MARINE MAMMAL COMMISSION — Annual Report for 1992 
it reassess information on the lobster and bottomfish 
fisheries to identify actions that may be needed to 
address interactions between seals and fishing opera- 
tions or fishery resource allocations. 
The Service’s 11 March 1992 letter noted that it 
planned to continue placing observers on bottomfish 
fishing vessels in the Northwestern Hawaiian Islands, 
but that in the absence of data indicating interactions 
with the lobster fishery, it did not plan to place 
observers on those vessels. Regarding the latter 
fishery the Service noted that on 7 February 1992 it 
had adopted the Council’s recommendation to close 
the lobster fishery in the Northwestern Hawaiian 
Islands pending recovery of lobster stocks to optimum 
levels. The Service also noted that it had consulted 
with the Council, and while it recognized that there 
were few data on the importance of lobsters in the 
monk seal diet, it had concluded that lobster fishing 
did not have a significant effect on the availability of 
lobsters to seals. 
In its letter of 17 April 1992 to the Service, the 
Commission questioned the basis for concluding that 
lobster fishing did not significantly affect the availabil- 
ity of lobsters. Regarding the Service’s plans to 
continue placing observers aboard bottomfish fishing 
vessels, the Commission noted it was pleased that the 
program was being continued and asked that the 
results be provided as they became available. As of 
the end of 1992, the Commission had received no 
further information from the Service on these points. 
Prey Consumption and Feeding Areas 
As indicated above, food resources may be limiting 
recovery of monk seals at French Frigate Shoals, and 
prey availability may be affected by overfishing and 
natural factors. Information on monk seal prey 
species and feeding areas, however, is scant. The 
satellite-linked tracking studies noted above were 
recommended, in part, to help address uncertainties 
regarding feeding areas. In addition, the Commis- 
sion’s December 1991 letter recommended that the 
Service review available information on monk seal 
prey species, and based on the results of that review, 
undertake studies of the distribution, abundance, and 
productivity of prey species. 
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The Service shared these concerns, and for the 
1992 field season developed plans to place VHF radio 
tags and time-depth recorders on seals in addition to 
those tagged with satellite-linked transmitters. It also 
planned to resume collections of scat and spew 
samples at all major breeding sites to identify prey 
taken by monk seals, to summarize similar data that 
had been collected in the past but had not been 
thoroughly analyzed and reported, and to investigate 
possible changes in reef fish composition. The 
Recovery Team reviewed and endorsed these plans 
and also recommended that the Service arrange for an 
assessment of whether oceanographic conditions had 
changed in recent years and how such changes might 
have affected productivity in the Northwestern Hawai- 
ian Islands. 
During 1992 the Service undertook work in all of 
these areas. Preliminary results of the depth-of-dive 
studies indicate that most dives were to depths less 
that 75 meters. Further results of this work and other 
investigations were being analyzed by the Service at 
the end of 1992. 
Mobbing Behavior 
As noted above, the death and injury of adult 
female and juvenile seals due to attacks by groups of 
male seals apparently attempting to mate have been 
identified as a major factor inhibiting recovery of seal 
populations at Laysan and Lisianski Islands. Adult 
sex ratios at both sites are skewed strongly towards 
males, and this is thought to be contributing to the 
behavior. To address the problem, the Service has 
developed plans to physically remove some males 
known to have been involved in mobbing incidents 
and/or to chemically treat such animals with a testos- 
terone-suppressing drug to reduce their libido. 
At the time of the Commission’s November 1991 
review, the results of preparatory work done by the 
Service had not been provided, and precise research 
plans were not fully presented. Therefore, while the 
Commission agreed that it was urgent to protect 
remaining female seals at these locations, it felt that it 
was not in a position to offer advice on the best or 
most appropriate approach. In its December 1991 
letter, the Commission urged that the Service carefully 
