2005 Florida Striped Mullet Stock Assessment

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The 2005 Update of the Stock Assessment
for Striped Mullet, Mugil cephalus, in Florida

Behzad Mahmoudi
Florida Fish and Wildlife Conservation Commission
Florida Fish & Wildlife Research Institute
St. Petersburg, FL
December 2005

EXECUTIVE SUMMARY

This report updates commercial and recreational fisheries statistics through 2004. The commercial fishery constituted 84% percent of the total landings during 2000-2004. The west coast of Florida contributed to 85% of the total commercial landings during 2000-2004. Since the 1995 net-ban, Florida's commercial landings have sharply declined to an annual average of 8.1 million pounds, a 67% reduction if compared to the recent historical (1967-1990) average level of 25 million pounds. The total commercial landings in 2004 were 7.6 million pounds. The number of commercial fishing trips declined from an annual average of 62,345 trips before the net-ban took effect (1986-1994) to 28,785 trips after the net-ban took effect (1995-2004), a total reduction of 54%. Total number of fishing trips in 2004 was 23,768.

The proportion of the roe-season landings to the total landings increased during the post net-ban period in the southwest region and remained unchanged in the east coast and northwest regions. In the southwest region, the roe season landings in 1999, 2001, and 2002 ranged from 4.0 to 4.4 million lbs, similar to the landings levels observed in 1993 and 1994 (4.6 million lbs in 1993 and 4.2 million pounds in 1994). There has been a substantial decline of the no-roe season landings since the 1995 net-ban on both coasts of Florida.

Statewide recreational landings of striped mullet have been variable from 1.0 million pounds in 1985 to 5.1 million pounds in 1996. Recreational landings have averaged 1.6 million pounds during 2000-2004.

Commercial catch rates for striped mullet increased following the elimination of entangling gears in Florida waters on both coasts. This increase probably reflects the increase in the stock size.

A non-equilibrium, surplus production model indicated that the F/Fmsy trajectories for the post net-ban period were consistently below 1 with average F/Fmsy ratios of 0.43 for the east coast region, 0.19 for the NW region, and 0.35 for the SW region, indicating that overfishing of striped mullet stocks was not occurring in these regions in recent years.

A forward-projecting, statistical catch-at-age model indicated a significant decline in total fishing mortality rate since the 1995 net-ban on both coasts of Florida. The fishing mortality rates in recent years (2001-2004) were below the management target levels (F35% = 0.69 for the east coast, F35% = 0.55 for the NW region, and F35% = 0.64 for the SW region) and they ranged from 0.32 to 0.65 per year on the east coast region, from 0.28 to 0.40 per year on the NW region, and from 0.19 to 0.42 per year on the SW region. The decline in fishing mortality rates since the net-ban has resulted in gradual increase of the spawning stock biomass especially in the NW and SW regions where over 85% of striped mullet were landed. The fishing mortality estimates for the SW region were comparable to the fishing mortality rate of 0.5 per year estimated from the fishery-independent age compositions data collected during the spawning season in Tampa Bay and Charlotte Harbor.

Current stocks in the east coast, NW, and SW regions appear to be healthy and current levels of fishing effort appear to be sustainable. Future values of fishing mortality rates in the striped mullet fishery are affected by amount of catch, changes in gear selectivity, and stock size and recruitment. Landings trends in the recent years suggest that mullet production has stabilized at about 1.8 million pounds on the east coast region, 2.3 million pounds on the NW region, and 6.5 million pounds on the southwest region. Given current regulations, at these recent landings levels, fishing mortality rates should decline further if recoveries of the mullet stocks continue at the present rate.

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.