Algalita Marine Research Blog

Deepest Plastic Trawl Ever

Posted by: ORV Alguita

September 20, 2007
Today we conducted the deepest trawl ever looking for plastic debris. We used paired bongo nets, and let out enough cable for them to reach a depth of 100 meters. The bongo net looks like a pair of bongo drums, one meter in diameter each, but instead of a skin stretched over the mouth, a net extends behind each drum.
In order to close the choke collar on the bongo nets at that depth, we used our heaviest fishing poles and attached the end of the line to the closure. The monofilament fishing line exerted less drag on the closure, so that it would not close before the end of the trawl. After one-half hour, the fisherman pulled in like they had a marlin and closed the choke collar on the bongo nets and we pulled in the cable with the winch. There appeared to be a couple of small plastic pieces in the collection bag, along with the zooplankton. Because the bongo collects down deep, we are able to run the Manta Trawl at the same time. While we were trawling, a black footed albatross flew over the Manta, a beautiful soaring scavenger of the deep ocean.
Our noon position today was 38 41 N, 142 02 W. A question for you, how many meters of cable did we have to let out at an angle of 45 degrees with the surface to reach a depth of 100 meters?
Aloha from ORV Alguita
Hoy hicimos la draga mas profunda para plastico que aun se ha hecho. Usamos una draga que se llama bongo. Parece al instrumento, pero con un diametro de un metro cada lado y una red atras de cada cilindro. Usamos canas de pesca para cerar el collar, porque la linea delgada no jalo demaciado, y no cerro el collar antes de la media hora que la jalamos. Despues de una media hora, regresamos la red con la grua y las canas de pesca, y encontramos un pedacito chiquito de plastico intermezclado con el zooplankton que atrapamos. Al mismo tiempo estabamos dragando con la manta, porque esa red trabaja la superficie, y volo encima un albatros negro. Nuestro posicion medio dia, 38 41 N, 142 02 W. Estamos en el centro del giro, con una prescion atmosferica de 1030 milibars. Una pregunta, cuanto cabo tuvimos que soltar a un angulo de la superficie de 45 grados para llegar a una profundidad de cien metros?
Saludos desde ORV Alguita
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Date Posted: September 21, 2007 @ 2:50 pm Comments (0) | Comment Shortcut

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