Research Document - 2007/057

Progress Report on the Development of an In-season Management and Assessment Framework for Prince Rupert Humpback Shrimp (Pandalus hypsinotus)

By Rutherford, D.T., H. Nguyen, and J.S. Dunham

Abstract

The Prince Rupert Harbour humpback shrimp trap fishery takes place in Pacific Fishery Management Areas (PFMA) 4-10 and 4-11. This is a relatively small fishery with an average of 5 active vessels in a season. The maximum recorded catch was 77,601 kg in 1998 and has averaged 23,000 kg from 1999 to 2005. Output from a surplus production model suggests a MSY of 28,274 kg of humpback shrimp from Prince Rupert Harbour. This MSY value is qualified in that is not to be interpreted as a recommended or definitive MSY value.

Weekly CPUE (kg/trap) obtained from logbook data shows a declining trend throughout the duration of the fishing seasons. Annual CPUE was relatively stable from 1984 to 1994 then showed a declining trend to 2000. Annual CPUE has been increasing from 2001 to 2005.

Currently the humpback shrimp trap fishery in Prince Rupert Harbour is managed by a seasonal closure, vessel trap limits and restrictions. There are no biologically-based decision rules to prevent recruitment overfishing. Thus, shrimp stocks are vulnerable to a large increase in effort during the commercial fishing season. In response to this concern an in-season assessment and management framework is under development. The in-season biological sampling program is not currently providing the data necessary for application of biologically based in-season control models. The in-season sampling program has a major problem in that the limited in-season samples cannot be obtained from a consistent trap type, given the diversity of gear used in the commercial fishery, thus making effort standardization impossible. There are two ways of rectifying this situation, either by manage the fishery so all the in-season data needed is obtained from a standardized trap type, or alternatively by conducting controlled experiments to "standardize” effort from all the different commercial gear types. The former approach is recommended.

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