MARINE MAMMAL COMMISSION — Annual Report for 1992 
¢ take account of situations where either marine 
mammal survival or productivity has been or may 
be affected by habitat degradation or destruction; 
¢ identify situations and propose criteria for deciding 
when recovery plans and conservation plans for 
endangered, threatened, and depleted species 
should be used to establish removal levels less than 
the level calculated using the general formula for 
estimating potential biological removal levels; 
e revise the definitions of Class A, B, and C stocks 
to make it clear that the burden of proof will 
remain, as presently is the case under the Marine 
Mammal Protection Act, on potential users to 
demonstrate that levels of taking do not disadvan- 
tage the affected marine mammal species and 
stocks; 
¢ describe the program or programs the Service is 
planning or proposing to move toward the zero 
mortality rate goal; 
¢ provide an estimate of the funding and special 
logistic requirements that would be required to 
implement the proposed assessment, monitoring, 
and mortality reduction programs; and 
¢ revise the assessments of possible economic im- 
pacts in the Legislative Environmental Impact 
Statement to use the Marine Mammal Protection 
Act prior to 1988, to which the interim exemption 
will revert without enactment of new legislation, as 
the baseline against which the environmental and 
economic impacts of the various alternatives are 
compared. 
The National Marine Fisheries Service’s 
Proposed Regime 
After considering comments received on its draft 
proposals, the National Marine Fisheries Service 
completed and on 4 December 1992 transmitted to 
Congress its Proposed Regime to Govern Interactions 
Between Marine Mammals and Commercial Fishing 
Operations. The proposed regime retained the Marine 
Mammal Protection Act’s goal of maintaining marine 
mammal stocks at optimum sustainable population 
levels and reaffirmed the goal of reducing marine 
mammal mortalities to insignificant levels approaching 
zero. Incidental taking of endangered, threatened, or 
depleted marine mammals, or from stocks of unknown 
Status, could be authorized, but only in those instances 
when the taking would not prevent or significantly 
delay recovery of the stock to optimum levels. 
Taking of endangered and threatened species would 
have to be authorized under both the Marine Mammal 
Protection Act and the Endangered Species Act. 
The proposal clarifies that, when making determi- 
nations with respect to optimum sustainable population 
levels, the Service will use current carrying capacity 
as adjusted to account for human-caused habitat 
degradation and destruction. Where such degradation 
of the marine environment has occurred, but is 
correctable, the estimated carrying capacity levels of 
affected marine mammal stocks would be increased 
accordingly. 
As with the earlier proposal, a potential biological 
removal (PBR) level would be set for each marine 
mammal stock from which animals are taken inciden- 
tal to commercial fishing. The potential biological 
removal level would be the maximum number of 
animals that could be removed from a stock by all 
sources. When data are sufficient to demonstrate that 
a stock is within its optimum range, that determination 
would form the basis for setting the potential removal 
level. The potential biological removal level for these 
stocks would be determined by multiplying the best 
estimate of minimum stock abundance by the per 
capita rate of increase in the population at its maxi- 
mum net productivity level (Rup). That is, the 
calculation would not include a 10 percent safety 
factor as had been included in the Service’s initial 
draft proposal. 
The Service retained the use of recovery factors for 
calculating potential biological removal levels for 
depleted stocks and stocks for which status determina- 
tions currently cannot be made. Application of the 
recovery factors, however, would be based on the 
legal status of a population, not necessarily its status 
relative to carrying capacity. The recovery factor for 
populations listed as endangered would be 0.1. For 
stocks that are threatened, depleted, or of unknown 
