2002 Halfbeak Stock Assessment

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A review of Florida's halfbeak bait fishery,
halfbeak biology, and a preliminary stock assessment

Behzad Mahmoudi and Richard S. McBride
Florida Fish and Wildlife Conservation Commission
Florida Marine Research Institute
St. Petersburg, FL
June 21, 2002

EXECUTIVE SUMMARY

In this report, we provide an update on commercial and recreational landings of halfbeak species and fishing effort, review their biological characteristics, and present a preliminary assessment of the south Florida halfbeak fishery.

Three species of halfbeaks (Hemiramphidae) constitute a small but valuable baitfish fishery in south Florida. Commercial fishers harvest halfbeaks to sell as bait for pelagic and benthic gamefishes (e.g., billfishes and groupers). Recreational charter boat captains and private sport anglers also catch their own bait. Commercial landings were highest during winter and lowest during summer. Annual halfbeak commercial landings had been relatively stable (median=1.2 million lb) even though fishing effort declined during 1986-2000. Our analysis show that the catch rate in the commercial fishery has increased in recent years in association with an increase in the number of larger boats with larger holding capacities and the expansion of the fishery to new fishing grounds. This in turn has resulted in increasing harvests rates from 750-1,000 lbs per day to 1,000-1,250 lbs per day. The estimated annual recreational halfbeak landing was relatively small and varied between 2,924 and 38,690 lbs during 1982/83-2000/01.

Ballyhoo and balao are short-lived and their populations are subject to high natural mortality and large recruitment fluctuations. The size structure of both species changes rapidly with respect to season. They initially recruit into the fishery in June as age-0 fish and at sizes as small as 100 mm FL. These young-of-the-year are fully recruited by October. Maximum observed ages were 4 years for ballyhoo and 2 for balao. Ages 0 and 1 dominate the commercial catches. Spawning occurs in waters less than 10 m deep and spawning is greatest during March-July. The sizes at 50% maturity were calculated at 160 mm FL for balao and 198 mm FL for ballyhoo. Maximum size observed is 313 mm FL for ballyhoo and 283 mm FL for balao.

For this stock assessment, we chose methods such as a modified De Lury and surplus production that use fisheries landings and effort data, to generate estimates of population size and fishing mortality rates. Diagnostic measurements indicated that models fits of the observed commercial and recreational catch data were satisfactory. The mortality estimates derived from these models fit in the range of independent mortality values available in the literature. The fishing mortality estimates (0.83-1.2 per year) from the De Lury method were in the range of the estimated natural mortality rates (0.75-1.15 per year) which indicates the fishery is operating at or above the MSY level (fully exploited). In addition, the results from the surplus production model show that the total F has generally been at or above the F _MSY through most of the 1990s, and this may have kept the biomass below the B _MSY level in recent years.

This preliminary assessment indicates that the recent expansion in fishing effort and potential for future increase of fishing effort may be a cause for concern and some level of management is necessary. Given the extent of the recruitment variability and the market demand for halfbeaks, the current F could exceed the F_MSY level even further and reduce the population biomass to a lower level.

For other information:
Stock assessments for finfish and invertebrate
Ballyhoo and Balao species account

Prior to July 1, 2004, the Fish and Wildlife Research Institute was known as the Florida Marine Research Institute. The institute name has not been changed in historical articles and articles that directly reference work done by the Florida Marine Research Institute.