab that was brought up from a depth greater than 1,500 feet in a bottom trawl off San Diego.

Deploying the Issacs-Kidd Midwater Trawl

Kevin Swagel and the marine technician deploying the Issacs-Kidd midwater Trawl off the stern of the R/V Robert Gordon Sproul.

Cod End of Trawl Sinking

Kevin Swagel and marine technician releasing the net of the Issacs-Kidd Midwater Trawl as the cod end (white PVC tube at end) submerges at the trawl begins to descend to greater than 3,500 feet.

Issacs-Kidd Midwater Trawl Ascending

Issacs-Kidd midwater trawl ascending from a depth of greater than 3,800 feet. As the boat is moving, you put out 2.5 times as much wire as the depth you are trying to sample. For this trawl, nearly 9,000 feet of cable was released and then pulled back in over a period of nearly three hours.

Jellyfish

A beautiful red jellyfish collected over the San Diego Trench. Like other jellyfishes, this species has venomous nematocysts (stinging cells).

Lampfish

A Highseas Lampfish (Triphoturus) collected in a midwater trawl. The white speckles on its body are bioluminescent light organs.

Dover Sole

A very small Dover Sole (Microstomus) collected in a midwater trawl. The eyes of flatfishes, such as this sole, start out like a regular fish with one on each side, but as they mature the eye migrates from the "blind" side to the "eyed" side. This individual has recently finished the eye migration.

Blackdragon

A Blackdragon (Idiacanthus) with its mouth wide open. The lure in front of its mouth is bioluminescent, and this species uses it to aid predation.

Large and Small Squid

A large and small squid taken in one of the midwater trawls.

Fangtooth

One of the classic deep-sea fishes, the Fangtooth (Anoplogaster cornuta). Despite numerous trawls, we only collected a single specimen of the Fangtooth.

Pelagic Octopus

A large example of one of the pelagic octopi species that we caught in one of our midwater trawls.

Phronima

Phronima, a common hyperiid amphipod. These remarkable deep-sea crustacean travels in a "house" that is a hollowed-out salp test.

A Trio of Bigscales

Three Big Scale (Melamphaeidae) individuals collected in a midwater trawl. The scales are incredibly delicate in these deep-sea fishes, so these came up in remarkable shape. Frequently, they come up with few to no scales.

Anglerfish

A female deep-sea anglerfish with its characteristic, bioluminescent dorsal-fin lure. All of the large individuals of this group of fishes are female, as the males are typically parasitic, even frequently "fusing" permanently with the females.

Vampire Squid

A Vampire Squid (Vampyroteuthis) after losing much of its characteristic black skin. We caught several individuals of this rare and beautiful squid.

Boafish

A deepsea Boafish (Stomias) that has its characteristic unusual scales and ventral bioluminescent photophores. All of the midline fins and the non-terminal end of the barbel in this species are bright red when they come up in the trawl.

Hatchet Fish

A deep-sea Pacific Hatchet Fish (Argyropelecus) in Susan Mochel's hand. This group has the characteristic ventral light organs that "match" the downwelling light from the surface to avoid casting a shadow beneath them.