1998 



OUR LIVING OCEANS 



Mortality 

 rate 



Figure 1 



Average fishing mortality rate (F) for fish ages 4 and older 

 in the Gulf of Mexico group of the king mackerel fishery. 

 The red line denotes the best estimate, and the shading 

 represents approximate 80% confidence intervals. 



81- 

 82 



82- 

 83 



84- 

 85 



Stock biomass 

 (X 1,000,000 



pounds) 



50 - 



45 



40 



36 



30 



25 



20 

 15 - 

 10 - 

 5 - 

 - 



Figure 2 



Stock biomass (x 1,000,000 pounds) for fish ages 4 and 

 older in the Gulf of Mexico group of the king mackerel 

 fishery. The red line denotes the best estimate, and the 

 shading represents approximate 80% confidence inter- 

 vals. 



81- 

 82 



83- 

 84 



are used in an attempt to limit the amount of catch 

 due to the recreational sector, thus the fishery is 

 no longer closed during a fishing season, although 

 it has been in the past. These regul.uiuns have not 

 been successhil, resulting in annual overruns ol 

 the recreational allocation of 41% on average 

 (1986-96). 



ISSUES OF CONCERN 



Stock Definition 



As more intorniation becomes available, par- 

 ticularly a recent otolith-shape analysis, it is be- 

 coming apparent that the king mackerel caught 

 in the mixing zone in the winter are more likely 

 to be fi-om the Atlantic group than troni the Gulf 

 of Mexico group. The repercussions of changing 

 the group designation for these fish are not trivial. 

 Preliminary calculations suggest that classifying 

 these fish as of the Atlantic group increases the 

 total acceptable catch and SPR in the Atlantic and 

 decreases the total acceptable catch and ,SPR in 

 the Gulf of Mexico. TheseTAC changes are slightly 

 greater than ihe amount ot fish caught within the 

 mixing zone, and thus it could potentially be a 

 net benefit to the fishermen in the Atlantic and a 

 net loss to fishermen in the Gulf of Mexico. 



AdditionalK', Mexictis king mackerel catches 

 are currently not included in stock assessments. 

 The level of catch is not well known but thought 

 to be large, especially relative to the catches from 

 the western Gulf of Mexico. It has been hypoth- 

 esized that there are two stocks of king mackerel 

 within the Gulf of Mexico, eastern and western, 

 which mix in the summer in the northern Gulf of 

 Mexico. If this hypothesis is correct, the Mexican 

 catches are most likely the largest source of mor- 

 talit\' for the western Ciulf stock, and cooperative 

 management between the United States and 

 Mexico will have to be undertaken to successfully 

 evaluate and regulate this fishery. 



Allocation 



The subdivision of the TAG is a contentious 

 issue due to its zero-stun nature; for one sector to 

 increase its portion, at least one other must de- 

 crease. This is especially important during the re- 

 covery phase when catches should be reduced rela- 

 tive to the status quo. Once the fishery has recov- 

 ered, the TAC" should increase and reduce this 

 source of conflict. 



Of special nine in the context of allocation is 

 the fact that reductions in theTAG impact mainly 

 the coiTimercial fishery due to its stringent moni- 

 torins; and the ability to close the fishins; season, 



8 4 



