Tuesday, July 29, 2014

Matthew Mischke - Week 3: Ocean Travels and Eels

Hey everyone, 

Week 3 was busy and exciting! Most notable about the week was my first trip out on the ocean and simultaneously my first chance to do data collection and field work this summer. Bridget and I along with Matt Yergey, Lorenzo Ciannelli and Gonzalo all went out on the R/V Elakha equipped with a small beam trawl. A beam trawl is a kind of fishing rig in this case with two wheeled sleds for tracking distance, a thick metal beam connecting them and a fine mesh net trailing behind forming a cone-like shape on the ocean floor pulled along by nylon cord hauled by medium sized winch. The net was dragged through the benthic zone in order to sample the marine flatfish community. We cruised along the NH Line (Newport Hydrographic Line), which runs roughly perpendicular to the coastline going strait out from the jetties off of Yaquina Bay. At each of the six stations (NH 3, 5, 10, 15 and MB 30 and 40 where NH #'s represent distance from the coast in nautical miles and MB #'s represent depth in meters) a CTD was deployed to measure conductivity (salinity), temperature, dissolved oxygen and turbidity and was left overboard for a few minutes. After the CTD was reeled in and measurements were recorded, the beam trawl would go into the water, drag on the floor for 10 min or so then it would be reeled in. When the net was pulled up, the contents were emptied into standard size coolers and dumped in manageable quantities onto a sorting table with a drain leading off the bough for excess liquid. While out on the rocky boat we sorted fish into general size categories in gallon-sized freezer bags for ID and measuring/weighing later in the lab while trying not to lose too many sloshing over the side. Any especially large organisms were measured, noted, and released quickly to give them a chance at survival. All crustaceans, cnidarians and echinoderms were roughly counted on the spot, noted, and tossed overboard as well.

Besides just sampling the community through capture, the beam trawl was also equipped with an HD in situ camera mounted to the center of the beam pointed towards the net with two mounted lasers 10 cm apart in the center of the camera shot. This camera was linked to a live feed in the house of the vessel and was recorded for further review at a later date as well. The camera provided data on the behavior of flatfish and other benthic organisms as they were disturbed by the ticker chain and capture in the net. The lasers were set at 10 cm for relatively accurate measurements while reviewing footage later and a general sense of scale of the organisms caught on film.

The voyage itself was fun at first but I found out that day that I get sea-sick. After the first couple hours, the nonstop rocking and wind lost their charm and sorting through large quantities of jellies that kept sloshing around didn't exactly help settle the stomach. I ended up laying down and sleeping through most of the voyage, but it was still fun to assist with and see the data collection first hand. I did miss the reception of the OSU glider though, which was little dissapointing. These gliders measure many of the same parameters as a CTD but are unmanned water craft that bob up and down from the surface to deep waters while moving back and forth perpendicular to the coast for months at a time. On the way in we caught one of the gliders to be brought in for cleaning, fresh batteries and for downloading the data.

In addition to the exciting ocean travels week 3, there was also a great seminar on Thursday led by Laurie Weitkamp, talking about Pacific Lamprey. Her presentation was interesting and informative and personally important to me as I spent several weeks this last year learning about the Confederated Siletz Tribe as well as other major tribes in the area as part of a NW history class and I am very aware of the importance of "eels" to the Native Americans of this region. I was honestly very surprised to know that the lamprey populations were doing so poorly and are so understudied, but it was good to hear what work is being done and be made aware.

Overall it was a great week and I look forward to several more at HMSC this summer. Thanks for reading and have a great day!

Matthew M.

1 comment:

  1. I appreciate the clear explanations and details about the beam trawl and NH Line. Thanks for sharing! I'm curious about ow eels are important to Native Americans of this region.