Florida Pompano Size Limit Evaluation
Executive Summary
In this report, the impacts of raising the minimum size limit from 11 inches (FL) to 12 inches (FL) in the Florida pompano fishery were evaluated. It was assumed that the effects of all other existing regulatory measures remained unchanged. A catch-based projection and an equilibrium yield-per-recruit model were used for evaluating the impact of the proposed 12-inch minimum size limit on fishery yield and stock condition. These methods used information on the fisheries landings and size composition data reported for Florida pompano during 2006-09 from the Atlantic and Gulf coasts of Florida. Biological data, size selectivity patterns, and estimates of exploitation rates were also utilized for the evaluation. The size-frequency data were generally sparse for the 2006-09 periods and mostly limited to the hook-and-line samples from the commercial and recreational landings.
The proportion of the average total landings in the size categories of 11-inch and smaller was fairly large, 45% on the Atlantic coast and 40% on the Gulf coast during 2006-09. The catch-based projection runs predicted that the annual landings of Florida pompano could potentially drop between 12% and 24% on the Atlantic coast and drop between 10% and 21% on the Gulf coast with the implementation of the 12-inch minimum size limit under four different compliance rates (85%, 90%, 95%, and 100%). The projected annual landings reductions for 85% compliance were 12% on the Atlantic coast and 10% on the Gulf coast. The stock abundance of Florida pompano was predicted to increase by 19% on the Atlantic coast and 14% on the Gulf coast under the 85% compliance rate.
Results from the length based yield per recruit analysis show that, at current levels of fishing mortality, raising the minimum size limit from 11 inches FL to 12 inches FL in the Florida pompano fishery, will result in an increase in the spawning biomass per recruit (SB/R) on both coasts of Florida. The SB/R was predicted to increase by 29% on the Atlantic coast and by 18% on the Gulf coast based on the ascending selectivity pattern. Slightly higher gains were estimated for the SB/R from the model runs with a knife-edge selectivity pattern. Estimates of the Spawning Potential Ratio (SPR) for different combinations of size-at first capture (minimum size limits) and fishing mortality rates showed 1) The SPR increased with increase in minimum size limit; and 2) the risk of the SPR dropping below 20% was reduced significantly under the 12-inch minimum size limit if the fishing mortality increased above the existing rates.
Results from these analyses must be viewed with caution. The size composition data used in the catch-based projections were limited mostly to the hook-and-line fishery low sample sizes. There was little size information available from the commercial gill-net fishery, which constitutes a large proportion of the total landings on the Gulf coast. A number of simplifying assumptions were made: 1) no stock-recruitment feedback was included in the projections; 2) models assumed constant fishing catchability and selectivity; 3) model projections did not include potential effects of other management measures (e.g., bag-limit, commercial vessel limit) already in place in the pompano fishery; and 4) the analysis assumed no interplay between the minimum size limit and other management measures in place in the fishery.