MARINE MAMMAL COMMISSION — Annual Report for 1992 
during the subsequent year. The Service was also 
required to submit a comprehensive report to Con- 
gress by 1 April 1992 setting forth the results of the 
efforts to reduce dolphin mortality and recommenda- 
tions for actions that should be taken to reduce 
incidental mortality further. 
The Service convened the third and last of the 
annual reviews on 13-14 November 1991. In addition 
to representatives of conservation groups, U.S. tuna 
fishermen, U.S. tuna canners, the Marine Mammal 
Commission, and other Federal agencies, participants 
included representatives of the Inter-American Tropi- 
cal Tuna Commission and several tuna fishing nations. 
Data and trends for the 1990 and 1991 fishing seasons 
and research underway to develop tuna fishing meth- 
ods that do not involve setting on dolphins were 
discussed. 
In July 1992 the National Marine Fisheries Service 
published the report of the third annual review meet- 
ing. As required, the report discusses efforts under- 
taken by the Service and others to reduce incidental 
dolphin mortality. The report identifies four goals 
that, if achieved, would significantly reduce or 
eliminate incidental dolphin mortality and recommends 
actions towards achieving those goals. 
The first goal is to develop and evaluate methods 
of purse seine fishing for tuna that do not involve 
chasing or encircling dolphins. Recommended actions 
for achieving this goal include (1) investigating the 
potential utility of fish aggregating devices as a way 
of capturing yellowfin tuna not associated with dol- 
phins; (2) investigating the potential utility of optical 
scanners as an alternative method of locating schools 
of tuna; and (3) examining the association between 
tuna and dolphins to determine if there are times when 
tuna can be caught without encircling dolphins. 
The second goal is to develop fishing methods that 
involve chasing but not encircling dolphins. The 
report recommended that acoustic, visual, and chemi- 
cal stimuli be explored as possible ways to separate 
associated tuna and dolphins before encirclement. 
The third goal is to improve existing purse seine 
fishing techniques to decrease incidental dolphin 
mortality to levels approaching zero. Among the 
106 
actions recommended to pursue this goal are (1) 
investigating the use of acoustic doppler current 
profilers to detect subsurface currents that may cause 
purse seine nets to collapse; (2) evaluating different 
net materials, cable materials, hang-ratios, and cork 
lines as possible ways to reduce the incidence of roll- 
ups and net collapse; (3) assessing the utility of jet 
skis to free entangled dolphins from purse seine nets; 
(4) developing an international program to educate 
skippers about new developments in dolphin saving 
fishing techniques; (5) establishing an international 
skipper performance program to identify and remove 
sub-standard operators; and (6) establishing an inter- 
national dolphin quota that would be reduced and 
eliminated over a fixed period of time. 
The final goal identified in the Service’s report is 
to develop alternative methods for catching tuna that 
do not involve the use of purse seine nets. Among 
the possible alternatives methods noted by the Service 
are the use of pair trawls and longline fishing. 
Status of Dolphin Stocks 
As discussed in the previous annual report, envi- 
ronmental groups petitioned the National Marine 
Fisheries Service in 1991 to have the eastern spinner 
dolphin (Stenella longirostris orientalis) and the 
northern offshore stock of spotted dolphins (Stenella 
attenuata) designated as depleted under the Marine 
Mammal Protection Act and listed as threatened under 
the Endangered Species Act. The petitioners asserted 
that these stocks had been reduced substantially since 
the 1950s by the eastern tropical Pacific tuna fishery. 
Under the Marine Mammal Protection Act, any 
population that is below its maximum net productivity 
level, the lower bound of the optimum sustainable 
population range, is considered to be depleted. The 
National Marine Fisheries Service has determined that 
maximum net productivity in small cetaceans, such as 
these dolphin species, occurs at about 60 percent of 
carrying capacity. A threatened species is one “which 
is likely to become endangered in the foreseeable 
future throughout all or a significant portion of its 
range.” 
On 17 June 1992 the National Marine Fisheries 
Service published a proposed rule to designate the 
