Forecasting offshore brown shrimp catch from early life history stages.

A prediction of adult brown shrimp harvest, based on an index derived from Galveston Bay bait fishery CPUE, is issued to the industry by the National Marine Fisheries Service Galveston Laboratory every June. This prediction has been the most reliable index of future shrimping success, but it is available only weeks before the shrimping season begins. Studies are underway to develope an earlier forecast by establishing valid abundance indices at the advanced postlarval and early juvenile stages of the brown shrimp life cycle. Postlarval shrimp are sampled with a beam trawl twice weekly at the entrance of Galveston Bay. Predictions based on postlarval abundance have been quite variable, but the regular sampling yields information regarding timing and magnitude of shrimp immigration. Future work will attempt to improve predictions at this life stage which would give the earliest information to the fishery. Juvenile brown shrimp abundance has been evaluated at several coast ponds. Preliminary data from these mark-recapture studies suggest that there may be a relationship between juvenile shrimp standing stock and subsequent offshore abundance. If a prediction could be developed from juvenile stage shrimp it would be available as much as a month earlier than the bait index prediction.