FEATURE ARTICLE 3 

 STATUS REVIEW OF KING MACKEREL IN THE GULF OF MEXICO 



while the recreational sector is allowed to continue 

 to fish throughout the year. This disparity in im- 

 pact of smaller TAC's could be reduced by lower- 

 ing the recreational bag limit or closing parts ot 

 the fishing season or specific areas lor recreational 

 fishing (SEP, 1998). 



Total Acceptable Catch Overruns 



A related point is the consistent overruns of 

 the TAC allocations by both the recreational and 

 commercial sectors every year since management 

 began. These overruns significantly reduce the 

 ability ot king mackerel to recover from an over- 

 fished state, especially when the TAC set is risk- 

 prone from the stat t. These overruns are expected 

 to continue in the recreational sector due to hu- 

 man population increases and increases in fishing 

 power, for example, through bigger boats, better 

 location devices (GPS), and improved gear, and 

 as accumulated information regarding when, 

 where, and how to fish spreads rapidly through 

 the sportfishing media. As king mackerel recover, 

 more fish will become available, and thus a con- 

 stant bag limit will allow more fish to be caught, 

 thereby increasing the probability of recreational 

 fishery allocation overruns. Thus, recreational an- 

 glers may be htced with the counterintuitive situ- 

 ation of reduced bag limits as the fish become more 

 abundant, at least until fiill recovery is achieved 

 (SEP, 1998). 



Recovery Times 



The Gull ot Mexico group ol king mackerel 

 was supposed to have been recovered to a level ot 

 30% SPR by the 1997-98 tlshmg season, based 

 on the Coastal Migratory Pelagic Resources Fish- 

 ery Management Plan begun in 198S, the imple- 

 mentation ot the 602 Guidelines in 1991, and a 

 12-year generation time. The generation time is a 

 measure ot how quickly a fish is able to replace 

 itself in the stock, on average, imder conditions of 

 no fishing. This recovery plan has not been met. 

 The redefinition ot overfishing guidelines which 

 are in review in 1999 will most likely increase the 

 recovery SPR goal. It is unclear whether a new 

 12-year period will be allowed tor recovery to this 

 level or it a shorter recovery time will be required. 



Spawning 

 potential 

 ratio (%) 



40 - 

 35 

 30 

 25 

 20 

 15 



ABC midpoint 



86- 

 87 



go- 

 al 



91- 

 92 



92- 

 93 



93- 

 94 



94- 

 95 



95- 

 96 



Fishing year 



What Could Have Happened 



The king mackerel group in the Gulf of 

 Mexico could have been recovered already to lev- 

 els approximating maximum sustainable yield 

 (40% SPR) if the midpoint of the acceptable bio- 

 logical catch range provided by the Stock Assess- 

 ment Panel had been caught (Figure 3) (see Pow- 

 ers, 1996). Additionally, if the TAC had been 

 caught without overruns, the stock would currently 

 be defined as not overfished (Figure 3). Of course, 

 these gains in spawning potential ratio would have 

 come at the expense of catches during this time 

 period (Figure 4). It should be noted that the 

 methods used to estimate the acceptable biologi- 

 cal catch ranges, as well as important parameter 

 values such as natural mortality and tuning indi- 

 ces, have changed during this time period. Thus, 

 these scenarios do not accurately reflect upon the 

 management ot the fishery; rather, they provide a 

 demonstration ot what could have happened. 

 These "what it" scenatios were generated by start- 

 ing at the estimated 1986-87 fishing season, pro- 

 jecting the population forward under a modified 

 catch using the same estimated historical selectiv- 

 ity pattern and recruitment values. This was re- 

 peated 400 times incorporating tmcertainty in the 

 inpius. 



It the cinrent methods, parameter values, and 

 risk-neutral TAC's associated with a 30% SPR fish- 



95- 

 97 



97- 

 98 



98- 

 99 



Figure 3 



Spawning potential ratio, a 

 measure of stock health 

 where bigger values are bet- 

 ter, under three scenarios of 

 what could have happened 

 and what actually hap- 

 pened. The three scenarios 

 are: 1) the midpoint of the 

 acceptable biological catch 

 (ABC) range provided by the 

 Stock Assessment Panel had 

 been caught, 2) theTAC cho- 

 sen by the Council had been 

 caught without overruns, 

 and 3) the current methods 

 and parameter values had 

 been used to set a risk-neu- 

 tral TAC, which was then 

 caught without overruns. 



85 



