Friday, July 6, 2012

Ecology/Fisheries Cruise Summer 2012

The F/V St. Andrew Bay used for this research cruise.
Photo courtesy of Leonardo Bueno
The first fish ecology Deep-C cruise took place June 30th-July 6th of 2012. Among those on board were the FSU Coastal and Marine Lab's Dr. Chris Koenig and Dr. Dean Grubbs, graduate student Jo Imhoff, visiting scientist Leonardo Bueno, and technician Justin Lewis. The team surveyed the edge of the continental shelf all the way to the deep slope regions of the DeSoto Canyon. Although this cruise was somewhat of a trial to see if they could conduct labor-intensive high volume sampling on a commercial fishing vessel, the F/V St. Andrew Bay, it proved to be a great success.

The Man-of-war fish (Nomeus gronovii)
named for its commensal relationship
with the Portuguese Man-of-war.
Chris Koenig said that they caught a wide variety of fish ... some he had only ever read about -- six-gill sharks, gulper sharks, several species of dogfish, big-nose sharks, seven-gill sharks, hagfish, yellowedge groupers, two species of hake, tilefish, and deep water isopods. They even caught spawning-ready amberjack at depths of 75 and 100 meters, which is unknown to scientists actually researching this species’ reproductive cycle. The number of pregnant sharks that were caught during this trip suggested that the DeSoto Canyon is an important nursery for sharks.

The blotched swimming crab (Portunus spinimanus).
Relative to the blue crab, it is a common crab
on the edge of the continental shelf in the Gulf.
Jo Imhoff explained that her anticipation of the catch when long-lining in deep water is because of the imminent possibility of there being a species she has never seen before on the other end. During the cruise, she was in charge of recording data on their catches. This included photographing, recording measurements, collecting samples, and stowing the catches away appropriately. Jo said there was a need for multi-tasking because of the number of fish that was caught.

FSUCML’s Dr. Dean Grubbs pulling in a
large chevron trap on the edge of the continental
shelf.  The trap contains many very large
adult greater amberjacks (Seriola dumerili).
Dean Grubbs says that he is satisfied with the outcome of the cruise as it was an extension of work he started for a project funded by the Florida Institute of Oceanography. They had previously conducted three other research cruises between 2011 and 2012 but the Deep-C cruise has a concentration on shallower water and deep sea fishes. Through this cruise and future ones, they hope to examine the community structure of deep sea fish, model the trophic structure of deep-sea communities, and test deep-sea fish for evidence of exposure to oil-derived toxins.

A nighttime shot of Dr. Dean Grubbs tagging a silky shark.

On this trip, several new species were caught to add to the Deep-C database including juveniles of species they had only ever seen as adults and animals pregnant with very near-term pups, further confirming the idea that the DeSoto Canyon must house a nursery.

A silky shark (Carahrhinus falciformis) which is a common pelagic shark
occasionally caught in upper continental slope water (200-300 meters).

Posted by:
Brittany Sims, FSU Coastal and Marine Laboratory

No comments:

Post a Comment