Observations of Fish and Shrimp Behavior in Ocean Shrimp (Pandalus jordani) Trawls, Information Reports 2003-03

Identification Information

Citation

Originator: Hannah, R.W., S.A. Jones and K.M. Matteson

Publish Date: November 2003

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Cedric Cooney

Job Position: Natural Resources Data and Systems Manager

Telephone: 503-947-6094

E-Mail Address: cedric.x.cooney@odfw.oregon.gov

Description

Abstract: Underwater video observations of ocean shrimp (Panda/us jordani) and fish inside shrimp trawls and interacting with bycatch reduction devices (BRDs) were summarized. Ocean shrimp behavior inside trawl nets was passive and reactive in comparison to fish which generally exhibited the more typical optomotor responses. Mesh escapement for shrimp was mostly a two stage process in which shrimp entered an open mesh tail first. Escapement would occur a few seconds to many minutes later after a stimulus, such as motion of the catch or movement of the netting, initiated an escape response (tail flip) from the shrimp. Observations of rigid-grate BRDs showed that an accelerator funnel or panel was an important component of a successful BRD, keeping shrimp away from the escape hole and accelerating shrimp transport into the codend. Rigid-grate BRDs also provided a much more consistent net shape and grate angle with minimal water flow out the escape hole. Soft-panel BRDs were shown to deliver unpredictable angles in the deflector panel, due to an unpredictable net shape and diameter in the intermediate portion of shrimp nets, with associated water flow out the escape hole. Observations of the fisheye BRD showed it to be an ineffective BRD in ocean shrimp nets and very sensitive to placement.

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Geographic Extent: Oregon Coast line

Status: Final

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Format: PDF File

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Is a physical copy maintained for reference at Headquarters? Yes